Changes in lipase activity of Acinetobacter radioresistens during cultivation on wheat bran

The aim of the work was to study the lipase activity of the bacterial culture Acinetobacter radioresistens, a part of the microbiota of wheat bran which is secondary raw materials of wheat processing. Secondary raw materials of food and agricultural production are of scientific and practical interest as sources of microorganisms – producers of hydrolytic enzymes. In this work, the effect of the composition of wheat bran for food and feed purposes on the lipase activity of the A. radioresistens isolate was studied. The studied bacterial culture was isolated by VNIIPD employees from a batch of dietary wheat bran. As a result of deep fermentation of bran in rocking flasks under conditions of a Multitron shaker incubator with A. radioresistens isolate, it was found that feed bran is more preferable as a source of carbohydrate, protein, and lipid substrates for the vital activity of bacterial culture and the manifestation of lipase activity. The amount of biomass was 17 ± 2 g/l, the achieved level of lipase activity was 45 ± 2 units/ml. The regularity of the effect of fermentation duration on the change in lipase activity has been established and it has been shown that substrates from feed bran induce the synthesis of lipolytic enzymes to a greater extent. Productive biosynthesis of lipase with an activity in the range of 10–47 units/ml, depending on the time of cultivation of A. radioresistens isolate on wheat bran for both food and feed purposes, is possible, moreover, with one-stage (sterilization of wheat bran hydromodule) preparation of raw materials for the biotechnological process. The achieved values of lipase activity are at the level of some well-known enzyme preparations for feed purposes. When studying the fatty acid composition of the obtained culture liquid by gas chromatography with mass spectrometric detection, fatty acids with an alkyl chain length from C12 to C22 carbon atoms, including Omega-9, Omega-6, and Omega-3 acids, were identified. The results obtained can be used to develop technologies for new food and feed ingredients, biologically active additives.