Multivariate analysis of buckwheat sourdough fermentations for metabolic screening of starter cultures

This study investigated the metabolic activity of 35 strains of lactic acid bacteria (LAB), which were able to grow in buckwheat sourdoughs and delivers a detailed explanation of LAB metabolism in that environment. To interpret the high-dimensional dataset, descriptive statistics and linear discriminant analysis (LDA) were used. Heterofermentative LAB showed a clear different metabolism than facultative (f.) heterofermentative and homofermentative LAB, which were more similar. Heterofermentative LAB were mainly characterized by high free SH groups and acetic acid production; they were also able to consume arabinose and glucose. Homofermenters were mainly characterized by lower free amino nitrogen content and they did not show a good capacity to consume arabinose and fructose. Except for the heterofermentative Weissella cibaria strain, only homofermentative strains showed high ornithine yields. Some f. heterofermentative strains differed from homofermentative due to the high lactic acid production as well as low glucose and arginine consumption. LAB containing more genes encoding peptidase activities and genes involved in aroma production showed a high consumption of free amino acids. Strain-dependent activities could be clearly distinguished from group dependent ones (homofermentative, f. heterofermentative and heterofermentative), e.g., some Lactobacillus paracasei and Lactobacillus plantarum strains showed the highest carbohydrate consumption. However, some microbial activities were more strain-dependent than group-dependent. Multivariate analysis of raw data delivered a detailed and clear explanation of LAB metabolism in buckwheat sourdough fermentations.