FT Vol.43(1)

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Browsing FT Vol.43(1) by Author "Surendran, P.K."

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    Antibacterial activity of shrimp chitosan against Escherichia coli, Salmonella, and Pseudomonas aeruginosa isolated from seafoods
    (Society of Fisheries Technologists(India), Cochin, 2006) Kumar, R.; Surendran, P.K.; Thankappan, T.K.
    Antibacterial activity of shrimp shell based chitosan was determined against three food borne pathogens viz., Escherichia coli, Salmonella, and Pseudomonas aeruginosa isolated from seafoods. Tests were carried out in phosphate buffered saline (PBS) at pH 6.0. Four different concentrations, 0.01%, 0.03%, 0.05% and 0.1% (w/v) of chitosan were used against E.coli and Salmonella, and 0.01%, 0.05%, 0.5% and 1% were against P.aeruginosa. Chitosan showed stronger bactericidal activity against Salmonella compared to E.coli and P.aeruginosa as evidenced by 3 log cfu.ml super(-1) reduction in Salmonella count with 0.01% chitosan concentration. There was complete elimination of 5 log cfu.ml super(-1) cell count of Salmonella within 24 h at 0.1% chitosan level. There was 3 log reduction in E.coli count at 0.01% chitosan, but not completely inhibited even at the maximum used concentration (0.1%). The inhibition concentration against P.aeruginosa was higher level compared to Enterobacteriaceae and it was found that reduction in 5 log cfu.ml super(-1) was achieved only at 72 h of chitosan exposure. Different chitosan concentrations 0.05%, 0.1% and 1% had almost same inhibition pattern for P.aeruginosa at 6h. 18h 36h and 72h of exposure. The effectiveness of chitosan against tested pathogens showed Salmonella was most susceptible towards chitosan followed by E.coli and P.aeruginosa.
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    Isolation and Characterization of Shewanella putrefaciens from farm reared freshwater prawn and farm environment
    (Society of Fisheries Technologists (India), Cochin, India, 2006) Lalitha, K.V.; Surendran, P.K.
    Farmed Macrobrachium wscnbergii, farm water and mud were analysed for hydrogen sulphide producing bacteria including Sliauanella putrefaciens. The biochemical characteristics and spoilage potential of S. putrefaciens strains isolated from M. rosenbergii were investigated and compared to marine and brackishwater strains isolated from fish (Rastrclligcr kaiia$urta) and black clam( Villorita cyprinoides) respectively. The H2S producing bacteria including S. putrefaciens constituted a low proportion (<2% ) of the total aerobic flora of pond water and mud and 12% of the total aerobic population on fresh prawn. On icing, there was a lag or slight decrease in the counts of H2S producing bacteria including S. putrefaciens in the muscle of M. rosenbergii. The proliferation started on 16th day of iced storage and the count of sulphide producers reached ca. 6.25 log 1() cfu g "1 in prawn muscle at the time of rejection after 3 weeks. Gram-negative, non-fermentative, motile rods constituted 16-25% of the hydrogen sulphide producing bacteria on prawn muscle and intestine and they were identified as Shezuanella putrefaciens. The results indicate that S. putrefaciens is an important spoiler of freshwater prawn. All the S. putrefaciens isolates from M rosenbergii were able to produce. H2S and reduce TMAO and exhibited high spoilage potential. The present study suggests that counts of H2S producing bacteria can be a useful indicator of quality deterioration of farm reared M. rosenbergii.