Aflatoxin B₁ removal by three bacterial strains and optimization of fermentation process parameters

Abstract

Aflatoxin B1 (AFB1) removing bacterial strains were isolated from different habitats that were easily contaminated by AFB1. Furthermore, the composition of the fermentation medium and conditions of fermentation process were optimized, including carbon source, nitrogen source, metal ions, temperature, initial pH value, inoculation volume, and culture broth volume. Using coumarin as the sole carbon and energy source, we primarily screened 31 strains, and 10 strains were found to be capable to remove AFB1. Among them, the highest removal rate of 71.91% appeared in those isolated from rotten wood (poplar). Strains XY1, XY3, and T6 were carried out to identify, and the results were Klebsiella sp., Klebsiella pneumonia, and Pantoea sp., respectively. Corn cob powder and tryptone can significantly increase the AFB1 removal activity of these strains. The AFB1 removal activity of Klebsiella sp.XY1 and K. pneumonia XY3 can be enhanced by Ca2+, and those of Pantoea sp. T6 can be enhanced by Cu2+. Temperature and initial pH were positively correlated with the AFB1 removal activity of these strains in a certain range. This study not only provides reference for the screening and application of AFB1 removing bacteria, but also provides a basis for possible application in the food and feed industry.

Inhibition of Aflatoxin Production in Aspergillus flavus by a Klebsiella sp. and Its Metabolite Cyclo(l-Ala-Gly)

“…As a report has demonstrated that Klebsiella sp. degrades AF [ 18 ], the AF degradation activity of the strain KTTM was examined. When AFB 1 was added to a liquid medium and the strain KTTM was cultured in the medium for 3 days, the concentration of AFB 1 in the culture broth was consistent with that of the control in which AFB 1 was kept in the liquid medium without inoculation of the bacterium for 3 days ( Figure 5 ).…”

“…The culture supernatant of two Klebsiella sp. strains was reported to degrade AF [ 18 ], as the amount of AF decreased by approximately 70% after incubation with the culture supernatant for 3 days. Compared to the activity of the reported strains, that of the strain KTTM was weak.…”