Genomics analysis of the steroid estrogen-degrading bacterium Serratia nematodiphila DH-S01

At present, the oestrogens detected in the environment have been classified as group 1 carcinogens by the World Health Organization. They have obvious effects on organisms at extremely low environmental concentration (1.0 ng/L) and easily accumulate in the ecosystem, which has adverse effects on the environment and ecological health. The use of microbial degradation to remove steroid estrogens from polluted environments has received increasing attention. In this study, a bacterium capable of degrading 17β-estradiol was isolated from a sewage treatment plant in Jilin, China, and identified as Serratia nematodiphila DH-S01. The results of degradation experiments showed that after culturing the bacteria for 4 days, the degradation rate of oestrone and 17β-estradiol at 15 mg/L reached 93.47% and 93.2%, respectively. Genome-wide sequencing showed that the genome of strain DH-S01 consists of a single circular chromosome, 5,256,558 bp in length, which contains 4,874 predicted coding genes. Based on genome annotation, high abundance genes are related to the metabolism of terpenoids and polyketides. Nine types of sterol- and oestrogen-degrading enzymes were annotated in this strain, and the existence and expression of the enzymes were analyzed by polymerase chain reaction (PCR) and reverse transcription polymerase chain reaction (RT-PCR). Comparative genomic analysis showed that there are genes encoding eight enzymes in the common genes of the four Serratia strains, highlighting the potential of the other three Serratia strains to degrade steroid estrogen.