Characterization of <i>Vibrio</i> sp. strain <scp>AB15</scp> and <scp><i>Pseudomonas fluorescens</i></scp> strain <scp>NB14</scp> from the biofloc of shrimp culture ponds capable of high ammonia and nitrite removal efficiency
Le Dou, Wenbin Chen, Luqing Pan, Fei Huang
Abstract
Abstract The development of intensive aquaculture industry has aggravated the dangers of ammonia and nitrite in aquatic ecosystems. Probiotics have been widely used to maintain and improve water quality by removal of ammonia and nitrite in aquaculture. In this study, two facultative anaerobic strains AB15 and NB14, capable of efficient ammonia and nitrite removal, were isolated from biofloc, which acts as a natural micro‐flora storeroom in shrimp culture ponds, and were identified as Vibrio sp. and Pseudomonas fluorescens , respectively. The removal efficiency of ammonia and nitrite by AB15 and NB14 was 96.8 and 89.6%, respectively. The optimum conditions of AB15 and NB14 were as follows: temperature (25°C vs. 30°C), salinity (25‰ both), initial pH (7.5 vs. 8.0), C/N ratio (15 vs. 10). The two strains had great performance on inhibiting the common pathogens ( Vibrio harveyi , Vibrio splendidus , Vibrio anguillarum ) in aquaculture at concentrations of 10 5 –10 8 CFU/mL. Biosecurity assessment indicated that both AB15 and NB14 were harmless for survival and could be beneficial for the growth and immune enhancement of Litopenaeus vannamei . All results demonstrate that the two isolated strains have high promise for future applications of removing ammonia and nitrite and maintaining biosecurity in shrimp culture ponds.