Petroleum hydrocarbon (PHC) contamination of soil is a widespread global environmental concern due to the persistence and recalcitrant nature of PHCs. The PHCs are highly toxic and their removal from the terrestrial ecosystem is necessary to maintain soil as well as human health. Here, a pot experiment was performed to examine the impact of Enterobacter sp. MN17 and biochar addition on the growth of mungbean plants and PHCs removal from diesel-polluted soil. For this purpose, soil was contaminated artificially with diesel to achieve a final concentration of 5000 mg kg−1. Untreated and Enterobacter sp. MN17 treated mungbean seeds were sown in pots. Sugarcane bagasse biochar was applied as an amendment in respective pots along with the recommended levels of essential nutrients. Results showed that PHCs significantly suppressed the seedling emergence as well as agronomic and physiological attributes of mungbean as compared to un-contaminated controls. However, the co-application of Enterobacter sp. MN17 and biochar significantly reduced the phytotoxicity of PHCs to mungbean plants and effectively increased the seedling emergence, shoot and root length, shoot fresh and dry biomass, root fresh and dry biomass of plants up to 24%, 54%, 52%, 52%, 54%, 55% and 60%, respectively as compared to controls. Similarly, 30%, 57%, 64%, 36% and 57% increase in chlorophylls contents, transpiration rate, stomatal conductance, sub-stomatal conductance, and photosynthetic rate, respectively were observed in their combined application as compared to respective controls. Furthermore, the co-addition of biochar and Enterobacter sp. MN17 could remove 69% and 85% higher PHCs from unplanted and planted pots, respectively, than that of their respective controls. Our results suggest that the co-application of biochar and Enterobacter sp. MN17 may be useful in enhancing plant growth and eliminating PHCs from contaminated soil.

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Contamination by petroleum hydrocarbons (PHs) is a great threat to environment due to the higher persistence and bio-toxicity of PHs. Therefore, removal of PHs from contaminated environment and strategies to reduce their toxic effects on living organisms are crucial for environmental safety and human health. The toxic effects of PHs from the polluted soil can be reduced by the addition of microbes and biochar. In this study, a pot trial was carried out to evaluate the effects of sugarcane bagasse (SB) biochar and Bacillus sp. MN54 addition on phytoremediation of PHs and growth of maize (Zea mays L.) in soil artificially contaminated with diesel. Maize seeds were sown in uncontaminated or contaminated (with PHs) soil, treated with biochar and Bacillus sp. MN54. The results revealed that PHs showed significant phytotoxicity to maize plants and the application of strain MN54 and biochar greatly reduced the toxic effects of PHs on plants growth and physiology by increasing the nutrients uptake in PHs contaminated soil. Interestingly, the phytotoxicity of PHs on maize plants was further reduced in the co-supplementation of strain MN54 and biochar. Plants physiological (25–48%) and agronomic (38–47%) attributes were significantly higher as compared to only PHs contaminated soil in the co-supplementation of strain MN54 and biochar. Similarly, nitrogen (41%), phosphorus (43%) and potassium (37%) concentrations were also increased in the co-supplementation of strain MN54 and biochar. Furthermore, maize plants successfully phytoremediate a considerable amount of PHs from soil particularly in the presence of strain MN54 and biochar, and this PHs removal was further enhanced in the co-supplementation of strain MN54 and biochar (i.e., 46% and 77% of initial PHs were removed in unplanted and planted treatments, respectively). The present results indicate that co-supplementation of biochar and Bacillus sp. MN54 could be effective in enhancing the degradation of PHs and improving plant growth in the hydrocarbons contaminated soil.

The main purpose of this study was to examine the impact of different phosphorus (P) fertilizers and organic manures alone and in combination with Bacillus sp. MN-54 on growth, yield, nutrient uptake, chlorophyll (SPAD value) and crude proteins content of chickpea. The simple manure (SM), processed manure (PM), single super phosphate (SSP), and rock phosphate (RP) were applied individually and in different combinations to the soil in pots, and the chickpea seeds treated with Bacillus sp. MN-54 were sown in the selective pots. Results showed that individual use of SM, PM, SSP, RP, and strain MN-54 significantly increased (p ≤ 0.05) the nutrient uptake, growth, yield, and protein content of chickpea as compared to control treatments. While the combined use of SM or PM, SSP or RP, and MN-54 further enhanced this effect. Among different treatments, combined use of RP, PM and MN-54 proved the most effective treatment showing increase of 37.5 and 42.6% in shoot and root lengths, 43.4 and 38.3% in fresh and dry shoot weights, 36.1 and 36.5% in fresh and dry root weights, 45.8% in no. of pods, 43.6% in nodules counts, 16.0% in 100-grain weight and 31–36% nutrient uptake over control treatments. Our findings suggest that the co-addition of organic manures and P fertilizers along with plant growth promoting bacteria (i.e., Bacillus sp. MN-54) not only increases the growth and yield but also improves nodulation, nutrient uptake, and crude proteins content in chickpea.