Altered Metabolic Strategies: Elaborate Mechanisms Adopted by Oenococcus oeni in Response to Acid Stress

Oenococcus oeni plays a key role
in inducing malolactic fermentation in wine. Acid stress is often
encountered under wine conditions. However, the lack of systematic
studies of acid resistance mechanisms limits the downstream fermentation
applications. In this study, the acid responses of O. oeni were investigated by combining transcriptome,
metabolome, and genome-scale metabolic modeling approaches. Metabolite
profiling highlighted the decreased abundance of nucleotides under
acid stress. The gene-metabolite bipartite network showed negative
correlations between nucleotides and genes involved in ribosome assembly,
translation, and post-translational processes, suggesting that stringent
response could be activated under acid stress. Genome-scale metabolic
modeling revealed marked flux rerouting, including reallocation of
pyruvate, attenuation of glycolysis, utilization of carbon sources
other than glucose, and enhancement of nucleotide salvage and the
arginine deiminase pathway. This study provided novel insights into
the acid responses of O. oeni, which
will be useful for designing strategies to address acid stress in
wine malolactic fermentation.