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Bacterial Growth (bacterial + growth)
Terms modified by Bacterial Growth Selected AbstractsPOTENTIAL FOR BACTERIAL GROWTH ON THE FRESH CUT TROPICAL SQUASH, CALABAZA (CURCUBITA MOSCHATA), DURING STORAGEJOURNAL OF FOOD SAFETY, Issue 3 2003REBECCA MONTVILLE ABSTRACT Calabaza (Curcubita moschata) is a tropical squash which is gaining popularity as a specialty crop for agricultural producers in the Northeast United States. It is commonly marketed by being cut in half, wrapped in plastic and may be held unrefrigerated until sold. This method of display is essential for consumer acceptance, yet unrefrigerated storage means that some potential for food safety problems exists. Experiments were conducted to determine the potential for bacterial growth during storage of cut calabaza. Freshly cut calabaza contained between 1.3 and 4.7 log10CFU/g aerobic mesophiles. By 10 h, duplicate counts from some samples exceeded 4 log10 CFU/g. After 24 h of room temperature storage, total aerobic plate counts ranged from 5.2 to 7.7 log10 CFU/g. Rapid bacterial growth on cut calabaza stored at room temperature indicates that these products are highly perishable, and may be able to support the growth of pathogenic bacteria, should they be introduced during the slicing process. [source] Correlation of Minimum Inhibitory Concentrations Toward Oral Bacterial Growth Based on the Abraham ModelMOLECULAR INFORMATICS, Issue 10 2006Christina Mintz Abstract The Abraham solvation parameter model is used to construct mathematical correlations for describing the minimum inhibitory concentration of organic compounds for growth inhibition toward Porphyromonas gingivalis, Selenomonas artemidis, and Streptococcus sorbrinius. The derived mathematical correlations describe the observed published inhibitory data to within an overall average standard deviation of approximately 0.30 log units. A principal component analysis, shows that the derived equations for the three growth inhibitions are quite close to each other, are near to some, but not to all, equations for aqueous toxicity toward various organisms, and are quite far from most equations for water to solvent partition. A further analysis suggests that the three growth inhibition systems behave as though a solute is transferred from water to an environment that is still quite water-like. [source] Photodegradation of Soil Organic Matter and its Effect on Gram-negative Bacterial GrowthPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 5 2008Gabriela N. Bosio ABSTRACT To learn more about the role of the reactive oxygen species (ROS) in the production of bioavailable products of the dissolved organic matter, we investigate here the effect of the photolysis (,exc > 320 nm) of a soil extract (SE) on the growth of bacteria isolated from the same soil as used for obtaining the extract. Comparative experiments with Aldrich humic acid (AHA) as substrate were performed. The photodegradation of the SE was evaluated with different techniques,UV,visible absorption spectroscopy, fluorescence excitation emission matrices (EEM) and Fourier transform infrared spectroscopy (FTIR). Known ROS scavengers were employed to study the effect of photochemically produced ROS on the photodegradation of the substrates. To evaluate the effect of irradiation on the bioavailability of the SE and AHA, photolyzed and nonphotolyzed substrates were added to different culture media and the growth of Pseudomonas sp. isolated from the soil and a strain of Escherichia coli were studied. The different results obtained were assigned to the dissimilar metabolisms of both bacteria. [source] Growth response of the bacterial community to pH in soils differing in pHFEMS MICROBIOLOGY ECOLOGY, Issue 1 2010David Fernández-Calviño Abstract The effect of pH on the instantaneous growth of soil bacterial communities was studied in five soils with different pH (4.5,7.8) using leucine (Leu) and thymidine (TdR) incorporation. The pH dependency of bacterial growth was modelled using three different unimodal functions, and the pHopt for growth and the pH range in which growth was >50% of the optimal growth were compared. Leu and TdR incorporation yielded very similar results. The best fits were obtained using a third-degree polynomial function and the cardinal pH model. However, a simple second-degree function was adequate in most cases, yielding very similar pHopt values to the other two models. Bacterial growth was highly influenced by pH, showing optimum growth at a pH related to the soil pH. The lowest pHopt was found in the most acidic soil and the highest pHopt in the soil with the highest pH. The pHopt for bacterial growth was close to the soil pH measured in water, but higher (0.7,2.1 units) than the pH measured with 0.1 M KCl. The pH range in which bacterial growth was >50% of that at optimum was, on average, 1.7 units below and above the optimum pH. [source] Bactericidal effect of a 405-nm diode laser on Porphyromonas gingivalisLASER PHYSICS LETTERS, Issue 5 2009Y. Kotoku Abstract The study was conducted to determine the effect of 405-nm diode laser irradiation on periodontopathic bacteria such as Porphyromonas gingivalis in vitro. A diluted suspension of P. gingivalis was irradiated directly with a 405-nm diode laser under conditions of 100 mW-10 sec, 100 mW-20 sec, 200 mW-5 sec, 200 mW-10 sec, 200 mW-20 sec, 400 mW-5 sec, 400 mW-10 sec, and 400 mW-20 sec. The energy density ranged from 2.0 to 16.0 J/cm2. The irradiated bacterial suspension was spread on a blood agar plate and growth of the colonies was examined after an anaerobic culture for 7 days. Bacterial growth was inhibited under all irradiation conditions, but the bactericidal effect of the 405-nm diode laser depended on the energy density. More than 97% of bacterial growth was inhibited with irradiation at an energy density > 4.0 J/cm2. The mechanism of the bactericidal effect is photochemical, rather than photothermal. These findings suggest that a 405-nm diode laser has a high bactericidal effect on P. gingivalis. