绰墩山遗址古水稻土的一些微生物学特性研究

MICROBIOLOGICAL PROPERTIES OF AN ANCIENT PADDY SOIL DISCOVERED IN CHUODUNSHAN RELICS OF KUNSHAN,CHINA

在江苏绰墩山遗址考古发掘中，发现了在剖面不同深度埋藏的距今约6500a的史前古水稻田土层（100～200cm）和距今约3320a的商周时期的古水稻田土层（42～100cm）。本研究为了解古水稻土的生物学性状及其与现代水稻土的差别，以土壤剖面P-01（包含史前古水稻土和商周时期古水稻土）与P-03（仅含商周时期古水稻土）为对象，利用土壤厌氧培养、Biolog分析和广古生菌界16SrDNA的V3区的PCR—DGGE分析，初步研究了不同土层厌氧微生物多样性、产甲烷潜势以及产甲烷古菌群落多样性的变化。结果表明，史前古水稻土仍有较多厌氧微生物存活，可达7．0×10^5cfu g^-1干土，并且其单一碳源利用能力和多样性也显著高于其湖相沉积母质和相同时期的非水稻土（黄土母质）。与现代水稻土相比，古水稻土仅存留了很微弱的产甲烷潜势。但史前古水稻土比同期非水稻土和商周时期古水稻土的产甲烷潜势较高。PCR—DGGE结果显示，水稻土层都有其区别于非水稻土层的产甲烷古菌群落结构，而现代水稻土、商周时期古水稻土和史前古水稻土也各有不同的优势产甲烷古菌种群，不同时期的水稻耕作方式是造成这种差异的可能的重要原因之一。

Two layers of ancient paddy soil were discovered in archeological excavation of Chuodunshan Relics in Kunshan, China. One of them could ascend to 6 500 a BP （prehistoric）, and the other 3 320 a BP （Shang-Zhou Period）. Two soil profiles, not far apart, named P-01 （containing both soil layers） and P-03 （containing only the latter） respectively, were fixed and soil samples were collected according to soil color and texture. The techniques of soil anaerobic incubation, Biolog analysis and PCR-DGGE of 16S rDNA gene fragments encoding Euryarchaeota variable V3 region were used to study microbial diversity of anerobic microbes, methane emission potential and the genetic diversity of methanogenic archaea communities in different soil layers. The aim of this study is to determine biological properties of the ancient paddy soils. The results show that among all the underground soil layers of the two profiles, the prehistoric ancient paddy soil layer still had quite a number of anaerobic microbes surviving in the soil, up to 7.0 × 105 cfu g^-1 soil, and it also showed better carbon utilization capacity and diversity than the other soil layers. A tendency was noticed that the prehistoric ancient paddy soil showed slightly higher methane emission potential than its parent material - lake sediment and homoehronous non-paddy soil - loess, though it was very weak compared with that of recent paddy soils. PCR-DGGE analysis revealed that the methanogenie archaea community made paddy soil layers different from the other soil layers, and paddy soils of different ages have their respective special predominant populations.