发酵脱氢产氢过程对微生物铁还原的影响

发酵型微生物是铁还原菌中的主要类群，但其发酵产氢过程对铁还原的作用尚不清楚，为此采用接种水稻土浸提液混合培养的方法对微生物分别利用葡萄糖、丙酮酸盐和乳酸盐为碳源时，Fe（Ⅲ）还原过程中脱氢酶活性变化、培养体系pH、氢气分压及铁还原特征进行分析，探讨了发酵微生物脱氢产氢过程与微生物Fe（Ⅲ）还原的内在关系。结果表明：2种水稻土浸提液中的微生物均能够以葡萄糖为优势碳源进行脱氢、产氢及还原氧化铁，Fe（OH），可以诱导脱氢酶的产生，利用葡萄糖时脱氢酶活性在厌氧培养的4-6d出现最大峰值，利用丙酮酸盐和乳酸盐时脱氢酶活性出现峰值的时间分别为培养的15d和21-22d，脱氢酶活性出现峰值的时间与最大铁还原速率Vmax显著负相关、与最大反应速率对应的时间zk存在显著正相关关系。脱氢产氢过程中产生的H＋导致培养体系pH的变化是影响铁还原过程的主要原因，培养体系pH与体系氢气分压及Fe（Ⅱ）累积量呈极显著负相关。微生物利用不同碳源产氢时，利用葡萄糖的产氢能力最高，丙酮酸盐次之，乳酸盐最低。Fe（OH）3的加入增加了氢气的消耗量，培养体系氢气分压与Fe（Ⅱ）累积量存在极显著正相关关系。

Microbial Iron Reduction as Influenced by Fermentative Dehydrogenation and Hydrogen Production

Fermentative microorganism is the major group of iron reducing bacteria in paddy soil. However, it is unclear how dehydrogenation and hydrogen production impact microbial iron reduction. In an anaerobic incubation, dehydrogenase activity, pH, partial pressure of hydrogen and iron （ Ⅲ ） reduction were investigated using paddy soil extract solution as microorganism source, Fe（ OH ）3 as electron acceptor, and glucose, pyruvate and lactate as C source. Results showed that glucose was a dominant electron donator for microorganisms＇in dehy- drogenation, hydrogenation and iron reduction in paddy soils collected from Jilin and Guizhou provinces. With Fe（ OH ）3 as sole electron acceptor, the dehydrogenase activity peaked at about 4-6 d of anaerobic incubation with glucose, 15 d with pyruvate and 21-22 d with lactate. The time when the peak of dehydrogenase activity occurred was negatively correlated with the maximum iron reduction rate（Vmax）, but positively with the time to reach the max reduction rate（ Tvmax）： There was a negative correlation between pH and the partial pressure of hydrogen as well as iron（ Ⅱ ） concentrations. The change of pH caused by microbial fermentation was the major factor affecting iron reduction process. Carbon sources had a great impact on hydrogen production, with the maximum hydrogen production occurred under glucose, followed by pyruvate and the least under lactate. Addition of Fe（ OH ）3 increased the consumption of hydrogen in the incubation. In addition, an extremely significant positive correlation was found between the partial pressure of hydrogen and iron（ Ⅱ ） accumulation.