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Culture of Staphylococcus xylosus in fish processing by-product-based media for lipase productionLETTERS IN APPLIED MICROBIOLOGY, Issue 6 2008F. Ben Rebah Abstract Aims:, The objective of this study was to demonstrate that fish-processing by-products could be used as sole raw material to sustain the growth of Staphylococcus xylosus for lipase production. Methods and Results:, Bacterial growth was tested on supernatants generated by boiling (100°C for 20 min) of tuna, sardine, cuttlefish and shrimp by-products from fish processing industries. Among all samples tested, only supernatants generated from shrimp and cuttlefish by-products sustained the growth of S. xylosus. Shrimp-based medium gave the highest growth (A600 = 22) after 22 h of culture and exhibited the maximum lipase activity (28 U ml,1). This effect may be explained by better availability of nutrients, especially, in shrimp by-products. Standard medium (SM) amendments to sardine and tuna by-product-based media stimulated the growth of S. xylosus and the highest A600 values were obtained with 75% SM. Lipase activity, however, remained below 4 U ml,1 for both sardine and tuna by-product-based media. Conclusions:, Fish by-products could be used for the production of highly valuable enzymes. Significance and Impact of the Study:, The use of fish by-products in producing S. xylosus- growth media can reduce environmental problems associated with waste disposal and, simultaneously, lower the cost of biomass and enzyme production. [source] Occurrence and survival of potato scab pathogens (Streptomyces species) on tuber lesions: quick diagnosis based on a PCR-based assayPLANT PATHOLOGY, Issue 3 2004M. J. Lehtonen A time-saving and cost-effective polymerase chain reaction (PCR)-based method was developed for species-specific detection of the scab pathogens (Streptomyces scabies and S. turgidiscabies) prevalent in potato (Solanum tuberosum) in northern Scandinavia. Species specificity of primers was verified using a collection of previously characterized Streptomyces strains isolated from potato scab lesions in Finland and Sweden. A total of 1245 scab lesions was tested from potato cvs Matilda and Sabina grown in the field in two geographic regions of Finland in 2000 and 2001. Freshly harvested or stored potato tubers were incubated at room temperature (18,21°C) under humid conditions for a few days. Bacterial growth was collected from scab lesions for DNA isolation and PCR. The two scab pathogens were detected in the same potato fields, tubers and scab lesions. The relative incidence of S. scabies was high in freshly harvested tubers but was much lower than that of S. turgidiscabies following storage. Both pathogens were seed-transmitted in Matilda and Sabina after 24 weeks of storage at 4°C. [source] Differential analysis of Bacillus anthracis after pX01 plasmid curing and comprehensive data on Bacillus anthracis infection in macrophages and glial cellsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 20 2007Sung-Ha Park Abstract Bacillus anthracis is a gram-positive bacterial organism responsible for anthrax. This organism has two pathogenic plasmids: pX01 and pX02. The genetic function of pX01, which comprises about 198,kb, is not known, except for a region called the pathogenic island, which contains three genes,pag, lef, and cya,that code for three toxic proteins. A 2-D difference gel electrophoresis (2-D DIGE) system was used to verify the existence of proteins controlled by the pX01 plasmid, and protein regulation data were obtained using DeCyder software. A total of 1728 proteins were identified in the wild-type strain of this organism and 1684 in the pX01 plasmid. Twenty-seven of these proteins disappeared and eight appeared when the pX01 plasmid was removed. An additional 52 proteins were downregulated and 15 were upregulated when this plasmid was removed. A total of 102 proteins have been identified using the MALDI-TOF method of analysis, including 49 whose functions are unknown. Among these, 31 participate in metabolic processes, two in cellular processes, 15 in the processing of genetic information, and five in the processing of extracellular information. Another seven proteins participate in bacterial virulence and pathogenesis. We investigated the functions of these proteins in other bacteria, particularly the B. anthracis derivative H9041. Bacterial growth differed between pX01+/pX02+ B. anthracis and its pX01,/pX02+ derivative as did the cytotoxicity of macrophages infected by pX01+/pX02+ B. anthracis and the pX01,pX02+ derivative. We also found that S100B protein levels increased in the host infected with pX01+/pX02+ B. anthracis or its pX01,/pX02+ derivative. These data suggest that the pX01 plasmid plays a key role in the regulation of protein functions in B. anthracis. [source] Effects of Oxygen Exposure and Gentamicin on Stallion Semen Stored at 5 and 15°CREPRODUCTION IN DOMESTIC ANIMALS, Issue 3 2008S Price Contents This study was undertaken to investigate the effects of storage of stallion semen in a defined milk protein extender at 5 and 15°C under either anaerobic or aerobic conditions, with or without addition of the antibiotic gentamicin. Semen samples were collected from eight fertile stallions and stored for 96 h (day 0,4) and assessed daily for motility, velocity and membrane integrity (viability) using a CASA system. Samples for bacteriology assessment were taken on day 2 of storage. No significant (p > 0.05) differences in motility, velocity or viability were observed between treatments on days 0,2. On days 3 and 4, semen stored without gentamicin