Lactobacillus fermentum on ammonia reduction and growth promotion of Macrobrachium rosenbergii post-larvae, and in vitro competitive exclusions of pathogenic bacteria

Abstract

The effect of a probiotic bacterium, Lactobacillus fermentum on ammonia reduction and growth promotion of Macrobrachium rosenbergii post-larvae, and in vitro competitive exclusion of certain pathogenic bacteria, Shigella sonnei, Salmonella bongori, Klebsiella pneumoniae, Escherichia coli and Pseudomonas aeruginosa were studied. It was also aimed to recommend the ideal quantum of water for maintenance of M. rosenbergii PL. L. fermentum was viable in the feed even on day 15 after the feed was formulated, and hence, the feed was freshly prepared once in 15 days and fed to experimental PL. Three groups of prawns (0.09±0.02 g) consisted of 15, 30 and 45 PL respectively were maintained with 25 L of ground water irrespective of number of PL. Each group was fed with 0.5, 1.0 and 1.5% of L. fermentum incorporated diet for a period of 60 days without renewing the water medium. Control was received the feed without incorporation of L. fermentum. Up to 30 days, there was no mortality of PL observed in any of the three experimental as well as control groups. The results revealed that up to 1.8 PL staged prawns can be maintained per liter of water without mortality for 30 days (1.8 PL l-1). The mortality was related with density of PL, ammonia content and concentration of L. fermentum in the aquarium. The ammonia concentration was found to be significantly reduced in each experimental group when compared with control. After 30 days, the survival rate was found to be the best in the experimental group maintained with 30 PL (1.2 PL l-1) and fed with 1% of L. fermentum incorporated feed, followed by 0.5% and 1.5% when compared with control. In this group, the nutritional indices, such as weight gain, specific growth rate, food conversion ratio and protein efficiency ratio were also found to be the best. The concentrations of total protein, amino acid, carbohydrate and lipid were also found to be significantly (P