Isolation of a novel dextransucrase producer from the intestine of Harpadon nehereus

Lactobacilli are almost ubiquitous and are found in a variety of ecological niche including the gastrointestinal tract of humans and animals. The current study was aimed at understanding the diversity of lactobacilli in the intestinal microflora of Bombay duck (Harpadon nehereus). A total of 23 isolates were obtained from the 15 fish samples procured from Ferry Wharf (Bhaucha Dhakka). After confirming the purity of the isolates, they were subjected to microscopic and biochemical analysis and were characterized up to the species level. Out of the 23 isolates obtained, 6 of them were found to belong to L.brevis, 9 belonged to L.plantarum, 7 belonged to L.fermentum whereas 1 belonged to L.confusus. These isolates were further evaluated for their ability to produce dextransucrase. Out of the 23 isolates, only L.confusus demonstrated this ability and produced 4.98 DSU/ml of the enzyme. The identity of L.confusus was further confirmed by determining its 16S rRNA gene sequence. Owing to its ability to produce dextransucrase and being GRAS, this novel isolate is a potential candidate for industrial production of dextransucrase and thereby dextran.