巨大芽胞杆菌luxAB标记菌株的根际定殖研究

STUDY ON ROOT COLONIZATION OF WHEAT BY luxAB GENES-MARKED BACILLUS MEGATERIUM ATCC14581

通过三亲本杂交方法成功地用发光酶基因luxAB标记巨大芽胞杆菌ATCC1 45 81 ,所获得的标记菌株ATCC1 45 81 L在不同的条件下能稳定发光。将该标记菌株制成微生物接种剂 ,并利用土壤微缩系统将其接种小麦进一步研究它在小麦根际的定殖动态和散布规律。结果发现 ,ATCC1 45 81 L在灭菌土壤中的定殖水平高于不灭菌土壤 ,在垂直方向上主要的定殖在 0～ 7cm根段间 ,且随深度增加而降低。ATCC1 45 81 L在小麦种后第 7d之前就已达到最高定殖水平 ,在初始接种量为 3 40× 1 0 7cfu/g根情况下 ,第 7d时灭菌土壤处理的根际菌数为 2 5 4× 1 0 5cfu/g根 ,而不灭菌土壤的根际菌数为 8 87× 1 0 4 cfu/g根 ;随着时间的增长 ,定殖数量明显降低。

By triparental mating,Bacillus megaterium ATCC14581 strain marked by luxAB gene were successfully obtained,then the ATCC14581-L strain was made to microbial inoculant.After it was inoculated on seeds of wheat,the colonizing dynamics and distribution of the luminescent bacteria ATCC14581-L in the rhizosphere of wheat plant in rhizoboxes were studied by the method of X-ray film imaging and enumeration of luminescent colonies on agar media.The results showed that ATCC14581-L successfully colonized in the rhizosphere of wheat.The population reached to the highest level,2.54×10 5 and 8.87×10 4cfu/g root respectively in the sterile soil and unsterile soil after 7 days,with initial inoculant dose of 3.40×10 7 cfu/g root.The population of them trended to be stable and decreased to 4.47×10 3 and 8.57×10 2 cfu/g root respectively after 16 th day.