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Kinds of Lab Terms modified by Lab Selected AbstractsEstimation of the soil,water partition coefficient normalized to organic carbon for ionizable organic chemicals,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2008Antonio Franco Abstract The sorption of organic electrolytes to soil was investigated. A dataset consisting of 164 electrolytes, composed of 93 acids, 65 bases, and six amphoters, was collected from literature and databases. The partition coefficient log KOW of the neutral molecule and the dissociation constant pKa were calculated by the software ACD/Labs®. The Henderson-Hasselbalch equation was applied to calculate dissociation. Regressions were developed to predict separately for the neutral and the ionic molecule species the distribution coefficient (Kd) normalized to organic carbon (KOC) from log KOW and pKa. The log KOC of strong acids (pKa < 4) was not correlated to these parameters. The regressions derived for weak acids and bases (undissociated at environmental pH) were similar. The highest sorption was found for strong bases (pKa > 7.5), probably due to electrical interactions. Nonetheless, their log KOC was highly correlated to log KOW. For bases, a nonlinear regression was developed, too. The new regression equations are applicable in the whole pKa range of acids, bases, and amphoters and are useful in particular for relatively strong bases and amphoters, for which no predictive methods specifically have been developed so far. [source] Social anxiety disorder: what are we losing with the current diagnostic criteria?ACTA PSYCHIATRICA SCANDINAVICA, Issue 3 2010A. S. Filho Filho AS, Hetem LAB, Ferrari MCF, Trzesniak C, Martín-Santos R, Borduqui T, de Lima Osório F, Loureiro SR, Busatto Filho G, Zuardi AW, Crippa JAS. Social anxiety disorder: what are we losing with the current diagnostic criteria? Objective:, To assess the rate of comorbidities and the functional impairment associated with the social anxiety disorder (SAD), with an emphasis on the so-called subthreshold clinical signs and symptoms. Method:, Psychiatric comorbidities and psychosocial functioning were evaluated in 355 volunteers (college students) who had been diagnosed as SAD (n = 141), Subthreshold SAD (n = 92) or Controls (n = 122). Results:, The rate of comorbidities was 71.6% in the SAD group and 50% in subjects with Subthreshold SAD, both significantly greater than Controls (28.7%). Concerning psychosocial functioning, the SAD group had higher impairment than the other two groups in all domains evaluated, and subjects with Subthreshold SAD presented intermediate values. Conclusion:, The rates of psychiatric comorbidities and the impairment of psychosocial functioning increase progressively along the spectrum of social anxiety. The fact that Subthreshold SAD causes considerable disability and suffering in comparison with control subjects justifies a review of the validity of the diagnostic criteria. [source] A Liquid Adhesive Bandage for the Treatment of Minor Cuts and AbrasionsDERMATOLOGIC SURGERY, Issue 3 2002William H. Eaglstein MD Background. Octyl-2-cyanoacrylate is U.S. Food and Drug Administration (FDA) approved for the closure of incisions and lacerations. In animal studies, a more flexible formulation of octyl-2-cyanoacrylate suitable for cuts and abrasions produced faster healing of partial thickness wounds than traditional bandages. Objective. To evaluate the effectiveness of a more flexible octyl-2-cyanoacrylate liquid adhesive bandage for the treatment of minor cuts and abrasions. Methods. One hundred sixty-two volunteers with recent minor cuts or abrasions were recruited and randomized to treatment with either liquid adhesive bandage (LAB) or a control device (Band-Aid brand adhesive bandage, sheer, 2.5 cm). The primary efficacy criterion was complete healing at day 12. Secondary efficacy criteria were the ability of patients to properly apply LAB, and the ability of LAB to stop bleeding, to reduce pain, and to remain on the wound. Results. At day 12 there was no statistical difference between the number of completely healed wounds in the LAB and the bandage-treated patients (P = .493). The ability of patients, as rated by investigators, to effectively apply the LAB device and the bandage was not significantly different (P = .165). Only the LAB provided significant hemostasis (P = .0001) and pain relief (P = .002). conclusion. In this randomized, controlled trial, the LAB was as effective as the control at promoting healing as measured by complete healing at day 12. The LAB was easy to use and gave rapid control of bleeding and pain, forming a film that stayed on wounds well. [source] Changes in faecal bacteria associated with concentrate and forage-only diets fed to horses in trainingEQUINE VETERINARY JOURNAL, Issue 9 2009B. WILLING Summary Reasons for performing study: Diets rich in readily fermentable carbohydrates, fed traditionally to meet the increased energy requirements of the performance horse, are associated with a number of gastrointestinal disorders that involve disturbances in the intestinal microbiota, however, these changes are poorly understood. Objectives: With the long-term objective of improving intestinal health and to increase understanding of the relationship between diet and microbiota, the effect of feeding Standardbred horses a high-energy forage-only (F) diet was studied compared to a more traditional forage-concentrate (C) diet on faecal microbiota. Methods: Diets were fed in a cross-over design to 6 mature geldings on a scheduled training regime, both periods consisting of 29 days. DNA was extracted from faecal samples collected at 4 time points from each period, bacterial 16S rRNA genes were amplified and community composition assessed by