Enzyme producing bacterial flora isolated from fish digestive tracts

Isolation and enumeration of aerobic bacterial flora in the gastrointestinal tract of nine culturable freshwater teleosts, namely catla, rohu, mrigal, silver carp, grass carp, common carp, tilapia, walking catfish and murrel have been carried out. Amylolytic, cellulolytic, lipolytic and proteolytic microflora were identified from the culture plate using selective media. The isolates were qualitatively screened on the basis of their extracellular enzyme producing ability. The selected strains were further quantitatively assayed for amylase, cellulase, lipase and protease activities. Protease activity was exhibited by almost all the bacterial isolates, while strains isolated from tilapia, grass carp and common carp showed considerable amylolytic and cellulolytic activities. Maximum activity of lipase was exhibited by a strain isolated from silver carp. The study indicates that there is a distinct microbial source of the digestive enzymes - amylase, cellulase, lipase and protease, apart from endogenous sources in fish gut. The information generated from the present investigation might contribute towards better feed formulations for carp at low cost, incorporating the enzyme producing bacterial isolates as probiotics.