宁夏黄土高原马铃薯连作栽培对土壤可培养细菌遗传多样性的影响

采用平板培养、BOXAIR-PCR和16S rDNA RFLP技术对宁夏黄土高原马铃薯连作栽培土壤可培养细菌遗传多样性进行研究。结果表明，4个连作年限2个生育期8份土样共分离到91株细菌菌株， BOXAIR-PCR分析发现，91株细菌菌株的遗传相似系数为0.531～0.939，相同连作年限不同生育期根际土细菌菌群分布不同，不同连作年限同一生育期根际土细菌菌群的分布也不同，随着连作年限增加，可培养细菌遗传多样性呈现下降趋势；结合16S rDNA 的序列分析，从91株菌株中筛选出的41个代表菌株可分为23个物种，分属于细菌域的12个属，其中，芽孢杆菌属（Bacillus）占同一连作年限菌株数的53.6%。连作导致土壤细菌菌群结构发生变化，出现各自特有的菌属。系统发育分析表明，23个细菌物种分布于6个系统发育群。

Effect of Potato Continuous Cropping on the Genetic Diversity of Soil Culturable Bacteria in Ningxia Loess Plateau Zone

The genetic diversity of culturable bacteria in potato continuous cropping soil in Loess Plateau in Ningxia was studied by the plateculture technique,BOXAIR-PCR and 16S rDNA sequences analysis technology. It is shown that the total amount of 91 bacterial strains were isolated from 8 rhizosphere soil samples of potato continuous cropping, with the genetic similarity coefficients varying from 0.531 to 0.939, indicating high diversity among the 91 strains.The bacterial communities in rhizosphere soil were distributed differently at various growth stages in the same continuous cropping year, as well as in same growth stages of different continuous cropping year. The genetic diversity of culturable bacteria declined as the continuous cropping year increased. Further experiment with 16S rDNA sequences analysis provided evidences to select 41 representative strains from the 91 bacterial strains. The representative strains were classified into 23 species of 12 genera of bacteria. The largest proportion, 53.6%, of the representative strains belong to Bacillus. This study indicated that continuous cropping could induce change in the bacteria community structure and the specific bacteria can develop in different rhizosphere soil. The phylogenetic analysis revealed that 23 bacteria species were distributed in 6 phylogenetic groups.