As a traditional Asian food for several centuries, vinegar is known to be produced by acetic acid bacteria. The Acetobacter species is the primary starter for vinegar fermentation and has evolutionarily acquired acetic acid resistance, in which Acetobacter pasteurianus Ab3 is routinely used for industrial production of rice vinegar with a high acidity (9 %, w/v). In contrast to the documented short-term and low acetic acid effects on A. pasteurianus, here we investigated the molecular and cellular signatures of long-term and high acetic acid responses by proteomic profiling with bidimensional gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF/MS) analyses. Protein spots of interest were selected based on the threshold ANOVA p value of 0.05 and minimal twofold of differential expression, leading to the identification of 26 proteins that are functionally enriched in oxidoreductase activity, cell membrane, and metabolism. The alterations in protein functioning in respiratory chain and protein denaturation may underlay cellular modifications at the outer membrane. Significantly, we found that at higher acidity fermentation phase, the A. pasteurianus Ab3 cells would adapt to distinct physiological processes from that of an ordinary vinegar fermentation with intermediate acidity, indicating increasing energy requirement and dependency of membrane integrity during the transition of acetic acid production. Together, our study provided new insights into the adaptation mechanisms in A. pasteurianus to high acetic acid environments and yield novel regulators and key pathways during the development of acetic acid resistance.

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Cooperation is the crux of many social problems, thus third‐party sanction, as one of the most important ways to promote cooperation, is worth studying. The present study compared the effects of third‐party punishment alone, third‐party reward alone, and the combination of third‐party reward and third‐party punishment on cooperation in the context of a public goods experiment. In addition, we explored the characteristics of third‐party sanctioning behaviors. A total of 280 students participated in the present study. The results showed that the operation of third‐party sanctions did raise the level of cooperation and changed the discrete trend of cooperation—specifically, the differences between the cooperation level of every group member and the average level of the whole group. Furthermore, when third‐party rewards and third‐party punishments were used simultaneously in the public goods game (PGG), the level of cooperation was greatly enhanced, which meant that in the context of the third party, when punishment opportunities and reward opportunities coexist, they may have a “compensatory effect.” In terms of the characteristics of sanctioning behaviors, the frequency of third‐party sanctions did not differ significantly under different conditions (third‐party punishment alone, third‐party reward alone, and a combination of third‐party reward and third‐party punishment), and neither did expenditures on third‐party sanctions, but the strategies that third parties used changed under different conditions, thus their effects on other group members’ cooperative behavior varied under different conditions. The present study provides a comprehensive picture of how third parties behave in different conditions of third‐party sanctions and how these sanctions exert influence on cooperation. Understanding these mechanisms can help us build more effective institutions.