Molecular Characterization and Gene Expression Profiling ... - CUSAT

Chapter 6
production of inhibitory compounds or by competition for nutrients, space
or oxygen (Fuller, 1989); Adherence and colonization of the probiotic
microbes thereby preventing the pathogens from inhabiting the gastro-
intestinal tract; production of essential nutrients to enhance the nutrition of
the cultured animals (Ahilan, 2003); reduction in the potential availability of
oxygen to pathogens; stimulation of humoral and/or cellular immune
response (Fuller, 1989); alteration of microbial metabolism by the increase or
decrease of the relevant enzyme level (Fuller, 1989); facilitation of improved
lactose utilization by lactic acid bacteria and detoxification of the metabolites
produced by intestinal pathogens.
Probiotics are a welcome addition to the armament of disease
prophylaxis in aquaculture although the technology and science behind it is
still very much in a developmental phase. In recent years there has been an
increasing interest to understand the relevance of microbial communities in
aquaculture systems and their importance in pond productivity (Moriarty,
1997). Reports on the potential of probiotics in shrimp aquaculture are,
however, on the increase. Although several of publications about the
probiotics and its role in aquaculture emerged (Moriarty, 1996; Mishra et al.,
2001; Ahilan, 2003; Haung, 2003; Nayak et al., 2003; Antony and Philip,
2008), the approach is generally empirical and the arguments with regard to
the mode of action are often circumstantial and have not been studied
systematically. The mode of action of probiotics is likely to be multi-factorial
and from existing evidence, appears to be strain specific (Touhy et al., 2003;
Antony and Philip, 2008). Variation in biochemical parameters (prophenol
oxidase activity and total haemocyte count) seems to be the usual criteria for
studying the effects of these probiotics in the experimental organism (Nappi
and Vass, 1993; Rodriguez and Le Moullac, 2000).
In some countries it is reported that probiotic use has significantly
reduced antibiotic use in shrimp hatcheries. Probiotics have been used to
Molecular Characterization and Gene Expression Profiling of Antimicrobial Peptides in Penaeid Shrimps
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