重组粘粒pIXUR3502对甘蓝黑腐黄单胞菌胞外多糖生物合成的负调控

RECOMBINANT COSMID PIXUR3502 INVOLVED IN NEGATIVE REGULATION OF SYNTHESISOF EXOPOLYSACCHARIDE IN Xanthomonas campestris pv. campestris

通过三亲交配，XCCNAU-1基因文库中的重组粘粒可以从Ecoli转移到XCCNAU－R3中，绝大多数重组粘粒的转入对甘蓝黑腐菌胞外多糖（Eps）生物合成无明显影响，但导致菌株生长较慢。重组粘粒pIXUR3502（约50kb）对Eps生物合成有负调控，使产量降低35.1％，发酵液粘度降低40．6％，其中，载体pIJ3200本身使产量降低6．7％，发酵液粘度降低9．4％，约28kb的外源DNA片段使产量降低28．4％，发酵液粘度降低31．2％。

The recomnant cosmids of XCCNAU - 1 gene library were transferred from E. coi intoXCCNA - R3 by triparental mating. Moot of thc recominants have no evidently effect on syntheds of exopolysaccharide (Eps) in Xanthomonas campestris pv. campestris but leads to theslower growth. The recominant cosmid p1XUR3502 (atout 50kb) invoved in negtive regulation of synthesis of Eps, decreasing the yield by 35. 1%, the viareity of the fermented liquid by40. 6%. The vecto itself decreases the yield by 6. 7 % and the visasity of the fermented liquld by9. 4% respectively. About 28kb of foreign DNA fragment of p1XR3502 decreases the yield by 28.4 %, the viscosity of the fermented liquld by 31. 2 %.