Enhancement of heat resistance of Bacillus thermoamylovorans drives enhanced PET degradation

Abstract

Microbial polyethylene terephthalate (PET) degradation has emerged as an environmentally friendly approach to reducing plastic pollution, but microbial activity is often limited by the high temperatures (60–70 °C) required for efficient degradation. In this study, six endogenous thermotolerant genes were identified in the PET-degrading strain Bacillus thermoamylovorans JQ3. Overexpression of the genes hrcA, hsp20A, and hsp20B significantly enhanced thermotolerance in Escherichia coli, which increased cell viability by > 24.2% at temperatures above 40 °C. Similarly, overexpression of hsp20A in B. thermoamylovorans (B. th_Hsp20A) improved its thermotolerance, increasing cell viability by 46.8% at 50 °C and 69.8% at 60 °C. The hsp20A-encoded protein was identified as a small heat shock protein (sHSP). B. th_Hsp20A exhibited significantly improved PET degradation at 60 °C compared with 50 °C, which released 282 μg of terephthalic acid after 7 days of incubation, representing an 84.3% increase compared with the wildtype strain (153 μg). These results highlight that the overexpression of thermotolerant proteins, particularly sHSPs, significantly enhances microbial PET degradation under high-temperature conditions, offering a novel pathway for enhancing microbial PET waste degradation.

Keywords

Thermotolerance / Heat shock protein / Bacillus thermoamylovorans / PET degradation / Protein synthesis

Data availability statement

The data will be made available upon request.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

CRediT authorship contribution statement

Yi-Mei Cai: Writing – original draft, Methodology, Investigation, Formal analysis. Kang-Qi Hu: Methodology, Investigation, Formal analysis. Xin-Yu Zhang: Investigation, Formal analysis. Hui Liu: Investigation, Formal analysis. Yan Huang: Investigation, Formal analysis. Wei Xia: Investigation, Formal analysis. Jing Wu: Conceptualization. Zheng-Fei Yan: Writing – review & editing, Supervision, Project administration, Funding acquisition.

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