Saleh S S, Glick B R
Department of Biology, University of Waterloo, ON, Canada.
Can J Microbiol. 2001 Aug;47(8):698-705. doi: 10.1139/w01-072.
The plant growth-promoting bacteria Enterobacter cloacae CAL2 and UW4 were genetically transformed with a multicopy plasmid containing an rpoS or gacS gene from Pseudomonas fluorescens. The transformed strains were compared with the nontransformed strains for growth, indoleacetic acid (IAA) production, antibiotic production, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, siderophore production, cell morphology, and the ability to promote canola root elongation. All transformed strains had a longer lag phase, were slower in reaching stationary phase, and attained a higher cell density than the nontransformed strains. Transformation resulted in cells that were significantly shorter than the nontransformed cells. The transformed strains also produced significantly more IAA than the nontransformed strains. Introduction of rpoS or gacS from Pseudomonas fluorescens was associated with a reduction in the production of both antibiotics, 2,4-diacetylphloroglucinol and mono-acetylphloroglucinol, produced by Enterobacter cloacae CAL2. With Enterobacter cloacae CAL2, plasmid-borne rpoS, but not gacS, increased the level of ACC deaminase activity, while introduction of rpoS in Enterobacter cloacae UW4 caused a decrease in ACC deaminase activity. Neither gacS nor rpoS significantly affected the level of siderophores synthesized by either bacterial strain. Overproduction of either GacA or RpoS in Enterobacter cloacae CAL2 resulted in a significant increase in the root lengths of canola seedlings when seeds were treated with the bacteria, and overproduction of RpoS caused an increase in canola shoot as well as root lengths.
植物促生细菌阴沟肠杆菌CAL2和UW4用含有来自荧光假单胞菌的rpoS或gacS基因的多拷贝质粒进行遗传转化。将转化菌株与未转化菌株在生长、吲哚乙酸（IAA）产生、抗生素产生、1-氨基环丙烷-1-羧酸（ACC）脱氨酶活性、铁载体产生、细胞形态以及促进油菜根伸长的能力方面进行比较。所有转化菌株的延滞期更长，达到稳定期的速度较慢，并且比未转化菌株达到更高的细胞密度。转化导致细胞明显比未转化细胞短。转化菌株产生的IAA也明显多于未转化菌株。从荧光假单胞菌引入rpoS或gacS与阴沟肠杆菌CAL2产生的两种抗生素2,4-二乙酰基间苯三酚和单乙酰基间苯三酚的产量降低有关。对于阴沟肠杆菌CAL2，质粒携带的rpoS而非gacS增加了ACC脱氨酶活性水平，而在阴沟肠杆菌UW4中引入rpoS导致ACC脱氨酶活性降低。gacS和rpoS均未显著影响任一菌株合成的铁载体水平。当用细菌处理种子时，阴沟肠杆菌CAL2中GacA或RpoS的过量产生导致油菜幼苗根长显著增加，并且RpoS的过量产生导致油菜地上部分以及根长增加。
