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( Yunlei Han ),( Rui Wang ),( Zhirong Yang ),( Yuhua Zhan ),( Yao Ma ),( Shuzhen Ping ),( Liwen Zhang ),( Min Lin ),( Yongliang Yan ) 한국미생물 · 생명공학회 2015 Journal of microbiology and biotechnology Vol.25 No.7
1-Aminocyclopropane-1-carboxylate (ACC) deaminase, which is encoded by some bacteria, can reduce the amount of ethylene, a root elongation inhibitor, and stimulate the growth of plants under various environmental stresses. The presence of ACC deaminase activity and the regulation of ACC in several rhizospheric bacteria have been reported. The nitrogen-fixing Pseudomonas stutzeri A1501 is capable of endophytic association with rice plants and promotes the growth of rice. However, the functional identification of ACC deaminase has not been performed. In this study, the proposed effect of ACC deaminase in P. stutzeri A1501 was investigated. Genome mining showed that P. stutzeri A1501 carries a single gene encodingACC deaminase, designated acdS. The acdS mutant was devoid of ACC deaminase activity and was less resistant to NaCl and NiCl2 compared with the wild-type. Furthermore, inactivation of acdS greatly impaired its nitrogenase activity under salt stress conditions. It was also observed that mutation of the acdS gene led to loss of the ability to promote the growth of rice under salt or heavy metal stress. Taken together, this study illustrates the essential role of ACC deaminase, not only in enhancing the salt or heavy metal tolerance of bacteria but also in improving the growth of plants, and provides a theoretical basis for studying the interaction between plant growth-promoting rhizobacteria and plants.
Xuying Nan,Lili Sun,Xinming Song,Mingshu Wu,Guangying Chen,Yuhua Yao 한국섬유공학회 2019 Fibers and polymers Vol.20 No.8
A water-soluble silk peptide (SP) was fractioned to a series of SP fractions with different molecular weight. Theantioxidant activity of these fractions was investigated by the ABTS and DPPH assays, and the co-initiating ability of eachfraction in type II photoinitiator was evaluated in photopolymerization of acrylamide, using camphorquinone as thesensitizer. Gel permeation chromatograph was used to investigate molecular weight distributions of SP fractions. The resultsshowed that with the increase of the proportion of the component with molecular weight of about 200 in SP fractions,antioxidant activity and co-initiation ability became poor. Four essential amino acids, Ala, Gly, Ser and Tyr of SP and theirrespective pentapeptides were also assessed for these two functions. Among them, pentatyrosine exhibited the most excellentperformance in two functions, which might be ascribed to its excellent electron/hydrogen donation capability. Andpentaglycine had good behavior in these two functions, suggesting that the polypeptide chain was responsible for electron/hydrogen donation. By 1H NMR analysis, it was speculated that the photoinitiation active center was located on themethylene group of pentaglycine. The electron/hydrogen donor of SP is the inherent reason for antioxidant function andphotoinitiation performance of SP.