JOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2000
OWSKI, ROMAN KOT
ABSTRACT Oligonucleotide primers designed to flank a 635 bp fragment of the gene encoding glyceraldehyde-3-phosphate dehydrogenase (gpd) from Araanita muscaria were used to amplify the corresponding gpd fragment from Amanita phalloides. The A. phalloides PCR product was cloned, sequenced and found to be 70 - 77% similar to the known basidiomycetes gpd genes within the exon part and 25 - 52% within the intron part. Based on these data, species-specific amplification was achieved using a pair of oligonucleotide primers complementary to the A. phalloides gpd intron sequences. These primers allowed the amplification of the corresponding gpd fragment from the A. phalloides but not from various other basidiomycetes, ascomycetes and human matrices. PCR amplification of the A. phalloides DNA gave the predicted PCR product of 284 bp. The created PCR system is an efficient tool for the specific, rapid and sensitive detection of A. phalloides mycelium and spores. [source]

EFFECT OF HIGH HYDROSTATIC PRESSURE ON SPORES OF GEOBACILLUS STEAROTHERMOPHILUS SUSPENDED IN SOYMILK

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 5 2007
YOKIUSHIRDHILGILMARA ESTRADA-GIRÓN
ABSTRACT The inactivation of Geobacillus stearothermophilus spores (ATCC 7953) inoculated in soymilk was investigated using high hydrostatic pressure (550, 585 and 620 MPa) in combination with temperature (70, 80 and 90C) for selected times (2 s to 15 min). Inactivation of spores occurred at all selected treatments. Less than 10 CFU/mL of G. stearothermophilus were observed after 7 min of treatment at 620 MPa and 90C. An increase in the inactivation rate constant, at the highest pressure, was observed, resulting in a decrease in D values at all temperatures. D values were calculated as 10.6, 6.2 and 3.5 min for 70, 80 and 90C, respectively after pressurization at 620 MPa. zp values decreased as temperature increased with values ranging from 142 to 238 MPa. The activation energy required for inactivation of G. stearothermophilus spores in soymilk, at the selected treatments, was in the range of 37.9,57.4 kJ/mol. [source]

GROWTH INHIBITION OF CLOSTRIDIUM PERFRINGENS VEGETATIVE CELLS AND SPORES USING CHICKEN IMMUNOGLOBULIN Y

JOURNAL OF FOOD SAFETY, Issue 4 2009
MIN S. SONG
ABSTRACT Egg yolk antibody (IgY) was isolated by the water dilution method from the egg yolk of chickens immunized with Clostridium perfringens vegetative cells and spores. Specific binding activity of IgY against C. perfringens vegetative cells and spores remained relatively high during the immunization period (up to 9 weeks). The titer of specific IgY against C. perfringens spores was 1.4-fold less than that of specific IgY against C. perfringens vegetable cells. The specific IgY powder (10 µg/mL) was found to inhibit the growth of C. perfringens vegetative cells or C. perfringens spores in a liquid medium. The difference of C. perfringens vegetative cell growth between the treatment and control groups was 8.9 × 106 colony forming units (cfu)/mL at 8 h of incubation and 9.95 × 107 cfu/mL at 24 h of incubation. Significant cfu reductions in C. perfringens spores were also observed with specific IgY powder at 24 h of incubation. PRACTICAL APPLICATIONS IgY antibody exerts an antimicrobial activity against pathogens by binding, immobilizing and consequently reducing or inhibiting the growth, replication or colony forming ability of pathogenic bacteria; thus, it is proved to be a viable alternative for antibiotics and preservatives. In this study, IgY against Clostridium perfringens can be used to replace chemical preservatives in food industries. Because IgY functions well at low temperature, it can be used to inhibit the growth of Clostridia which germinate in refrigerated storage conditions, thus preventing foodborne enterotoxicity caused by such bacteria. In practical applications, natural antimicrobial IgY antibody can be applied to meat products for the improvement of food safety. [source]

INACTIVATION OF BACTERIAL SPORES BY COMBINED ACTION OF HYDROSTATIC PRESSURE AND BACTERIOCINS IN ROAST BEEF

JOURNAL OF FOOD SAFETY, Issue 4 2003
N. KALCHAYANAND
ABSTRACT Foodborne bacterial spores are normally resistant to high hydrostatic pressure; however, at moderate pressure, they can be induced to germinate and outgrow. At this stage, they can be killed by bacteriocin-based biopreservatives (BP-containing pediocin and nisin at 3:7 ratio; BPX, BP + 100 ,g/mL lysozyme; BPY, BPX+ 500 ,g/mL Na-EDTA). Based on this principle, spores of the meat spoilage organism, Clostridium laramie (1,2 × 102 spores/bag) alone or a mixture of four clostridial spores (5 × 103 spores/bag), Clostridium sporogenes, Clostridium perfringens, Clostridium tertium, and Clostridium laramie, were inoculated in roast beef in the presence of 5000 AU/g of bacteriocin-based biopreservatives. The roast beef samples were subjected to hydrostatic pressure (HP) at 345 MPa for 5 min at 60C and stored at 4 or 12C for 84 days or at 25C for 7 days. The HP treatment of roast beef samples inoculated with a mixture of clostridial spores could be stored for 42 days at 4C. The HP in combination with either BPX or BPY extended the shelf-life of roast beef up to 7 days at 25C. The combined treatment of HP and BP controlled the growth of C. laramie spores and extended the shelf-life of roast beef for 84 days when stored at 4C. [source]

