Effects of duckweed (Lemna polyrhiza) meal incorporated diet on enzyme producing autochthonous gut bacteria in fingerling mrigal, Cirrhinus mrigala (Hamilton)

Abstract

Effects of duckweed (Lemna polyrhiza) meal based diet on growth performance and enzyme-producing autochthonous gut bacteria of mrigal (Cirrhinus mrigala) fingerlings were investigated in a feeding trial lasting for 90 days. Lemna leaf meal incorporated diet resulted in the best growth performance of mrigal fingerlings. Population levels of amylase and cellulase-producing bacterial strains was recorded in higher densities than the protease-producing strains in the group of fish fed Lemna meal diet. The isolated gut bacteria were qualitatively screened and quantitatively assayed for amylase, cellulase, and protease activities. The Lemna meal diet resulted in increased activities of amylase by CMF6, isolated from the proximal intestine (PI) and cellulase by CMH9, isolated from the distal intestine (DI). The results indicate diet-associated differences in the production of extracellular enzymes by the gut bacterialrncommunity.