Kim Bokyung, Woo Dong Kyun, Jeong Juhwan, Sim Min Sub
School of Earth and Environmental Sciences, Seoul National University, Seoul, South Korea.
PLoS One. 2025 Jan 22;20(1):e0317320. doi: 10.1371/journal.pone.0317320. eCollection 2025.
The oxidation states of vanadium determine its mobility and toxicity, and dissimilatory vanadate reduction has been reported in several microorganisms, highlighting the potential significance of this pathway in the remediation of vanadium contamination and the biogeochemical cycle. However, to date, most known microorganisms capable of reducing vanadate are Gram-negative respiratory bacteria belonging to the phylum Proteobacteria. In this study, we isolated Tepidibacter mesophilus strain VROV1 from deep-sea sediments on the northern Central Indian Ridge and investigated its ability to reduce vanadium and the impact of vanadate on its cellular metabolism. A series of culture experiments revealed that the isolated strain efficiently reduces V(V) to V(IV) during fermentation, even at mM levels, and this reduction involves a direct biological process rather than indirect reduction via metabolic products. Vanadium affects microbial carbon and nitrogen metabolism. Notably, in the presence of vanadate, alanine production decreases, suggesting that metabolic flux is diverted from the transamination reaction to vanadate reduction. T. mesophilus VROV1 is the second Gram-positive bacterium identified to reduce vanadium, following Lactococcus raffinolactis, but these bacteria belong to different classes: T. mesophilus is classified as Clostridia, whereas L. raffinolactis is classified as Bacilli. The specific rate of vanadate removal by VROV1 was as high as 2.8 pmol/cell/day, which is comparable to that of metal-reducing bacteria and markedly exceeds that of L. raffinolactis. Our findings expand the distribution of vanadate-reducing organisms within the bacterial domain. Given the wide range of natural habitats of T. mesophilus and its close relatives, we speculate that fermentative vanadate reduction may have a greater impact on the global biogeochemical cycle of vanadium than previously thought.
钒的氧化态决定了其迁移性和毒性，并且已有报道称几种微生物可进行异化钒酸盐还原，这突出了该途径在钒污染修复和生物地球化学循环中的潜在重要性。然而，迄今为止，大多数已知能够还原钒酸盐的微生物是属于变形菌门的革兰氏阴性呼吸细菌。在本研究中，我们从印度洋中脊北部的深海沉积物中分离出嗜温温养杆菌菌株VROV1，并研究了其还原钒的能力以及钒酸盐对其细胞代谢的影响。一系列培养实验表明，分离出的菌株在发酵过程中能有效地将V(V)还原为V(IV)，即使在毫摩尔水平也是如此，并且这种还原涉及直接的生物学过程，而非通过代谢产物的间接还原。钒会影响微生物的碳和氮代谢。值得注意的是，在钒酸盐存在的情况下，丙氨酸产量会降低，这表明代谢通量从转氨反应转向了钒酸盐还原。嗜温温养杆菌VROV1是继棉籽糖乳球菌之后被鉴定出的第二种能够还原钒的革兰氏阳性细菌，但这些细菌属于不同的类别：嗜温温养杆菌被归类为梭菌纲，而棉籽糖乳球菌被归类为芽孢杆菌纲。VROV1去除钒酸盐的比速率高达2.8 pmol/细胞/天，这与金属还原细菌相当，且明显超过棉籽糖乳球菌。我们的研究结果扩展了细菌域内钒酸盐还原生物的分布范围。鉴于嗜温温养杆菌及其近缘种的自然栖息地范围广泛，我们推测发酵性钒酸盐还原对全球钒生物地球化学循环的影响可能比之前认为的更大。
