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

Abstract

Bacteria-mediated plant growth promotion is a well-established and complex phenomenon that is often achieved by the activities of more than one plant growthpromoting (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-1carboxylic (ACC) deaminase activity. The synergism in terms of the PGP traits in the biofilms revealed their promise as superior PGP inoculants.

Development of Mesorhizobium ciceri-Based Biofilms and Analyses of Their Antifungal and Plant Growth Promoting Activity in Chickpea Challenged by Fusarium Wilt

“…Biofilms also showed increase in HCN and ammonia production as compared to their individual partners, which are correlated to antifungal activity. Similar results were observed by Triveni et al [7] in case of B. subtilis-T. viride and P. fluorescens-T. viride biofilms. Arfaoui et al [17] has reported suppression of Fusarium wilt of chickpea under in vitro and in vivo conditions by six rhizobial strains positive for HCN production.…”

“…In the last few years the focus has shifted from single inoculation to coinoculation to use of consortium of microorganisms to obtain maximum benefits. Another strategy developed is the biofilmed biofertilizers wherein fungi, cyanobacteria or bacteria are used as matrix and agriculturally important bacteria like Azotobacter, Rhizobium, Bacillus and Pseudomonas are used as associate partners [4][5][6][7][8].…”

Biofilm Formation of Zinc Solubilizing, Potassium Releasing Bacteria on the Surface of Fungi

“…Triveni et al, (2013) highlighted that compost and vermiculite (1:1) was a suitable carrier for the novel biofilmed biofertilizers. Triveni et al, (2012) recorded Trichoderma -Azatobacte r biofilm was recorded the highest nitrogenase activity and ACC deaminase activity. Xuan et al, (2012) reported maximum concentration of soluble phosphorus (P) was determined in the mixed culture of P. chlororaphis and A. pascens.…”

“…micas and feldspars) (Sparks and Huang, 1985) or the addition of K fertilizers. Many microorganisms in the soil are able to solubilize 'unavailable' forms of K-bearing minerals, such as micas, illite and orthoclases, by excreting organic acids which either directly dissolves rock K or chelate silicon ions to bring the K into solution (Groudev, 1987;Friedrich et al, 1991;Ullman et al, 1996;Bennett et al, 1998). Biofilm formation of this zinc solubilizers and potassium releasers has an immense importance in agriculture.…”

“…Biofilm (ZnSF-4 + ZnSB-2) was confirmed based on the positive result for Vogues Proskuers test and biofilm (ZnSB-2 + KSF-2) was confirmed based on the positive result for gelatin liquefaction. (Triveni et al, 2012) Screening of biofilms for zinc solubilization and potassium releasing characters Biofilms were screened further for their efficacy in zinc solubilization as well as potassium releasing ability in order to compare over the individual cultures. The in vitro formed biofilms were shown comparatively higher amount of zinc solubilization and potassium releasing ability as compared to individual cultures.…”