A Highly Salt-Tolerant Bacterium Brevibacterium sediminis Promotes the Growth of Rice (Oryza sativa L.) Seedlings

Soil salinity has emerged as a serious issue for food security due to global climate change. It is estimated that currently about 62 million hectares or 20 percent of the world’s irrigated land is affected by salinity. Salinity is a serious problem in the coastal areas of Bangladesh. Isolation of salt-tolerant plant growth-promoting bacteria (PGPB) and applying them as bioinoculants in crop plants are considered promising and effective biotechnological approaches to combat soil salinity. This study aimed to screen salt-tolerant PGPB from the root, leaf, and rhizospheric soils of rice plants collected from salt-affected coastal areas including Chattogram, Noakhali, Lakshmipur, and Cox’s Bazar districts of Bangladesh and evaluated their performances on the seedling growth of rice. Out of forty-one salinity-tolerant bacterial isolates screened, Brevibacterium sediminis showed salinity tolerance up to 12% NaCl (w/v). In vitro bioassay revealed that B. sediminis promoted the seedling growth of rice cv. BRRI dhan29 (salinity susceptible) and BINAdhan-10 (salinity tolerant), and the growth-promoting effects were higher in BINAdhan-10. This study for the first time identified B. sediminis strain IBGE3C as a salt-tolerant PGPB from a widely cultivated rice variety, BRRI dhan28 in the Lakshmipur district of Bangladesh. Our results suggest that salt-tolerant PGPB isolated from the root, leaf, and rhizospheric soil of rice plants could be used as a low cost and environmentally friendly option for overcoming the detrimental effects of salt stress on rice plants in the southern coastal regions of Bangladesh. However, further studies are needed for assessing the efficacy of B. sediminis on enhancement of salinity tolerance, and growth and yield of rice under salinity stressed conditions.