Evaluating the biochemical traits of novel Trichoderma-based biofilms for use as plant growth-promoting inoculants

Bacteria-mediated plant growth promotion is a well-established and complex phenomenon that is often achieved by the activities of more than one plant growth-promoting (PGP) trait, which may not always be present in a single organism. Biofilms developed using a combination of two organisms with useful plant growth-promoting rhizobacteria (PGPR) traits may provide a definite advantage. In this context, in vitro studies were conducted evaluating the PGP traits of novel biofilms developed using Trichoderma as matrix and agriculturally important bacteria (Azotobacter chroococcum, Pseudomonas fluorescens and Bacillus subtilis) as partners. Such biofilms exhibited higher values for various biochemical attributes as compared to the individual organisms and dual cultures. Trichoderma-Bacillus and Trichoderma-Pseudomonas biofilms exhibited enhanced antifungal activity, ammonia, indole acetic acid (IAA) and siderophore production, as compared to the other treatments. Trichoderma-Azotobacter biofilm recorded the highest nitrogenase activity and 1-aminocyclopropane-1-carboxylic (ACC) deaminase activity. The synergism in terms of the PGP traits in the biofilms revealed their promise as superior PGP inoculants.