Bacteria Associated with Biofilms in a Macrobrachium rosenbergii Hatchery

Abstract

Biofilms are important biological structures formed on most submerged aquatic surfaces. They comprise a unique niche wherein a community of microorganisms co-exist. The study was undertaken to identify the bacterial flora associated with biofilms formed on the surface of larval rearing tanks in a prawn hatchery. Surface swabs of two randomly chosen larval rearing tanks in a hatchery were taken regularly throughout the hatchery cycle and the bacterial loads were estimated. The counts varied from 1.8x103 to 4.3x104 CFU.cm-2 in Tank I and 5.1x103 to 3.5x104 CFU.cm-2 in Tank II. No significant difference was observed between Tank I and Tank II in respect of biofilm bacterial count when enumerated (p<0.05). The common bacterial genera isolated in both tanks comprised gram-negative bacteria including Pseudomonas, Vibrio and Aeromonas. Bacillus and other non-spore formers were the predominant gram-positive bacteria isolated. Bacteria associated with biofilms are more resistant to antibiotics and water sanitizers generally used in tank water treatment. Biofilms can be a reservoir of pathogens and bacteria such as Pseudomonas, Aeromonas and Vibrio isolated from the biofilms in this study may be potential pathogens of prawn larvae in hatcheries.

Actinomycetes as a promising candidate bacterial group for the health management of aquaculture systems: A review

“…Many phenotypes are modulated (or controlled) by it, including biofilm formation, antibiotic synthesis, and virulence factor such as motility and lytic enzyme production. 150,[156][157][158][159] In addition, they can also serve as reservoirs of pathogens thereby leading to recurrent infections. 160,161 The use of therapeutic chemicals that interfere with the QS system was considered to be a novel anti-infective strategy in aquaculture.…”

“…The formation of biofilm is regulated by a cell density‐dependent phenomenon called quorum sensing (QS), 155 and is one of the targets regulating systems in the bacterial physiological process (QS). Many phenotypes are modulated (or controlled) by it, including biofilm formation, antibiotic synthesis, and virulence factor such as motility and lytic enzyme production 150,156–159 . In addition, they can also serve as reservoirs of pathogens thereby leading to recurrent infections 160,161 .…”