Alleviation of nickel stress by halophilic bacteria in mungbean (Vigna radiata)

Mungbean is an important, short-duration legume crop with high nutritive value for poor families, where protein and micronutrient scarcity are most pervasive. In developing countries, like Pakistan, where mungbean is one of the greatest sources of protein for underprivileged people, salinity and metal stresses are drastically limiting its yield. Therefore, it is necessary to explore the ways for promoting the growth of mungbean under stressed conditions. This study provides the basis for the use of two previously isolated halophilic and nickel-resistant bacteria [Bacillus subtilis and Halomonas aquamarina (1)] in promoting the growth of mungbean plant under nickel-stressed environments. These bacterial strains were previously found to improve the growth of plants under salinity because of their good biofilm-forming abilities. We hypothesized that these two halophilic and nickel-resistant biofilm-forming bacteria can help the plants to grow under nickel-stressed environments by promoting soil aggregation as they were previously reported to resist salinity and nickel stress, as well as were found to promote plant growth under saline environments. The results revealed that under nickel stress, both bacteria promote plant growth by facilitating the formation of soil aggregates through an increase in their extra polymeric substance (EPS) production