Bacterial flora associated with the selected life stages and organs of farmed giant freshwater prawn Macrobrachium rosenbergii (de Man)

Abstract

Bacteria associated with different life stages of giant freshwater prawn (Macrobrachium rosenbergii de Man) were analyzed. The gill, hepatopancreas, haemolymph of brood and juveniles as well as the egg, larvae and larval rearing water were sampled to understand the quantity and the quality of bacteria associated with the animals.A total number of 93 representative isolates were identified. The identified bacterial isolates could be distributed in to 14 genera. A mean bacterial total plate count (TPC) of 4.5x105 colony forming units (cfu) g-1 in eggs, 6.0x106 cfu g-1 in larvae and 4.6x105 cfu ml-1 in water were observed. Among all the organs highest TPC of 3.5x107 cfu g-1 were observed in juvenile’s gills. The brood haemolymph was found to be devoid of any bacteria. Identification of isolates representing different colony morphotype indicated that 89.77% of the bacterial population was gram negative dominated by Aeromonas hydrophilla (16.74%), Enterobacter aerogenes (12.09%) and Citrobacter frundii (10.16%). Among Gram-positive bacteria Bacillus, Streptococcus and Micrococcus were identified. Study of quantitative and qualitative aspects of bacterial prevalence with the different life stages of M. rosenbergii would be helpful in identification of disease causing bacteria and therefore in better management of M.rosenbergii culture.