Conidial dispersal of Gremmeniella abietina: climatic and microclimatic factors

FOREST PATHOLOGY, Issue 6 2003
R.-L. Petäistö
Summary The conidia dispersal started in Suonenjoki, in central Finland, in 1997,99 by the end of May or beginning of June, and continued occasionally at least to the middle of September. The temperature sum, day degrees (d.d., threshold temperature = 5°C) was between 100 and 165 d.d. at the beginning of dispersal. In years 1997,99, 80, 94 and 82% of the dispersal had occurred by the end of July , beginning of August when the temperature sum reached 800 d.d. All the spore data are coming from the spore traps. Cumulative number of conidia increased linearily with logarithm of temperature sum. A binary logistic regression model with temperature sum and rainfall as explanatory variables predicted accurately the date of the first spores in the spring: the prediction error was at most 3 days. The model classified 69% of all the days in the analysis correctly to the spore-free days and correspondingly 74% to the days of at least one spore caught. A regression model for the number of spores per day explains 21, 5 and 51% of the within-season variation in 1997,99 (24, 37 and 62% on a logarithmic scale). The explanatory weather variables in the model were d.d., rain and year. The very low explanatory coefficient of determination in 1998 results from one exceptionally high number of conidia. The between-differences in the total number of spores were large and could not be explained by the measured weather variables. In the regression model, these differences were taken into account by adding a constant for each year in the model. Rain increased conidia dispersal significantly but conidia were found also in consecutive rainless days. Résumé La dissémination des conidies a démarré fin mai-début juin à Suonenjoki, dans le centre de la Finlande, pour les années 1997,1999, et s'est poursuivie occasionnellement au moins jusqu'à mi-septembre. La somme de température (seuil de 5°C) est de 100-165 degrés-jours au début de la période de dissémination. Pour les années 1997, 1998 et 1999, 80%, 94% et 82% de la dissémination s'était produite fin juillet-début août, quand la somme de température avait atteint 800 degrés-jours. Le nombre cumulé de conidies augmente linéairement avec le logarithme de la somme de températures. Un modèle de régression logistique binaire avec la somme de températures et les précipitations comme variables explicatives prédit de façon précise la date des premières émissions au printemps: l'erreur de prédiction est au plus de trois jours. Le modèle assigne correctement 69% de l'ensemble des jours analysés à des jours sans spores et 74% des jours avec au moins une spore piégée. Un modèle de régression pour le nombre de spores par jour explique 21%, 5 % et 51 % de la variation intra-saison en 1997, 1998 et 1999 (24, 37 et 62% pour une échelle logarithmique). Les variables climatiques explicatives du modèle sont les degrés-jours, les précipitations et l'année. Le très faible coefficient de détermination de 1998 provient d'un seul comptage exceptionnellement élevé de conidies. Les différences entre années pour le nombre total de spores sont importantes et ne peuvent s'expliquer par les variables climatiques mesurées. Dans le modèle de régression, ces différences sont prises en compte en ajoutant une constante pour chaque année. Les pluies augmentent significativement la dissémination des conidies mais des conidies ont été observées également dans des périodes de plusieurs jours consécutifs sans pluie. Zusammenfassung Die Ausbreitung der Konidien von Gremmeniella abietina begann in Suonenjoki, Zentralfinnland, in den Jahren 1997 , 1999 Ende Mai oder Anfang Juni und dauerte gelegentlich bis mindestens Mitte September an. Die Temperatursumme (Schwellenwert 5 °C) lag zu Beginn der Ausbreitung zwischen 100 und 165. Ende Juli bis Anfang August, wenn die Temperatursumme 800 erreicht hatte, war in den Jahren 1997, 1998 und 1999 jeweils 80%, 94% bzw. 82% der mit einer Sporenfalle erfassten Sporulation abgeschlossen. Die kumulierte Anzahl der Sporen nahm linear mit dem Logarithmus der Temperatursumme zu. Ein binäres logistisches Regressionsmodell mit der Temperatursumme und dem Niederschlag als erklärenden Variablen sagte das Datum der ersten Sporenfreisetzung im Frühjahr zutreffend voraus, der Vorhersagefehler lag hier bei höchstens drei Tagen. Das Modell klassifizierte 69% der Tage ohne Sporulation richtig und analog 74% der Tage mit zumindest einer erfassten Spore. Ein Regressionsmodell für die Anzahl Sporen pro Tag erklärte 21%, 5% und 51% der Variation innerhalb einer Saison für die Jahre 1997, 1998 und 1999 (24, 37 und 62% auf der Skala des natürlichen Logarithmus). Die erklärenden Wettervariablen in dem Modell waren Temperatursumme, Niederschlag und Jahr. Der sehr kleine Wert des erklärenden Koeffizienten für 1998 ist die Folge eines einzelnen Ereignisses mit ungewöhnlich hoher Sporenzahl. Innerhalb der Anzahl der Sporen waren die Unterschiede gross und konnten nicht mit den gemessenen Wetterdaten erklärt werden. Im Regressionsmodell wurden diese Unterschiede berücksichtigt, indem für jedes Jahr eine Konstante hinzugefügt wurde. Regen erhöhte die Konidienausbreitung signifikant, aber Sporen waren auch an den nachfolgenden regenfreien Tagen nachweisbar. [source]

Light and Electron Microscopy of the Spore of Myxobolus heckelii n. sp. (Myxozoa), Parasite from the Brazilian Fish Centromochlus heckelii (Teleostei, Auchenipteridae)

THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2009
CARLOS AZEVEDO
ABSTRACT. A myxosporean parasitizing the gill filaments of the freshwater teleost fish Centromochlus heckelii collected in the Tocantins River (Lower Amazonian Region, Brazil) is described using light and electron microscopy. This parasite produces spherical to ellipsoidal cyst-like plasmodia up to 250 ,m in diameter, with a thick wall strengthened by several stratified juxtaposed crossed collagen layers, whose thickness varies according to the number of the layers. Several compressed fibroblasts are observed among the collagen fibrils. Deposits of spherical dense material are scattered at the internal periphery of the cysts. Plasmodia and different developmental stages, including immature and mature spores, filled the central region of the cysts. The spore body is ellipsoidal in valvar view and biconvex in sutural view. It is formed by two equal-sized and symmetric valves measuring 12.7 ,m long (12.2,13.1) (n=50), 6.6 ,m wide (6.3,6.9) (n=25), and 4.0 ,m (3.7,4.4) (n=20) thick. A thin layer formed by fine and anastomosed microfibrils is observed at the spore surface. Two equal, elongated pyriform polar capsules measure 2.9 ,m (2.7,3.3) × 1.7 ,m (1.4,2.0) (n=25), each containing four or five oblique polar filament coils. The binucleated sporoplasm contains numerous spherical sporoplasmosomes, glycogen particles, and a large vacuole with fine granular matrix. Based on the morphological and ultrastructural differences and specificity of the host, we describe this isolate as a new myxosporidian, Myxobolus heckelii n. sp. (Myxozoa, Myxosporea). [source]

Analysis of the germination of spores of Bacillus subtilis with temperature sensitive spo mutations in the spoVA operon

FEMS MICROBIOLOGY LETTERS, Issue 1 2004
Venkata Ramana Vepachedu
Abstract A Bacillus subtilis strain with a base substitution in the ribosome-binding site of spoVAC was temperature sensitive (ts) in sporulation and spores prepared at the permissive temperature were ts in l -alanine-triggered germination, but not in germination with Ca2+ -dipicolinic acid (DPA) or dodecylamine. Spores of a ts spo mutant with a missense mutation in the spoVAC coding region were not ts for germination with l -alanine, dodecylamine or Ca2+ -DPA. These findings are discussed in light of the proposal that SpoVA proteins are involved not only in DPA uptake during sporulation, but also in DPA release during nutrient-mediated spore germination. [source]

Relationship between stump treatment coverage using the biological control product PG Suspension, and control of Heterobasidion annosum on Corsican pine, Pinus nigra ssp. laricio

FOREST PATHOLOGY, Issue 1 2008
K. V. Tubby
Summary The relationship between the proportion of the stump surface covered by the biological stump treatment agent PG Suspension, containing Phlebiopsis gigantea and its efficacy against the pathogen Heterobasidion annosum sensu stricto was studied during a first thinning of Corsican pine (Pinus nigra ssp. laricio) in Thetford Forest, UK. PG Suspension was manually applied to 100%, 75%, 50% or 0% of the surface of 150 stumps. Spores of H. annosum were inoculated onto 75 of the stumps, and the remaining stumps exposed to natural airborne spore deposition. The relationship between coverage and efficacy was found to be quantitative. Covering all the stump surface with PG Suspension completely excluded the pathogen, whereas stumps not treated with PG Suspension (the 0% treatment) became infected with H. annosum. Partial (75%) PG Suspension coverage resulted in the pathogen colonizing 40% of stumps following artificial inoculation with H. annosum, and just 7% of stumps exposed to ambient H. annosum spore infection. Decreasing levels of coverage allowed increasing areas of the stump surface to be colonized by H. annosum. Some small gaps in coverage were closed by lateral growth of P. gigantea, but it is recommended that operators aim for full stump coverage to give complete protection against H. annosum. [source]

Colonization of beech leaves by two endophytic fungi in northern Japan

FOREST PATHOLOGY, Issue 2 2000
N. Sahashi
Summary Leaves of Japanese beech (Fagus crenata) were collected monthly during the vegetation period at five sites in the Tohoku district in Japan to isolate endophytic fungi. Leaves were also collected only once at two additional sites. Two endophytic fungi were dominant, a Discula species and a sterile mycelium. This result strongly suggests that these two fungi are generally associated with leaves of the Japanese beech at different sites. At most sites the isolation frequency of Discula sp. was greatest in June and gradually decreased from July to October whereas the isolation frequency of the sterile mycelium increased during the vegetation period and remained at a high isolation frequency in October. Spores of Discula sp. were released for a very short time in late May, just after the disappearance of the snow cover on the forest floor. These spores may be important for the infection of newly sprouting leaves. [source]

Occurrence of Arbuscular Mycorrhizas and Dark Septate Endophytes in Hydrophytes from Lakes and Streams in Southwest China

INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 1 2006
Wang Kai
Abstract In this study, the colonization of arbuscular mycorrhizas (AM) and dark septate endophytes (DSE) in 140 specimens of 32 hydrophytes collected from four lakes and four streams in southwest China were investigated. The arbuscular mycorrhizal fungi (AMF) and DSE colonization in these hydrophytes were rare. Typical AM structures were observed in one of the 25 hydrophytic species collected in lakes and six of the 17 species collected in streams. Spores of 10 identified AMF species and an unidentified Acaulospora sp. were isolated from the sediments. The identified AMF came from the four genera, Acaulospora, Gigaspora, Glomus and Scutellospora . Glomus and G. mosseae were the dominant genus and species respectively in these aquatic environments. The presence of DSE in hydrophytes was recorded for the first time. DSE occurred in one of the 25 hydrophyte species collected in lakes and three of the 17 species collected in streams. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

