Dynamic Variation of Camel Gastrointestinal Bacterial Communities Contributing to Benzo(a)pyrene Degradation
Abstract Benzo(a)pyrene (BaP) is one of the most common organic pollutants in the environment, and its microbial removal has great ecological and economic value. Here, using BaP (50 mg/L) as the sole carbon source, dynamic changes in camel rumen and gut bacterial communities were analyzed by high-throughput sequencing. Next, cultivable BaP-degrading isolates were obtained, and their degradation characteristics were explored. The relative abundance of most bacteria in the gut and rumen underwent apparent changes after BaP treatment. The rumen and gut bacteria have the ability to degrade BaP but fluctuated during iterative culturing from the first to the fifth generation of gut communities displaying the highest BaP degradation efficiency (BDE) (74.4 and 81.1%, respectively). Moreover, 37 isolates exhibiting BDE were identified. Among these isolates, CL9 ( Klebsiella sp.), CL16 ( Ochrobactrum sp.), CC6 ( Ochrobactrum sp.), and CC16 ( Bacillus sp.) showed BDEs of up to 70.8, 69.3, 68.4, and 76.2%, respectively. The enzyme catechol-2,3-dioxygenase was involved in BaP degradation in these four BaP-degrading isolates and represented the main BaP degradation pathway in isolates CL9 and CL16; however, the relative expression level of the gene phnAc was higher in isolates CC6 and CC16 than in isolates CL9 and CL16. Our results provided promising bacterial resources for the removal of BaP and laid the foundation for the application of animal gastrointestinal bacteria to degrade environmental pollutants.
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