at 5°C had a significantly (p < 0.05) better semen quality compared with storage at 15°C without gentamicin, irrespective of oxygen exposure. On days 3 and 4, motility and velocity were greater in samples stored at 15°C with gentamicin, compared with the corresponding treatments without antibiotic (p < 0.05). This effect was also evident for viability on day 4. The decline in semen quality observed at 15°C most likely resulted from the effect of bacterial growth. Bacterial growth was the greatest in samples stored at 15°C without gentamicin, under both anaerobic and aerobic conditions (p < 0.05). Bacterial growth was inhibited by adding of gentamicin at 15°C, which accordingly reduced the decline in semen quality. Addition of antibiotic to samples stored at 5°C had no significant effect on any parameter analysed. In conclusion, storage at 15°C can be achieved by using an extender containing the antibiotic gentamicin. Storage at 5°C tended to maintain better semen quality irrespective of oxygen exposure, and did not necessitate an antibiotic treatment. [source] Prevention of Nosocomial Infection During Dermoscopy?DERMATOLOGIC SURGERY, Issue 4 2006SUSAN C. KELLY DO BACKGROUND Dermatoscopes are applied directly to cutaneous or mucocutaneous surfaces with immersion fluid (IF) such as oil or alcohol to reduce light reflection. Recently, Staphylococcus aureus has been isolated from dermatosopes that used mineral oil as the IF. Thus, dermatoscopes might be a potential source of nosocomial infection. OBJECTIVE In this study we propose the use of an alcohol-based antibacterial gel to reduce nosocomial infection transmission while optimizing optical resolution during dermatoscopic examination. MATERIALS AND METHODS Aerobic bacterial cultures were performed on three dermatoscopes used in an outpatient setting after routine examination of 31 patients with an alcohol-based antibacterial gel as IF. RESULTS There was no bacterial growth after using the antibacterial gel with the dermatoscopes. The optical resolution for the antibacterial gel appeared equal to the ,dermatoscopy oil' and superior to alcohol wipes. CONCLUSIONS Alcohol-based antibacterial gel appears to inhibit bacterial colonization while offering excellent optical resolution during dermoscopic examination. The use of alcohol-based IF appears to obviate the risk of nosocomial infections. [source] Bacterial protein kinase inhibitorsDRUG DEVELOPMENT RESEARCH, Issue 3 2010Michio Kurosu Abstract Protein kinases have become the second most important group of drug targets for the pharmaceutical industry next to G-protein-coupled receptors. Thus, over the past decade, a significant number of small molecules have been generated for protein kinase drug optimization programs. The vast majority of kinase inhibitors target the ATP binding site of the enzyme; however, the poor protein kinase selectivity of ATP-competitive protein kinase inhibitors (PKIs) limits their use for treating chronic diseases. In contrast, for inhibitors of bacterial signal transduction systems targeting bacterial kinase(s), there are no such selectivity requirements as long as the inhibitor does not act on any human kinases at the effective concentrations for killing bacteria in vivo. Protein phosphorylation in bacteria is performed by two-component signal transduction systems (2CSTSs) and eukaryotic-like serine/threonine kinases or bacterial tyrosine kinases. Recently, a large number of studies of protein kinases essential for sustaining bacterial growth and kinases required for virulence have been reported. Thus, bacterial protein kinases offer considerable potential as new drug targets. To identify bacterial PKIs, large chemical libraries of ATP-competitive inhibitors developed for eukaryotic protein kinases are an invaluable asset. This manuscript reviews progress on the development of prokaryotic protein kinase inhibitors. Drug Dev Res 2010. © 2010 Wiley-Liss, Inc. [source] Bacteria in oral secretions of an endophytic insect inhibit antagonistic fungiECOLOGICAL ENTOMOLOGY, Issue 6 2006YASMIN J. CARDOZA Abstract 1.,Colonisation of host trees by an endophytic herbivore, the spruce beetle, Dendroctonus rufipennis, is accompanied by invasion of its galleries by a number of fungal species. Four of these associated species were identified as Leptographium abietinum, Aspergillus fumigatus, Aspergillus nomius, and Trichoderma harzianum. 2.,Trichoderma and Aspergillus significantly reduced spruce beetle survival and reproduction in controlled assays. 3.,A previously undescribed behaviour was observed, in which spruce beetle adults exuded oral secretions, especially within fungus-pervaded galleries. 4.,These oral secretions inhibited the growth of fungi except A. nomius, and disrupted the morphology of the latter. Administration of these secretions indicated a dose-dependent inhibitory effect. 5.,Oral secretions cultured on microbiological media yielded substantial bacterial growth. 6.,Filter-sterilised secretions failed to inhibit fungal growth, evidence that the bacteria are responsible for the antifungal activity. 7.,Nine bacterial isolates belonging to the Actinobacteria, Firmicutes, Gammaproteobacteria, and Betaproteobacteria taxa were obtained from the secretions. 8.,Bacterial isolates showed species-specific inhibitory activity against the four fungi antagonistic to spruce beetle. The bacterium with the strongest fungal inhibition activity was the actinomycete Micrococcus luteus. 