Enzyme-producing bacteria isolated from fish gut: a review


  • A.K. Ray,

    Corresponding author
    • Fisheries Laboratory, Department of Zoology, Visva-Bharati University, Santiniketan, West Bengal, India
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  • K. Ghosh,

    1. Aquaculture Laboratory, Department of Zoology, University of Burdwan, Burdwan, West Bengal, India
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  • E. Ringø

    1. Norwegian College of Fishery Science, Faculty of Biosciences, Fisheries and Economics, University of Tromsø, Tromsø, Norway
    2. Aquaculture Protein Centre (a CoE), Department of Aquatic Medicine and Nutrition, Norwegian School of Veterinary Medicine, Oslo, Norway
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Correspondence: Arun Kumar Ray, Fisheries Laboratory, Department of Zoology, Visva-Bharati University, Santiniketan-731 235, West Bengal, India. E-mail: aray51@yahoo.com, arun_ray1@rediffmail.com


Digestion of food depends on three main factors: (i) the ingested food and the extent to which the food is susceptible to the effects of digestive enzymes, (ii) the activity of the digestive enzymes and (iii) the length of time the food is exposed to the action of the digestive enzymes. Each of these factors is affected by a multitude of secondary factors. The present review highlights the experimental results on the secondary factor, enzymatic activity and possible contribution of the fish gut microbiota in nutrition. It has been suggested that fish gut microbiota might have positive effects to the digestive processes of fish, and these studies have isolated and identified the enzyme-producing microbiota. In addition to Bacillus genera, Enterobacteriaceae and Acinetobacter, Aeromonas, Flavobacterium, Photobacterium, Pseudomonas, Vibrio, Microbacterium, Micrococcus, Staphylococcus, unidentified anaerobes and yeast are also suggested to be possible contributors. However, in contrast to endothermic animals, it is difficult to conclude the exact contribution of the gastrointestinal microbiota because of the complexity and variable ecology of the digestive tract of different fish species, the presence of stomach and pyloric caeca and the relative intestinal length. The present review will critically evaluate the results to establish whether or not intestinal microbiota do contribute to fish nutrition.