terminal-restriction fragment length polymorphism, cloning and sequencing. Faecal pH and cultivable lactic acid bacteria (LAB) and enterobacteria were also assessed on the final collection day of each period. Results: Diet F resulted in a microbial composition that was more stable between sampling periods and had lower counts (P<0.05) of cultivable LAB and specifically members of the Streptococcus bovis/equinus complex. Motile and swarming Lactobacillus ruminis was present in all horses on diet C and not in horses on diet F. Diet C also resulted in the increase (P<0.05) in members of Clostridiaceae cluster III and a concomitant reduction (P<0.05) in an unknown group of Bacteroidales. Conclusions and potential relevance: The greater microbial stability and reduction in LAB and members of the Streptococcus bovis/equinus complex on diet F indicate an opportunity to develop feeding strategies that support equine health and welfare. Novel changes identified in the faecal microbiota that resulted from carbohydrate inclusion merit further investigation. [source] Prenatal stress reduces postnatal neurogenesis in rats selectively bred for high, but not low, anxiety: possible key role of placental 11,-hydroxysteroid dehydrogenase type 2EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2009P. J. Lucassen Abstract Prenatal stress (PS) produces persistent abnormalities in anxiety-related behaviors, stress responsivity, susceptibility to psychopathology and hippocampal changes in adult offspring. The hippocampus shows a remarkable degree of structural plasticity, notably in response to stress and glucocorticoids. We hypothesized that PS would differentially affect hippocampal neurogenesis in rats selectively bred for genetic differences in anxiety-related behaviors and stress responsivity. Pregnant dams of high anxiety-related behavior (HAB) and low anxiety-related behavior (LAB) strains were stressed between days 5 and 20 of pregnancy. The survival of newly generated hippocampal cells was found to be significantly lower in 43-day-old HAB than in LAB male offspring of unstressed pregnancies. PS further reduced newly generated cell numbers only in HAB rats, and this was paralleled by a reduction in doublecortin-positive cell numbers, indicative of reduced neurogenesis. As maternal plasma corticosterone levels during PS were similar in both strains, we examined placental 11,-hydroxysteroid dehydrogenase type 2 (11,-HSD2), which catalyses rapid inactivation of maternal corticosterone to inert 11-dehydrocorticosterone and thus serves as a physiological ,barrier' to maternal glucocorticoids. PS significantly increased placental 11,-HSD2 activity in LAB, but not HAB, rats. We conclude that PS differentially affects the number of surviving newly generated cells and neurogenesis in HAB and LAB rats. The high sensitivity of hippocampal neurogenesis to PS in HAB rats is paralleled by a failure to increase placental 11,-HSD2 activity after stress rather than by different maternal corticosterone responses. Hence, stress-induced placental 11,-HSD2 expression may be critical in protecting the fetal brain from maternal stress-induced effects on adult neurogenesis. [source] Thickness of the lithosphere east of the Dead Sea TransformGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2006Ayman Mohsen SUMMARY We use the S receiver function method to study the lithosphere at the Dead Sea Transform (DST). A temporary network of 22 seismic broad-band stations was operated on both sides of the DST from 2000 to 2001 as part of the DESERT project. We also used data from six additional permanent broad-band seismic stations at the DST and in the surrounding area, that is, in Turkey, Saudi Arabia, Egypt and Cyprus. Clear S -to- P converted phases from the crust,mantle boundary (Moho) and a deeper discontinuity, which we interpret as lithosphere,asthenosphere boundary (LAB) have been observed. The Moho depth (30,38 km) obtained from S receiver functions agrees well with the results from P receiver functions and other geophysical data. We observe thinning of the lithosphere on the eastern side of the DST from 80 km in the north of the Dead Sea to about 65 km at the Gulf of Aqaba. On the western side of the DST, the few data indicate a thin LAB of about 65 km. For comparison, we found a 90-km-thick lithosphere in eastern Turkey and a 160-km-thick lithosphere under the Arabian shield, respectively. These observations support previous suggestions, based on xenolith data, heat flow observations, regional uplift history and geodynamic modelling, that the lithosphere around DST has been significantly thinned in the Late Cenozoic, likely following rifting and spreading of the Red Sea. [source] A comparison of the physicochemical, microbiological and aromatic composition of Traditional and Industrial Leben in TunisiaINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 1 2010OLFA SAMET-BALI Traditional Tunisian Leben (TL) was produced according to the traditional method. Physicochemical and microbiological characteristics and major aromatic compounds were studied and compared to industrial Leben (IL) and experimental Leben (EL). The results show a decrease in lactose content and pH value and an increase in lactic acid during spontaneous fermentation. TL and EL were characterised by higher protein, lactose and ash contents but were less fatty and acidic than IL. Lactic acid bacteria (LAB) and yeasts present in TL were responsible for lactic acid fermentation and aroma development. The LAB and yeast counts in TL were higher than that in EL and IL. Dynamic headspace extraction procedure shows the existence of four major volatile compounds: acetaldehyde, ethanol, diacetyl and acetoin in TL, IL and EL. However, TL has the most important quantity of aroma. [source] Incidence and antibiotic