The formation of spores in biofilms of Anoxybacillus flavithermus

JOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2009
S.A. Burgess
Abstract Aims:, To examine the rate and the extent of spore formation in Anoxybacillus flavithermus biofilms and to test the effect of one key variable , temperature , on spore formation. Methods and Results:, A continuous flow laboratory reactor was used to grow biofilms of the typical dairy thermophile A. flavithermus (strain CM) in skim milk. The reactor was inoculated with either a washed culture or a spore suspension of A. flavithermus CM, and was run over an 8·5 h period at three different temperatures of 48, 55 and 60°C. Change in impedance was used to determine the cell numbers in the milk and on the surface of the stainless steel reactor tubes. The biofilm developed at all three temperatures within 6,8 h. Spores formed at 55 and 60°C and amounted to approx. 10,50% of the biofilm. No spores formed at 48°C. Conclusions:, The results suggest that both biofilm formation and spore formation of A. flavithermus can occur very rapidly and simultaneously. In addition, temperature variation has a considerable effect on the formation of spores. Significance and Impact of the Study:, This information will provide direction for developing improved ways in which to manipulate conditions in milk powder manufacturing plants to control biofilms and spores of A. flavithermus. [source]

Effects of modification of membrane lipid composition on Bacillus subtilis sporulation and spore properties

JOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2009
K.K. Griffiths
Abstract Aims:, To determine effects of inner membrane lipid composition on Bacillus subtilis sporulation and spore properties. Methods and Results:, The absence of genes encoding lipid biosynthetic enzymes had no effect on B. subtilis sporulation, although the expected lipids were absent from spores' inner membrane. The rate of spore germination with nutrients was decreased c. 50% with mutants that lacked the major cardiolipin (CL) synthase and another enzyme for synthesis of a major phospholipid. Spores lacking the minor CL synthase or an enzyme essential for glycolipid synthesis exhibited 50,150% increases in rates of dodecylamine germination, while spores lacking enzymes for phosphatidylethanolamine (PE), phosphatidylserine (PS) and lysylphosphatidylglycerol (l-PG) synthesis exhibited a 30,50% decrease. Spore sensitivity to H2O2 and tert-butylhydroperoxide was increased 30,60% in the absence of the major CL synthase, but these spores' sensitivity to NaOCl or OxoneÔ was unaffected. Spores of lipid synthesis mutants were less resistant to wet heat, with spores lacking enzymes for PE, PS or l-PG synthesis exhibiting a two to threefold decrease and spores of other strains exhibiting a four to 10-fold decrease. The decrease in spore wet heat resistance correlated with an increase in core water content. Conclusions:, Changing the lipid composition of the B. subtilis inner membrane did not affect sporulation, although modest effects on spore germination and wet heat and oxidizing agent sensitivity were observed, especially when multiple lipids were absent. The increases in rates of dodecylamine germination were likely due to increased ability of this compound to interact with the spore's inner membrane in the absence of some CL and glycolipids. The effects on spore wet heat sensitivity are likely indirect, because they were correlated with changes in core water content. Significance and Impact of the Study:, The results of this study provide insight into roles of inner membrane lipids in spore properties. [source]

Influence of relative gas humidity on the inactivation efficiency of a low temperature gas plasma

JOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2008
P. Muranyi
Abstract Aims:, To investigate the effect of relative gas humidity on the inactivation efficiency of a cascaded dielectric barrier discharge (CDBD) in air against Aspergillus niger and Bacillus subtilis spores on PET foils. Methods and Results:, The inactivation kinetics as a function of treatment time were determined using synthetic air with different relative humidity as the process gas. Spores of A. niger and B. subtilis respectively were evenly sprayed on PET foils for use as bioindicators. In the case of A. niger, increased spore mortality was found at a high relative gas humidity of 70% (approx. 2 log10). This effect was more evident at prolonged treatment times. In contrast, B. subtilis showed slightly poorer inactivation at high gas humidity. Conclusions:, Water molecules in the process gas significantly affect the inactivation efficiency of CDBD in air. Significance and Impact of the Study:, Modifying simple process parameters such as the relative gas humidity can be used to optimize plasma treatment to improve inactivation of resistant micro-organisms such as conidiospores of A. niger. [source]

Difference between the spore sizes of Bacillus anthracis and other Bacillus species

JOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2007
M. Carrera
Abstract Aims:, To determine the size distribution of the spores of Bacillus anthracis, and compare its size with other Bacillus species grown and sporulated under similar conditions. Methods and Results:, Spores from several Bacillus species, including seven strains of B. anthracis and six close neighbours, were prepared and studied using identical media, protocols and instruments. Here, we report the spore length and diameter distributions, as determined by transmission electron microscopy (TEM). We calculated the aspect ratio and volume of each spore. All the studied strains of B. anthracis had similar diameter (mean range between 0·81 ± 0·08 ,m and 0·86 ± 0·08 ,m). The mean lengths of the spores from different B. anthracis strains fell into two significantly different groups: one with mean spore lengths 1·26 ± 0·13 ,m or shorter, and another group of strains with mean spore lengths between 1·49 and 1·67 ,m. The strains of B. anthracis that were significantly shorter also sporulated with higher yield at relatively lower temperature. The grouping of B. anthracis strains by size and sporulation temperature did not correlate with their respective virulence. Conclusions:, The spores of Bacillus subtilis and Bacillus atrophaeus (previously named Bacillus globigii), two commonly used simulants of B. anthracis, were considerably smaller in length, diameter and volume than all the B. anthracis spores studied. Although rarely used as simulants, the spores of Bacillus cereus and Bacillus thuringiensis had dimensions similar to those of B. anthracis. Significance and Impact of the Study:, Spores of nonvirulent Bacillus species are often used as simulants in the development and testing of countermeasures for biodefence against B. anthracis. The data presented here should help in the selection of simulants that better resemble the properties of B. anthracis, and thus, more accurately represent the performance of collectors, detectors and other countermeasures against this threat agent. [source]

