混合培养中晶体磷酸铁的异化还原能力

Dissimilatory reduction capability of crystal ferric phosphate in enrichment cultivation

采用厌氧混合培养方法,分别以来源四川、吉林和江西的水稻土浸提液作为接种液,选择Fe()浓度及游离磷酸盐浓度变化为指标,研究不同来源微生物对晶体磷酸铁的微生物还原特征,探讨晶体磷酸铁微生物还原反应中对不同碳源利用能力的差异。结果表明,来源于不同水稻土的微生物对晶体磷酸铁的最大还原速率(Vmax)、潜在最大铁还原量及Fe()还原率均有显著差异,其中四川水稻土微生物的Vmax较大,而吉林和江西水稻土微生物的潜在最大Fe()还原量及铁还原率较高。3种水稻土微生物对晶体磷酸铁的还原反应速率及铁还原量明显低于无定型氧化铁。不同水稻土的微生物能够利用丙酮酸盐、乙酸盐及葡萄糖作为惟一电子供体,使晶体磷酸铁发生异化还原,产生Fe()并释放磷酸盐,且Fe()累积量与磷素累积量呈极显著相关。体系中可溶性磷酸盐数量对以用葡萄糖为碳源的Fe()还原反应有显著影响,在缺乏可溶性磷酸盐的环境下,可能通过抑制发酵微生物生长,阻断了葡萄糖发酵生成有机酸和H的过程,使晶体磷酸铁的异化还原过程被显著抑制。

The process of dissimilatory reduction of crystal ferric phosphate by microbs and the difference of carbon source utilizing ability was investigated by adopting anaerobic co-cultivation in which three kinds of water-extracted paddy soil solutions were inoculated and crystal ferric phosphate as election acceptor of dissimilatory iron respiration was added. These results showed that the microbs from different paddy soils had remarkable effects on the maximal reaction rate （Vmax） of crystal ferric phosphate reduction,the potential reduction capacity of iron and iron reduction rate. In detail,the microbs from Sichuan paddy soil possessed much more Vmax,however,the microbs from Jilin and Jiangxi paddy soils had a higher level of the potential reduction capacity of iron; the reduction rate and iron reduction capacity of crystal ferric phosphate were less than that of ferrihydrite by microbs from three kinds of paddy soils. The microbs from different paddy soils could utilize glucose,acetate and pyruvate as solely electron donor and dissimilatory reduction of ferric phosphate could take place,producing Fe （ Ⅱ ） and releasing phosphate. Further more,the accumulation of Fe （ Ⅱ） and phosphate showed remarkable correlation. The content of soluble phosphate had a great influence on iron reduction with glucose as carbon source. When soluble phosphate was deficient,the process of producing organic acid and H2 would be blocked by suppressing the growth of the microbs,then the process of dissimilatory reduction of crystal ferric phosphate would be greatly inhibited.