Potential of Pseudarthrobacter chlorophenolicus BF2P4-5 as a Biofertilizer for the Growth Promotion of Tomato Plants

Abstract

BF2P4-5 was isolated from the rhizosphere soil of tomato plants, and its potential to promote plant growth was investigated in tomato plants. An in vitro test revealed that the strain could fix nitrogen, solubilize phosphate and potassium, and synthesize indole acetic acid. The bacterial strain was identified and characterized as a kind of Pseudarthrobacter chlorophenolicus based on the analysis of culture characteristics, physiological and biochemical characteristics, and 16S rRNA gene sequence (GenBank accession number OP135548.1). pH 7.0, 15% NaCl, and 35 °C temperature were ideal for optimal strain growth under culture conditions. Tomato plants grown on a cocopeat substrate were inoculated with BF2P4-5 suspension (OD600 2.0). Positive control plants were inoculated with Nitrogen Phosphorus Potassium (NPK) fertilizer. This BF2P4-5 strain and NPK treatments were complemented with a negative control, in which only tap water was applied to tomato roots, thus, establishing three distinct treatment modalities with five replications each. Two months of greenhouse trials of inoculated tomato plants improved growth parameters. Interestingly, in most of the growth metrics evaluated, tomato plants treated with strain BF2P4-5 showed little to no variation with NPK fertilizer treatment, including plant height, stem length, girth, leaf number per plant, and chlorophyll content, when compared to uninoculated plants. Furthermore, the conditions for the cocopeat plants, including pH, EC, and moisture, were within acceptable limits. Furthermore, inoculation with BF2P4-5 increased the nitrogen, phosphorus, and potassium content available in the cocopeat medium. The results showed that the strain exhibited traits for the promotion of plant growth and could be deployed as an eco-friendly microbial biofertilizer for tomatoes and probably other essential crops.