2021

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Browsing 2021 by Author "Abdulla, Mohamed Hatha"

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    Efficacy of a Closed Water Depuration System with Charcoal filter on the Bacteriological quality of Villorita cyprinoides var. cochinensis (Hanley, 1866)
    (Society of Fisheries Technologists (India)Cochin, 2021) Antony, Ally C.; Silvester, Reshma; Aneesa, P. A; Francis, Bini; Abdulla, Mohamed Hatha
    Bivalves are good bio-indicators of the sanitary quality of the aquatic bodies in which they survive. The sanitary quality of the shellfish harvesting areas is assessed based on the faecal coliforms/E. coli levels of the harvesting water/shellfish tissue; on exceeding the regulatory limits depuration suggested. In the present study, the efficacy of a closed water depuration system attached with a charcoal filter to depurate Indian black clams (Villorita cyprinoides var. cochinensis (Hanley, 1866) was evaluated. The depuration system consisted of a closed water holding glass tank, with a wall-hung immersion water pump which re-circulated (18 l min-1) the seawater [salinity – 10 ppt, pH -7.3, ambient temperature (29-30°C)] through a coconut shell based activated carbon (charcoal) filter. Clams were sampled at time intervals of 0, 6, 12, 24, 72, and 96 h to assess the reduction of total coliforms (TC), faecal coliforms (FC) and faecal streptococci (FS). Initial TC, FC, FS and Salmonella loads were assessed using standard microbiological methods. Salmonella was not detected in any of the clam samples. Complete removal of both FC and FS whose initial loads were 4.6 x 104 MPN 100 g-1 and 1.1 × 105 MPN 100 g-1 respectively was observed within 48 h. Maximum rate of depuration of TC, FC as well as FS were observed during the initial first 6 h. However, TC could not be fully depurated even after 96 h of depuration. The differences in the depuration rates of TC, FC and FS were found to be statisticallysignificant (p<0.05). The FC load of the black clams selected for the study conformed only to the class C shellfish growing area of EU which could be reduced to acceptable regulatory limits of <230MPN 100 g-1 of depurated shellfish; which proved the system used is efficient. The system uses simple, cost-effective, easily available, natural, and renewable water treating agent such as coconut shellbased activated carbon and is suitable for household purposes. In India, black clams do not have much export value and is also not preferred to be eaten raw. Hence less stringent, cost-effective, and simple depuration measures as mentioned above may be sufficient enough to meet the required sanitary quality as it is consumed only after proper cooking.
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    Prevalence of Biofilm associated Pathogenic Escherichia coli in Seafood Pre-processing factories - A potential threat to seafood safety
    (Society of Fisheries Technologists (India)Cochin, 2021) Francis, Bini; Abdulla, Mohamed Hatha
    Microbial adhesion and biofilm formation on food contact surfaces in the seafood industry pose major problems and risks to human health. Escherichia coli is a common inhabitant of the intestinal tract of humans and animals and can be easily disseminated in different ecosystems through the food chain and water causing serious infection in human beings. The present study attempted to analyse the biofilm forming capacity of 90 E. coli strains isolated from food contact surfaces in seafood pre-processing plants. Quantification of biofilm formation was done by microtiter plate assay. Among them, 20% of the isolates were strong biofilm producers, 26.67% and 13.33% were moderate and weak producers respectively. Biofilm production was not observed in 40% of the isolated E. coli. All the strong biofilm producers were exo-enzyme producers, which is indicative of their capability in reducing the nutritional value of food and causing spoilage. In addition, the distribution of the genes encoding virulence and biofilm functions in strong biofilm forming E. coli isolates were examined. Multiplex PCR analysis revealed the presence of shiga toxin genes stx1 (44.44%), and stx2 (77.78%), intimin (eae, 38.89%) and enterohemolysin genes (hlyA, 66.67%). Biofilm-associated genes, sdiA and rpoS (100%), were most prevalent, while rcsA (55.56%) was least prevalent in strong biofilm producing E. coli strains. Field emission scanning electron microscopy (FESEM) showed that strain with strongest biofilm producing capability by in vitro methods establishedbiofilm on stainless steel, plastic and rubber. The findings of this study revealed that food contact surfaces in seafood pre-processing plant harbors biofilm forming E. coli, indicating chance of contamination of seafood with E.coli and high risk of seafood-related illnesses in humans