9.,The production of bark beetle secretions containing bacteria that inhibit fungal growth is a novel finding. This suggests an additional level of complexity to ecological associations among bark beetles, conifers, and microorganisms, and an important adaptation for colonising subcortical tissue. [source] Ion transport and osmotic adjustment in Escherichia coli in response to ionic and non-ionic osmoticaENVIRONMENTAL MICROBIOLOGY, Issue 1 2009Lana Shabala Summary Bacteria respond to osmotic stress by a substantial increase in the intracellular osmolality, adjusting their cell turgor for altered growth conditions. Using Escherichia coli as a model organism we demonstrate here that bacterial responses to hyperosmotic stress specifically depend on the nature of osmoticum used. We show that increasing acute hyperosmotic NaCl stress above ,1.0 Os kg,1 causes a dose-dependent K+ leak from the cell, resulting in a substantial decrease in cytosolic K+ content and a concurrent accumulation of Na+ in the cell. At the same time, isotonic sucrose or mannitol treatment (non-ionic osmotica) results in a gradual increase of the net K+ uptake. Ion flux data are consistent with growth experiments showing that bacterial growth is impaired by NaCl at the concentration resulting in a switch from net K+ uptake to efflux. Microarray experiments reveal that about 40% of upregulated genes shared no similarity in their responses to NaCl and sucrose treatment, further suggesting specificity of osmotic adjustment in E. coli to ionic and non-ionic osmotica. The observed differences are explained by the specificity of the stress-induced changes in the membrane potential of bacterial cells highlighting the importance of voltage-gated K+ transporters for bacterial adaptation to hyperosmotic stress. [source] The association between non-biting midges and Vibrio choleraeENVIRONMENTAL MICROBIOLOGY, Issue 12 2008Meir Broza Summary Vibrio cholerae is a natural inhabitant of aquatic ecosystems, yet its interactions within this habitat are poorly understood. Here we describe the current knowledge on the interaction of V. cholerae with one group of co-inhabitants, the chironomids. Chironomids, non-biting midges (Chironomidae, Diptera), are an abundant macroinvertebrate group encountered in freshwater aquatic habitats. As holometabolous insects, chironomids start life when their larvae hatch from eggs laid at the water/air interface; through various feeding strategies, the larvae grow and pupate to become short-lived, non-feeding, adult flying insects. The discovery of the connection between V. cholerae and chironomids was accidental. While working with Chironomus transavaalensis, we observed the disintegration of its egg masses and searched for a possible microbial agent. We identified V. cholerae as the primary cause of this phenomenon. Haemagglutinin/protease, a secreted extracellular enzyme, degraded the gelatinous matrix surrounding the eggs, enabling bacterial growth. Observation of chironomids in relation to V. cholerae continuously for 7 years in various types of water bodies in Israel, India, and Africa revealed that environmental V. cholerae adhere to egg-mass surfaces of various Chironomini (,bloodworms'). The flying adults' potential to serve as mechanical vectors of V. cholerae from one water body to another was established. This, in turn, suggested that these insects play a role in the ecology of V. cholerae and possibly take part in the dissemination of the pathogenic serogroups during, and especially between, epidemics. [source] Biofilm formation and cellulose expression among diverse environmental Pseudomonas isolatesENVIRONMENTAL MICROBIOLOGY, Issue 11 2006Susanne Ude Summary The ability to form biofilms is seen as an increasingly important colonization strategy among both pathogenic and environmental bacteria. A survey of 185 plant-associated, phytopathogenic, soil and river Pseudomonas isolates resulted in 76% producing biofilms at the air,liquid (A,L) interface after selection in static microcosms. Considerable variation in biofilm phenotype was observed, including waxy aggregations, viscous and floccular masses, and physically cohesive biofilms with continuously varying strengths over 1500-fold. Calcofluor epifluorescent microscopy identified cellulose as the matrix component in biofilms produced by Pseudomonas asplenii, Pseudomonas corrugata, Pseudomonas fluorescens, Pseudomonas marginalis, Pseudomonas putida, Pseudomonas savastanoi and Pseudomonas syringae isolates. Cellulose expression and biofilm formation could be induced by the constitutively active WspR19 mutant of the cyclic-di-GMP-associated, GGDEF domain-containing response regulator involved in the P. fluorescens SBW25 wrinkly spreader phenotype and cellular aggregation in Pseudomonas aeruginosa PA01. WspR19 could also induce P. putida KT2440, which otherwise did not produce a biofilm or express cellulose, as well as Escherichia coli K12 and Salmonella typhimurium LT2, both of which express cellulose yet lack WspR homologues. Statistical analysis of biofilm parameters suggest that biofilm development is a more complex process than that simply described by the production of attachment and matrix components and bacterial growth. This complexity was also seen in multivariate analysis as a species-ecological habitat effect, underscoring the fact that in vitro biofilms are abstractions of those surface and volume colonization processes used by bacteria in their natural environments. [source] Genetic variability in environmental isolates of Legionella pneumophila from Comunidad Valenciana (Spain)ENVIRONMENTAL MICROBIOLOGY, Issue 6 2006Mireia Coscollá Summary Legionella pneumophila is associated to recurrent outbreaks in several Comunidad Valenciana (Spain) localities, especially in Alcoi, where social and climatic conditions seem to provide an excellent environment for bacterial growth. We have analysed the nucleotide sequences of three loci from 25 environmental isolates from Alcoi and nearby locations sampled over 3 years. The analysis of these isolates has revealed a substantial level of genetic variation, with consistent patterns of variability across loci, and comparable to that found in a large, European-wide sampling of clinical isolates. Among