Genetic diversity among toxigenic clostridia isolated from soil, water, meat and associated polluted sites in South India.

Purpose: To investigate the genetic diversity of toxigenic Clostridium strains isolated from soil, water, meat and its associated polluted sites of Southern India. Materials and Methods: A total of 27 identified isolates of six different toxigenic clostridial species including C. bifermentans , C. botulinum , C. chauvoei , C. ramosum , C. tetani and C. novyi were isolated and characterized by conventional DNA restriction digestion analysis (REA) and by whole-cell and excretory protein patterns on SDS-PAGE. Results: The DNA fragment size ranged from 35-160 kilobases and the protein bands 30-200 KDa, followed by numerical analyses and phylogenetic analyses. Whole-cell protein banding pattern were unique with strains of C. chauvoei , C. novyi and C. ramosum . All the strains were heterogeneous and distinct in restriction digestion pattern and excretory protein patterns. Conclusion: These analyses contribute to the understanding of prevalence of toxigenic clostridial species and phylogeny within the species and assist in development of improved diagnostics and therapeutics for the treatment of clostridial infections.

Growth and amylase production by Aspergillus oryzae during solid state fermentation using banana waste as substrate.

Aspergillus oryzae, isolated from the starch rich litter soil, produced amylase when banana fruit stalk was used as substrate in a solid state fermentation system. The effects of incubation period, pH, temperature and various carbon sources on the production of amylase were studied. A maximum yield of 380U/mg was recorded on 96th hour of incubation. The amylase is tolerant to wide range of initial culture pH values (3 to 8) and temperature (25 to 35 degrees C), with an optimum pH of 5 and temperature of 35 degrees C. In SSF addition of starch (1%) increased the amylase production, when compared with other carbon sources used.

Metabolic characteristics of an aerobe isolated from a methylotrophic methanogenic enrichment culture.

An anaerobic methylotrophic methanogenic enrichment culture, with sustained metabolic characteristics, including that of methanation for over a decade, was the choice of the present study on interspecies interactions. Growth and methanation by the enrichment were suppressed in the presence of antibiotics, and no methanogen grown on methanol could be isolated using stringent techniques. The present study confirmed syntrophic metabolic interactions in this enrichment with the isolation of a strain of Pseudomonas sp. The organism had characteristic metabolic versatility in metabolizing a variety of substrates including alcohols, aliphatic acids, amino acids, and sugars. Anaerobic growth was favoured with nitrate in the growth medium. Cells grown anaerobically with methanol, revealed maximal nitrate reductase activity. Constitutive oxidative activity of the membrane system emerged from the high-specific oxygen uptake and nitrate reductase activities of the aerobically and anerobically grown cells respectively. Cells grown anaerobically on various alcohols effectively oxidized methanol in the presence of flavins, cofactor FAD and the methanogenic cofactor F420, suggesting a constitutive alcohol oxidizing capacity. In cells grown anaerobically on methanol, the rate of methanol oxidation with F420 was three times that of FAD. Efficient utilization of alcohols in the presence of F420 is a novel feature of the present study. The results suggest that utilization of methanol by the mixed culture would involve metabolic interactions between the Pseudomonas sp. and the methanogen(s). Methylotrophic, methanogenic partnership involving an aerobe is a novel feature hitherto unreported among anaerobic syntrophic associations and is of ecological significance