Inhibitory effect of Bacillus megaterium on aflatoxin biosynthetic pathway genes expression of Aspergillus flavus in peanuts
Previous studies in our laboratory demonstrated that a marine Bacillus megaterium could inhibit the growth of Aspergillus flavus and turn off the biosynthesis of aflatoxin B<sub>1</sub>. In order to investigate the mechanisms of inhibition by B. megaterium on A. flavus growth and aflatox...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Zhejiang University Press
2015-09-01
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| Series: | 浙江大学学报. 农业与生命科学版 |
| Subjects: | |
| Online Access: | https://www.academax.com/doi/10.3785/j.issn.1008-9209.2015.03.061 |
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| Summary: | Previous studies in our laboratory demonstrated that a marine Bacillus megaterium could inhibit the growth of Aspergillus flavus and turn off the biosynthesis of aflatoxin B<sub>1</sub>. In order to investigate the mechanisms of inhibition by B. megaterium on A. flavus growth and aflatoxin production in peanuts and to evaluate the possible application of B. megaterium as a biocontrol agent, genes expression analysis using whole A. flavus genome gene chip when A. flavus was co-cultured with B. megaterium in peanuts were performed.The aim of this research was to study the inhibitory effect of B. megaterium on aflatoxin biosynthetic pathway genes expression in A. flavus. The effects of B. megaterium on aflatoxin biosynthesis and genes expression in A. flavus were tested in two types of peanut varieties, UF 715133-1 and Jinhua 1012 by the aid of high performance liquid chromatography (HPLC), gene chip and quantitative real-time polymerase chain reaction (qRT-PCR). UF 715133-1 is a kind of peanut that could resist to A. flavus invasion, while Jinhua 1012 is susceptible to the infection of A. flavus.The results showed that though more than 85% of aflatoxin B<sub>1</sub> was inhibited by the treatment of B. megaterium in UF 715133-1 and Jinhua 1012, no important aflatoxin biosynthetic pathway gene was differentially expressed. Peanuts unsuitable for the growth of B. megaterium was the main reason for B. megaterium unthoroughly inhibit the biosynthesis of aflatoxin like in minimal medium (MM) or potato dextrose broth (PDB). Furthermore, the experimental condition (28 ℃, relative humidity 85%), which is the optimal condition for aflatoxin biosynthesis, wasn't suitable for the growth of B. megaterium neither. So we inferred that B. megaterium inhibited aflatoxin biosynthesis by inhibiting the growth of A. flavus in peanuts, and the secondary metabolites in B. megaterium accounted for the inhibition. Furthermore, the results showed some coding protease genes were highly downregulated, such as short-chain dehydrogenase, and non-ribosomal peptide synthetase, which may relate to aflatoxin biosynthesis.In conclusion, this strain of marine B. megaterium isolated from the Yellow Sea of East China could significantly inhibit the aflatoxin biosynthesis in peanuts through inhibiting genes expression in A. flavus. While the role of most highly downregulated genes in aflatoxin biosynthesis hasn't been clarified, the mechanism remains to be further studied. |
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| ISSN: | 1008-9209 2097-5155 |