Pseudomonas and Acinetobacter spp. capable of metabolizing aromatics displays multifarious plant growth promoting traits: Insights on strategizing consortium-based application to agro-ecosystems

Abstract

The persistence and slow rate of natural attenuation of genotoxic and endocrine-disrupting aromatic pollutants has impacted the soil heath of agro-ecologies leading to various health and environmental issues. Ecotoxic-xenobiotic compounds degradation property along with plant growth promoting traits of microbes are beneficial for devising strategies for improved agricultural soil health and its clean-up. Present study assessed the multipartite plant growth promoting-, biocontrol- and niche adaptive- traits of five aromatic degrading soil bacteria viz. Pseudomonas bharatica CSV86^T, Pseudomonas sp. C5pp, Pseudomonas sp. PP4, Pseudomonas sp. PPD and Acinetobacter sp. ISP4. Solubilization of rock phosphate (P) and feldspar (K), production of plant growth hormone (auxin; IAA), ammonia, siderophores and ACC deaminase by strain CSV86^T, C5pp and PP4 were observed. Similarly, high fusaric acid resistance (MIC: 1–1.2 mg mL⁻¹) and tolerance to salinity (5–7.5 %) was observed. In vitro application of CSV86^T, C5pp, PP4 and ISP4 as consortium resulted in significant increase (P < 0.05) in the seedling shoot length (15–37 %), root length (65–150 %) and biomass (30–40 %) of wheat, mung bean and fenugreek. In-soil microcosm assay confirmed the plant growth promoting and phytoprotective ability of this consortium against toxicity of aromatics in contaminated soil. Antifungal activity against phytopathogenic fungi Magnaporthe oryzae and Aspergillus spp., ability to produce lytic enzymes and HCN suggests their biocontrol potential. Four aromatic degrading bacteria (as a consortium) exhibiting plant growth promotion and biocontrol activity could be used as an eco-friendly bioremediator-biofertilizer-biocontrol agent (bioformulation) for restoration of agricultural soil with improved crop productivity.