Tolerance to challenges miming gastrointestinal transit by spores and vegetative cells of Bacillus clausii

JOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2006
G. Cenci
Abstract Aims:, To study Bacillus clausii from a pharmaceutical product (Enterogermina O/C, N/R, SIN, T) and reference strains (B. clausii and Bacillus subtilis) for eco-physiological aspects regarding the gut environment. Methods and Results:, Spores and vegetative cells were challenged in vitro miming the injury of gastrointestinal transit: pH variations, exposure to conjugated and free bile salts, microaerophilic and anaerobic growth. No relevant differences were found studying the growth at pH 8 and 10, whereas at pH 7 the yields obtained for O/C and SIN were higher than those obtained for N/R and T strains. The spores were able to germinate and grow in the presence of conjugated bile salts (up to 1%, w/v) or free bile salts (0·2%) and also exhibited tolerance for the combined acid-bile challenge. As evidenced by lag-time, growth rate and cell yield the tolerance of Enterogermina isolates for conjugated salts was comparable with that of B. clausii type strain (DSM 8716T), and resulted higher than that observed for B. subtilis (ATCC 6051T). All the considered B. clausii strains demonstrated microaerophilic growth, but only some grew anaerobically in a nitrate medium. Conclusions:, The ability of B. clausii spores to germinate after an acid challenge and grow as vegetative cells both in the presence of bile and under limited oxygen availability is consistent with the beneficial health effects evidenced for spore-forming probiotics in recent clinical studies. Significance and Impact of the Study:, The experimental evidence from this study emphasizes some functional properties of B. clausii strains regarding their use as probiotics. [source]

Inactivation of Bacillus spores in reconstituted skim milk by combined high pressure and heat treatment

JOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2006
K.J. Scurrah
Abstract Aims:, To determine the resistance of a variety of Bacillus species spores to a combined high pressure and heat treatment; and to determine the affect of varying sporulation and treatment conditions on the level of inactivation achieved. Methods and Results:, Spores from eight Bacillus species (40 isolates) were high pressure,heat treated at 600 MPa, 1 min, initial temperature 72°C. The level of inactivation was broad (no inactivation to 6 log10 spores ml,1 reduction) and it varied within species. Different sporulation agar, high pressure equipment and pressure-transmitting fluid significantly affected the response of some isolates. Varying the initial treatment temperature (75, 85 or 95°C) shifted the relative order of isolate high pressure,heat resistance. Conclusions:, The response of Bacillus spores to combined high pressure,heat treatment is variable and can be attributed to both intrinsic and extrinsic factors. The combined process resulted in a high level of spore inactivation for several Bacillus species and is a potential alternative treatment to traditional heat-only processes. Significance and Impact of the Study:, Sporulation conditions, processing conditions and treatment temperature all affect the response of Bacillus spores to the combined treatment of high pressure and heat. High levels of spore inactivation can be achieved but the response is variable both within and between species. [source]

Treatment with oxidizing agents damages the inner membrane of spores of Bacillus subtilis and sensitizes spores to subsequent stress

JOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2004
D.E. Cortezzo
Abstract Aims:, To determine if treatment of Bacillus subtilis spores with a variety of oxidizing agents causes damage to the spore's inner membrane. Methods and Results:, Spores of B. subtilis were killed 80,99% with wet heat or a variety of oxidizing agents, including betadine, chlorine dioxide, cumene hydroperoxide, hydrogen peroxide, OxoneTM, ozone, sodium hypochlorite and t-butylhydroperoxide, and the agents neutralized and/or removed. Survivors of spores pretreated with oxidizing agents exhibited increased sensitivity to killing by a normally minimal lethal heat treatment, while spores pretreated with wet heat did not. In addition, spores treated with wet heat or the oxidizing agents, except sodium hypochlorite, were more sensitive to high NaCl in plating media than were untreated spores. The core region of spores treated with at least two oxidizing agents was also penetrated much more readily by methylamine than was the core of untreated spores, and spores treated with oxidizing agents but not wet heat germinated faster with dodecylamine than did untreated spores. Spores of strains with very different levels of unsaturated fatty acids in their inner membrane exhibited essentially identical resistance to oxidizing agents. Conclusions:, Treatment of spores with oxidizing agents has been suggested to cause damage to the spore's inner membrane, a membrane whose integrity is essential for spore viability. The sensitization of spores to killing by heat and to high salt after pretreatment with oxidizing agents is consistent with and supports this suggestion. Presumably mild pretreatment with oxidizing agents causes some damage to the spore's inner membrane. While this damage may not be lethal under normal conditions, the damaged inner membrane may be less able to maintain its integrity, when dormant spores are exposed to high temperature or when germinated spores are faced with osmotic stress. Triggering of spore germination by dodecylamine likely involves action by this agent on the spore's inner membrane allowing release of the spore core's depot of dipicolinic acid. Presumably dodecylamine more readily alters the permeability of a damaged inner membrane and thus more readily triggers germination of spores pretreated with oxidizing agents. Damage to the inner spore membrane by oxidizing agents is also consistent with the more rapid penetration of methylamine into the core of treated spores, as the inner membrane is likely the crucial permeability barrier to methylamine entry into the spore core. As spores of strains with very different levels of unsaturated fatty acids in their inner membrane exhibited essentially identical resistance to oxidizing agents, it is not through oxidation of unsaturated fatty acids that oxidizing agents kill and/or damage spores. Perhaps these agents work by causing oxidative damage to key proteins in the spore's inner membrane. Significance and Impact of the Study:, The more rapid heat killing and germination with dodecylamine, the greater permeability of the spore core and the osmotic stress sensitivity in outgrowth of spores pretreated with oxidizing agents is consistent with such agents causing damage to the spore's inner membrane, even if this damage is not lethal under normal conditions. It may be possible to take advantage of this phenomenon to devise improved, less costly regimens for spore inactivation. [source]

