Isolation and characterization of new potential probiotic bacteria based on quorum-sensing system.
OBJECTIVE
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.


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.


CONCLUSIONS
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.
Chu
W
W
Department of Microbiology, School of Life Science & Technology, China Pharmaceutical University, Nanjing, China. chuweihua2002@yahoo.com.cn
Lu
F
F
Zhu
W
W
Kang
C
C
D054742:Acyl-Butyrolactones / Q000378:metabolism; D016980:Aeromonas hydrophila / Q000201:enzymology / Q000378:metabolism; D000818:Animals; D017756:Aquaculture; D001419:Bacteria / Q000302:isolation & purification; D005393:Fish Diseases / Q000517:prevention & control*; D005798:Genes, Bacterial; D006054:Goldfish / Q000382:microbiology; D016905:Gram-Negative Bacterial Infections / Q000517:prevention & control; D007422:Intestines / Q000382:microbiology; D010447:Peptide Hydrolases / Q000096:biosynthesis; D019936:Probiotics / Q000627:therapeutic use*; D053038:Quorum Sensing
D054742:Acyl-Butyrolactones; D010447:Peptide Hydrolases