susceptibility of bacteriocin-producing lactic acid bacteria from dairy productsINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 4 2008MAHBOUBEH MIRHOSSEINI Screening for bacteriocin production by strains of lactic acid bacteria (LAB) from local dairy products in Iran resulted in the detection of 10 bacteriocin-producing strains. Among 105 isolated, 10 bacteriocin producers were phenotypically and genotypically identified as Enterococcus spp. The antimicrobial compounds produced by these novel strains were inactivated by trypsin, proteinase k. These bacteriocins also were active in a wide range of pH and temperature values, and inhibited not only the closely related LAB, but also Listeria monocytogenes. [source] Technological characterization of the natural lactic acid bacteria of artisanal Turkish White Pickled cheeseINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 2 2008ELIF DAGDEMIR The aim of this study was to characterize the lactic acid bacteria (LAB) isolated from White Pickled cheeses produced with traditional methods; and to improve the quality of cheesemaking with a selection of bacterial cultures from artisanal White cheeses. LAB were isolated and identified from 30 White Pickled cheese samples collected from various cities in Turkey. Also, the numbers of several microbial groups (total aerobic mesophilic bacteria, LAB, enterococci, coliforms, moulds and yeasts) of cheese samples were enumerated. Lactobacilli, lactococci and enterococci were the most abundant microbial groups. The numbers of Enterococcus and Lactobacillus isolates were higher than those of the other LAB. Enterococcus faecalis (24.43%), Enterococcus faecium (17.61%) and Lactobacillus fermentum (19.88%) isolates were the most frequently isolated species. Lactococcus strains showed the highest acidifying activity, followed by Enterococcus and Lactobacillus strains. Proteolytic activity of Enterococcus faecalis strains was higher than that of the other enterococci species, except Enterococcus avium strains. Within lactobacilli strains, the highest mean proteolytic activity was that of Lactobacillus bifermentans, Lactobacillus brevis and Lactobacillus casei strains. [source] Effect of temperature and salt on the maturation of white-salted cheeseINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 1 2004Mutlag M Al-Otaibi White-salted cheeses were prepared from ultrafiltered (UF) cows' milk and salted to give final salt-in-moisture (SM) levels of 2.5, 3.2 and 4.0%. The cheeses were stored at 5°C and 10°C for up to 15 weeks. The microflora was dominated by lactic acid bacteria (LAB) but some mould growth was evident within 15 weeks at all SM levels and both temperatures. Levels of water-soluble nitrogen (WSN), attributed to chymosin activity, increased significantly with time, the rate being inversely proportional to the SM level and increasing with storage temperature. Similar effects were noted for trichloroacetic acid-soluble nitrogen (TCA-SN) and free amino acid (FAA) levels, both of which would also be affected by bacterial protease activity. The proteolytic activity was reflected by changes in the hardness and fracturability of the cheeses. [source] Probiotic lactic acid bacteria from Kung-Som: isolation, screening, inhibition of pathogenic bacteriaINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 3 2010Noraphat Hwanhlem Summary Lactic acid bacteria (LAB) were isolated from Kung-Som at various fermentation periods. Only ten strains, named D2SM22, D6SM3, D6SM24, D6SM26, D8SM21, D10SM5, D10SM11, D10SM16, D10SM20 and D16SM26 showed a survival rate of more than 50% under the simulated gastric juice. After being subjected to simulated gastric juice, four strains (D6SM3, D8SM21, D10SM16 and D10SM20) showed a survival rate of more than 50% in simulated small intestinal juices. Growth of strain D6SM3, D8SM21 and D10SM16 under micro-aerobic and anaerobic conditions was not different. Tested pathogenic strains (Escherichia coli, Staphylococcus aureus, Bacillus cereus, Vibrio parahaemolyticus and Salmonella sp.) were inhibited by probiotic LAB. However, none of strains could produce bacteriocins. All strains were identified as Lactobacillus plantarum. No differences in pH, acidity, LAB count and liking scores between Kung-Som produced with starter culture and conventional method were observed (P > 0.01). [source] Chemical and microbiological quality of Garris, Sudanese fermented camel's milk productINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 3 2006Abdel Moneim El-Hadi Sulieman Summary In the present study, some of the chemical and microbiological characteristics of garris, a Sudanese traditionally fermented camel's milk product, were investigated. The chemical analyses included, pH, titrable acidity and ethanol contents. A total of 100 strains of lactic acid bacteria (LAB) were isolated from twenty samples of traditionally fermented household garris. The selected isolates were phenotypically characterized by their ability to ferment 49 carbohydrates using API 50 CHL kits and additional biochemical tests. LAB dominated the microflora of garris samples, and the major genera were Lactobacillus (74%), followed by Lactococcus (12%), Enterococcus (10%) and Leuconostocs (4%). The most predominant Lactobacillus species were identified as Lactobacillus paracasei ssp. paracasei (64 strains), L. fermentum (seven strains) and only three strains as L. plantarum. Most strains produced the enzymes that are relevant to cultured dairy product processing. The Lactococcus species were identified as Lactococcus lactis. The average pH value of the samples was 4.42 ± 0.21. The pH values were accompanied with increasing of titrable acidity which averaged 1.72 ± 0.04%. The relatively high amounts of ethanol detected in all samples (average 1.40 ± 0.03%) together with the high yeasts counts (6.0 ± 0.53 log10 cfu mL,1), indicated that the fermentation process of garris is a yeast-lactic fermentation. [source] Probiotic characteristics of lactic acid bacteria isolated from kimchiJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2010J.