Rhizobacteria Strain from a Hypersaline Environment Promotes Plant Growth of Kengyilia thoroldiana

Abstract

Kengyilia thoroldiana is a nutritionally rich grass species of the Qinghai-Tibet Plateau. Here, to improve its quality and biomass via biological fertilization, we sought out plant-growth promoting rhizobacteria. Our screening found one Bacillus species capable of nitrogen fixation, indole-3-acetic acid production, and tolerating the extreme saline-alkali soil of Qinghai Province. We determined the strain’s growth performance and antagonistic effects with pathogens (Fusarium graminearum, F. acuminatum) and evaluated its impact on K. thoroldiana. The test strain KKLW1 was identified as Bacillusamyloliquefaciens by morphology, adversity culture, and 16S rDNA and gyrB partial sequence analyses. KKLW1 strongly tolerates saline conditions (11% salt, pH 11), and showed stable nitrogen fixation activity and IAA production capacity; its Phl gene, which we amplified, was significant antagonistic to pathogenic pasture fungi. Furthermore, compared with the control, the strain showed clear germination and growth-promoting activity after soaking grass seeds and root-irrigating with the Bacillus suspension, increasing each by 8 and 10–12%, respectively. In sum, the strain KKLW1 has excellent biological properties and stable physiological characteristics in this extreme environment of the Qinghai-Tibet Plateau. We propose KKLW1 for use as a functional strain of microbial fertilizer to increase production and restore vegetation coverage of the Plateau’s grassland.