Exploiting Potential Probiotic Lactic Acid Bacteria Isolated from Chlorella vulgaris Photobioreactors as Promising Vitamin B12 Producers

Abstract

Lactic acid bacteria (LAB) have been documented as potential vitamin B12 producers and may constitute an exogenous source of cobalamin for the microalga <i>Chlorella vulgaris</i>, which has been described as being able to perform vitamin uptake. Hence, there is an interest in discovering novel B12-producing probiotic LAB. Therefore, the purpose of the current work was to perform a phenotype-genotype analysis of the vitamin B12 biosynthesis capacity of LAB isolated from <i>C. vulgaris</i> bioreactors, and investigate their probiotic potential. Among the selected strains, <i>Lactococcus lactis</i> E32, <i>Levilactobacillus brevis</i> G31, and <i>Pediococcus pentosaceus</i> L51 demonstrated vitamin B12 biosynthesis capacity, with the latter producing the highest (28.19 ± 2.27 pg mL^-1). The genomic analysis confirmed the presence of pivotal genes involved in different steps of the biosynthetic pathway (<i>hemL</i>, <i>cbiT</i>, <i>cobC</i>, and <i>cobD</i>). Notably, <i>P. pentosaceus</i> L51 was the only strain harboring <i>cobA</i>, <i>pduU</i>, and <i>pduV</i> genes, which may provide evidence for the presence of the cobalamin operon. All strains demonstrated the capability to withstand harsh gastrointestinal conditions, although <i>P. pentosaceus</i> L51 was more resilient. The potential for de novo cobalamin biosynthesis and remarkable probiotic features highlighted that <i>P. pentosaceus</i> L51 may be considered the most promising candidate strain for developing high-content vitamin B12 formulations.