-H. Chang Abstract Aims:, The present work was aimed at identifying strains of lactic acid bacteria (LAB) from kimchi, with properties suitable for use as starter cultures in yogurt fermentation. Methods and Results:, A total of 2344 LAB strains were obtained from two different sources, one group consisted of commercial LAB strains from kimchi, and the second group consisted of those strains isolated from various types of kimchi. The LAB strains from both groups were screened for resistance to biological barriers (acid and bile salts), and the four most promising strains were selected. Further analysis revealed that KFRI342 of the four selected strains displayed the greatest ability to reduce the growth of the cancer cells, SNU-C4. The in vivo efficacy of strains in quinone reductase induction assay was evaluated, and the extent of DNA strand breakage in individual cells was investigated using the comet assay. Strain KFRI342 was identified as Lactobacillus acidophilus by 16S rRNA sequence analysis, showed protection against tumour initiation and imparted immunostimulation as well as protection against DNA damage. Conclusions:, Strain KFRI342, which showed probiotic characteristics reducing cancer cell growth, could be a suitable starter culture for yogurt fermentation because of its strong acid production and high acid tolerance. Significance and Impact of the Study:, This is the first report to describe a bacterium, isolated from kimchi, Lact. acidophilus KFRI342 which has the probiotic characteristics and the acid tolerance needed for its use as a starter culture in yogurt fermentation. [source] The use of a quantitative real-time polymerase chain reaction assay for identification and enumeration of Lactobacillus buchneri in silageJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2008R.J. Schmidt Abstract Aims:, To detect and quantify Lactobacillus buchneri in plant samples with the aid of polymerase chain reaction (PCR) methods. Methods and Results:, DNA from silage samples spiked with different amounts of L. buchneri cells was isolated using a lysozyme/sodium dodecyl sulfate lysis and phenol/chloroform extraction method. The DNA served as a template for PCR amplification with primers specific for the bacterium. The primers were developed by comparison of 16S rDNA sequences from different lactic acid bacteria (LAB) and testing for specificity with 11 different strains of LAB. As few as 100 L. buchneri colony-forming units per gram of silage could be detected. Additionally, the technique was successfully applied to quantify the population of L. buchneri in two cultivars of corn with or without inoculation. Conclusions:, The PCR assay provided a specific and rapid tool for identifying and enumerating L. buchneri in silage samples. Significance and Impact of the Study:, The use of microbial inoculants for silage production is a safe and environment friendly practice, but the full potential of such additives can only be achieved with a better understanding of the fate and activity of the microbes involved. The current study describes a methodology to detect and enumerate L. buchneri, a micro-organism used as an inoculant. [source] Preliminary characterization of lactic acid bacteria isolated from Zlatar cheeseJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2007K. Veljovic Abstract Aims:, Isolation, characterization and identification of lactic acid bacteria (LAB) from artisanal Zlatar cheese during the ripening process and selection of strains with good technological characteristics. Methods and Results:, Characterization of LAB was performed based on morphological, physiological and biochemical assays, as well as, by determining proteolytic activity and plasmid profile. rep-polymerase chain reaction (PCR) analysis and 16S rDNA sequencing were used for the identification of LAB. PCR analysis was performed with specific primers for detection of the gene encoding nisin production. Strains Lactobacillus paracasei subsp. paracasei, Lactobacillus plantarum, Lactobacillus brevis, Lactococcus lactis subsp. lactis, Enterococcus faecium and Enterococcus faecalis were the main groups present in the Zlatar cheese during ripening. Conclusions:, Temporal changes in the species were observed during the Zlatar cheese ripening. Mesophilic lactobacilli are predominant microflora in Zlatar cheese. Significance and Impact of the Study:, In this study we determined that Zlatar cheese up to 30 days old could be used as a source of strains for the preparation of potential starter cultures in the process of industrial cheese production. As the Serbian food market is adjusting to European Union regulations, the standardization of Zlatar cheese production by using starter culture(s) based on autochtonous well-characterized LAB will enable the industrial production of this popular cheese in the future. [source] Purification and characterization of two bacteriocins produced by lactic acid bacteria isolated from Mongolian airagJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2006B. Batdorj Abstract Aims:, The aim of this study was to isolate and identify bacteriocin-producing lactic acid bacteria (LAB) issued from Mongolian airag (traditional fermented mare's milk), and to purify and characterize bacteriocins produced by these LAB. Methods and Results:, Identification of the bacteria (Enterococcus durans) was carried out on the basis of its morphological, biochemical characteristics and carbohydrate fermentation profile and by API50CH kit and 16S rDNA analyses. The pH-neutral