Survival of spores of Rhizopus stolonifer, Aspergillus niger, Botrytis cinerea and Alternaria alternata after exposure to ethanol solutions at various temperatures

JOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2004
F. Mlikota Gabler
Abstract Aims:, To quantify and model the toxicity of brief exposures of spores of Rhizopus stolonifer, Aspergillus niger, Botrytis cinerea and Alternaria alternata to heated, aqueous ethanol solutions. These fungi are common postharvest decay pathogens of fresh grapes and other produce. Sanitation of produce reduces postharvest losses caused by these and other pathogens. Methods and Results:, Spores of the fungi were exposed to solutions containing up to 30% (v/v) ethanol at 25,50°C for 30 s, then their survival was determined by germination on semisolid media. Logistical, second-order surface-response models were prepared for each fungus. Subinhibitory ethanol concentrations at ambient temperatures became inhibitory when heated at temperatures much lower than those that cause thermal destruction of the spores by water alone. At 40°C, the estimated ethanol concentrations that inhibited the germination of 50% (LD50) of the spores of B. cinerea, A. alternata, A. niger and R. stolonifer were 9·7, 13·5, 19·6 and 20·6%, respectively. Conclusions:, Ethanol and heat combinations were synergistic. Control of spores of these fungi could be accomplished with much lower temperatures and ethanol concentrations when combined compared with either used alone. Botrytis cinerea and A. alternata were less resistant to the combination than A. niger or R. stolonifer. [source]

Myxobolus erythrophthalmi sp. n. and Myxobolus shaharomae sp. n. (Myxozoa: Myxobolidae) from the internal organs of rudd, Scardinius erythrophthalmus (L.), and bleak, Alburnus alburnus (L.)

JOURNAL OF FISH DISEASES, Issue 3 2009
K Molnár
Abstract During a survey of myxosporean parasites of cyprinid fish in Hungary, infections caused by unknown Myxobolus spp. were found in the internal organs of rudd, Scardinius erythrophthalmus, and bleak, Alburnus alburnus. Small plasmodia developed in blood vessels of the kidney, liver, testes and intestinal wall. The parasites were studied on the basis of spore morphology and by histological and molecular methods. In most cases, plasmodia were surrounded by host tissue without a host reaction; however, in advanced cases, a connective tissue capsule was seen around plasmodia. Spores collected from the two fish species differed from each other and from the known Myxobolus spp. both in their morphology and 18S rDNA sequences. The two species, described as M. erythrophthalmi sp. n. from rudd and M. shaharomae sp. n. from bleak, are characterized by a specific histotropism to blood vessels, while the organ specificity involves the kidney and for the latter species, most internal organs. [source]

Observations of Dermocystidium sp. infections in bullheads, Cottus gobio L., from a river in southern England

JOURNAL OF FISH DISEASES, Issue 4 2004
S W Feist
Abstract Bullheads, Cottus gobio, with macroscopic external cysts on the skin and fins measuring up to 3 mm in diameter were detected in the River Allen and its tributaries in southern England between 1992 and 1998. The prevalence of these cysts was up to 50% at some sites. Examination of cyst contents revealed the presence of numerous spores, typical of the genus Dermocystidium, measuring 8 ,m in diameter. The parasite developed within well-defined cysts, which were located in the hypodermal connective tissues of the host. No cysts were present on the fins of any of the fish examined. Histological examination revealed a cyst wall consisting of an inner layer of dense eosinophilic material similar to that reported for Dermocystidium spp. forming coenocytic hyphae. No evidence was found of systemic infection or hyphal formation. Spores contained a prominent refractile body, which gave a weakly positive reaction for polysaccharides with the periodic-acid Schiff reaction and was positively stained with acidic dyes. Several examples of ruptured cysts were seen in histological sections and in some of these cases the host epithelial layer was breached, allowing release of the spores to the environment. Morphological features of, and host response towards, the Dermocystidium sp. in bullheads are compared with similar infections in salmonids and other freshwater fish species. [source]

