Steroid Metabolism In Thermophilic Actinobacteria Saccharopolyspora Hirsuta Subsp. Hirsuta VKM Ac-666T

Abstract

Application of thermophile microorganisms opens new prospects in steroid biotechnology, however little is known on steroid catabolism by the thermophile strains.The thermophilic Saccharopolyspora hirsuta subsp. hirsuta strain VKM Ac-666T is capable of structural modification of different steroids, and fully degrades cholesterol. The intermediates of the cholesterol degradation pathway were identified as cholest-4-en-3-one, cholesta-1,4-dien-3-one, 26-hydroxycholest-4-en-3-one, 3-oxo-cholest-4-en-26-oic acid, 3-oxo-cholesta-1,4-dien-26-oic acid, 26-hydroxycholesterol, 3β-hydroxy-cholest-5-en-26-oic acid by MS, and H1- and C13-NMR analyses. The data evidence sterol degradation by the strain occurs simultaneously through the aliphatic side chain hydroxylation at C26 and the A-ring modification that are putatively catalyzed by cytochrome P450 monooxygenase CYP125 and cholesterol oxidase, respectively.The genes orthologous to those related to the sterol side chain degradation, steroid core rings A/B and C/D disruption and the steroid uptake were revealed. Most of the genes related to steroid degradation are grouped in three clusters. The sets of the genes putatively involved in steroid catabolism and peculiarities of their organization in S. hirsuta are discussed.Despite steroids abundancy in the environments, the ability to degrade them is not widespread among thermophilic bacteria as follows from the bioinformatic analysis of 52 publicly available genomes. Only seven candidate strains were revealed to possess the key genes related to the only known 9(10)-seco pathway of steroid degradation.The results contribute to the knowledge on diversity of microbial steroid degraders, the features of sterol catabolism by thermophilic actinobacteria and could be useful for application in the pharmaceutical and environmental biotechnology.