Improving the utilization efficiency of nitrogen source through co-culture of Lactobacillus strains with different nitrogen source metabolisms

Abstract

The growth of lactic acid bacteria depends largely on a sufficient source of nitrogen as well as a wide variety of nitrogen sources. Nutrient dependence, especially in relation to nitrogen sources, plays a key role in controlling the positive interactions between microorganisms. However, little is known regarding the relationship between co-culture and nitrogen source dependence in current studies. This study aimed to obtain a higher proliferation of strains with the same nitrogen source content by co-cultivation of Lactobacillus. First, upon the detection of various commercial nitrogen sources, notable differences in peptide molecular weight distributions were observed. In addition, diverse Lactobacillus strains exhibit varying proficiencies in utilizing these nitrogen sources. Second, in the exploration of co-cultivation of distinct bacterial strains, three synergistic combinations were identified. These assemblies exhibited superior total viable cell counts, growth trajectories, and glucose consumption. Finally, strains possessing capsular proteinase genes adeptly hydrolyzed large peptides, yielding smaller peptides and amino acids for strains lacking analogous enzymatic and peptide transport mechanisms. This culminated in optimized utilization of the nitrogen source and provided a method for the direct production of multi-strain probiotics.