Abstract

Elucidation of the acetic acid resistance (AAR) mechanisms is of great significance to the development of industrial microbial species, specifically to the acetic acid bacteria (AAB) in vinegar industry. Currently, the role of population heterogeneity in the AAR of AAB is still unclear. In this study, we investigated the persister formation in AAB and the physiological role of HicAB in Acetobacter pasteurianus Ab3. We found that AAB were able to produce a high level of persister cells (10⁻² to 10⁰ in frequency) in the exponential-phase cultures. Initial addition of acetic acid and ethanol reduced the ratio of persister cells in A. pasteurianus by promoting the intracellular ATP level. Further, we demonstrated that HicAB was an important regulator of AAR in A. pasteurianus Ab3. Strains lacking hicAB showed a decreased survival under acetic acid exposure. Deletion of hicAB significantly diminished the acetic acid production, acetification rate, and persister formation in A. pasteurianus Ab3, underscoring the correlation between hicAB, persister formation, and acid stress resistance. By transcriptomic analysis (RNA-seq), we revealed that HicAB contributed to the survival of A. pasteurianus Ab3 under high acid stress by upregulating the expression of genes involved in the acetic acid over-oxidation and transport, 2-methylcitrate cycle, and oxidative phosphorylation. Collectively, the results of this study refresh our current understanding of the AAR mechanisms in A. pasteurianus, which may facilitate the development of novel ways for improving its industrial performance and direct the scaled-up vinegar production.

Key points

• AAB strains form persister cells with different frequencies.

• A. pasteurianus are able to form acid-tolerant persister cells.

• HicAB contributes to the AAR and persister formation in A. pasteurianus Ab3.

中文翻译：

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毒素-抗毒素HicAB调节巴氏醋杆菌中耐酸性胁迫的持久性细胞的形成

摘要

阐明耐乙酸性（AAR）机制对工业微生物物种的发展，特别是对醋工业中的乙酸细菌（AAB）具有重要意义。目前，尚不清楚种群异质性在AAB的AAR中的作用。在这项研究中，我们调查了AAB中的持久性形成以及HicAB在巴斯德醋杆菌Ab3中的生理作用。我们发现AAB能够在指数期培养物中产生高水平的持久性细胞（频率为10 ^-2至10 ⁰）。最初添加乙酸和乙醇会降低巴氏曲霉中持久性细胞的比例通过促进细胞内ATP水平。此外，我们证明了HicAB是AAR的一个重要的调节A.巴氏Ab3的。缺乏hicAB的菌株在乙酸暴露下存活率下降。hicAB的删除显着减少了巴氏曲霉Ab3的乙酸产量，乙酸化速率和持久性形成，从而强调了hicAB，持久性形成和耐酸胁迫之间的相关性。通过转录分析（RNA-SEQ），我们发现，HicAB促成了生存的A.巴氏Ab3在高酸胁迫下，通过上调与乙酸过度氧化和转运，2-甲基柠檬酸循环和氧化磷酸化有关的基因的表达来调节。总的来说，这项研究的结果刷新了我们对巴氏曲霉AAR机制的当前理解，这可能有助于开发改善其工业性能并指导醋生产规模扩大的新颖方法。

关键点

•AAB菌株形成具有不同频率的持久性细胞。

•巴氏杆菌能够形成耐酸的持久性细胞。

•HicAB有助于巴斯德曲霉Ab3中的AAR和持久性形成。