the tree loci studied, fliC showed the highest level of nucleotide diversity. The analysis of isolates sampled in different years revealed a clear differentiation, with samples from 2001 being significantly distinct from those obtained in 2002 and 2003. Furthermore, although linkage disequilibrium measures indicate a clonal nature for population structure in this sample, the presence of some recombination events cannot be ruled out. [source] Perchlorate reduction by a novel chemolithoautotrophic, hydrogen-oxidizing bacteriumENVIRONMENTAL MICROBIOLOGY, Issue 10 2002Husen Zhang Summary Water treatment technologies are needed that can remove perchlorate from drinking water without introducing organic chemicals that stimulate bacterial growth in water distribution systems. Hydrogen is an ideal energy source for bacterial degradation of perchlorate as it leaves no organic residue and is sparingly soluble. We describe here the isolation of a perchlorate-respiring, hydrogen-oxidizing bacterium (Dechloromonas sp. strain HZ) that grows with carbon dioxide as sole carbon source. Strain HZ is a Gram-negative, rod-shaped facultative anaerobe that was isolated from a gas-phase anaerobic packed-bed biofilm reactor treating perchlorate-contaminated groundwater. The ability of strain HZ to grow autotrophically with carbon dioxide as the sole carbon source was confirmed by demonstrating that biomass carbon (100.9%) was derived from CO2. Chemolithotrophic growth with hydrogen was coupled with complete reduction of perchlorate (10 mM) to chloride with a maximum doubling time of 8.9 h. Strain HZ also grew using acetate as the electron donor and chlorate, nitrate, or oxygen (but not sulphate) as an electron acceptor. Phylogenetic analysis of the 16S rRNA sequence placed strain HZ in the genus Dechloromonas within the , subgroup of the Proteobacteria. The study of this and other novel perchlorate-reducing bacteria may lead to new, safe technologies for removing perchlorate and other chemical pollutants from drinking water. [source] Phylogenetic 16S rRNA analysis reveals the presence of complex and partly unknown bacterial communities in Tito Bustillo cave, Spain, and on its Palaeolithic paintingsENVIRONMENTAL MICROBIOLOGY, Issue 7 2002Claudia Schabereiter-Gurtner Summary Tito Bustillo cave (Ribadesella, Spain) contains valuable Palaeolithic paintings, which date back 15 000,20 000 years. Since 1969, the cave has been open to the public. Rock wall surfaces, spelaeothems and soils are covered by apparent biofilms of phototrophic microorganisms, which develop under artificial lighting. In addition, rock surfaces present conspicuous bacterial growth in the form of round colonies of different colours and about 1,2 mm in diameter. Even the famous Paintings Panel shows some evident microbial growth. In the present study, bacterial communities on the paintings and on the rock surfaces near the paintings were analysed by culture-independent techniques, including polymerase chain reaction (PCR) amplification of bacterial 16S rRNA genes (16S rDNA), phylogenetic sequence analyses and genetic community fingerprinting by denaturing gradient gel electrophoresis (DGGE). DGGE fingerprints showed complex bacterial community patterns. Forty-one clones matching DGGE bands of the community fingerprints were sequenced, representing about 39% of DNA fragments in the DGGE patterns. Phylogenetic sequence analyses revealed a high number of phylogenetically novel 16S rDNA sequence types and a high diversity of putatively chemotrophic and heterotrophic bacteria. Sequences were phylogenetically most closely related to the Proteobacteria (20 clones), green non-sulphur bacteria (three clones), Planctomycetales order (one clone), Cytophaga,Flexibacter, Bacteroides division (one clone) and the Actinobacteria (four clones). Furthermore, we report the presence of members of the Acidobacterium division (12 clones) in a karstic hypogean environment. Members of this phylum have not so far been detected in these particular environments. [source] Evaluation of in vitro properties of di-tri-octahedral smectite on clostridial toxins and growthEQUINE VETERINARY JOURNAL, Issue 7 2003J. S. Weese Summary Reasons for performing study: Clostridial colitis and endotoxaemia of intestinal origin are significant causes of morbidity and mortality in horses. Intestinal adsorbents are available for treatment of these conditions; however, little information exists supporting their use. Objectives: To evaluate the ability of di-tri-octahedral smectite to bind to Clostridium difficile toxins A and B, C. perfringens enterotoxin and endotoxin, inhibit clostridial growth and the actions of metronidazole in vitro. Methods: Clostridium difficile toxins, C. perfringens enterotoxin and endotoxin were mixed with serial dilutions of di-tri-octahedral smectite, then tested for the presence of clostridial toxins or endotoxin using commercial tests. Serial dilutions of smectite were tested for the ability to inhibit growth of C. perfringens in culture broth, and to interfere with the effect of metronidazole on growth of C. perfringens in culture broth. Results: Clostridium difficile toxins A and B, and C. perfringens enterotoxin were completely bound at dilutions of 1:2 to 1:16. Partial binding of C. difficile toxins occurred at dilutions up to 1:256 while partial binding of C. perfringens enterotoxin occurred up to a dilution of 1:128. Greater than 99% binding of endotoxin occurred with dilutions 1:2 to 1:32. No inhibition of growth of C. difficile or C. perfringens was present at any dilution, and there was no effect on the action of metronidazole. Conclusions: Di-tri-octahedral smectite possesses the ability to bind C. difficile toxins A and B, C. perfringens enterotoxin and endotoxin in vivo while having no effect on bacterial growth or the action of metronidazole. Potential