Lysinibacillus spp.: an IAA-producing endospore forming-bacteria that promotes plant growth

Abstract

Lysinibacillus is a bacterial genus that has generated recent interest for its biotechnological potential in agriculture. Strains belonging to this group are recognized for their mosquitocidal and bioremediation activity. However, in recent years some reports indicate its importance as plant growth promoting rhizobacteria (PGPR). This research sought to provide evidence of the PGP activity of Lysinibacillus spp. and the role of the indole-3-acetic acid (IAA) production associated with this activity. Twelve Lysinibacillus spp. strains were evaluated under greenhouse conditions, six of which increased the biomass and root architecture of corn plants. In most cases, growth stimulation was evident at 108 CFU/mL inoculum concentration. All strains produced IAA with high variation between them (20–70 µg/mL). The bioinformatic identification of predicted genes associated with IAA production allowed the detection of the indole pyruvic acid pathway to synthesize IAA in all strains; additionally, genes for a tryptamine pathway were detected in two strains. Extracellular filtrates from all strain’s cultures increased the corn coleoptile length in an IAA-similar concentration pattern, which demonstrates the filtrates had an auxin-like effect on plant tissue. Five of the six strains that previously showed PGPR activity in corn also promoted the growth of Arabidopsis thaliana (col 0). These strains induced changes in root architecture of Arabidopsis mutant plants (aux1-7/axr4-2), the partial reversion of mutant phenotype indicated the role of IAA on plant growth. This work provided solid evidence of the association of Lysinibacillus spp. IAA production with their PGP activity, which constitutes a new approach for this genus. These elements contribute to the biotechnological exploration of this bacterial genus for agricultural biotechnology.

Encephalartos villosus associated bacterial communities and extracellular enzymes improve soil nutrition in rhizosphere soils in forest ecosystem soils

“…According to Ano and Ubochi (2007), the most abundant bacteria in soils belong to the Paenibacillus, Lysinibacillus, Pseudomonas, Paraburkholderia, Bradyrhizobium, and Rhizobium genera. These genera have plant growth promoting traits and play a role in N-cycling, N-xing, and P-solubilization (Sitaram, 2015;Jaiswal et al, 2021;Favero et al, 2022;Bellѐs-Sancho et al, 2023;Pantoja-Guerra et al, 2023). Thus, the presence of bacteria belonging to the Pseudomonas, Paraburkholderia, and Bradyrhizobium genera in E. villosus rhizosphere and non-rhizosphere soils may be attributed to the abundance of these genera on soils and their plant growth promoting traits.…”