Abstract:
The aim of this study was to screen strains capable of simultaneously degrading
AFB
1 and ZEN from soil samples, fermented food, animal manure, as
well as moldy peanuts and corn collected from multiple provinces across the
country. The results showed that the strain
Bacillus
amyloliquefaciens HNGD-Yq12 isolated from Chongqing maize-field soil
exhibited degradation capabilities for both AFB
1 and ZEN in its
cell-free culture supernatant at 40 °C under neutral pH conditions, with
degradation rates of 91.1% and 94.6%, respectively. The
temperature-optimization experiments demonstrated that 40 °C was the optimal temperature for the degradation enzyme of
this strain. When the temperature deviates from this range, the degradation efficiency is reduced,
and, in particular, at temperatures below 30 °C the enzyme activity is markedly diminished, a pattern
consistent with the typical activity-temperature characteristics of most
microbial enzymes. Mn
2+ significantly promoted the degradation of
both AFB
1 and ZEN, whereas Cu
2+ specifically enhanced the
degradation of AFB
1. The metal-ion influence experiments suggested
that different metal ions exert distinct regulatory effects on the degradation
process. Notably, Mn
2+ may serve
as a cofactor or activator for certain degradation enzymes, whereas the
specific promotion of AFB
1 degradation by Cu
2+ suggests that the degradation
pathways of the two toxins may involve distinct enzymatic systems. Furthermore,
based on analysis using ultra-performance liquid chromatography-mass
spectrometry (UPLC-MS), AFB
1 was transformed into C
16H
14O
5 and C
14H
12O
4, whereas ZEN was converted into
13-OH-ZEN-quinone (C
18H
20O
6) . It is
speculated that the toxic structures of these mycotoxins have been disrupted.
Mass-spectrometric fragment analysis further revealed that the furan ring and
coumarin moiety of AFB
1 may undergo ring-opening reactions, while
the lactone ring of ZEN was opened and subsequently oxidized; these structural
alterations are identified as the key modifications responsible for the
reduction in toxicity. In practical applications, treating peanut powder and
corn powder with this strain achieved detoxification rates of 72.18% and 67.29%
for AFB
1 and ZEN, respectively. In conclusion,
Bacillus amyloliquefaciens HNGD-Yq12
exhibits excellent application potential in the simultaneous degradation of
multiple mycotoxins. Future research will focus on the isolation,
purification, and identification of
degradation-active components, the cloning and heterologous expression of
degradation gene clusters, and the development of enzyme preparation processes
applicable to large-scale production to facilitate the translation of this technology from laboratory
research to practical application.