relevance: In vivo studies are required to determine whether di-tri-octahedral smectite might be a useful adjunctive treatment of clostridial colifis and endotoxaemia in horses. [source] Antibiotic-Loaded PLGA Nanofibers for Wound Healing Applications,ADVANCED ENGINEERING MATERIALS, Issue 4 2010David A. Soscia Incorporating antibiotics into biocompatible nanoscale non-woven fibrous mats could provide utility for wound healing applications and for incorporation into wound dressing materials. In this study, the antibiotic chloramphenicol (Cm) was incorporated into electrospun poly(lactic-co-glycolic acid) (PLGA) nanofibers, which were then tested for inhibition of bacterial growth for multiple bacterial species (Escherichia coli, Staphylococcus aureus, Bacillus cereus, Salmonella typhimurium, and Pseudomonas aeruginosa). In addition, the cytotoxicity of Cm-PLGA nanofibers was examined for two types of mammalian cells including mouse embryonic stem cells and fibroblasts. Electrospun PLGA nanofibers containing Cm were able to reduce bacterial growth on solid agar plates for all species except for P. aeruginosa. In liquid culture, Cm-loaded nanofibers inhibited growth for E. coli, B. cereus and S. typhimurium by 93% or greater, while P. aeruginosa and S. aureus growth was inhibited by 42% and 56%, respectively. Cm-loaded nanofibers showed limited cytoxicity on fibroblasts and embryonic stem cells, with viability greater than 96% for all conditions tested. These results suggest that Cm can be successfully incorporated into electrospun nanofibers and that these fibers could be used for wound healing applications with minimal cytotoxicity to the surrounding tissue. [source] Effects of maxillary sinus floor elevation surgery on maxillary sinus physiologyEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 3 2003Nicolaas M. Timmenga In a prospective study, the effects of elevation surgery of the maxillary sinus floor on maxillary sinus physiology were assessed. Seventeen consecutive patients without preoperative anamnestic, clinical and radiological signs of maxillary sinusitis underwent sinus floor elevation surgery with iliac crest bone grafts. All patients were subjected to unilateral endoscopic examination of the maxillary sinus, taking of a biopsy specimen from the sinus floor mucosa, and collection of a sinus lavage-fluid aspirate. This triad of evaluations was performed immediately preceding the elevation procedure, and 3 months (at implant insertion) and 9 months (at uncovering of implants) postoperatively. All procedures were performed under general anesthesia. Preoperatively, three out of 17 patients showed pre-existing mucosal pathology endoscopically, while the 3- and 9-month results revealed the presence of mucosal pathology in four and two patients, respectively. The 3-month microbiological evaluation showed a significant increase in cultures with bacterial growth, while the 9-month culture results were comparable to the preoperative status of the maxillary sinus. Morphologically, neither fibrosis nor an altered inflammatory response or thickening of the epithelium and lamina propria was observed postoperatively. The number of goblet cells in the epithelial layer was increased. From this study it is concluded that the effect of maxillary sinus floor elevation surgery with autogenous bone grafts does not appear to have clinical consequences in patients without signs of pre-existing maxillary sinusitis. [source] Analysis of the interaction of 16S rRNA and cytoplasmic membrane with the C-terminal part of the Streptococcus pneumoniae Era GTPaseFEBS JOURNAL, Issue 21 2001Julie Qi Hang Era, an essential GTPase, plays a regulatory role in several cellular processes. The Era protein of Streptococcus pneumoniae has recently been shown to bind to 16S rRNA and the cytoplasmic membrane. However, exact locations of Era responsible for RNA- and membrane-binding were unknown. To identify the regions in Era that interact with the RNA and membrane, the C-terminal part of S. pneumoniae Era was systematically deleted while the N-terminal part, responsible for the GTPase activity of the protein, was kept intact. The resulting truncated Era proteins were purified and characterized. The C-terminal deletion of 9 or 19 amino-acid residues did not affect 16S rRNA-binding activity while further deletions of the C-terminus (29,114 amino-acid residues) abolished the activity. These results indicate that the integrity of the putative KH domain of Era, spanning the amino-acid residues between ,,22,83 from the C-terminus, is required for 16S rRNA-binding. Furthermore, the Era proteins with a deletion up to 45 residues from the C-terminus retained membrane-binding activity, but longer deletions significantly reduced the activity. These results indicate that part of the putative KH domain is also required for membrane-binding. Thus, these results indicate for the first time that the regions critical for the membrane- and 16S rRNA-binding activities of Era overlap. The era gene with a deletion of 9 or 19 codons from its 3, terminus complemented an Escherishia coli mutant strain deficient in Era production whereas the genes with longer deletions failed to do so, thereby indicating that the KH domain is essential for Era function. Taken together, the results of this study indicate that the putative KH domain is required for 16S rRNA-binding activity and that part of the KH domain is also required for membrane-binding activity. The results also suggest that the interaction between Era and 16S rRNA is essential for bacterial growth. [source] Roles of endogenous cytokines in liver apoptosis of mice in lethal Listeria monocytogenes infectionFEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 4 2000Tomisato Miura Abstract Various bacterial pathogens have been identified as mediators of apoptosis. Apoptosis reportedly shows