Biosurfactants are microbial amphiphilic compounds which can reduce surface tension between aqueous and hydrocarbon mixtures. Bacterial strains isolated from petroleum contaminated soil of various motor workshops were characterized morphologically and biochemically. Biosurfactant producing ability of the strains was determined and their emulsification activity was screened against different oils. All the selected bacterial strains showed enhanced biosurfactants production with yeast extract as nitrogen source and glucose as carbon source at optimized conditions. These strains also exhibited multiple metal and antibiotics resistance. Isolated biosurfactants of three most promising strains SF-1, SF-4 and SM-1 were extracted by solvent extraction and subjected to TLC technique. The technique indicates the glycolipid nature of the compounds and presence of rhamnose sugar, which was further confirmed by FT-IR analysis. 16srRNA analysis revealed that SF-1 and SM-1 had close resemblance with Pseudomonas sp. while SF-4 showed homology with Enterobacter sp. Isolation and screening of biosurfactant producing strains from petroleum polluted places proved to be a quick and effective means to find bacterial strains with possible industrial uses.

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The present study was proposed to investigate the toxicological and prophylactic potential of ethanolic extracts of Rosa damascena and Nymphaea alba and their mixture in albino mice. For toxicity study, three different doses of plant extracts were orally administrated to three groups of mice for 14 successive days. Blood biochemistry and histological examinations of liver and kidney revealed that these extracts had no harmful effects up to 1000 mg/kg. To determine the prophylactic effects of Rosa damascena, Nymphaea alba, and their mixture, an infection model of Listeria monocytogenes was established in a pilot study. Establishment of infection was confirmed by changes in haematological parameters and reisolation of Listeria monocytogenes from different tissues. Results showed that these extracts alone or in combination could restrict the growth of Listeria monocytogenes in different organs. Neutrophils were high in positive control group but remained in normal range in all treated groups. Listeria monocytogenes was recovered in low numbers from animals treated with extract of single plant but was negligible in group treated with mixture of extract of plants. Platelets count was increased in treated groups as compared to control. Results confirmed that these extracts are potent source of antimicrobial compounds and that they have synergistic effect in combined form.

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