Calcite solubilizing, Multi-metal Tolerant Strain Isolated from Dolomite Affected Tea Garden Shows Plant Growth Promoting Activity.

Bacteria mediated calcite solubilization along with plant growth promoting activity can be a sustainable approach for dolomite affected agricultural soil. This study focuses on isolation of calcite solubilizing, multi-metal tolerant, alkalinity enduring soil bacteria with plant growth promoting characteristics for possible reclamation of dolomite affected tea plantation soil. A potential strain (NJCT2a), molecularly characterized as Lysinibacillus macroides with 4.78 calcite solubilization index, was isolated and exhibited tolerance against copper, zinc and lead at 10 mg/ml while 15 mg/ml and 5 mg/ml against iron and aluminium respectively. This studied strain can thrive under calcium hydroxide (0.5%-6%) and pH (5 to 8) stress. Also, displayed resistance against antibiotics, including streptomycin, colistin, cefuroxime, methicillin and fosfomycin. In vitro plant growth promoting study with NJCT2a showed positive results for production of ammonia, HCN, indole acetic acid, phosphate solubilization and negative for siderophore production. The superiority of the strain was proved by its germination promoting ability (100%) and vigor index (850) for Vigna radiata seeds. Significant increases in plant height, root length, leaf length and biomass were noted for Phaseolus vulgaris and Vigna radiata on its soil application, with similar effects on increases in chlorophyll content. Overall findings displayed the potentiality of this strain may be used as a bioinoculant in dolomite affected tea gardens for sustainable agriculture.