Bioprospecting of a Novel Plant Growth-Promoting BacteriumBacillus altitudinisKP-14 for EnhancingMiscanthusxgiganteusGrowth in Metals Contaminated Soil

Simple Summary Marginal land represents poor soil with low agricultural characteristics and crop productivity, which is sometimes additionally contaminated. The exploitation of marginal land for normal agriculture is not possible but it suitable for cultivation of energy crops, especiallyMiscanthusxgiganteus(Mxg), however, the harvest biomass value in such land is lower. The producedMxgbiomass can be converted to alternative energy like biofuel and biogas, or used for production of other value-added products like insulation fibers, building materials or paper, etc. It is well known fact that plant growth-promoting bacteria are beneficial for stimulating the overall development of plants even under stress conditions. In the current study, a number of strains were isolated from the metal-contaminated post-mining land, identified, biochemically characterized, and evaluated for abiotic stress tolerance: pH, temperature, salinity, and heavy metal (lead). Among different isolates, the multiple abiotic stress-tolerant plant growth-promoting bacteriaBacillus altitudinisKP-14 showed the best properties. Its effect on the growth ofMxgunder the severe stress of metal-contaminated soil was evaluated. It was found that selected bacterial strain KP-14 significantly enhanced the biomass production. The overall results suggested thatB. altitudinisKP-14 can be recommended as a potent biofertilizer for marginal lands. Use of plant growth-promoting bacteria (PGPB) for cultivation of the biofuel cropMiscanthusxgiganteus(Mxg) in post-military and post-mining sites is a promising approach for the bioremediation of soils contaminated by metals. In the present study, PGPB were isolated from contaminated soil and screened for tolerance against abiotic stresses caused by salinity, pH, temperature, and lead (Pb). Selected strains were further assessed and screened for plant growth-promoting attributes. The isolate showing the most potential,Bacillus altitudinisKP-14, was tested for enhancement ofMxggrowth in contaminated soil under greenhouse conditions. It was found to be highly tolerant to diverse abiotic stresses, exhibiting tolerance to salinity (0-15%), pH (4-8), temperature (4-50 degrees C), and Pb (up to 1200 ppm). The association ofB. altitudinisKP-14 withMxgresulted in a significant (p <= 0.001) impact on biomass enhancement: the total shoot and dry root weights were significantly enhanced by 77.7% and 55.5%, respectively. The significant enhancement ofMxgbiomass parameters by application ofB. altitudinisKP-14 strongly supports the use of this strain as a biofertilizer for the improvement of plant growth in metal-contaminated soils.