小麦土霉素抗性内生细菌分离、鉴定及分布

研究通过培养的方法研究了小麦根际土壤、根、茎、叶各部位的土霉素抗性内生菌数量、种类和分布特征.结果表明,小麦内生菌数目在1×104cfu g-1～1.95×106 cfu g-1 之间,土霉素抗性内生菌数目介于6.9×103cfu g-1和5.67×105 cfu g-1,从中分离出22株土霉素抗性内生菌,包括15株G+和7株G-,经16s rRNA基因序列分析,它们与Bacillaceae,Alphaproteobacteria 和Gammaproteobacteria 三大类微生物聚在一起,其中Bacillaceae类细菌最多,占59.1%.土霉素抗性的Bacillus licheniformis在小麦根际土壤、根、茎等器官中都分离得到表明该抗性菌种在小麦内生系统中具有较高的传播性;具有土霉素抗性的人类机会致病菌Bacillus cereus和Stenotrophomonas属的细菌在小麦的根际土壤、根以及叶子中也均分离到,但是在小麦种子中没有分离到任何土霉素抗性的内生菌.

Isolation and distribution of oxytetracycline\|resistant entophytic bacteria in plant of wheat

In this study, the quantity, species and distribution characteristics of oxytetracycline resistant entophytic bacteria in wheat rhizosphere, root, stem, leaves and seeds were researched by isolation and cultivation methods. The results indicated that the total amount of entophytic bacteria in wheat was between 1×104 cfu g-1and 1.95×106 cfu g-1, in which the oxytetracycline resistant strains were from 6.9×103 cfu g-1 to 5.67×105 cfu g-1. 22 strains of oxytetracycline resistant entophytic bacteria were isolated, including 15 G+ and 7 G-. The 22 isolates were clustered into Bacillaceae, Alphaproteobacteria and Gammaproteobacteria based on their full length 16S rRNA gene sequences. Among them, strains of Bacillaceae occupied the predominance with 59.1% in various wheat organs. Oxytetracycline resistant strains of Bacillus licheniformis were isolated from wheat rhizosphere, root and stem indicating their high abilities of spreading. Opportunistic human pathogenic bacterial strains with oxytetracycline resistance such as Bacillus cereus and Stenotrophomonas sp. were also isolated from various wheat organs. No oxytetracycline resistant bacterium could be detected from wheat seeds.