全球稻田面積約1.5億公頃,，75%處于淹水狀態(tài)。厭氧環(huán)境使得水稻土含有豐富的小分子有機酸,。通過代謝這些物質(zhì),，微生物驅(qū)動著稻田土壤生物地球化學循環(huán)過程。甲酸是稻田有機質(zhì)降解過程中重要中間產(chǎn)物之一,，但水稻土中甲酸代謝微生物及其生態(tài)功能卻鮮有報道,。
中科院南京土壤研究所林先貴研究員團隊通過穩(wěn)定性同位素核酸探針技術(shù)，利用13C標記的甲酸培育水稻土,，讓微生物“吃掉”甲酸的13C,；再利用超高速密度梯度離心對土壤總DNA進行分層，獲得甲酸代謝微生物13C-DNA,；借助實時定量PCR技術(shù),、指紋圖譜技術(shù)和系統(tǒng)發(fā)育分析，清楚表明13C-甲酸被土壤梭菌和紫色非硫細菌利用,。前者可利用甲酸為電子供體促進水稻土中硫酸鹽和鐵還原過程,；紫色非硫細菌是首次原位條件下被發(fā)現(xiàn)可在黑暗中有機異養(yǎng)生長。
這些結(jié)果不僅僅揭示了水稻土中甲酸代謝微生物,，更擴展了人們對甲酸在生物地球化學循環(huán)過程中重要性的認知,，為全面理解微生物驅(qū)動下的土壤養(yǎng)分循環(huán)過程及其調(diào)控機制提供了重要科學依據(jù)。
該成果發(fā)表在Soil Science Society of America Journal上,，并選為研究亮點在美國農(nóng)作物科學協(xié)會(Crop Science Society of America)創(chuàng)辦的CSA (Crops,， Soils， Agronomy) news 雜志的2012年2月刊上報道,。（生物谷Bioon.com）
doi:10.2136/sssaj2011.0216
PMC:
PMID:
Identification of Formate-Metabolizing Bacteria in Paddy Soil by DNA-Based Stable Isotope Probing
Youzhi Feng, Xiangui Lin *, Zhongjun Jia and Jianguo Zhu
As one of the fermentation products of plant biomass, formate is an important organic acid in flooded rice (Oryza sativa L.) fields. Little is known, however, about the identity of formate-metabolizing bacteria in paddy soil. In this study, a paddy soil microcosm was incubated with 13C-labeled formate; bacterial and eukaryotic communities incorporating formate C were analyzed by DNA-stable isotope probing. Real-time quantitative polymerase chain reaction analysis revealed that 13C-formate-derived C was actively assimilated by a subset of bacteria. Molecular fingerprinting and sequencing analysis of 16S rRNA genes revealed that the active formate-metabolizing bacteria in the paddy soil were mainly the bacteria in the Clostridia class and purple nonsulfur bacteria (PNSB). The former might facilitate SO42− and Fe reduction using formate. Observed for the first time, PNSB are able to assimilate organic matter for growth under in situ conditions without light. These results extend our knowledge of not only the formate-assimilating bacteria but also the ecological significance of formate in paddy soil.
