Novel bacterial isolates used for the bioconversion of some agriculture wastes into important steroid hormones

Abstract

Background and objectives Microbial bioconversion of phytosterols produces many compounds especially steroid intermediate hormones. One of the most important transformation reactions is side chain degradation of sterols especially phytosterols β-sitosterol to androstenedione (AD), and androstadienedione (ADD). These compounds are considered to be critical intermediates in the preparation of testosterone, estrogen hormones. The main objective is to study the bioconversion of some agriculture wastes as a cheap source of phytosterols to more valuable products AD and ADD. Materials and methods In the present study, phytosterols of some agriculture products especially soybean, rice bran, and wheat bran were used as a substrate for the production of both AD and ADD using locally isolated bacterial strain. Different physiological and biochemical factors were tested as well as qualitative and quantitative estimation of the transformation products were carried out according to a previously recorded method. Results and discussion The results showed that screening experiments were carried out to investigate the ability of 12 bacterial isolates to transform plant agriculture wastes phytosterols into steroid hormone intermediates AD and ADD. The results also indicated that only four strains possess this ability. One of which was selected to complete this study according to its high AD and ADD productivity. Different physiological and biochemical tests involving catalase, oxidase, coagulase, indole production, urease, citrate and voges-proskauer, type of the agriculture waste, moisture content, parentage of the waste as well as some additives were tested. The results showed that the best bioconversion (3.98 and 3.37 mg/100 ml of both AD and ADD, respectively) were obtained by using soybean − what bran mixture at a ratio of 1 : 1. Qualitative and quantitative analyses of the transformation products were investigated. The phylogenic analysis was carried out and the results indicated that the new strain referred to is Ochrobactrum anthropi, which is first recorded to be a phytosterol transformer. Conclusion The study has indicated that the newly isolated bacterial strain Ochrobactrum is first recorded to perform the side chain degradation of phytosterols presented in soybean and wheat bran to AD and ADD under the above-selected fermentation conditions.