Alicyclobacillus acidoterrestris has unique thermo-acidophilic properties and is the main cause of fruit juice deterioration. Given the acidic environment and thermal treatment during juice processing, the effects of acid adaptation (pH 3.5, 3.2, and 3.0) on the resistance of A. acidoterrestris to heat (65 °C, 5 min) and acid (pH = 2.2, 1 h) stresses were investigated for the first time. The results showed that acid adaptation induced cross-protection against heat stress of A. acidoterrestris and acid tolerance response, and the extent of induced tolerance was increased with the decrease of adaptive pH values. Acid adaptation treatments did not disrupt the membrane potential stability and intracellular pH homeostasis, but reduced intracellular ATP concentration, increased cyclic fatty acids content, and changed the acquired Fourier transform infrared spectra. Transcription levels of stress-inducible (dnaK, grpE, clpP, ctsR) genes and genes related to spore formation (spo0A, ctoX) were up-regulated after acid adaptation, and spore formation was observed by scanning electron microscopy. This study revealed that the intracellular microenvironment homeostasis, expression of chaperones and proteases, and spore formation played a coordinated role in acid stress adaptive responses, with implications for applications in fruit juice processing.

酸热脂环酸杆菌具有独特的嗜热酸性质，并且是果汁变质的主要原因。考虑到果汁加工过程中的酸性环境和热处理，酸适应性（pH 3.5、3.2和3.0）对酸曲霉耐热性（65°C，5分钟）和酸（pH = 2.2，1）的影响h）首次研究了压力。结果表明，酸适应诱导了对拟南芥热应激的交叉保护。酸耐性响应，诱导耐性的程度随适应性pH值的降低而增加。酸适应处理不会破坏膜电位稳定性和细胞内pH稳态，但会降低细​​胞内ATP浓度，增加环脂肪酸含量，并改变获得的傅立叶变换红外光谱。的胁迫诱导型（转录水平的DnaK，GRPE，CLPP，CTSR）基因和基因有关孢子形成（spo0A，ctoX在酸适应后被上调，并且通过扫描电子显微镜观察到孢子形成。这项研究表明，细胞内微环境的动态平衡，伴侣蛋白和蛋白酶的表达以及孢子的形成在酸胁迫适应性反应中起着协调的作用，对果汁加工中的应用具有重要意义。