苔藓密度对生物结皮土壤微生物的影响

Effect of Moss Density on Soil Microbes of Biological Soil Crust

采用平板培养法和梯度凝胶电泳法,分别对不同植株密度苔藓(主要为齿肋赤藓,纯度>95%)结皮土壤中可培养、非培养微生物的数量和物种多样性进行了研究。结果表明:自然状态下细菌是苔藓结皮土壤中的优势微生物类群;随着苔藓植株密度降低可培养微生物中细菌比重下降而放线菌比重上升;可培养微生物的数量随着苔藓植株密度降低而下降,物种多样性无显著变化;非培养细菌的数量和物种数表现出与可培养微生物相反的变化趋势。初步推断造成两者差异的主要原因在于:1)研究方法不同,平板培养反映了细菌、放线菌和真菌三种不同微生物的数量和种类变化,而梯度凝胶电泳技术仅反映了细菌的数量和多样性变化;2)可培养微生物多为土壤中的优势种属,而梯度凝胶电泳技术则可以检测到更多的非优势物种。

The quantity and diversity of microbes are influenced by soil texture,plant type and weather conditions. In this study, the influences of moss （mostly syntrichia caninervis Mitt, the purity was more than 95 % ） density on microbes＇ quantity and diversity are analyzed through plating culture and denaturing gradient gel eleetrophoresis. The results indicated that under natural condition, bacteria were the dominant species of soil microbes of moss crusts. With the decrease of moss density, quantity pro- portion of bacteria decreased,but the proportion of actinomycosis increased;when moss density declined, under culturing condition,microbes quantity decreased, but diversity was constant;on the contrary with cultural condition, by denaturing gradient gel electrophoresis method,quantity and diversity of bacteria increased with the decrease of moss density. We attributed the differ ence to two reasons： （1） The difference of research method： culturing method reflected bacteria, actinomyeosis and fungi changes of quantity and diversity,but denaturing gradient gel electrophoresis method only reflected bacteria changes. （2） Under cultu ring condition,most cultured microbes were dominant species,but by denaturing gradient gel eleetrophoresis method,many bac teria which were not dominant species could be detected.