Isolation and characterization of potential lactic acid bacteria (LAB) from freshwater fish processing wastes for application in fermentative utilisation of fish processing waste

Proteolytic and/or lipolytic lactic acid bacteria (LAB) were isolated from visceral wastes of different fresh water fishes. LAB count was found to be highest in case of visceral wastes of Mrigal (5.88 log cfu/g) and lowest in that of tilapia (4.22 log cfu/g). Morphological, biochemical and molecular characterization of the selected LAB isolates were carried out. Two isolates FJ1 (E. faecalis NCIM5367) and LP3 (P. acidilactici NCIM5368) showed both proteolytic and lipolytic properties. All the six native isolates selected for characterization showed antagonistic properties against several human pathogens. All the native isolates were sensitive to antibiotics cephalothin and clindamycin; and, resistant to cotrimoxazole and vancomycin. Considering individually, P. acidilactici FM37, P. acidilactici MW2 and E. faecalis FD3 were sensitive to erythromycin. The two strains FJ1 (E. faecalis NCIM 5367) and LP3 (P. acidilactici NCIM 5368) that had both proteolytic and lipolytic properties have the potential for application in fermentative recovery of lipids and proteins from fish processing wastes.

Lipid classes and fatty acid profile of selected Indian fresh water fishes.

Lipid extracts from meat, head and viscera of Indian fresh water fishes, viz., catla, rohu, mrigal, common carp and tilapia were analyzed for lipid class distribution and fatty acid profile. The yield of meat ranged from 66.0-79.5% and total lipid content in meat was 0.8-3.8%. The total lipid content was higher (>4.0%) in head and viscera. Neutral lipids constituted 71.5-93.3% of the total lipid extract. Higher glycolipid content of 25.2% was observed in lipid extract from meat of common carp and higher phospholipid content (13.7%) was observed in lipid extract from meat of mrigal. Hydrocarbons, sterolesters and triacylglycerol were the major fractions of neutral lipids. Unsaturated fatty acids dominated in all the samples. Palmitic and oleic acids were the major fatty acids found in all the lipid extracts. Docosahexaenoic acid content was higher than 3% in lipid extract from meat of all the fishes. However, in most of the fishes, the content of eicosapentaenoic acid and docosahexaenoic acid were higher in visceral lipids.