Ochratoxin A biocontrol and biodegradation by Bacillus subtilis CW 14

BACKGROUND: Ochratoxin A (OTA) is a mycotoxin produced by some Aspergillus and Penicillium species. In this study a strain of Bacillus subtilis was tested for its effects on OTA-producing Aspergillus and OTA degradation. The mechanisms of the effects were also investigated. RESULTS: A strain of Bacillus spp. isolated from fresh elk droppings was screened out using the methods described by Guan et al. (Int J Mol Sci 9:1489(-1)503 (2008)). The 16S rRNA gene sequence suggested that it was B. subtilis CW 14. It could inhibit the growth of the OTA-producing species Aspergillus ochraceus 3.4412 and Aspergillus carbonarius, with inhibition rates of 33.0 and 33.3% respectively. At 6 mu g mL(-1) OTA, both viable and autoclaved (121 degrees C, 20 min) cells of CW 14 bound more than 60% of OTA. In addition, OTA was degraded by the cell-free supernatant of CW 14. By high-performance liquid chromatography, the cell-free supernatant degraded 97.6% of OTA after 24 h of incubation at 30 degrees C, and no degradation products were produced. The fastest degradation occurred during the first 2 h. In 3 g samples of contaminated maize, 47.1% of OTA was degraded by 50 mL inocula of overnight cultures of CW 14. CONCLUSION: These findings indicated that B. subtilis CW 14 could both prevent OTA contamination and degrade OTA in crops. (C) 2013 Society of Chemical Industry