Tseng Y H, Ting W Y, Chou H C, Yang B Y, Chen C C
Department of Botany, National Chung Hsing University, Taichung, Taiwan.
Lett Appl Microbiol. 1992 Feb;14(2):43-6. doi: 10.1111/j.1472-765x.1992.tb00643.x.
Previously, genomic banks of Xanthomonas campestris were constructed in Escherichia coli, using mobilizable broad-host-range cosmids as the vectors. Following conjugal transfer, genes involved in the biosynthesis of xanthan polysaccharide (XPS) were cloned by the ability to restore the mucoid phenotype to the non-mucoid mutants. In this study, all clones were transferred into the wild-type strain Xc17 to evaluate the effects of the cloned genes on XPS production. Most clones showed no significant effect; however, two plasmids, pP2401 and pP2201, caused 10 and 15% yield increases, respectively, compared with that of controls. While it was not clear how pP2201 caused the yield increase, the effect of pP2401 seemed to result from elevated phosphomannose isomerase activity. Since XPS synthesis in X. campestris is a very efficient process, only relatively small increases are to be expected; an enhancement of productivity by 10-15% is important to the commercial production of xanthan.
以前，利用可移动的广宿主范围黏粒作为载体，在大肠杆菌中构建了野油菜黄单胞菌的基因组文库。通过接合转移后，依据恢复非黏液型突变体黏液表型的能力，克隆了参与黄原胶多糖（XPS）生物合成的基因。在本研究中，将所有克隆转移至野生型菌株Xc17中，以评估克隆基因对XPS产生的影响。大多数克隆未显示出显著影响；然而，与对照相比，两个质粒pP2401和pP2201分别使产量提高了10%和15%。虽然尚不清楚pP2201如何导致产量增加，但pP2401的作用似乎源于磷酸甘露糖异构酶活性的提高。由于野油菜黄单胞菌中XPS的合成是一个非常高效的过程，预计只会有相对较小的增加；生产力提高10% - 15%对黄原胶的商业生产很重要。
