Drought-tolerant plant growth promoting<i>Bacillus</i>spp.: effect on growth, osmolytes, and antioxidant status of maize under drought stress

In present study Bacillus spp. screened for drought tolerance could tolerate minimal water potential (-0.73 MPa) were evaluated for plant growth promoting properties at –0.73 MPa. Drought stress affected growth of isolates as indicated by increased intracellular free amino acids, proline, total soluble sugars, and exopolysaccharides. Drought-tolerant Bacillus spp. HYD-B17, HYTAPB18, HYDGRFB19, BKB30, RMPB44 identified as Bacillus amyloliquefaciens, Bacillus licheniformis, Bacillus thuringiensis, Paenibacillus favisporus, Bacillus subtilis based on 16S rDNA gene sequence were used to study the effect of inoculation on growth, osmolytes, antioxidant status. Inoculation increased plant biomass, relative water content, leaf water potential, root adhering soil/root tissue ratio, aggregate stability, decreasing leaf water loss. Bacillus spp. effect on osmoregulation increased proline, sugars, free amino acids and decreased electrolyte leakage. Inoculation reduced the activity of antioxidant enzymes ascorbate peroxidase, catalase, glutathione peroxidase. As a result, Bacillus spp. inoculated maize seedlings showed physiological response that could alleviate drought stress negative effects.