电子穿梭体对菌株Clostridium butyricum LQ25异化铁还原性质影响

【目的】在异化铁还原细菌培养体系中,通过外加电子穿梭体,分析电子穿梭体种类与浓度对细菌异化铁还原性质的影响。【方法】以一株发酵型异化铁还原细菌Clostridium butyricum LQ25为研究对象,设置水溶性介体蒽醌-2-磺酸钠和核黄素作为外加电子穿梭体。【结果】在氢氧化铁为电子受体、葡萄糖为电子供体培养条件下,不同浓度蒽醌-2-磺酸钠和核黄素对菌株LQ25异化铁还原效率影响具有显著性差异。外加蒽醌-2-磺酸钠浓度为0.5 mmol/L时,菌株累积产生Fe(Ⅱ)浓度最高,为12.95±0.08 mg/L,相比对照组提高88%。核黄素浓度为100mg/L时,菌株累积产生Fe(Ⅱ)浓度是11.06±0.04mg/L,相比对照组提高61%。外加电子穿梭体能够改变菌株LQ25发酵产物中丁酸和乙酸浓度,提高乙酸相对含量。【结论】蒽醌-2-磺酸钠和核黄素作为外加电子穿梭体能显著促进细菌异化铁还原效率,为揭示发酵型异化铁还原细菌胞外电子传递机制提供实验支持。

Characteristics of Fe(III) reduction by Fe(III)-reducing bacterium Clostridium butyricum LQ25 under the condition of electron shuttles

Objective] This study aimed to investigate the characteristics of microbial Fe(III) reduction under the condition of adding electron shuttles. Methods] The effects of anthraquinone-2-sulfonic acid (AQS) and riboflavin on cell growth and Fe(II) concentration by a fermenting bacterium Clostridium butyricum LQ25 were investigated. Results] The results showed that Fe(II) concentrations were significantly different under the series of electron shuttle concentrations, Fe(OH)₃ as electron acceptor and glucose as electron donor. The highest Fe(II) concentration under Fe(III)-reducing conditions by strain LQ25 was 12.95±0.08 mg/L at the AQS concentration of 0.5 mmol/L, which was 88% higher compared to the control without added AQS. When riboflavin was added as the electron shuttle, Fe(II) concentration was 11.06±0.04 mg/L at the riboflavin concentration of 100 mg/L, which was 61% higher compared to the control. The adding of electron shuttles could change the concentration of butyrate and acetic acid in fermentation products by strain LQ25, with the increasing of relative content of acetic acid. Conclusion] The adding of electron shuttle AQS and riboflavin could significantly promote microbial Fe(III) reduction, which will provide the experimental evidence for the mechanism of extracellular electron transfer by fermentative Fe(III)-reducing bacteria.