Flagellar motility plays important role in Biofilm formation of Bacillus cereus and Yersinia enterocolitica

Bacteria live either independently as planktonic cells or in organized surface associated colonies called as biofilms. Biofilms play an important role in increased pathogenesis of bacteria and it is assumed that motility is one of the contributing factors towards biofilm initiation. This study was planned to identify the role of flagella in biofilm formation by constructing flagellated [wild type] and physically disrupted variants [non-motile]. Total 10 clinical bacterial strains were isolated and characterized. Morphological and biochemical study identified these strains as Enterobacter spp., Pseudomonas spp., Yersinia spp., Escherichia spp., Salmonella spp., Proteus spp., Staphylococcus spp., Streptococcus spp., Lactobacillus spp. and Bacillus spp. Among all strains, two strains including Yersinia spp and Bacillus spp. showed higher antibiotic resistance, hence studied at molecular and physiological level. Biofilm formation capacity of strains was analyzed using three methods including Congo red assay, Test tube assay and Liquid-interface coverslip assay. Afterwards, flagellar disintegration was induced by blending and centrifugation for 5, 10 and 15 minutes. 16S rRNA sequencing showed two strains as Bacillus cereus and Yersinia enterocolitica. Both strains produced significant biofilm by all three above mentioned methods. A motility test of these blended variants showed partial/diminished motility with increased blending time. The significant loss in biofilm formation after 15 minutes blending confirmed the important flagellar contribution to the initiation of biofilm formation. This biofilm defect observed in flagella paralysed/minus variants presumably may be due to defects in attachments to surface at early stages. This study indicated that flagellar motility is crucial initially for surface attachment and subsequently for biofilm formation

Antibacterial activity of different plant extracts and antibiotics on pathogenic bacterial isolates from wheat field water

The present work was carried out to study bacterial pathogens isolated from wheat field water and also effect of some plant extracts on these bacterial pathogens. Five bacterial strains were isolated from wheat field water. Different morphological and biochemical tests were performed to identify and characterize bacterial pathogens. Among isolated strains two belonged to genus Staphylococcus sp., other two were Pseudomonas spp. and one strain belonged to genus Salmonella sp. Effect of various parameters such as temperature, pH, antibiotics and heavy metals of these pathogens were also studied. Optimum temperature for all bacterial strains was 37°C and optimum pH was 7 except strain 3 which had pH 6. Different antibiotics with different potency were applied to check the resistance of bacterial strains against them. Among these antibiotics Cloxacillin and Teicoplanin were most potent while Oxacillin was as less potent antibiotic because three bacterial strains were resistant against it. While remaining antibiotics proved as potent. Seven heavy metals which were zinc [Zn[+2]], copper [Cu[+2]], Ferrous [Fe[+2]], mercury [Hg[+2]], Nickel [Ni[+2]], chromium [Cr[+2]]and cobalt [Co[+2]] with different concentrations were applied to bacterial strains. Minimum inhibitory concentration of heavy metals for all bacterial was different. Different plant extracts [Artemezia incise, Colebrookia oppositifolia, Rhynchosia pseudocajan] checked for their antibacterial activity against these pathogens. These plant extracts showed antibacterial activity against antibiotic and metal resistant bacterial isolates

Effect of medicinal plants, Heavy metals and antibiotics against P pathogenic bacteria isolated from raw, Boiled and pasteurized milk

Present study has been undertaken to isolate and identify the bacterial flora in raw, boiled and pasteurized milk. Agar disc diffusion method was used to determine their sensitivity using medicinal plants, antibiotics and heavy metals. Methylene blue reduction test was used to test the quality of milk samples. Total 10 pathogenic strains were isolated, five strains were isolated from raw milk, three from boiled milk and 2 two from pasteurized milk. To determine optimum conditions for growth, these pathogenic microorganisms were incubated at various temperatures and pH. Gram's staining and biochemical tests revealed that these pathogenic bacteria include Lactobacillus sp., E. coll, Salmonella sp., Pseudomonas sp., Streptococcus sp. and Staphylococcus. Ribotyping revealed S2 as Pseudomonas fluorescens, S5 as Lactococcus lactis and S9 as Lactobacillus acidophilus. Prevalence of pathogenic organisms provided the evidence that contamination of milk arises during milking, transportation and storage of milk. Raw milk is more contaminated than other two types of milk because it contains highest percentage of pathogenic organisms and pasteurized milk was found to be of best quality among three types. So it is recommended to drink milk after proper boiling or pasteurization. Proper pasteurization and hygienic packing of milk is essential to minimize contamination in milk which can save human beings from many milk borne diseases. Our study suggests that antimicrobial use in animal husbandry should be minimized to reduce the hazard of antibiotic resistance. Plant extracts are better alternative against pathogenic bacteria in milk