Silicon-Solubilizing Media and Its Implication for Characterization of Bacteria to Mitigate Biotic Stress

Abstract

Silicon (Si), the second most abundant element on earth, remains unavailable for plants' uptake due to its poor solubility. Microbial interventions to convert it in soluble forms are well documented. However, studies on discrimination of Si and P solubilizing microbes due to common estimation method and sharing of solubilization mechanism are still obscure. A defined differential media, i.e. silicon-solubilizing media (NBRISSM) is developed to screen Si solubilizers. NBRISN13 (Bacillus amyloliquefaciens), a Si solubilizer, exhibiting antagonistic property against Rhizoctonia solani, was further validated for disease resistance. The key finding of the work is that NBRISSM is a novel differential media for screening Si solubilizers, distinct from P solubilizers. Dominance of Pseudomonas and Bacillus spp. for the function of Si solubilization was observed during diversity analysis of Si solubilizers isolated from different rhizospheres. Sphingobacterium sp., a different strain has been identified for silicon solubilization other than Pseudomonas and Bacillus sp. Role of acidic phosphatase during Si solubilization has been firstly reported in our study in addition to other pH dependent phenomenon. Study also showed the combinatorial effect of feldspar and NBRISN13 on elicited immune response through (i) increased Si uptake, (ii) reduced disease severity, (iii) modulation of cell wall degrading and antioxidative enzyme activities, and (iv) induced defense responsive gene expression.

Enhanced solubilization of insoluble silicate from quartz and zeolite minerals by selected Aspergillus and Trichoderma species

“…It indicated that citrate has the strongest influence on the solubilization silica from quartz sand (R 2 = 0.89) and zeolite (R 2 = 0.85). The result of the study suggested that the major mechanism of silica solubilization is due to the action of organic acids synthesized by SSF as reported by Bist et al (2020) that the major mechanisms for the solubilization of silica by fungi is acidolysis. These phenomena lead to the assumption that citric acid is responsible for lowering the pH medium providing proton (H + ) to increase the silica solubilization.…”

Genomic Landscape Highlights Molecular Mechanisms Involved in Silicate Solubilization, Stress Tolerance, and Potential Growth-Promoting Activity of Bacterium Enterobacter sp. LR6

“…The plates were incubated at 37 °C for 24 h. The isolates were then evaluated for silicate solubilization activity on Bunt and Rovira agar medium supplemented with 0.25% of Insoluble magnesium trisilicate [ 4 ]. The isolates were also checked for their ability to solubilize insoluble phosphate in NBRIP medium [ 17 ]. The purified isolate (10 µL) was spotted on the agar plate, followed by incubation at 30 °C for 2 days.…”

Trichoderma‐primed rice straw alters structural and functional properties of sodic soil

“…The total phenolic content was determined according to the Folin-Ciocalteu procedure and expressed as μmol gallic acid equivalents in mg ml À1 (Singleton & Rossi, 1965). Soluble silica was determined by the modified molybdate method as reported earlier (Bist et al, 2020).…”