BIOLOGICAL VALIDATION OF TOMATO PULP CONTINUOUS HEAT PROCESS

JOURNAL OF FOOD PROCESS ENGINEERING, Issue 6 2004
CRISTIANA DE PAULA PACHECO
ABSTRACT This research validated the commercial process applied to tomato pulp (pH 4.3 and 8 Brix) packed in Tetra Brik packages. Spores of Bacillus coagulans and Neosartorya fischeri were selected as targets. The heat resistance of both microorganisms, tested independently, was compared. The redesigned thermal processes were carried out in a aseptic processing and tested by indirect inoculation and retrieval with spores immobilized in alginate/tomato balls. The results showed that processes for 30 s at 115C or greater did not allow the survival of heat-resistant molds. For bacterial spores, processes for 30 s at 109C or greater showed no survivors. Although, 30 s at 115C will control both types of spoilage spores, concern for possible C. botulinum growth attributed to metabiosis in product with varying initial populations of molds and residual oxygen content dictated, a process recommendation of 60 s at 126C for safety reasons. [source]

Sporulation and Germination Gene Expression Analysis of Bacillus anthracis Sterne Spores in Skim Milk under Heat and Different Intervention Techniques

JOURNAL OF FOOD SCIENCE, Issue 3 2009
Y. Liu
ABSTRACT:, To investigate how B. anthracis Sterne spores survive in milk under heat (80 °C, 10 min), pasteurization (72 °C, 15 s), microfiltration, and pasteurization and microfiltration, the expression levels of genes related to sporulation and germination were tested using real-time PCR assays. Twenty-seven sporulation- and germination-related genes were selected for the target genes. Our results demonstrated that gene expression levels were altered by heat and microfiltration whereas the pasteurization and pasteurization and microfiltration resulted in less alteration of gene expression. Heat activated and inhibited both sporulation- and germination-related genes, suggesting that bacterial spores underwent different molecular mechanism for heat treatments. Our results may provide some insight into the molecular mechanisms of spore survival in response to heat treatment and different intervention strategies used to treat fluid skim milk. [source]

The Effects of Oligosaccharide and Spores from Aspergillus niger on the Defence Responses of Taxus chinensis Leaves In vitro

JOURNAL OF PHYTOPATHOLOGY, Issue 10 2003
M. Y. Li
Abstract Spores and oligosaccharide of a strain of Aspergillus niger, which had been isolated from the inner bark of Taxus chinensis, were used to treat T. chinensis leaves. The spores decreased the dry weight and chlorophyll content of the leaves, but increased their malondialdehyde content; oligosaccharide induced similar but more moderate changes. The changes in soluble protein, phenolic content, and peroxidase and phenylalanine ammonia-lyase activity were also analysed. Oligosaccharide significantly increased all these, whereas the spores had contrary effects. Results indicate that oligosaccharide, but not the fungal spores, elicited a defence reaction in T. chinensis. Possible reasons for these different effects on T. chinensis leaves in vitro are discussed. [source]

Studies on Cell Number and Nuclei in Spores and on Ploidy Level in Ascochyta rabiei Isolates

JOURNAL OF PHYTOPATHOLOGY, Issue 5 2001
Bruns
Isolates of the phytopathogenic ascomycete Ascochyta rabiei (Pass.) Labr. were stained with the DNA-specific fluorochrome 4,,6-diamidino-2-phenylindole (DAPI) and compared for differences in number of nuclei per pycnidiospore and the ploidy level. Microscopic analyses revealed that within the examined isolates five different combinations of cell number and number of nuclei in spores exist. A one-celled spore may contain one, two and four nuclei, respectively, and in the case of two-celled spores there exist types with one and two nuclei in one cell. Microfluorometric analyses of wild types and benomyl-treated isolates revealed differences in ploidy level among the wild types. [source]

Effect of germicidal UVC light on fungi isolated from grapes and raisins

LETTERS IN APPLIED MICROBIOLOGY, Issue 3 2007
A. Valero
Abstract Aims:, To examine how UVC affects the different genera of fungi commonly isolated from grapes, with the aim of understanding changes in mycobiota during grape ripening and possible applications for preventing grape decay during storage. Methods and Results:, Spores of Aspergillus carbonarius, Aspergillus niger, Cladosporium herbarum, Penicillium janthinellum and Alternaria alternata (between 100,250 spores/plate agar) were UVC irradiated for 0 (control), 10, 20, 30, 60, 300 and 600 s. Plates were incubated at 25°C and colonies were counted daily up to 7 days. Alternaria alternata and Aspergillus carbonarius were the most resistant fungi. Conidial germination in these species was reduced by approx. 25% after 10 s of exposure, compared with greater than 70% reduction for the remaining species tested. Penicillium janthinellum spores were the most susceptible at this wavelength. UVC exposures of 300 s prevented growth of all isolates studied, except for Alternaria alternata. Conclusions:, UVC irradiation plays a major role in selecting for particular fungi that dominate the mycobiota of drying grapes. Significance and Impact of the Study:, The UVC irradiation of harvested grapes could prevent germination of contaminant fungi during storage or further dehydration. [source]

Non-uniform assembly of the Bacillus anthracis exosporium and a bottle cap model for spore germination and outgrowth

MOLECULAR MICROBIOLOGY, Issue 2 2007
Christopher T. Steichen
Summary Spores of Bacillus anthracis are enclosed by an exosporium composed of a basal layer and an external hair-like nap. The nap is formed by a collagen-like glycoprotein called BclA, while the basal layer contains many different proteins, one of which is a spore-specific alanine racemase (Alr). In this study, we employed fluorescence microscopy and a fluorescently labelled anti-Alr monoclonal antibody (mAb) to examine the distribution of Alr within the exosporium. Binding of the mAb occurred over approximately three-quarters of the exosporium but not in a cap-like region at one end of the spore, indicating the absence or inaccessibility of Alr in this region. We also determined that the cap-like region, or cap, corresponds to the first part of the exosporium assembled within the mother cell during sporulation and the only part of the exosporium assembled in a ,exsY mutant strain of B. anthracis. Our results provide the first direct evidence that exosporium assembly is a non-uniform process and suggest that exosporium formation is discontinuous. Finally, we demonstrated that during spore germination and outgrowth, the outgrowing cell always escapes from its exosporium shell by popping through the cap, suggesting that the cap is designed to facilitate the emergence of the outgrowing cell. [source]

