Microbe-Assisted Rhizoremediation of Hydrocarbons and Growth Promotion of Chickpea Plants in Petroleum Hydrocarbons-Contaminated Soil

Abstract

The present work aimed to develop and investigate microbial consortia for petroleum hydrocarbons (PHCs) detoxification and plant growth improvement in hydrocarbons-contaminated soil. Here, we isolated several bacteria from PHCs-contaminated soils to make bacterial consortia and two of the best consortia were tested in a pot experiment to evaluate their potential for PHCs removal and chickpea growth promotion in PHCs-contaminated soil. Results demonstrated that the PHCs exerted considerable phytotoxic effects on chickpea growth and physiology by causing a 13–29% and a 12–43% reduction in agronomic and physiological traits, respectively. However, in the presence of bacterial consortia, the phytotoxicity of PHCs to chickpea plants was minimized, resulting in a 7.0–24% and a 6.0–35% increase in agronomic and physiological traits, respectively over un-inoculated controls. Bacterial consortia also boosted nutrient uptake and the antioxidant mechanism of the chickpea. In addition, chickpea plants alone phytoremediated 52% of initial PHCs concentration. The addition of bacterial consortia in the presence of chickpea plants could remove 74–80% of the initial PHCs concentration in soil. Based on our research findings, we suggest that the use of multi-trait bacterial consortia could be a sustainable and environmentally friendly strategy for PHCs remediation and plant growth promotion in hydrocarbons in contaminated soil.

Enhanced wheat productivity in saline soil through the combined application of poultry manure and beneficial microbes

“…However, the application of individual microbe and/or their culture along with the PM caused significant impacts on plant growth by triggering nutrient assimilation under salt stress. The mixed culture having ACC deaminase activity may lower the ethylene concentration and reactive oxygen species (ROS) under stress conditions by the production of ACC deaminase and several organic acids [ 27 , 29 ]. The siderophore activities of the added microbes help to assimilate an adequate amount of iron in plants to strengthen metabolic phenomena like photosynthesis and respiration [ 57 ].…”

“…Firstly, the soil was cleaned for pebbles and crop residues, then air-dried and sieved by passing through a 2 mm sieve. For the pre-analysis of soil, water and PM, a series of laboratory experiments were performed to determine the various physicochemical attributes following standard protocols as described in our previous studies [ 13 , 27 , 29 ]. Results of analyses are provided in Table 1 .…”

“…The medium was autoclaved twice before inoculation and the pH of the medium was maintained at 7.0 ± 0.2. Two microbial strains that were previously isolated from the hydrocarbons-contaminated sites and identified as Alcaligenes faecalis MH-2 with accession number ON7114529 (MS1) and Achromobacter denitrificans MH-6 with accession number ON7114531 (MS2), were inoculated in TSB broth and incubated at 25 ± 3 ˚C at 150 rpm for 96 h [ 27 ]. After the incubation, the microbial growth was estimated by measuring the optical density (OD 600 ) of the cultures [ 29 ] and then the cultures were further used in the pot experiment.…”

“…Similarly, the relative water contents of fresh flag leaves were determined by following the protocols of Ali et al [ 27 ]. Briefly, 0.5 g fresh leaves samples were soaked in a test tube containing distilled water.…”

“…It has been reported that a variety of isolated microbes having growth-promoting characteristics from genera Microbacterium , Acinetobacter , Actinobacteria, Azotobacter , and Pseudomonas are effective in alleviating biotic and abiotic stresses in plants [ 23 – 25 ]. Microbes could improve plant growth and physiological traits by producing ACC-deaminase, siderophores, P-solubilization, and indole-3-acetic acid (IAA) even under abiotic stresses [ 26 , 27 ]. In return, plants release a massive amount of vitamins, organic acids, sugars, amino acids, and related compounds to attract a diversified microbial population near the root zone [ 28 , 29 ].…”