Whole genome sequencing and analysis of benzo(a)pyrene-degrading bacteria Bacillus cereus M72-4.

Abstract

Benzo(a)pyrene produced by food during high-temperature process enters the body through ingestion, which causes food safety issues to the human body. To alleviate the harm of foodborne benzo(a)pyrene to human health, a strain that can degrade benzo(a)pyrene was screened from Kefir, a traditional fermented product in Xinjiang. Bacillus cereus M72-4 is a Gram-positive bacteria sourced from Xinjiang traditional fermented product Kefir; under benzo(a)pyrene stress conditions, there was 69.39% degradation rate of 20 mg/L benzo(a)pyrene by strain M72-4 after incubation for 72 h. The whole genome of M72-4 was sequenced using PacBio sequencing technology in this study. The genome size was 5754 801 bp and a GC content was 35.24%; a total of 5719 coding genes were predicted bioinformatically. Through functional database annotation, it was found that the strain has a total of 219 genes involved in the transportation and metabolism of hydrocarbons, a total of 9 metabolic pathways related to the degradation and metabolism of exogenous substances, and a total of 67 coding genes. According to the Kyoto Encyclopedia of Genes and Genomes database annotation results, a key enzyme related to benzo(a)pyrene degradation, catechol 2,3-dioxygenase, was detected in the genome data of Bacillus cereus M72-4, encoding genes dmpB and xylE, respectively. There are also monooxygenases and dehydrogenases. Therefore, it can be inferred that this strain mainly degrades benzo(a)pyrene through benzoate metabolic.