Continuous cultivation of the lithoautotrophic nitrate-reducing Fe(II)-oxidizing culture KS in a chemostat bioreactor.
Continuous cultivation of the lithoautotrophic nitrate-reducing Fe(II)-oxidizing culture KS in a chemostat bioreactor.
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DOI：
10.1111/1758-2229.13149
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发表时间：
2023-08
影响因子：
3.3
通讯作者：
中科院分区：
文献类型：
--
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基于实验室的微生物Fe（II）氧化研究通常在高底物浓度的小体积中进行5-10天，导致采样引起的地球化学梯度和体积效应。我们使用恒化器来实现培养基的不间断供应，并研究了24天的自养硝酸盐还原Fe（II）氧化培养物KS。我们分析了Fe和N的形态，细胞矿物协会和矿物的身份。将结果与分批系统（50和700 mL-静态/振荡）进行比较。在恒化器中，Fe（II）的氧化速率最高，为7.57 mM Fe（II）d−1，而氧化程度与其他实验设置相似（所有Fe（II）的平均氧化率为92%）。短程有序的Fe（III）相，可能是水铁矿，沉淀，后来在恒化器中检测到针铁矿。1 mM固相Fe（II）保留在恒化器中，测量到高达15 μM的反应性亚硝酸盐，42%的可视化细胞部分或完全被矿物结壳，可能是由亚硝酸盐对Fe（II）的非生物氧化引起的。尽管（部分）结壳，细胞仍存活。我们的研究结果表明，即使在类似的氧化速率在分批培养，培养铁（II）氧化微生物在连续条件下揭示了活性氮中间体对铁（II）氧化，矿物形成和细胞-矿物相互作用的重要性。
Laboratory‐based studies on microbial Fe(II) oxidation are commonly performed for 5–10 days in small volumes with high substrate concentrations, resulting in geochemical gradients and volumetric effects caused by sampling. We used a chemostat to enable uninterrupted supply of medium and investigated autotrophic nitrate‐reducing Fe(II)‐oxidizing culture KS for 24 days. We analysed Fe‐ and N‐speciation, cell‐mineral associations, and the identity of minerals. Results were compared to batch systems (50 and 700 mL—static/shaken). The Fe(II) oxidation rate was highest in the chemostat with 7.57 mM Fe(II) d−1, while the extent of oxidation was similar to the other experimental setups (average oxidation of 92% of all Fe(II)). Short‐range ordered Fe(III) phases, presumably ferrihydrite, precipitated and later goethite was detected in the chemostat. The 1 mM solid phase Fe(II) remained in the chemostat, up to 15 μM of reactive nitrite was measured, and 42% of visualized cells were partially or completely mineral‐encrusted, likely caused by abiotic oxidation of Fe(II) by nitrite. Despite (partial) encrustation, cells were still viable. Our results show that even with similar oxidation rates as in batch cultures, cultivating Fe(II)‐oxidizing microorganisms under continuous conditions reveals the importance of reactive nitrogen intermediates on Fe(II) oxidation, mineral formation and cell–mineral interactions.
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