Functional characterization of endophytic bacilli from pearl millet (Pennisetum glaucum) and their possible role in multiple stress tolerance

Endophytic bacteria are common residents of living host tissue and occupy vital role in sustaining crop growth and health under adverse environmental situations. At present, scanty information is available about the salt-tolerant plant growth promoting (PGP) endophytic bacilli from pearl millet (Pennisetum glaucum). In the study, 102 endophytic Bacillus strains from root, leaf and stem region of pear millet host plant were isolated and limited to 28 strains depending on the salt (>= 10%) tolerance ability. Phenotypic and biochemical features, together with 16S rDNA gene sequence similarity comparison with type strains identified endophytes as Bacillus albus, B. amyloliquefaciens, B. aryabhattai, B. halotolerans, B. haynesii, B. pacific, B. paramycoides, B. proteolyticus, B. pumilus, B. subtilis, B. siamensis, B. tequilensis, B. wiedmannii and B. zhangzhouensis. The rigorous in vitro screening for PGP traits, nutrient solubilization, heavy metal, polyethelene glycol, extracellular enzyme production and antagonistic potential identified B. amyloliquefaciens EPP90 as a potent multi-stress tolerant crop growth promoter. Under greenhouse experiments, plants treated with this strain reflected significantly superior plant growth relative to untreated pearl millet seed grown under saline (200 mM NaCl) environment. The research findings clearly displayed the prospective function of endophytic B. amyloliquefaciens EPP90 as an excellent multi-stress reliever and crop growth promoter.