cell-free supernatant of this bacterium inhibited the growth of several Lactobacillus spp. and food-borne pathogens including Escherichia coli, Staphylococcus aureus and Listeria innocua. The antimicrobial agent (enterocin A5-11) was heat stable and was not sensitive to acid and alkaline conditions (pH 2,10), but was sensitive to several proteolytic enzymes. Its inhibitory activity was completely eliminated after treatment with proteinase K and , -chymotrypsin. The activity was however not completely inactivated by other proteases including trypsin and pepsin. Three-step purification procedure with high recovery yields was developed to separate two bacteriocins. The applied procedure allowed the recovery of 16% and 64% of enterocins A5-11A and A5-11B, respectively, present in the culture supernatant with purity higher than 99%. SDS-PAGE analyses revealed that enterocin A5-11 has a molecular mass of 5000 Da and mass spectrometry analyses demonstrates molecular masses of 5206 and 5218 Da for fractions A and B, respectively. Amino acid analyses of both enterocins indicated significant quantitative difference in their contents in threonine, alanine, isoleucine and leucine. Their N -termini were blocked hampering straightforward Edman degradation. Conclusions:, Bacteriocins A5-11A and B from Ent. durans belong to the class II of bacteriocins. Significance and Impact of the Study:, Judging from molecular masses, amino acid composition and spectrum of activities, bacteriocins A5-11A and B from Ent. durans show high degree of similarity with enterocins L50A and L50B isolated from Enterococcus faecium (Cintas et al. 1998, 2000) and with enterocin I produced by Ent. faecium 6T1a, a strain originally isolated from a Spanish-style green olive fermentation (Floriano et al. 1998). [source] Binding of Fusarium mycotoxins by fermentative bacteria in vitroJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2006V. Niderkorn Abstract Aims:,Fusarium toxins can occur in conserved forages impairing farm animal performances and health. On-farm biological decontamination methods could be an alternative to traditional physico-chemical methods. In this work, the ability to remove Fusarium toxins by fermentative bacteria was evaluated in vitro. Methods and Results:, Twenty-nine strains of lactic (LAB) and propionic acid bacteria (PAB) were tested for their ability to remove deoxynivalenol (DON) and fumonisins B1 and B2 (FB1, FB2) from an acid, pH 4, medium. Mycotoxin removal was widespread for LAB, but differences among strains were large. Removal was up to 55% for DON, 82% for FB1 and 100% for FB2. Selected strains were also capable of removing up to 88% zearalenone. The PAB strains were less efficient than the LAB. Binding, not biodegradation appeared to be the mode of action, as no toxin derivatives were observed and removal was not impaired in nonviable bacteria. Binding was not affected by pH, except for fumonisins that decreased to nearly 0% at neutral pH. Conclusions:, Selected fermentative bacteria are able to bind main Fusarium mycotoxins. Significance and Impact of the Study:, The binding ability of selected strains could be used to decrease the bioavailability of toxins in contaminated silages. [source] Characterization of dominant microbiota of a Ghanaian fermented milk product, nyarmie, by culture- and nonculture-based methodsJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2006M. Obodai Abstract Aims:, To characterize the predominant micro-organisms in a Ghanaian traditional fermented dairy product, nyarmie, made from cows' milk, using both culture- and nonculture-based methods. Methods and Results:, Samples of nyarmie were analysed from three production sites in Accra, by determining the counts on selective culture media. The microbial diversity occurring in nyarmie was also evaluated by 16S/18S ribosomal DNA PCR amplification and denaturing gradient gel electrophoresis. Results showed that nyarmie contained lactococci and lactobacilli in the range of 108 and 1010 CFU ml,1, respectively, and yeasts at around 107 CFU ml,1. The pH ranged between 3·49 and 4·25. The predominant lactic acid bacteria (LAB) in nyarmie were Leuconostocmesenteroides ssp. mesenteroides, Streptococcus thermophilus, Lactobacillus delbrueckii ssp. bulgaricus, Lact.helveticus, Lact. delbrueckii ssp. lactis and Lactococcus lactis, while Saccharomyces cerevisiae was the predominant yeast species. Lactobacillus delbrueckii ssp. delbrueckii was not detected by cultivation but its predominance was revealed by PCR-DGGE analysis. Conclusions:, The flora in products from different producers varied in the LAB composition present and may result in variations in product quality. Significance and Impact of the Study:, Development and use of starter cultures for nyarmie may be beneficial in improving the consistency of product quality. [source] Antilisterial activity of lactic acid bacteria isolated from rigouta, a traditional Tunisian cheeseJOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2004T. Ghrairi Abstract Aims:, Screening for lactic acid bacteria (LAB) producing bacteriocins and other antimicrobial compounds is of a great significance for the dairy industry to improve food safety. Methods and Results:, Six-hundred strains of LAB isolated from ,rigouta', a Tunisian fermented cheese, were tested for antilisterial activity. Eight bacteriocinogenic strains were selected and analysed. Seven of these strains were identified as Lactococcus lactis and produced nisin Z as demonstrated by mass spectrometry analysis of the purified antibacterial compound. Polymerase chain reaction experiments using nisin gene-specific primers confirmed the presence of nisin operon. Plasmid profiles analysis suggests the presence of, at least, three different strains in this group. MMT05, the