干湿交替条件下土壤氨基糖含量的动态变化

Dynamic changes of soil amino sugar contents under drying and wetting cycle

通过室内模拟培养试验,研究了恒湿和干湿交替条件下土壤中3种微生物来源氨基糖含量的动态变化,并且利用氨基葡萄糖和胞壁酸的比值分析了干湿交替条件下土壤真菌和细菌对土壤有机质转化的相对贡献.结果表明:恒湿条件下,细菌来源的胞壁酸在土壤中的分解速率大于真菌来源的氨基葡萄糖,氨基半乳糖在土壤中的分解速率较慢;干湿交替改变了土壤中3种氨基糖的分解特征,与恒湿处理相比,干湿交替培养前期以胞壁酸为代表的细菌残余物的分解速率高于以氨基葡萄糖为代表的真菌残余物,随着干湿交替频率的增大,以氨基葡萄糖为代表的真菌残余物分解速率高于以胞壁酸为代表的细菌残余物.可见,干湿交替条件改变了以氨基糖为代表的土壤氮素的微生物转化过程.

A soil incubation test was conducted to study the quantitative changes of three amino sugars（glucosamine,muramic acid,and galactosamine） derived from microbes under drying and wetting cycle,and to analyze the relative contribution of soil bacteria and fungi to the turnover of soil organic matter by using the measured glucosamine/muramic acid ratio.Under continuous wetting,the degradation of bacteria-derived muramic acid was faster than that of fungi-derived glucosamine,and the degradation rate of galactosamine was the lowest.Drying and wetting cycle altered the degradation characteristics of the three amino sugars.As compared with that under continuous wetting,the degradation rate of bacteria-derived muramic acid at the prophase of drying and wetting was faster than that of fungi-derived glucosamine,and,with the increasing frequency of drying and wetting cycle,the degradation rate of fungi-derived glucosamine was faster than that of bacteria-derived muramic acid.These results indicated that drying and wetting cycle changed the course of the microbial transformation of soil amino sugar-derived nitrogen.