The B. licheniformis CPQBA 571-12 DRM 07 was the only isolate that
showed inhibitory features against the pathogen V. alginolyticus BCCM
2068 with inhibition zone of 20 mmin diameter. This could be a probiotic
strain in tests in vivo formarine shrimp farming. A common way to
select probiotic candidates is conducting inhibition tests in vitro (Luis-
Villaseñor et al., 2011). Gullian et al. (2004) reported that the strain of
Bacillus P64 isolated from the hepatopancreas of L. vannamei had a
good inhibitory effect against V. harveyi S2 with inhibition zone of
15.3 mm in diameter. Similar results have been shown by Luis-
Villaseñor et al. (2011) with Bacillus spp. using the pathogens
V. parahaemolyticus (CAIM170) and V. harveyi (CAIM1793)with inhibition
zone diameters of 11 and 17.5mm, respectively. The Bacillus inhibitory
effects are attributed to the ability of these bacteria to secrete
substances, such as toxins, bacteriolytic enzymes, subproduct of primary
metabolic pathways, antibiotic substances and bacteriocins that may
exert a bacteriostatic or bactericidal effect on a wide range of Grampositives
and Gram-negatives, which also explains the inhibitory effect
on Vibrio (Schulz et al., 2005).