eighth strain of this antilisterial collection was identified, at molecular level, as Enterococcus faecalis. The purified bacteriocin produced by this strain showed a molecular mass of 10 201·33 ± 0·85 Da. This new member of class III bacteriocins was termed enterocin MMT05. Conclusions:, Seven lactococcal strains producing nisin Z were selected and could be useful as bio-preservative starter cultures. Additional experiments are needed to evaluate the promising strain MMT05 as bio-preservative as Enterococci could exert detrimental or beneficial role in foods. Significance and Impact of the Study:, Only a few antibacterial strains isolated from traditional African dairy products were described. The new eight strains described herein contribute to the knowledge of this poorly studied environment and constitute promising strains for fermented food safety. [source] Molecular characterization of lactic acid populations associated with wine spoilageJOURNAL OF BASIC MICROBIOLOGY, Issue 1 2004L. Beneduce We have investigated the prevalence of spoilage lactic acid bacteria (LAB) in table wines produced in the Apulia region. The occurrence of LAB was evaluated in wines produced with low sulphur dioxide doses and not supplemented with selected malolactic starters such as Oenococcus oeni. About 150 strains were isolated from wine must and a molecular characterization was performed using PCR-based techniques. Most of the strains analysed belonged to Lactobacillus plantarum species. However, some of the strains were identified as Pediococcus damnosus and Leuconostoc sp. The amplified fragments of Pediococcus damnosus were cloned and sequenced. The coding sequence was highly homologous to that of the ropy plasmid confirming that the isolated strain was a ropy+Pediococcus damnosus. In all the samples analysed, the final must pH value reached was relatively high (from 3.78 to 3.90). The high pH values had probably negatively influenced (counteracted) the activity of sulphur dioxide added, allowing proliferation of spoilage wine microorganisms. [source] PROTECTIVE CULTURES USED FOR THE BIOPRESERVATION OF HORSE MEAT FERMENTED SAUSAGE: MICROBIAL AND PHYSICOCHEMICAL CHARACTERIZATIONJOURNAL OF FOOD SAFETY, Issue 3 2008JAZILA EL MALTI ABSTRACT In this paper, 150 isolates, originating from horse meat, were subjected to step-by-step screening and characterization to search for potential protective cultures to be used in the meat industry. Isolates were first tested on their homofermentative and salt tolerance. Second, the antibacterial capacities toward Listeria monocytogenes were determined in an agar spot test. In total, 50% of the tested isolates were inhibitory toward Listeria monocytogenes. However, only 12 isolates produced a bacteriocin. Finally, three isolates with the strong bacteriocin activity were evaluated on their competitive nature by comparing their growth rate, acidifying character and lactic acid production at 15C under anaerobic conditions in a liquid broth. All three isolates combined a fast growth rate with a deep and rapid acidification caused by the production of high levels of lactic acid. Lactobacillus sakei was used as starter culture for producing sausage horse meat. In this study, fermentations were followed analyzing the microbiological and physicochemical aspects of this product. The sausages were characterized by an important microbial activity of lactic acid bacteria that resulted in a product with a final pH of about 4.56. No Listeria monocytogenes, Salmonella spp. or sulfite reducing clostridia were ever isolated from the raw materials or the fermented sausages during the maturation, underlining the microbial safety of this product. The final water activity of the product was 0.85. Starter cultures showed that Lactobacillus sakei was really efficient in reducing the amine production since this strain caused a quick pH drop during sausage fermentation. PRACTICAL APPLICATIONS A starter culture can be defined as a microbial preparation of large numbers of cells of at least one microorganism to be added to a raw material to produce a fermented food by accelerating and steering its fermentation process. The group of lactic acid bacteria (LAB) occupies a central role in these processes, and has a long and safe history of application and consumption in the production of fermented foods and beverages. They cause rapid acidification of the raw material through the production of organic acids, mainly lactic acid. Also, their production of acetic acid, ethanol, aroma compounds, bacteriocins, exopolysaccharides and several enzymes is of importance. The main reason for suitability of LAB is their natural origin, and they can contribute to food safety and/or offer one or more organoleptic, technological, nutritional or health advantages. [source] EFFECT OF THERMOPHILIC LACTIC ACID BACTERIA ON THE FATE OF ENTEROBACTER SAKAZAKII DURING PROCESSING AND STORAGE OF PLAIN YOGURTJOURNAL OF FOOD SAFETY, Issue 2 2008REYAD R. SHAKER ABSTRACT Survival and growth of Enterobacter sakazakii during processing and storage of plain yogurt were investigated. Preheated rehydrated milk was inoculated with a cocktail culture of E. sakazakii (103 cfu/mL of milk) and/or with thermophilic yogurt starter culture of Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus salivarius ssp. thermophilus. The inoculated milk was incubated at 40C for 5 h, then the samples were cooled and subsequently stored at 4C for up to 7 days. The results showed that E. sakazakii grew at an early stage of fermentation but declined at the end of the process. There was no significant difference between the populations of E. sakazakii in the presence or absence of lactic acid bacteria during the first 4 h of the incubation period but there was significant difference during the last hour of