荧光假单胞菌AS1.867和3-PHB的luxAB基因标记及其在小麦根际的定殖

Colonization on Wheat Root by luxAB Genes-markedPseudomonas fluourescens AS1.867 and 3-PHB

通过三亲本杂交方法成功地用发光酶基因 lux AB标记荧光假单胞菌 ( Pseudomonasflu-orescens) AS1 .86 7- L和 3 - PHB菌株 ,获得的标记菌株 AS1 .86 7- L和 3 - PHB- L在不同的条件下能稳定发光。将 AS1 .86 7- L和 3 - PHB- L制成固体微生物接种剂 ,并利用土壤微缩系统将其接种于小麦 ,研究它们在小麦根际的定殖动态和散布规律。结果发现 ,二株标记菌株在灭菌土壤上的定殖水平高于不灭菌土壤 ,在垂直方向上定殖主要发生于 0～ 8cm根段间 ,且随着深度的增加而降低。接种菌株在第 7天之前就已达到最高定殖水平 ,在每克根的初始接种量为 2 .3 2× 1 0 8cfu时 ,第 7天的灭菌土壤中 AS1 .86 7- L和 3 - PHB- L的根际菌数分别为 9.6 7× 1 0 6cfu和 6 .90× 1 0 6cfu,不灭菌土壤的根际菌数为 1 .41× 1 0 5cfu和 7.71× 1 0 5cfu。随着时间的延长 ,定殖数量均明显降低 ,3 - PHB- L在 40

By triparental mating, AS 1.867 and 3-PHB strains marked by luxAB gene were successfully obtained, then AS 1.867-L and 3-PHB-L strains were prepared as microbial inoculants. Being inoculated on wheat seed, the colonizing dynamics and distribution of the luminescent bacteria AS 1.867-L and 3-PHB-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 they have successfully colonized in the rhizosphere of wheat. In rhizoboxes of sterile soil the AS 1.867-L and 3-PHB-L strains reached the highest level 9.67×10 6 and 6.90×10 6cfu/g root respectively, after 7 days with initial inoculant dose of 2.32×10 8 cfu/g root. Their population trended towards stable and decreased to 4.93×10 3 and 4.47×10 3cfu/g root respectively after 16 days. On the contrary, in rhizoboxes of unsterile soil, the highest colonizing level was 1.41×10 5 and 7.71×10 5cfu/g root respectively after 7 days. On the 16 thday, their population trended towards stationary phase and reduced to 2.27×10 4 and 5.30×10 5cfu/g root. On the 16 thday, only AS 1.867-L (1.87×10 3cfu/g root) was tested from 8cm to 16cm under the seed, while the other marked strains were little.