Native Microbiota of Rapeseed Cake as Potential Source of Industrial Producers

Abstract

Rapeseed oil production is very active in Russia. Its main by-product is cake: its chemical composition and availability make it an excellent source of nutrients in microbial cultivation to be used as biologically active compounds or as part of functional products. The research objective was to study the native microbiota of rapeseed cake under conditions of high humidity, as well as to describe the morphology of isolated microorganisms and determine their genera by NGS sequencing. The study featured rapeseed cake and microbial colonies isolated after 2, 5, 7, and 9 days of fermentation. The microbial isolates were obtained by the method of surface and deep cultivation on solid and liquid nutrient media, respectively. The metagenomic analysis of the microbial taxonomy involved sequencing on the Illumina platform. The experiment revealed 16 types of colonies with different morphology. Colonies with morphology 1, 3, 8, 12, and 13 were predominant for all fermentation periods, which means that they grew as isolates during the liquid-phase fermentation. The metagenomic analysis revealed at least 28 genera of bacteria in the rapeseed cake suspensions. The highest percentage belonged to Weisella (≤ 45.8% on day 2), Acinetobacter (≤ 40.6% on day 7), Lactobacillus (≤ 15.7% on day 5), Leuconostoc (≤ 15.1% on day 7), Enterococcus (≤ 14.6% on day 5), and Paenibacillus (≤ 16.3% on day 9). The obtained isolates could be of interest as industrial producers of useful metabolites, e.g., enzymes, pigments, organic acids, etc. Further research will identify the microbial species, their useful properties, and optimal cultivation conditions.