W Chu1, F Lu, W Zhu, C Kang. 1. Department of Microbiology, School of Life Science & Technology, China Pharmaceutical University, Nanjing, China. chuweihua2002@yahoo.com.cn
Abstract
AIMS: This work was aimed at identifying strains which can degrade quorum-sensing (QS) molecules from fish gut, with properties suitable for use as probiotic in aquaculture. METHODS AND RESULTS: A total of 200 strains were obtained from the intestine gut of Carassius auratus gibelio after enrichment in KG medium contained 500 μg l(-1) of C6-HSL as the sole source of carbon and nitrogen; one strain named QS inhibitor (QSI)-1 was identified as the genus Bacillus spp. by morphological phenotypes, and the strain also possessed an aiiA homologue gene using PCR amplification. In vitro, QSI-1 strongly interfered with violacein production by Chromobacterium violaceum. Coculture of QSI-1 with fish pathogen effectively reduced the amount of acyl-homoserine lactones (AHLs) and the extracellular proteases activity of Aeromonas hydrophila YJ-1. The oral LD50 of QSI-1 to fish was more than 10(11) CFU shown that it was avirulent to fish. Fish fed diet supplemented with QSI-1 had good survival, suggesting that QSI-1 showed protection against Aer. hydrophila infection. CONCLUSIONS: The results indicate that the isolate QSI-1 might have the potential possibility to be used as a probiotic in aquaculture. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report to describe a bacterium isolated from the intestine gut of C. auratus gibelio which can degrade AHLs and has the probiotic characteristics for its use in aquaculture.
AIMS: This work was aimed at identifying strains which can degrade quorum-sensing (QS) molecules from fish gut, with properties suitable for use as probiotic in aquaculture. METHODS AND RESULTS: A total of 200 strains were obtained from the intestine gut of Carassius auratus gibelio after enrichment in KG medium contained 500 μg l(-1) of C6-HSL as the sole source of carbon and nitrogen; one strain named QS inhibitor (QSI)-1 was identified as the genus Bacillus spp. by morphological phenotypes, and the strain also possessed an aiiA homologue gene using PCR amplification. In vitro, QSI-1 strongly interfered with violacein production by Chromobacterium violaceum. Coculture of QSI-1 with fish pathogen effectively reduced the amount of acyl-homoserine lactones (AHLs) and the extracellular proteases activity of Aeromonas hydrophila YJ-1. The oral LD50 of QSI-1 to fish was more than 10(11) CFU shown that it was avirulent to fish. Fish fed diet supplemented with QSI-1 had good survival, suggesting that QSI-1 showed protection against Aer. hydrophila infection. CONCLUSIONS: The results indicate that the isolate QSI-1 might have the potential possibility to be used as a probiotic in aquaculture. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report to describe a bacterium isolated from the intestine gut of C. auratus gibelio which can degrade AHLs and has the probiotic characteristics for its use in aquaculture.
Authors: Bidhan C De; D K Meena; B K Behera; Pronob Das; P K Das Mohapatra; A P Sharma Journal: Fish Physiol Biochem Date: 2014-01-14 Impact factor: 2.794