盐地碱蓬内生耐盐碱枯草芽孢杆菌NXO3的促生抑菌潜力初探OA

To obtain saline-alkali tolerant bacterial strains with plant growth-promoting properties,an endophytic strain NXO3 was isolated from the stems and leaves of Suaeda salsa through selective culture screening in this study.The bacterial strain showed phosphorus solubilization,nitrogen fixation,indole acetic acid(IAA)production,and polyglutamic acid synthesis,as well as significant antagonistic activity against various plant pathogens.The strain was further identified as Bacillus subtilis NXO3 using morphological observation,physiological and biochemical characteristics analysis,and molecular biology methods.Whole-genome sequencing was performed to predict and analyse the NXO3 genes and gene clusters involved in the biosynthesis of stress-resistant plant growth-promoting metabolites like tryptophan,IAA,and glycine betaine.The analysis identified genes related to salt tolerance,including those encoding Na+/H+antiporter and K+-Cl-cotransport proteins.Under 0.24％sodium bicarbonate alkaline stress conditions,treatment with 20％fermentation broth of the strain NXO3 for 72 h significantly enhanced the germination rate of wheat seeds to 86.67％and cucumber seeds to 85.00％,with both outcomes showing significant improvements compared to the control groups(P＜0.05).Furthermore,stain NXO3 was formulated into an agricultural microbial inoculant,when applied to mildly saline-alkali coastal sandy soil(salt content 0.1％-0.3％)at 750 kg·hm-2,the inoculant significantly improved peanut germination rate to 83.15％and increased yield to 2 381.40 kg·hm-2 compared to the control group(P＜0.05).While in light to moderate saline-alkali soil(salinity content 0.1％-0.5％),application of 1 200 kg·hm-2 of NXO3 resulted in a yield of 5 785.65 kg·hm-2,showing significant difference from the control group(P＜0.05).The field experiments showed this agricultural microbial inoculant can improve the emergence rate and yield of peanuts in saline-alkali soil.This study provides a scientific foundation for developping agricultural microbial agents based on B.subtilis stain NXO3 for saline-alkali soil remediation,thereby enhancing agricultural productivity and promoting ecological sustainability in such soils.