硒砂瓜连作地微生物群落变化及一株优势芽孢杆菌的分离鉴定

Changes of microbial community and isolation and identification of a dominant bacillus strain from the continuous cropping of selenium sand watermelon

为揭示由于长期连作而造成硒砂瓜减产的主要因素,以不同连作年限的宁夏硒砂瓜种植区土壤微生物作为研究对象,分析连作1 a、连作3 a、连作5 a、连作7 a和连作10 a的硒砂瓜种植区土壤微生物群落的变化规律。在此基础上对一株优势芽孢杆菌NB1菌株进行分离纯化鉴定。结果表明,随着连作年限的增加,硒砂瓜土壤微生物总量呈明显的下降趋势,且微生物菌群结构也发生了变化,总体表现为真菌增加、细菌和放线菌减少的发展态势。通过芽孢细菌形态特征、生理生化反应结合16S rDNA基因序列分析,初步鉴定NB1菌株为枯草芽孢杆菌。研究结果不仅为改善土壤微生物群落结构提供了理论依据,也为最大限度地发挥有益微生物作用、解决硒砂瓜连作障碍提供了科学依据。

In order to reveal the main factors affecting the declined production of selenium sand watermelon, we used soil microorganism in continuous cropping soil of Ningxia selenium sand watermelon as the research object. We analyzed the changes regularity of 1 year＇s, 3 year＇s, 5 year＇s, 7 year＇s and 10 year＇s micro flora in continuous cropping soil of selenium sand watermelon. Then we separated and purified the bacterial in soil, and identified a dominant bacterial strain NB 1 to explore the role of bacteria in soil. The results showed the number of microorganisms decreased with increasing continuous cropping years, and the microbial population structure has changed. The overall trend was reducing the numbers of bacteria and actinomyces but increasing that of fungi. According to the results of morphological characteristics, physiological and biochemical reactions and 16S rDNA sequence, the NB1 strain was identified as Bacillus subtilis. Understanding of micro- organism population fluctuation under continuous cropping will lead to improvement of soil beneficial microorganisms, improving watermelon production in selenium sand fields.