Cai Pingping, Ning Zhuo, Zhang Min
School of Water Resources and Environment, Hebei GEO University, Shijiazhuang 050031, China.
Hebei Province Collaborative Innovation Center for Sustainable Utilization of Water Resources and Optimization of Industrial Structure, Shijiazhuang 050031, China.
Microorganisms. 2025 Jul 18;13(7):1688. doi: 10.3390/microorganisms13071688.
Groundwater at petroleum-contaminated sites typically exhibits elevated dissolved inorganic carbon (DIC) levels due to hydrocarbon biodegradation; however, our prior field investigations revealed an enigmatic DIC depletion anomaly that starkly contradicts this global pattern and points to an unrecognized carbon sink. In a breakthrough demonstration, this study provides the first experimental confirmation that sulfur-oxidizing bacteria (SOB) drive substantial carbon sequestration via a coupled sulfur oxidation autotrophic assimilation process. Through integrated hydrochemical monitoring and 16S rRNA sequencing in an enrichment culture system, we captured the complete DIC transformation trajectory: heterotrophic acetate degradation initially increased DIC to 370 mg/L, but subsequent autotrophic assimilation by SOB dramatically reduced DIC to 270 mg/L, yielding a net consumption of 85 mg/L. The distinctive pH dynamics (initial alkalization followed by acidification) further corroborated microbial regulation of carbon cycling. Critically, and were identified as the dominant carbon-fixing agents. These findings definitively establish that chemolithoautotrophic SOB convert DIC into organic carbon through a "sulfur oxidation-carbon fixation" coupling mechanism, overturning the conventional paradigm of petroleum-contaminated sites as perpetual carbon sources. The study fundamentally redefines natural attenuation frameworks by introducing microbial carbon sink potential as an essential assessment metric for environmental sustainability.
在受石油污染的场地中，由于烃类生物降解作用，地下水通常呈现出溶解无机碳（DIC）水平升高的现象；然而，我们之前的现场调查发现了一个神秘的DIC消耗异常现象，这与全球普遍模式形成了鲜明矛盾，并指向一个未被认识的碳汇。在一项突破性的论证中，本研究首次通过实验证实了硫氧化细菌（SOB）通过耦合硫氧化自养同化过程推动大量碳固存。通过在富集培养系统中进行综合水化学监测和16S rRNA测序，我们捕捉到了完整的DIC转化轨迹：异养乙酸降解最初使DIC增加到370 mg/L，但随后SOB的自养同化作用使DIC大幅降低至270 mg/L，净消耗量达85 mg/L。独特的pH动态变化（最初碱化随后酸化）进一步证实了微生物对碳循环的调节作用。至关重要的是， 和 被确定为主要的碳固定剂。这些发现明确证实，化能自养型SOB通过“硫氧化-碳固定”耦合机制将DIC转化为有机碳，颠覆了受石油污染场地作为永久碳源的传统范式。该研究通过引入微生物碳汇潜力作为环境可持续性的关键评估指标，从根本上重新定义了自然衰减框架。
