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Natural Microflora (natural + microflora)
Selected AbstractsUse of episcopic differential interference contrast microscopy to identify bacterial biofilms on salad leaves and track colonization by Salmonella ThompsonENVIRONMENTAL MICROBIOLOGY, Issue 4 2008J. C. Warner Summary Zoonotic pathogens such as Salmonella can cause gastrointestinal illness if they are ingested with food. Foods such as salads pose a greater risk because they are consumed raw and have been the source of major outbreaks of disease from fresh produce. The novel light microscopy methods used in this study allow detailed, high resolution imaging of the leaf surface environment (the phyllosphere) and allow pathogen tracking. Episcopic differential interference contrast microscopy coupled with epifluorescence was used to view the natural microflora in situ on salad leaves and their topographical distribution. Fluorescent nucleic acid staining was used to differentiate between bacterial colonists and inorganic debris. Salmonella enterica serovar Thompson expressing green fluorescent protein was inoculated onto individual spinach leaves for 24 h at 22°C in order to observe spatial and temporal patterning of colonization on the two surfaces of each leaf under different osmotic conditions. The results obtained show that salad leaves are host to high numbers of bacteria, typically 105 per square millimetre. Cells are present in complex three-dimensional aggregations which often have a slimy appearance, suggesting the presence of biofilms. Washing of the leaves had little effect on the number of adherent pathogens, suggesting very strong attachment. Episcopic differential interference contrast microscopy is a rapid alternative to both scanning electron microscopy and confocal laser scanning microscopy for visualizing leaf topography and biofilm formation in the natural state. [source] Microbial Inactivation Kinetics during High-Pressure Carbon Dioxide Treatment: Nonlinear Model for the Combined Effect of Temperature and Pressure in Apple JuiceJOURNAL OF FOOD SCIENCE, Issue 8 2008G. Ferrentino ABSTRACT:, Isobaric and isothermal semi-logarithmic survival curves of natural microflora in apple juice treated with high-pressure carbon dioxide at 7, 13, and 16 MPa pressures and 35, 50, and 60 °C temperatures were fitted with a nonlinear equation to find the values of the coefficient b(P ), b(T ), n(P ), and n(T ). Profiles of the model parameters were obtained as a function of pressure and temperature. The model fitted with good agreement (R2 > 0.945), the survival curves. An empirical equation was proposed to describe the combined effects of pressure and temperature. The equation, derived from a power law model, was written in the form: . The proposed model fitted the experimental data well. At 7 MPa and 50 and 60 °C, 13 MPa and 35 and 60 °C, 16 MPa and 35 °C, the model provided log10 reduction residual values (observed value , fitted value) lower than 0.284 showing a good agreement between the experimental and the predicted survival levels. [source] Effectiveness of Some Natural Antimicrobial Compounds in Controlling Pathogen or Spoilage Bacteria in Lightly Fermented Chinese CabbageJOURNAL OF FOOD SCIENCE, Issue 9 2005Yasuhiro Inatsu ABSTRACT: This study was designed to evaluate the bactericidal or bacteriostatic effect of chitosan, an allyl isothiocyanate (AIT) product, and nisin for the artificially inoculated pathogenic bacteria (Escherichia coli, Salmonella Enteritidis, Staphylococcus aureus, and Listeria monocytogenes) or natural microflora of fermented Chinese cabbage. Addition of 0.1% chitosan decreased the population of pathogens from 0.7 to 1.7 log colony-forming units (CFU)/g after 4 d of storage at 10 °C. The bactericidal activity of chitosan was found to be stronger than that of nisin (0.05 mg/g). Addition of 0.2% of the AIT product (containing AIT and hop extract) exhibited a bacteriostatic effect. However, a combination of AIT product and chitosan enhanced bactericidal efficacy against L. monocytogenes. The addition of chitosan or AIT product was observed to suppress the populations of mesophilic and coliform bacteria during storage at 10 °C for 4 d. Moreover, the use of chitosan or the AIT product did not change the sensory quality of the lightly fermented vegetable. Therefore, these results suggest that chitosan or the AIT product could be useful to improve the microbial safety and quality of lightly fermented vegetable. [source] The effect of incorporating straw or manure into the soil on the natural microflora of winter wheatPLANT PATHOLOGY, Issue 5 2001B. S. Rodgers-Gray Over 3 years, five crops of winter wheat with different fertilization or pesticide treatments were grown in replicated plots in which straw, cattle manure or nothing was incorporated into the soil. It was previously shown that severities of several foliar diseases were reduced by the treatment with straw. Treatments with straw slightly increased leaf microbial numbers at growth stage (GS) 10, and significantly but slightly decreased numbers at GS 60 and 70, when averaged over all crops. There was no evidence of differences in potential for biological control between plots, because no differences were demonstrated between treatments in the proportion of phylloplane residents able to produce chitinase, siderophores or antibiotics. There was no link between soil and leaf nitrogen and microbial populations or soil amendment. The two youngest leaves of straw-treated plants remained green longer than leaves from untreated or manure-treated plants. Microbial numbers differed between crops, but within crops were more stable on leaves and ears than in soil. Soil populations were larger before the crops were sown. Bacteria predominated over fungi in all habitats throughout the growing season. The ratio of Gram-negative to Gram-positive bacteria recovered was similar on leaves and in soil, but not on ears. Soil and leaf microbes utilized similar carbon sources. More leaf epiphytes than soil microbes produced siderophores. The majority of identified organisms belonged to only a few species. Chromogenic organisms were more abundant on aerial surfaces. A fungicide, chlorothalonil, was applied in one crop; it reduced the microbial population but did not alter its composition (without affecting the reduction in disease due to straw). It is postulated that straw acts in the field by altering plant physiology and thus altering both microbial colonization and disease. [source] Probiotic effect of Bacillus NL110 and Vibrio NE17 on the survival, growth performance and immune response of Macrobrachium rosenbergii (de Man)AQUACULTURE RESEARCH, Issue 9 2010K M Mujeeb Rahiman Abstract Eight hundred and eighty-five strains of bacterial isolates from various samples associated with the natural habitat of Macrobrachium rosenbergii were screened for their probiotic potential. Two putative probionts namely Bacillus NL110 and Vibrio NE17 isolated from the larvae and egg samples, respectively, were selected for experimental studies and were introduced to the juveniles of M. rosenbergii (0.080±0.001 g) through different modes such as through feed, water and both. The probiotic potential of the above bacteria in terms of improvements in water quality, growth, survival, specific growth rate (SGR), feed conversion ratio and immune parameters was evaluated. The treatment groups showed a significant improvement in SGR and weight gain (P<0.001). Survival among different treatment groups was better than that in the control group. There were also significant improvements in the water quality parameters such as the concentration of nitrate and ammonia in the treatment groups (P<0.05). Improvements in immune parameters such as the total haemocyte count (P<0.05), phenoloxidase activity and respiratory burst were also significant (P<0.001). It is concluded that screening of the natural microflora of cultured fish and shellfish for putative probionts might yield probiotic strains of bacteria that could be utilized for an environment-friendly and organic mode of aquaculture. [source] | ||||||||||