Inhibitory effects of Bacillus probionts on growth and toxin production of Vibrio harveyi pathogens of shrimp.
OBJECTIVE
To investigate the effects of Bacillus subtilis, Bacillus licheniformis and Bacillus megaterium in terms of toxin and growth of pathogenic Vibrio harveyi.


RESULTS
Three Bacillus probionts were isolated from probiotic BZT aquaculture and identified using a 16S rDNA sequence. Growth inhibition assay showed that supernatants from the 24-h culture of three Bacillus species were able to inhibit the growth of V. harveyi (LMG 4044); B. subtilis was the most effective based on the well diffusion method. Results of a liquid culture model showed that B. subtilis was also widely effective in inhibiting three strains of V. harveyi (isolated from Thailand, the Philippines and LMG 4044), and that both B. licheniformis and B. megaterium inhibit the growth of V. harveyi isolated from the Philippines. Moreover, a haemolytic activity assay demonstrated that V. harveyi (IFO 15634) was significantly decreased by the addition of B. licheniformis or B. megaterium supernatant.


CONCLUSIONS
Bacillus subtilis inhibited Vibrio growth, and both B. licheniformis and B. megaterium suppressed haemolytic activity in Vibrio.


CONCLUSIONS
The cell-free supernatants produced by Bacillus probionts inhibit Vibrio disease, and Bacillus probionts might have an influence on Vibrio cell-to-cell communications.
Nakayama
T
T
Ninewells Hospital Medical School, University of Dundee, UK.
Lu
H
H
Nomura
N
N
D000818:Animals; D000898:Antibiosis; D017756:Aquaculture; D001407:Bacillus / Q000145:classification / Q000502:physiology*; D001427:Bacterial Toxins / Q000378:metabolism; D015373:Bacterial Typing Techniques; D006460:Hemolysin Proteins / Q000378:metabolism; D050296:Microbial Viability; D033561:Penaeidae / Q000382:microbiology*; D019936:Probiotics; D014733:Vibrio / Q000254:growth & development* / Q000378:metabolism / Q000472:pathogenicity; D014735:Vibrio Infections / Q000382:microbiology
D001427:Bacterial Toxins; D006460:Hemolysin Proteins