Biosynthesis of pigment by strain Arthrobacter agilis wb28 during fermentation of secondary raw materials

The article presents the results of studies aimed at developing a cost-effective technology for producing microbial carotenoids using secondary raw materials from the agro-industrial sector. The article provides data on the fermentation of media made from wheat bran, soybean meal, rapeseed cake, and the biosynthesis of bacterioruberin, a rare microbial carotenoid. The article uses the Arthrobacter agilis wb28 strain, isolated from wheat bran, as the producer. Cultivation was carried out on solid and liquid media; in rocking flasks and a bioreactor. The pigment was isolated from the biomass using a well-known extraction method, modified to suit the specific characteristics of the producer. When cultured on medium with agar, visible growth of colonies was observed after 48 hours. In liquid media, the stationary growth phase was reached within 16–24 hours. Active aeration during fermentation in a bioreactor increased the pigment yield compared to the process in rocking flasks. Active aeration during fermentation in a bioreactor increased the pigment yield compared to the process in rocking flasks. The dependence of pigment synthesis on the composition of the nutrient medium and the aeration regime was revealed. It was shown that A. agilis wb28 selectively consumes substrates. It has the ability to hydrolyze poly- and oligosaccharides, lipids, and fatty acid esters, as well as complex proteins. It can use citrate as the only source of carbon and energy. Glucose is poorly assimilated by the strain’s enzyme system. The main stress factor in the composition of nutrient media from secondary raw materials for pigment formation was the concentration of carbohydrate. Protein components were mainly used for biomass production. The highest pigment yield was observed during fermentation of media from wheat bran (4.28 mg/g), while the lowest yield was observed from rapeseed cake (1.16 mg/l). The resulting bacterioruberin yield was comparable to the yield of carotenoids for known Arthrobacter strains.