Extracellular phytase activity of Bacillus amyloliquefaciens FZB45 contributes to its plant-growth-promoting effect
Extracellular phytase activity of Bacillus amyloliquefaciens FZB45 contributes to its plant-growth-promoting effect
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DOI：
10.1099/00221287-148-7-2097
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发表时间：
2002-07-01
期刊：
影响因子：
2.8
通讯作者：
Borriss, R
中科院分区：
文献类型：
--
作者：
Idriss, EE;Makarewicz, O;Borriss, R
李志强，李志强，等。（1998）土壤中枯草芽孢杆菌群对植物生长的影响[J].植物保护学报，32(4),393 - 398。在所调查的4株菌株中，有3株被鉴定为B. amylotiquefaciens，能够降解细胞外植酸盐（肌醇六磷酸）。菌株FZB45的胞外植酸酶活性最高，该菌株的稀释培养滤液在植酸存在的情况下促进了磷酸盐限制下玉米幼苗的生长。从FZB45克隆的植酸酶phyA基因推断出的氨基酸序列与已知的芽孢杆菌植酸酶高度相似。FZB45植酸酶与枯草芽孢杆菌碱性磷酸酶IV的相似性较弱，说明这两种酶可能具有共同的起源。由枯草芽孢杆菌MU331表达的重组蛋白具有3(l)-植酸酶活性，可产生D/ l - ins (1,2,4,5,6)P5作为植酸水解的第一个产物。用km::phyA片段取代FZB45染色体上的整个野生型基因，获得了phyya基因被破坏的植酸酶阴性突变株FZB45/M2，从FZB45/M2中获得的培养滤液对植物生长没有刺激作用。此外，在纯化植酸酶存在和培养滤液不存在的情况下，玉米幼苗的生长得到促进。这些遗传和生化实验有力地证明了B. amytoliquefaciens FZB45的植酸酶活性对磷酸盐限制下植物生长的促进作用。
Several Bacillus strains belonging to the B. subtilis/amytoliquefaciens group isolated from plant-pathogen-infested soil possess plant-growth-promoting activity [Krebs, B. et al. (11998) J Plant Dis Prot 105, 181-197]. Three out of the four strains investigated were identified as B. amylotiquefaciens and were able to degrade extracellular phytate (myo-inositol hexakisphosphate). The highest extracellular phytase activity was detected in strain FZB45, and diluted culture filtrates of this strain stimulated growth of maize seedlings under phosphate limitation in the presence of phytate. The amino acid sequence deduced from the phytase phyA gene cloned from FZB45 displayed a high degree of similarity to known Bacillus phytases. Weak similarity between FZB45 phytase and B. subtilis alkaline phosphatase IV pointed to a possible common origin of these two enzymes. The recombinant protein expressed by B. subtilis MU331 displayed 3(l)-phytase activity yielding D/L-Ins(1,2,4,5,6)P5 as the first product of phytate hydrolysis. A phytase-negative mutant strain, FZB45/M2, whose phyA gene is disrupted, was generated by replacing the entire wild-type gene on the chromosome of FZB45 with a km::phyA fragment, and culture filtrates obtained from FZB45/M2 did not stimulate plant growth. In addition, the growth of maize seedlings was promoted in the presence of purified phytase and the absence of culture filtrate. These genetic and biochemical experiments provide strong evidence that phytase activity of B. amytoliquefaciens FZB45 is important for plant growth stimulation under phosphate limitation.