the incubation period. The populations of E. sakazakii decreased significantly during cooling and storage of yogurt (pH 4.2,4.7) compared with nonfermented milk samples at 4C. The presence of E. sakazakii did not have a significant effect on the growth of LAB during fermentation and storage of yogurt. The results obtained from this study indicate that the pH of yogurt and storage temperature were critical to the survival and growth of E. sakazakii in the manufacture of plain yogurt. PRACTICAL APPLICATIONS Enterobacter sakazakii prevalence in milk products and the production environment has been documented. The results obtained from this study may be of use to dairy producers to manufacture safe products using thermophilic lactic acid bacteria. These bacteria decreased the pH of milk in less than 5 h, resulting in E. sakazakii reduction. pH of yogurt during the fermentation process is a critical control point that should be monitored to produce safe products. [source] Stabilizing Smoked Salmon (Oncorhynchus gorbuscha) Tissue after Extraction of OilJOURNAL OF FOOD SCIENCE, Issue 3 2010Cindy Bower ABSTRACT:, Alaska salmon oils are rich in n-3 polyunsaturated fatty acids and are highly valued by the food and pharmaceutical industries. However, the tissue that remains after oil extraction does not have an established market. Discarded pink salmon (Oncorhynchus gorbuscha) tissues were preserved using a combination of smoke-processing and acidification with lactic acid bacteria (LAB). All samples were analyzed for moisture, protein, ash, and lipid contents. Bacterial cell counts, pH, and lactic acid concentrations were recorded as a measure of LAB viability. Neither raw nor smoked salmon were free from spoilage during 60 d of storage. Only fermented samples successfully stabilized below pH 4.7, while retaining lactic acid concentrations over 15 g/L during storage. When smoked, fermented salmon head tissues were dried, the pH of the resulting high-protein "cracker" was significantly lower than when crackers were prepared only from the smoked (but not fermented) salmon material. Both cracker varieties retained valuable polyunsaturated fatty acids. This research suggests that salmon-head tissues discarded after oil extraction represent a good source of protein and high-value fatty acids in a shelf-stable form. Practical Application: Alaska salmon oils are rich in n-3 polyunsaturated fatty acids and are highly valued by the food and pharmaceutical industries. However, the tissue that remains after oil extraction does not have an established market. Material produced from salmon tissue discarded after oil extraction may represent a valuable resource for preparing high-protein crackers and other fish-based food products. In addition to providing a unique smoke-flavoring, the smoked, fermented fish material may also impart antioxidant factors thereby extending the shelf life of the product. [source] Antagonistic Activity of Spent Culture Supernatants of Lactic Acid Bacteria against,Helicobacter Pylori,Growth and Infection in Human Gastric Epithelial AGS CellsJOURNAL OF FOOD SCIENCE, Issue 6 2009Wen-Hsin Lin ABSTRACT:, We investigated the bactericidal activity and exclusion effect of 10 strains of lactic acid bacteria (LAB) isolated from different commercial food products and infant feces against,Helicobacter pylori,(H. pylori) in human gastric epithelial AGS cells. Antagonistic activity of spent culture supernatants (SCS) from LAB (LAB-SCS) was tested, and the content of organic acids in SCS was analyzed with high-performance liquid chromatography (HPLC). In addition, the bactericidal activities of LAB-SCS were estimated by a time-kill assay and by measuring the exclusion effect of LAB-SCS against,H. pylori,in AGS cells. The results showed that SCS from certain strains with higher concentrations of organic acids dramatically decreased the viability of,H. pylori. We also proved that the organic acids could inhibit,H. pylori,adhesion and invasion of AGS cells. Furthermore, the concentration and speciation of organic acids in SCS after fermentation of LAB are important factors in the inhibition of,H. pylori,infection. In addition, the,in vitro,methods used in this study might provide for the rapid screening of potential probiotics with anti- H. pylori,activity in the dairy industry. [source] Survival of Listeria monocytogenes, Listeria innocua, and Lactic Acid Bacteria in Chill BrinesJOURNAL OF FOOD SCIENCE, Issue 5 2009R.R. Boyer ABSTRACT:,Listeria monocytogenes is the pathogen of concern in ready-to-eat (RTE) meat products. Salt brines are used to chill processed meats. L. monocytogenes and lactic acid bacteria (LAB) can grow under saline conditions, and may compete with each other for nutrients. The objective of this study was to determine the effect of lactic acid bacteria (Enterococcus faecalis, Carnobacterium gallinarum, and Lactobacillus plantarum) on the survival of L. monocytogenes and Listeria innocua in brines stored under low temperatures for 10 d. Sterile tap water (STW) and 2 brine solutions (7.9% and 13.2% NaCl) were inoculated with 1 of 5 cocktails (L. monocytogenes, L. innocua, LAB, L. monocytogenes+ LAB, or L. innocua+ LAB) at initial concentrations of 7 log CFU/mL. Brines were stored for 10 d at 4 or 12 °C. Three replications of each brine concentration/cocktail/temperature combination were completed. No significant reductions of L. monocytogenes occurred in 7.9%[w/v] or 13.2%[w/v] brines when LAB were present; however, there were significant reductions after 10 d of L. monocytogenes in the STW solution when LAB were present (1.43 log CFU/mL at 4 °C and 3.02 log CFU/mL at 12 °C). L. innocua was significantly less resilient to environmental stresses of the brines than L. monocytogenes, both with and without LAB present (P, 0.05). These