AUTHOR=Zhao Hongyu , Liu Longxiang , Peng Shuai , Yuan Lin , Li Hua , Wang Hua 

TITLE=Heterologous Expression of Argininosuccinate Synthase From Oenococcus oeni Enhances the Acid Resistance of Lactobacillus plantarum

JOURNAL=Frontiers in Microbiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2019.01393

DOI=10.3389/fmicb.2019.01393

ISSN=1664-302X

ABSTRACT=<p><italic>Oenococcus oeni</italic> can survive well in wine (an acid-stress environment) and dominate malolactic fermentation (MLF). To demonstrate a possible role of argininosuccinate synthase gene (<italic>argG</italic>) in the acid tolerance response of <italic>O. oeni</italic>, a related <italic>argG</italic> gene was inserted into a plasmid pMG36e and heterologously expressed in <italic>Lactobacillus plantarum</italic> SL09, a wine isolate belonging to a species of relevant importance in MLF. The expression levels of the <italic>argG</italic> gene in <italic>L. plantarum</italic> were analyzed by RT-qPCR, argininosuccinate synthase (ASS) activity and cell properties (amino acids, pH, H<sup>+</sup>-ATPase activity, and ATP levels) were determined at pH 3.7 in comparison with that at pH 6.3. Results showed that the recombinant strain <italic>L. plantarum</italic> SL09 (pMG36e<italic>argG</italic>) exhibited stronger growth performance compared with the control strain (without <italic>argG</italic> gene), and the expression levels of <italic>hsp1</italic>, <italic>cfa</italic>, <italic>atp</italic>, the citrate and malate metabolic genes were apparently increased under acid stress. In addition, the recombinant strain exhibited 11.0-, 2.0-, 1.9-fold higher ASS activity, H<sup>+</sup>-ATPase activity and intracellular ATP level, compared with the corresponding values for control strain during acid-stresses condition, which may take responsible for the acid tolerance enhancement of the recombinant strain. This is the first work report on heterologous expression of <italic>argG</italic> gene, and the results presented in this study will be beneficial for the research on acid stress response of <italic>O. oeni.</italic></p>