AUTHOR=Bechtner Julia , Xu Di , Behr Jürgen , Ludwig Christina , Vogel Rudi F. 

TITLE=Proteomic Analysis of Lactobacillus nagelii in the Presence of Saccharomyces cerevisiae Isolated From Water Kefir and Comparison With Lactobacillus hordei

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.00325

DOI=10.3389/fmicb.2019.00325

ISSN=1664-302X

ABSTRACT=<p>Water kefir is a slightly alcoholic and traditionally fermented beverage, which is prepared from sucrose, water, kefir grains, and dried or fresh fruits (e.g., figs). <italic>Lactobacillus</italic> (<italic>L.</italic>) <italic>nagelii, L. hordei</italic>, and <italic>Saccharomyces</italic> (<italic>S.</italic>) <italic>cerevisiae</italic> are predominant and stable lactic acid bacteria and yeasts, respectively, isolated from water kefir consortia. The growth of <italic>L. nagelii</italic> and <italic>L. hordei</italic> are improved in the presence of <italic>S. cerevisiae</italic>. In this work we demonstrate that quantitative comparative proteomics enables the investigation of interactions between LAB and yeast to predict real-time metabolic exchange in water kefir. It revealed 73 differentially expressed (DE) in <italic>L. nagelii</italic> TMW 1.1827 in the presence of <italic>S. cerevisiae</italic>. The presence of the yeast induced changes in the changes in the carbohydrate metabolism of <italic>L. nagelii</italic> and affected reactions involved in NAD<sup>+</sup>/NADH homeostasis. Furthermore, the DE enzymes involved in amino acid biosynthesis or catabolism predict that <italic>S. cerevisiae</italic> releases glutamine, histidine, methionine, and arginine, which are subsequently used by <italic>L. nagelii</italic> to ensure its survival in the water kefir consortium. In co-culture with <italic>S. cerevisiae, L. nagelii</italic> profits from riboflavin, most likely secreted by the yeast. The reaction of <italic>L. nagelii</italic> to the presence of <italic>S. cerevisiae</italic> differs from that one of the previously studied <italic>L. hordei</italic>, which displays 233 differentially expressed proteins, changes in citrate metabolism and an antidromic strategy for NAD<sup>+</sup>/NADH homeostasis. So far, aggregation promotion factors, i.e., formation of a specific glucan and bifunctional enzymes were only detected in <italic>L. hordei</italic>.</p>