both detrimental and beneficial effects on biological functions. We studied the role of liver apoptosis in lethal Listeria monocytogenes infection and the regulation of apoptosis by endogenous cytokines during infection. Apoptosis was observed in the spleen but not in the liver of infected mice, whereas the induction of liver necrosis was evident by rising levels of serum aminotransferases in these animals. Apoptosis was detected in the liver of L. monocytogenes -infected mice which had been treated with monoclonal antibody (mAb) against tumor necrosis factor-, (TNF-,) or interleukin-6 (IL-6), or in TNF-,,/, mice, but not in ,- interferon (IFN-,),/, mice or mice which had been treated with mAb against IL-4 or IL-10. Augmentation of liver apoptosis in mice treated with mAb against TNF-, or IL-6 or in TNF-,,/, mice correlated with the increase in bacterial numbers in the organ, while no augmentation of apoptosis was observed in the liver of IFN-,,/, mice irrespective of the marked increase in bacterial numbers in the organs, indicating that augmentation of liver apoptosis may not be merely due to the increase in bacterial growth in the organs. These results suggest that TNF-, and IL-6 may play an important role in protecting the liver from apoptosis in lethal L. monocytogenes infection. [source] Growth response of the bacterial community to pH in soils differing in pHFEMS MICROBIOLOGY ECOLOGY, Issue 1 2010David Fernández-Calviño Abstract The effect of pH on the instantaneous growth of soil bacterial communities was studied in five soils with different pH (4.5,7.8) using leucine (Leu) and thymidine (TdR) incorporation. The pH dependency of bacterial growth was modelled using three different unimodal functions, and the pHopt for growth and the pH range in which growth was >50% of the optimal growth were compared. Leu and TdR incorporation yielded very similar results. The best fits were obtained using a third-degree polynomial function and the cardinal pH model. However, a simple second-degree function was adequate in most cases, yielding very similar pHopt values to the other two models. Bacterial growth was highly influenced by pH, showing optimum growth at a pH related to the soil pH. The lowest pHopt was found in the most acidic soil and the highest pHopt in the soil with the highest pH. The pHopt for bacterial growth was close to the soil pH measured in water, but higher (0.7,2.1 units) than the pH measured with 0.1 M KCl. The pH range in which bacterial growth was >50% of that at optimum was, on average, 1.7 units below and above the optimum pH. [source] Influence of arbuscular mycorrhizal mycelial exudates on soil bacterial growth and community structureFEMS MICROBIOLOGY ECOLOGY, Issue 2 2007Jonas F. Toljander Abstract Plant root systems colonized by arbuscular mycorrhizal (AM) fungi have previously been shown to influence soil bacterial populations; however, the direct influence of the AM extraradical mycelium itself on bacterial growth and community composition is not well understood. In this study, we investigated the effects of exudates produced by AM extraradical mycelia on the growth and development of an extracted soil bacterial community in vitro. The chemical composition of the mycelial exudates was analysed using proton nuclear magnetic resonance spectrometry. Following the addition of exudates to a bacterial community extracted from soil, bacterial growth and vitality were determined using a bacterial vitality stain and fluorescence microscopy. Changes in community composition were also analysed at various times over the course of 3 days by terminal restriction fragment length polymorphism analysis, in combination with cloning and sequencing of 16S rRNA genes. Mycelial exudates increased bacterial growth and vitality and changed bacterial community composition. Several Gammaproteobacteria, including a taxon within the Enterobacteriaceae, increased in frequency of occurrence in response to AM mycelial exudates. This study is the first attempt to identify carbohydrates from the extraradical mycelium of an AM fungus, and demonstrates the direct effects of mycelial exudates on a soil bacterial community. [source] Genome-wide expression analysis of iron regulation in Burkholderia pseudomallei and Burkholderia mallei using DNA microarraysFEMS MICROBIOLOGY LETTERS, Issue 2 2005Apichai Tuanyok Abstract Burkholderia pseudomallei and B. mallei are the causative agents of melioidosis and glanders, respectively. As iron regulation of gene expression is common in bacteria, in the present studies, we have used microarray analysis to examine the effects of growth in different iron concentrations on the regulation of gene expression in B. pseudomallei and B. mallei. Gene expression profiles for these two bacterial species were similar under high and low iron growth conditions irrespective of growth phase. Growth in low iron led to reduced expression of genes encoding most respiratory metabolic systems and proteins of putative function, such as NADH-dehydrogenases, cytochrome oxidases, and ATP-synthases. In contrast, genes encoding siderophore-mediated iron transport, heme-hemin receptors, and a variety of metabolic enzymes for alternative metabolism were induced under low iron conditions. The overall gene expression profiles suggest that B. pseudomallei and B. mallei are able to adapt to the iron-restricted conditions in the host environment by up-regulating an iron-acquisition system and by using alternative metabolic pathways for energy production. The observations relative to the induction of specific metabolic enzymes during bacterial growth under low iron conditions warrants further experimentation. [source] Genomic features of lactic acid bacteria effecting bioprocessing and healthFEMS MICROBIOLOGY REVIEWS, Issue 3 2005Todd R. Klaenhammer Abstract The lactic acid bacteria are a functionally