title: Influence of hydroxypropyl-β-cyclodextrin on phytosterol biotransformation by different strains of Mycobacterium neoaurum.
abstract: Cyclodextrins (CDs) can improve productivity in the biotransformation of steroids by increasing conversion rate, conversion ratio, or substrate concentration. However, little is known of the proportion of products formed by multi-catabolic enzymes, e.g., via sterol side chain cleavage. Using three strains with different androst-1,4-diene-3,17-dione (ADD) to androst-4-ene-3,17-dione (AD) ratios, Mycobacterium neoaurum TCCC 11028 (MNR), M. neoaurum TCCC 11028 M1 (MNR M1), and M. neoaurum TCCC 11028 M3 (MNR M3), we found that hydroxypropyl-β-cyclodextrin (HP-β-CD) can appreciably increase the ratio of ADD to AD, the reaction rate, and the molar conversion. In the presence of HP-β-CD, conversion of 0.5 g/L of phytosterol (PS) was 2.4, 2.4, and 2.3 times higher in the MNR, MNR M1, and MNR M3 systems, respectively, than in the controls. The ADD proportion increased by 38.4, 61.5, and 5.9 % compared with the control experiment, which resulted in a strong shift in the ADD/AD ratio in the ADD direction. Our results imply that the three PS-biotransforming strains cause efficient side chain degradation of PS, and the increased conversion of PS when using HP-β-CD may be associated with the higher PS concentration in each case. A similar solubilizing effect may not induce a prominent influence on the ADD/AD ratio. However, the different activities of the Δ¹-dehydrogenase of PS-biotransforming strains result in different incremental percentage yields of ADD and ADD/AD ratio in the presence of HP-β-CD.
authors.affiliation: Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, No. 29, 13th Avenue, TEDA, Tianjin 300457, People's Republic of China.
authors.forename: Yan-Bing
authors.initials: YB
authors.lastname: Shen
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Hua-Nan
authors.initials: HN
authors.lastname: Li
authors.forename: Yi-Bo
authors.initials: YB
authors.lastname: Wang
authors.forename: Jian-Mei
authors.initials: JM
authors.lastname: Luo
mesh_terms: D000073738:2-Hydroxypropyl-beta-cyclodextrin; D001711:Biotransformation; D009161:Mycobacterium / Q000145:classification / Q000254:growth & development / Q000378:metabolism*; D009170:Nontuberculous Mycobacteria / Q000145:classification / Q000254:growth & development / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D010840:Phytosterols / Q000378:metabolism*; D047392:beta-Cyclodextrins / Q000378:metabolism*
chemical_list: D010840:Phytosterols; D047392:beta-Cyclodextrins; D000073738:2-Hydroxypropyl-beta-cyclodextrin; D010088:Oxidoreductases