Isolation and selection of purple non-sulfur bacteria for aquaculture uses

Abstract

Purple non-sulfur bacteria are facultative photosynthetic bacteria and have potential use as bioremediation in aquaculture. The aims of this study were to isolate and to characterize the purple non-sulfur bacteria (PNSB) from shrimp pond sediment and water for further aquaculture application. Results showed that a total of 55 bacterial isolates were selected from sediment and water samples from extensive shrimp ponds in Ca Mau, Bac Lieu, and Tra Vinh provinces. Most of isolates were gramnegative and grew well in glutamate acetate (GA) broth displaying in pink or red culture under microaerobic-light and aerobic-dark conditions. Among isolates, thirteen isolates were selected based on the in vitro growth in GA medium under both anaerobic-light and aerobic-dark conditions. In addition, they also showed amylolytic, lipolytic and proteolytic activities. Especially, the BL3-TC, CM5.2N and BL1.2N strains had the highest extracellular enzyme activities. Interestingly, all thirteen isolates showed ammonium removal activity with values in a range of 21.3%-52.5% and sulfide removal ability from 49 to 87% after 5 days of incubation, of which CM5.2N strain was considered to be a promising candidate for further water treatment application in aquaculture systems.