Spores of ectomycorrhizal fungi: ecological strategies for germination and dormancy

NEW PHYTOLOGIST, Issue 2 2009
Kazuhide Nara
First page of article [source]

Effects of ultraviolet radiation and temperature on the ultrastructure of zoospores of the brown macroalga Laminaria hyperborea

PLANT BIOLOGY, Issue 3 2008
F. S. Steinhoff
Abstract The interactive effects of an 8 h exposure to UV radiation and altered temperatures on the ultrastructure and germination of zoospores of the sublittoral brown alga Laminaria hyperborea (Gunn.) Foslie were investigated for the first time. Spores were exposed to four temperatures (2, 7, 12 and 17 °C) and three light regimes (PAR, PAR + UV-A, PAR + UV-A+UV-B). Freshly-released spores of L. hyperborea lack a cell wall and contain a nucleus with fine granular nucleoplasm and a nucleolus, one chloroplast, several mitochondria, dictyosomes and an endoplasmatic reticulum. Further, several kinds of so-called adhesive vesicles, lipid globuli and physodes containing UV-absorbing phlorotannins are embedded in the cytoplasm. No eye-spot is present. Physodes were found but they were rare and small. After an 8 h exposure to UV-B, the nucleoplasm had a mottled structure, chloroplasts contained plastoglobuli, the structure of the mitochondria changed from crista- to sacculus-type and germination was strongly inhibited at all temperatures. UV-A only had an impact on the ultrastructure at the highest temperature tested. The strongest effects were found at 17 °C, where germination was reduced to 35%, 32% and 9% after exposure to PAR, PAR+UV-A and PAR + UV-A + UV-B, respectively. This study indicates that UV-B radiation has strong damaging effects on the physiology and ultrastructure of zoospores of L. hyperborea. The results are important for developing scenarios for the effect of enhanced UV radiation and increasing temperatures caused by global climate changes. [source]

Conidial dispersal by Alternaria brassicicola on Chinese cabbage (Brassica pekinensis) in the field and under simulated conditions

PLANT PATHOLOGY, Issue 5 2003
L. Y. Chen
This study investigated conidial dispersal in the field, and effects of simulated wind and rain on the dispersal of A. brassicicola on Chinese cabbage (Brassica pekinensis). Spores were sampled using a Burkard volumetric spore sampler and rotorod samplers in a Chinese cabbage crop. Disease incidence in the field was well fitted by a Gompertz curve with an adjusted r2 of >0·99. Conidia of A. brassicicola were trapped in the field throughout the growing season. Peaks of high spore concentrations were usually associated with dry days, shortly after rain, high temperature or high wind speed. Diurnal periodicity of spore dispersal showed a peak of conidia trapped around 10·00 h. The number of conidia trapped at a height of 25 cm above ground level was greater than that at 50, 75 and 100 cm. Conidial dispersal was also studied under simulated conditions in a wind tunnel and a rain simulator. Generalized linear models were used to model these data. The number of conidia caught increased significantly at higher wind speeds and at higher rain intensities. Under simulated wind conditions, the number of conidia dispersed from source plants with wet leaves was only 22% of that for plants with dry leaves. Linear relationships were found between the number of conidia caught and the degree of infection of trap plants. [source]

Euplotespora binucleata n. gen., n. sp. (Protozoa: Microsporidia), a Parasite Infecting the Hypotrichous Ciliate Euplotes woodruffi, with Observations on Microsporidian Infections in Ciliophora

THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 3 2008
SERGEI I. FOKIN
ABSTRACT. A new microsporidian species, Euplotespora binucleata n. gen., n. sp., from the brackish-water ciliate Euplotes woodruffi is described and defined on the basis of life history characteristics, light and electron microscopic features, and small subunit (SSU) ribosomal DNA (rDNA) sequencing. The life cycle of E. binucleata n. sp. probably has rather short merogonic and relatively long sporogonic phases. Some uninuclear meronts and sporonts, along with diplokaryotic sporoblasts and spores, were found in experimentally infected host cells. Such a peculiar life cycle has been induced experimentally in Euplotes eurystomus and constitutively microsporidian-free stocks of E. woodruffi. Spores of E. binucleata n. sp. are monomorphic, ovoid,cylindrical in shape, 3.44±0.17 × 1.65±0.22 ,m in size, and characterized by a diplokaryotic condition and a large posterior vacuole. The polar tube is isofilar, 4.5,5.5 ,m in length when ejected, and lacking a distinctive coiled region (half-coiled). The polaroplast is divided into two regions: the anterior part has a few lamellae close to the anchoring disc; and the posterior part is a rounded body (sack), about one-quarter of the spore length. Spores do not appear to cluster together as a group. Each spore is surrounded by a sporophorous membrane closely adjacent to the exospore layer. A phylogenetic analysis of SSU rDNA sequences by different methods placed E. binucleata n. sp. in a clade with representatives of the microsporidian genera Cystosporogenes and Vittaforma. Observations of microsporidia in several other ciliates are discussed in view of the microsporidian infection frequency in the phylum Ciliophora. [source]