A novel dehydrogenase 17β-HSDx from Rhodococcus sp. P14 with potential application in bioremediation of steroids contaminated environment.

Steroids are endocrine disrupting compounds in human and are distributed in various environments. Our previous study showed that a marine bacterium Rhodococcus sp. P14 was able to efficiently degrade one typical steroid estradiol. In this study, we showed that P14 could also use other steroids, including estriol and testosterone, as sole carbon source for growth. Two dehydrogenation products, 16-hydroxestrone and androst-4-ene-3, 17-dione, were detected during estriol and testosterone degradation, respectively. By screening the genome, a short chain dehydrogenase gene was identified and named as 17β-HSDx. Expression of 17β-HSDx was induced in P14 when estriol, estradiol or testosterone was used as single carbon source. In addition, 17β-HSDx was shown to have dehydrogenation ability of transforming estriol to 16-hydroxestrone, estradiol to estrone and testosterone to androst-4-ene-3, 17-dione. This is the first short chain dehydrogenase identified in bacteria with dehydrogenation ability on various steroids substrates. Overall, this study reveals that 17β-HSDx has potential application in the bioremediation of steroids contaminated environment.