Enzymatic Activities of Intestinal Bacteria Isolated from Farmed <i>Clarias gariepinus</i>

Abstract

The culturable bacteria associated with the digestive tract of a freshwater cultured fish, Clarias gariepinus , and their degradative abilities were established. The spread plate method was employed for bacterial isolation. The bacterial isolates were qualitatively screened for extracellular enzyme-producing ability using milk agar, starch agar, egg yolk agar and cellulose agar for protease, amylase, lipase and cellulase activities respectively. A total of 18 bacterial isolates were identified. Bacteria of the genera Bacillus , Staphylococcus , Vibrio , Aeromonas , Pseudomonas , Lactobacillus , Escherichia , Salmonella , Enterobacter , Micrococcus and Flavobacterium were isolated from fish digestive tract at different frequencies with Bacillus predominating. Enzymatic studies indicated that the bacterial isolates possess the ability to degrade proteins, starch, lipids and cellulose. The percentage composition of enzyme-producing bacteria are - protease producing strains (72.2%), lipase producing strains (61.1%), amylase producing strains (55.6%) and cellulose producing strains (38.9%). All the isolates possessed multienzyme activity. An isolate ( Bacillus sp. B 1 ) showed activity for protease, amylase, lipase and cellulase enzymes. Therefore, the isolated indigenous multiple enzyme-producing strains can be effectively exploited for use as probiotics while formulating aquafeeds.