Microbial Degradation of Benzimidazole Fungicide Carbendazim by Bacillus velezensis HY-3479

Abstract

Abstract Carbendazim (Methyl benzimidazol-2-ylcarbamate: MBC) is a fungicide of the benzimidazole group which is widely used in the cultivation of pepper, ginseng, and many other crops. To remove the remnant carbendazim, many rhizobacteria are used as biodegradation agents. A bacterial strain of Bacillus velezensis HY-3479 was found to be capable of degrading MBC in M9 minimal medium added with 250 mg/L carbendazim. The strain had a significantly higher degradation rate compared to the control strain Bacillus subtilis KACC 15590 in HPLC analysis and HY-3479 had the best degradation rate of 76.99% at 48 hours. In gene expression analysis, upregulation of carbendazim degrading genes (mheI, hdx) was observed in the strain. HY-3479 was able to use MBC as the sole source of carbon and nitrogen but the addition of 12.5 mM NH4NO3 significantly raised the degradation rate. HPLC analysis showed that the degradation rate increased to 87.19% when added with NH4NO3. Relative gene expression of mheI and hdx also increased higher for samples with NH4NO3 supplement. The enzyme activity of carbendazim degrading enzyme and the 2-aminobenzimidazole degrading enzyme was found to be highly present in the HY-3479 strain. The biodegrading activity of strain HY-3479 may be developed as useful means for bioremediation and used as a potential microbial agent in sustainable agriculture.