Bacterial flora associated with the giant freshwater prawn Macrobrachium rosenbergii, in the hatchery system

The objective of this study was to understand the microbial flora associated with the hatchery system of giant fresh water prawn, Macrobrachium rosenbergii during an entire rearing cycle. Bacteriological and physico-chemical analysis was done for different samples of water, larvae, and Artemia. The total bacterial load in well water, seawater and inlet water varied from 10(1) to 10(5) cfu ml(-1) with higher counts seen in larval rearing tank (LRT) water. The Vibrio count ranged between 10(1) to 10(3) cfu ml(-1). Larval samples harboured a bacterial load of 10(6) to 10(7) cfu/10 larvae. The bacterial load in Artemia hatching water ranged from 4.90 x 104 to 5.63 x 10(6) cfu ml(-1) while Artemia had a load ranging from 1.08 x 10(7) to 2.09 x 10(9) cfu g(-1). Vibrio count in the LRT water ranged from 10(1)-10(3) cfu ml(-1) while the count in larvae ranged from 10(2) to 10(4) cfu/10 larvae. The bacterial genera were predominantly Gram-negative and comprised of Aeromonas spp., Pseudomonas spp., Vibrio spp. and Bacillus spp. and non-spore formers (NSF) were the dominant Gram-positive bacteria. This study documents the bacterial flora associated with Macrobrachium hatchery system during a regular normal run. Knowledge of the qualitative and quantitative aspects of bacterial flora in the hatchery would help to understand disturbances, if any, brought about during disease outbreaks. (c) 2006 Elsevier B.V. All tights reserved.