related group of organisms known primarily for their bioprocessing roles in food and beverages. More recently, selected members of the lactic acid bacteria have been implicated in a number of probiotic roles that impact general health and well-being. Genomic analyses of multiple members of the lactic acid bacteria, at the genus, species, and strain level, have now elucidated many genetic features that direct their fermentative and probiotic roles. This information is providing an important platform for understanding core mechanisms that control and regulate bacterial growth, survival, signaling, and fermentative processes and, in some cases, potentially underlying probiotic activities within complex microbial and host ecosystems. [source] Predator-released compounds, ambient temperature and competitive exclusion among differently sized Daphnia speciesFRESHWATER BIOLOGY, Issue 4 2006JACOBUS VIJVERBERG Summary 1. We studied the effects of fish water and temperature on mechanisms of competitive exclusion among two Daphnia species in flow-through microcosms. The large-bodied D. pulicaria outcompeted the medium sized D. galeata × hyalina in fish water, but not in the control treatment. Daphnia galeata × hyalina was competitively displaced 36 days earlier at 18 °C than at 12 °C. 2. It is likely that the high phosphorus content of fish water increased the nutritional value of detrital seston particles by stimulating bacterial growth. Daphnia pulicaria was presumably better able to use these as food and hence showed a more rapid somatic growth than its competitor. This led to very high density of D. pulicaria in fish water, but not in the controls. The elevated D. pulicaria density coincided with high mortality and reduced fecundity in D. galeata × hyalina, resulting in competitive displacement of the hybrid. 3. It is clear that the daphnids competed for a limiting resource, as grazing caused a strong decrease in their seston food concentration. However, interference may also have played a role, as earlier studies have shown larger Daphnia species to be dominant in this respect. The high density of large-bodied D. pulicaria in fish water may have had an allelopathic effect on the hybrid. Our data are inconclusive with respect to whether the reached seston concentration was below the threshold resource level (R*) of the hybrid, where population growth rate and mortality exactly balance, as it would be set in the absence of interference, or whether interference actually raised the hybrid's R* to a value above this equilibrium particle concentration. 4. Our results do clearly show that fish-released compounds mediated competitive exclusion among zooplankton species and that such displacement occurred at a greatly enhanced rate at an elevated temperature. Fish may thus not only structure zooplankton communities directly through size-selective predation, but also indirectly through the compounds they release. [source] Thermal performance of juvenile Atlantic Salmon, Salmo salar L.FUNCTIONAL ECOLOGY, Issue 6 2001B. JONSSON Summary 1,Experimental data for maximum growth and food consumption of Atlantic Salmon (Salmo salar L.) parr from five Norwegian rivers situated between 59 and 70°N were analysed and modelled. The growth and feeding models were also applied to groups of Atlantic Salmon growing and feeding at rates below the maximum. The data were fitted to the Ratkowsky model, originally developed for bacterial growth. 2,The rates of growth and food consumption varied significantly among populations but the variation appeared unrelated to thermal conditions in the river of population origins. No correlation was found between the thermal conditions and limits for growth, thermal growth optima or maximum growth, and hypotheses of population-specific thermal adaptation were not supported. Estimated optimum temperatures for growth were between 16 and 20 °C. 3, Model parameter estimates differed among growth-groups in that maximum growth and the performance breadth decreased from fast to slow growing individuals. The optimum temperature for growth did not change with growth rate. 4, The model for food consumption (expressed in energy terms) peaked at 19,21 °C, which is only slightly higher than the optimal temperature for growth. Growth appeared directly related to food consumption. Consumption was initiated ,2 °C below the lower temperature for growth and terminated ,1·5 °C above the upper critical temperature for growth. Model parameter estimates for consumption differed among growth-groups in a manner similar to the growth models. 5,By combining the growth and consumption models, growth efficiencies were estimated. The maximum efficiencies were high, 42,58%, and higher in rivers offering hostile than benign feeding and growth opportunities. [source] Production of oxalates In Vitro by Microbes Isolated from Rock Surfaces with prehistoric paints in the Lower Pecos Region, TexasGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 1 2008Darren Hess Calcium oxalate-rich rock coatings are ubiquitous on limestone inside dry rock shelters and under bluff overhangs along canyon walls in southwestern Texas. Prehistoric pictographs occur in more than 250 such sites, and the ancient paints are encapsulated within the natural rock coating. Previous studies suggest lichens were the source of the oxalate; however, we report here that microbes cultured and isolated from samples of the coating produce oxalate in vitro. Twenty different bacteria species have been identified in samples from eight different sites, with Bacillus the most common genus, represented by five species. HPLC analyses of inoculated R2B medium after eight months of bacterial growth revealed the presence of oxalate ions in the solid phase of the growth medium. © 2008 Wiley Periodicals, Inc. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||