Takahiko Kondo, Surachat Sibponkrung, Ken-Yu Hironao, Panlada Tittabutr, Nantakorn Boonkerd, Shu Ishikawa, Hitoshi Ashida, Neung Teaumroong, Ken-Ichi Yoshida
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引用次数: 1
Abstract
Bacillus velezensis S141, a plant growth-promoting rhizobacteria (PGPR), was isolated from a soybean field in Thailand. Previous studies demonstrated that S141 enhanced soybean growth, stimulating nodulation for symbiotic nitrogen fixation with soybean root nodule bacteria, including Bradyrhizobium diazoefficience USDA110. Isoflavone glycosides are produced in soybean roots and hydrolyzed into their aglycones, triggering nodulation. This study revealed that S141 efficiently hydrolyzed two isoflavone glycosides in soybean roots (daidzin and genistin) to their aglycones (daidzein and genistein, respectively). However, S141, Bacillus subtilis 168, NCIB3610, and B. velezensis FZB42 hydrolyzed isoflavone glucosides into aglycones. A BLASTp search suggested that S141 and the other three strains shared four genes encoding β-glucosidases corresponding to bglA, bglC, bglH, and gmuD in B. subtilis 168. The gene inactivation analysis of B. subtilis 168 revealed that bglC encoded the major β-glucosidase, contributing about half of the total activity to hydrolyze isoflavone glycosides and that bglA, bglH, and gmuD, all barely committed to the hydrolysis of isoflavone glycosides. Thus, an unknown β-glucosidase exists, and our genetic knowledge of β-glucosidases was insufficient to evaluate the ability to hydrolyze isoflavone glycosides. Nevertheless, S141 could predominate in the soybean rhizosphere, releasing isoflavone aglycones to enhance soybean nodulation.
期刊介绍:
JGAM is going to publish scientific reports containing novel and significant microbiological findings, which are mainly devoted to the following categories: Antibiotics and Secondary Metabolites; Biotechnology and Metabolic Engineering; Developmental Microbiology; Environmental Microbiology and Bioremediation; Enzymology; Eukaryotic Microbiology; Evolution and Phylogenetics; Genome Integrity and Plasticity; Microalgae and Photosynthesis; Microbiology for Food; Molecular Genetics; Physiology and Cell Surface; Synthetic and Systems Microbiology.