Identification and genome analysis of strain JLU460ET, a novel steroid-degrading bacterium.

In this work, JLU460ET isolated from animal waste was confirmed to have great degradation capability for 17β-estradiol and testosterone. This bacterium could degrade nearly 90% of 17β-estradiol (5 mg L) in 4 days and transform it into estrone for further degradation. One hundred percent testosterone (144 mg L) could be completely degraded after 9 h of incubation. This is the first report of strains with the ability to degrade both estrogens and testosterone. The whole genome sequence of JLU460ET was obtained and annotated, containing one chromosome (5,497,097 bp) with 61.37% GC content. A total of 4805 protein-coding genes and 134 RNA genes (including 29 rRNA genes, 102 tRNA genes and three ncRNA genes) were identified. Furthermore, the complete genome sequence of JLU460ET was compared with four other strains. Altogether, these five strains contain 3508 core genes and 7616 pan genes. A steroid degradation pathway including 11 steroid degradation genes exists in core genes of five strains. Twenty-two steroid degradation genes were found in the JLU460ET genome, which has the most reported steroid degradation genes among the five genomes. Further functional genomic analysis identified a gene cluster responsible for testosterone degradation in JLU460ET, as well as a gene encoding 17β-HSD, the key enzyme for transforming 17β-estradiol into estrone. This work could enrich the genome sources of steroid-degrading strains and promote the study of steroid-degradation mechanism in bacteria.