title: [Biotransformation of daidzein by resting cell system of bacterial strain isolated from bovine rumen gastric juice].
abstract: In previous study we isolated a gram-positive bacterial strain, designated Niu-O16, from bovine rumen gastric juice. The growing cells of bacterial strain Niu-O16 is capable of biotransforming isoflavone daidzein into dihydrodaidzein efficiently under anaerobic conditions. In this study we investigated the optimal bioconversion conditions for the resting cells of bacterial strain Niu-O16 to convert daidzein into dihydrodaidzein. Single factor test showed that the optimal conditions for the initial pH of phosphate buffer, the concentration of the resting cell and the concentration of the substrate daidzein were 6.0-8.0, 32-64 mg/mL (wet weight) and 0.8-1.2 mmol/L, respectively. Orthogonal experiments were used to determine the optimal combination of the resting cell concentration, substrate concentration and biotransformation time. The results showed that the optimal combination included resting cell concentration 32 mg/mL, substrate concentration 0.8 mmol/L and the biotransformation time 24 h. Furthermore, the biotransformation kinetics under optimal conditions were studied, under which conditions the highest bioconversion rate was 63.9% in the resting cell system. The results might provide information for resting cell biotransforming of anaerobes as well as its industrial application.
authors.affiliation: College of Life Sciences, Agricultural University of Hebei, Baoding 071001, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhang
authors.forename: Xiuling
authors.initials: X
authors.lastname: Wang
authors.forename: Shiying
authors.initials: S
authors.lastname: Wang
authors.forename: Qinghong
authors.initials: Q
authors.lastname: Hao
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Guo
authors.forename: Shuxiang
authors.initials: S
authors.lastname: Wang
mesh_terms: D000693:Anaerobiosis; D000818:Animals; D001711:Biotransformation; D002417:Cattle; D046508:Culture Techniques / Q000379:methods; D005750:Gastric Juice / Q000382:microbiology*; D006094:Gram-Positive Bacteria / Q000254:growth & development / Q000302:isolation & purification / Q000502:physiology*; D007529:Isoflavones / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D012417:Rumen / Q000382:microbiology
chemical_list: D007529:Isoflavones; C433163:dihydrodaidzein; C004742:daidzein