Preparation, purification and characteristics of an aflatoxin degradation enzyme from Myxococcus fulvus ANSM068.

摘要

Aims. To prepare, purify and characterize an extracellular enzyme from Myxococcus fulvus ANSM068, designated as myxobacteria aflatoxin degradation enzyme (MADE), which possesses degradation activity against aflatoxin B₁ (AFB₁), G₁ (AFG₁) and M₁ (AFM₁) in solution. Methods and Results. The culture supernatant of strain M. fulvus demonstrated high degradation ability against AFB₁ (71.89%), AFG₁ (68.13%) and AFM₁ (63.82%) after 48 h of incubation. An enzyme was purified from the supernatant of M. fulvus using ethanol precipitation and chromatography on DEAE-Sepharose and Superdex 75. An overall 166-fold purification of the enzyme with a recovery of 57% and a final specific activity of 569.44 x 103 U mg--1 was obtained using the present purification protocol. The apparent molecular mass of MADE was estimated to be 32 kDa by SDS-PAGE. AFG₁ and AFM₁ were significantly degraded, by 96.96 and 95.80%, respectively, when treated with pure MADE (100 U ml--1) produced by strain ANSM068. MADE exhibited the largest amount of activity at 35 degrees C and pH 6.0, with Mg2+ ions greatly promoting and Zn2+ strongly inhibiting MADE activity. Conclusions. An aflatoxin degradation enzyme from bacterial isolates can effectively remove aflatoxin B₁, G₁ and M₁ in solution. Significance and Impact of the Study. The high activity and wide temperature and pH range of MADE for the degradation of aflatoxin have promising applications in control of mycotoxins during food and feed processing.