Degradation of aflatoxin B 1 by cell-free extracts of Rhodococcus erythropolis and Mycobacterium fluoranthenivorans sp. nov. DSM44556 T

Abstract

Biological degradation of aflatoxin B 1 (AFB 1) by Rhodococcus erythropolis was examined in liquid cultures and in cell-free extracts. Dramatic reduction of AFB 1 was observed during incubation in the presence of R. erythropolis cells (17% residual AFB 1 after 48 h and only 3–6% residual AFB 1 after 72 h). Cell-free extracts of four bacterial strains, R. erythropolis DSM 14303, Nocardia corynebacterioides DSM 12676, N. corynebacterioides DSM 20151, and Mycobacterium fluoranthenivorans sp. nov. DSM 44556 T were produced by disrupting cells in a French pressure cell. The ability of crude cell-free extracts to degrade AFB 1 was studied under different incubation conditions. Aflatoxin B 1 was effectively degraded by cell free extracts of all four bacterial strains. N. corynebacterioides DSM 12676 (formerly erroneously classified as Flavobacterium aurantiacum) showed the lowest degradation ability (60%) after 24 h, while >90% degradation was observed with N. corynebacterioides DSM 20151 over the same time. R. erythropolis and M. fluoranthenivorans sp. nov. DSM 44556 T have shown more than 90% degradation of AFB 1 within 4 h at 30 °C, whilst after 8 h AFB 1 was practicably not detectable. The high degradation rate and wide temperature range for degradation by R. erythropolis DSM 14303 and M. fluoranthenivorans sp. nov. DSM 44556 T indicate potential for application in food and feed processing.