4.7 Article

The adaptation mechanisms of Acidithiobacillus caldus CCTCC M 2018054 to extreme acid stress: Bioleaching performance, physiology, and transcriptomics

期刊

ENVIRONMENTAL RESEARCH
卷 199, 期 -, 页码 -

出版社

ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.envres.2021.111341

关键词

Acidithiobacillus caldus; Acid stress; Microbial physiology; Transcriptome; RT-PCR

资金

  1. National Natural Science Foundation of China [21878128, 21776113, 31701582]
  2. Social Development Projects of Jiangsu Province [BE2017625]
  3. Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education [KLCCB-KF202001]
  4. Key Laboratory of Industrial Biotechnology, Ministry of Education [KLIB-KF201903, KLIB-KF202005]
  5. Fundamental Research Funds for the Central Universities [2050205]
  6. Priority Academic Program Development of Jiangsu Higher Education Institutions
  7. Program of Introducing Talents of Discipline to Universities [111206]

向作者/读者索取更多资源

This study systematically investigated the physiological and metabolic changes of Acidithiobacillus caldus CCTCC M 2018054 under extreme acid stress, revealing that the organism utilizes various strategies like amino acid regulation, membrane fluidity maintenance, and differential gene expression to resist acidic conditions. The upregulation of specific genes like kdpB and the increased levels of certain amino acids play crucial roles in intracellular pH homeostasis and energy supply for combating acid stress, demonstrating the potential application of acidophiles in industrial bioleaching.
To understand the acid-resistant mechanism of bioleaching microorganism Acidithiobacillus caldus CCTCC M 2018054, its physiology and metabolic changes at the transcriptional level under extreme acid stress were systemically studied. Scanning electron microscopy (SEM), Fourier transform infrared reflection (FTIR) and Xray diffraction (XRD) showed that with an increase in acidity, the absorption peak of sulfur oxidation-related functional groups such as S-O decreased significantly, and a dense sulfur passivation film appeared on the surface of the ore. Confocal laser scanning microscopy (CLSM) revealed that coverage scale of extracellular polymeric substance (EPS) and biofilm fluctuated accordingly along with the increasing acid stress (pH-stat 1.5, 1.2 0.9 and 0.6) during the bioleaching process. In response to acid stress, the increased levels of intracellular glutamic acid, alanine, cysteine, and proline contributed to the maintenance of intracellular pH homeostasis via decarboxylation and alkaline neutralization. Higher unsaturated fatty acid content was closely related to membrane fluidity. Up to 490 and 447 differentially expressed genes (DEGs) were identified at pH 1.5 vs pH 1.2 and pH 1.2 vs pH 0.9, respectively, and 177 common DEGs were associated with two-component system (TCS) regulation, transporter regulation, energy metabolism, and stress response. The upregulation of kdpB helped cells defend against proton invasion, whereas the downregulation of cysB and cbl implied stronger oxidation of sulfur compounds. The transcriptional level of sqr, sor, and soxA was significantly increased and consolidated the energy supply needed for resisting acid stress. Furthermore, eight of the identified DEGs (sor, cbl, ompA, atpF, nuoH, nuoC, sqr, grxB) were verified as being related to the acid stress response process. This study contributes toward expanding the application of these acidophiles in industrial bioleaching.

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