Siju, Varghese M; Dr.Sarita,Bhat G(Cochin University of Science And Technology, October 11, 2013)
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Abstract:
The primary habitat of Salmonella is the gastrointestinal tract of
animals and they are discharged into the water bodies through the feces.
Aquatic animals act as asymptomatic reservoirs of a wide range of Salmonella
serotypes. The inevitable delay in the detection of Salmonella contamination
and the low sensitivity of the conventional methods is a serious issue in the
seafood industry. Due to the indiscriminate use, the antibiotics are finally
accumulated in the aquatic environment which provides the required antibiotic
stress for the emergence of more and more antibiotic resistant phenotypes ofSalmonella. Several genetic determinants like integrons, genomic islands etc.
play their role in acquisition and reshuffling of antibiotic resistance genes. A
large number of virulence determinants are required for Salmonella
pathogenicity. The virulence potential of Salmonella is determined, to some
extent, by the presence of phages or phage mediated genes in the bacterial
genome. There is much intra-serotype polymorphism in Salmonella and
epidemiological studies rely on genetic resemblance of the isolated strains.
Proper identification of the strain employing the traditional and molecular
techniques is a prerequisite for accurate epidemiological studies (Soto et al.,
2000).
In this context, a study was undertaken to determine the prevalence of
different Salmonella serotypes in seafood and to characterize them
Description:
Microbial Genetics Laboratory
Department of Biotechnology
Cochin University of Science and Technology
Jeena,Augustine; Dr.Sarita,Bhat G(Cochin University of Science and Technology, July 19, 2012)
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Abstract:
This thesis entitled Physicochemical and molecular characterization of bacteriophages ΦSP-1and ΦSP-3, specific for pathogenic Salmonella and evaluation of their potential as biocontrol agent . Salmonella were screened using standard methodologies from various environmental samples including chicken caecum. Salmonella strains, which were previously isolated and stocked in the lab, were also included in this study as host, for screening Salmonella specific lytic phages. The Salmonella strain in this study designated as S49 which helped in phage propagation by acting as host bacteria was identified as Salmonella enterica subsp. enterica by 16S rRNA gene analysis and serotyping .
A total of three Salmonella specific phage named as ΦSP-1, ΦSP-2 and ΦSP-3 were isolated from chicken intestine samples via an enrichment protocol employing the double agar overlay method. ΦSP-1 and ΦSP-3 showing consistent lytic nature were selected for further study and were purified by repeated plating after picking of single isolated plaques from the lawns of Salmonella S49 plates. Both the phages produced small, clear plaques indicating their lytic nature. ΦSP-1 and ΦSP-3 were concentrated employing PEG-NaCl precipitation method before further characterization.
The focus of present study was to isolate, characterize and verify the efficacy of lytic bacteriophages against the robust pathogen Salmonella, capable of surviving under various hostile conditions. Two phages, ΦSP-1 and ΦSP-3, belonging to two families, Podovoridae and Siphoviridae were isolated.
Description:
Department of Biotechnology, Cochin University of Science and Technology
Arul,James M; Dr.Samuel, C T(Cochin University of Science and Technology, May , 1983)
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Abstract:
This thesis deals initially with a literature reference survey ,taxonomy, their incidence in selected food fishes and shellfishes, and their incidence and distribution, their survival during different types of processing, their heat survival at temperatures of 50 ,55 and 60 degree centigrade their growth initiation at different low levels of pHs(4.0 to 10) ,and their developmental resistance to various chemical agents. The trials for the study were collected from various landing centre at cochin and the retail outlets. Based on these data collections the researcher was able to obtain more knowledge of the processing technology and the survival of pathogens like salmonella and vibrio parahaemolyticus.