strains of lactic acid bacteria are not effective at reducing L. monocytogenes in brines at low temperatures. Furthermore, use of L. innocua as a model for L. monocytogenes is not appropriate under these environmental conditions. [source] Effect of Modified Atmosphere Packaging and Soluble Gas Stabilization on the Shelf Life of Skinless Chicken Breast FilletsJOURNAL OF FOOD SCIENCE, Issue 2 2006Bjørn T. Rotabakk ABSTRACT The suitability of soluble gas stabilization (SGS) to dissolve CO2 into skinless chicken breast fillets before modified atmosphere (MA) packaging (MAP) was investigated. Head space gas composition (%), top web deflation (mm), muscle surface color (Minolta L*a*b*), pH, exudates in the packages (%), microbial characteristics, and off-odor were assessed in the packaged fillets. Increased SGS treatment time (2 versus 12 h) before MA packaging increased the CO2 content in the packaged fillets and counteracted package collapse. High package filling degree (51.8%) (low gas to product volume ratio) gave significantly (P < 0.001) lower CO2 content in head space than normal filling degree (29.7%). Color, pH, and package exudates were not affected by SGS treatment. Aerobic plate count (APC), Enterbacteriaceae count (EC), and lactic acid bacteria (LAB) increased significantly (P < 0.001) at each sampling during storage (5, 11, 17, and 24 d). SGS treatment significantly (P < 0.015) decreased APC, EC, and Pseudomonas spp. counts (PC) compared with no SGS treatment. Filling degree did not have a significant effect on the investigated microbiological characteristics. Off-odor scores correlated highest with EC (r2(adj)= 0.82). Fillets SGS treated in 12 h were the only one not rejected at off-odor evaluation on day 24. The samples stored in air spoiled after 5 d. SGS treatment in combination with MAP can be used successfully on chicken breast fillets to improve the microbiological (APC, EC, and PC) and sensorial characteristics, and in addition reduce package collapse and possibly increase the filling degree. [source] Effect of Combining Proteolysis and Lactic Acid Bacterial Fermentation on the Characteristics of Minced MackerelJOURNAL OF FOOD SCIENCE, Issue 3 2005Li-Jung Yin ABSTRACT: To improve the quality of fish muscle, mackerel muscle protein was hydrolyzed by proteases from Aspergillus oryzae, and then fermented by lactic acid bacteria (LAB). The highest protease activities were obtained from A. oryzae after 72 h incubation at 25°C. Acidic protease activity was much higher than neutral and alkaline proteases. SDS-PAGE indicated the degradation of muscle proteins after 1 or 2 h hydrolysis by A. oryzae proteases at 50°C. During 48 h fermentation by Pediococcus pentosaceus L and S at 37°C, rapid growth of LAB, decline in pH, and suppression in the growth of microflora, Enterobacteriaceae, Staphylococcus, and Pseudomonas, occurred while increases in whiteness, nonprotein nitrogen, sensory quality, and free amino acids were observed. These data suggested that the acceptability of LAB -fermented mackerel hydrolysates could be substantially improved. [source] Malolactic Activity of Lactic Acid Bacteria during Sauerkraut FermentationJOURNAL OF FOOD SCIENCE, Issue 8 2004S.D. Johanningsmeier ABSTRACT: The frequency of lactic acid bacteria (LAB) involved in sauerkraut fermentation with (MDC+) or without (MDC - ) the ability to decarboxylate malic acid was determined. The MDC+ phenotype was found in > 99% of homofermentative LAB isolated from commercial fermentations. In contrast, heterofermentative LAB isolates from 0.25, 3, 7, and 10 d had only 53%, 54%, 15%, and 11% MDC+ phenotype, respectively, indicating that more than 1 strain or species was involved. The malolactic reaction was demonstrated in cabbage juice with known strains of Leuconostoc mesenteroides, raising the question of desirability of such activity in cultures selected for the controlled fermentation of cabbage. [source] A Descriptive Model for the Kinetics of Gas Release in Different Types of PizzasJOURNAL OF FOOD SCIENCE, Issue 3 2003M.L. Cabo ABSTRACT: A model based on typical equations of microbial kinetics is proposed to describe gas release (GR) in ham, tuna, and meat pizzas packaged under different CO2 -enriched atmospheres: 20% CO2, 70% CO2, and 70% CO2 plus 500 mg/kg Nisaplin. CO2 -enriched atmospheres hardly influenced LAB growth but reduced GR, which points to the importance of yeasts for GR. Nonetheless, LAB also contributed significantly to GR, so Nisaplin also delayed GR. Gas release followed a diauxic pattern, the 2nd stage being presumably related to yeasts shifting from respiratory to fermentative metabolism once oxygen was depleted. However, storing pizzas for longer than 25 to 30 d does not seem appropriate in terms of shelf life, so the model proposed appears adequate for practical purposes. [source] Inhibition of Listeria monocytogenes on Hot Dogs Using Antimicrobial Whey Protein-based Edible CasingsJOURNAL OF FOOD SCIENCE, Issue 1 2003A. Cagri ABSTRACT: Whey protein isolate (WPI) films (pH 5.2) containing p-aminobenzoic acid (PABA) were heat-sealed to form casings. Hot dogs prepared with WPI, collagen, or natural casings were cooked, surface-inoculated to contain 103 Listeria monocytogenes CFU/g, and examined for numbers of L. monocytogenes, mesophilic aerobic bacteria (MAB), lactic acid bacteria (LAB), and yeast/mold during 42 d of storage at 4 °C. Listeria populations on hot dogs prepared with WPI-1.0%-PABA casings remained relatively unchanged; however, numbers of Listeria on hot dogs prepared with WPI-0.0%-PABA, collagen, and natural casings increased about 2.5 logs during 42 d of refrigerated storage. Populations of MAB, LAB, and mold on WPI-1.0%-PABA casings were 1 to 3 logs lower compared to others casings. [source] | ||||||||||||||||||||||||||||