AUTHOR=Harthern-Flint Sarah L. , Dolfing Jan , Mrozik Wojciech , Meynet Paola , Eland Lucy E. , Sim Martin , Davenport Russell J. 

TITLE=Experimental and Genomic Evaluation of the Oestrogen Degrading Bacterium Rhodococcus equi ATCC13557

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.670928

DOI=10.3389/fmicb.2021.670928

ISSN=1664-302X

ABSTRACT=<p><italic>Rhodococcus equi</italic> ATCC13557 was selected as a model organism to study oestrogen degradation based on its previous ability to degrade 17α-ethinylestradiol (EE2). Biodegradation experiments revealed that <italic>R. equi</italic> ATCC13557 was unable to metabolise EE2. However, it was able to metabolise E2 with the major metabolite being E1 with no further degradation of E1. However, the conversion of E2 into E1 was incomplete, with 11.2 and 50.6% of E2 degraded in mixed (E1-E2-EE2) and E2-only conditions, respectively. Therefore, the metabolic pathway of E2 degradation by <italic>R. equi</italic> ATCC13557 may have two possible pathways. The genome of <italic>R. equi</italic> ATCC13557 was sequenced, assembled, and mapped for the first time. The genome analysis allowed the identification of genes possibly responsible for the observed biodegradation characteristics of <italic>R. equi</italic> ATCC13557. Several genes within <italic>R. equi</italic> ATCC13557 are similar, but not identical in sequence, to those identified within the genomes of other oestrogen degrading bacteria, including <italic>Pseudomonas putida</italic> strain SJTE-1 and <italic>Sphingomonas</italic> strain KC8. Homologous gene sequences coding for enzymes potentially involved in oestrogen degradation, most commonly a cytochrome P450 monooxygenase (<italic>oecB</italic>), extradiol dioxygenase (<italic>oecC</italic>), and 17β-hydroxysteroid dehydrogenase (<italic>oecA</italic>), were identified within the genome of <italic>R. equi</italic> ATCC13557. These searches also revealed a gene cluster potentially coding for enzymes involved in steroid/oestrogen degradation; 3-carboxyethylcatechol 2,3-dioxygenase, 2-hydroxymuconic semialdehyde hydrolase, 3-alpha-(or 20-beta)-hydroxysteroid dehydrogenase, 3-(3-hydroxy-phenyl)propionate hydroxylase, cytochrome P450 monooxygenase, and 3-oxosteroid 1-dehydrogenase. Further, the searches revealed steroid hormone metabolism gene clusters from the 9, 10-<italic>seco</italic> pathway, therefore <italic>R. equi</italic> ATCC13557 also has the potential to metabolise other steroid hormones such as cholesterol.</p>