Bio-management of Fusarium spp. associated with fruit crops Sampat Nehra, Raj Kumar Gothwal, Alok Kumar Varshney, Pooran Singh Solanki, Shivani Chandra, et al. Fungi Bio Prospects in Sustainable Agriculture Environment and Nano Technology Volume 1 Fungal Diversity of Sustainable Agriculture, 2020
Bioactivation of Jhamarkotra rock phosphate by a thermotolerant phosphate-solubilizing bacterium Bacillus sp. BISR-HY63 isolated from phosphate mines Hemendra Yadav, Raj Kumar Gothwal, Sujata Mathur, Purnendu Ghosh Archives of Agronomy and Soil Science, 2015 Rock phosphate (RP) is a natural source of phosphorus (P), but due to its poor solubility, its application has been restricted to acidic soils. We performed bioactivation of RP in order to increase its efficacy as a fertilizer in direct application to alkaline soils. Simulation of super phosphate (SP) formation was performed, where inorganic acids used in the preparation of SP were replaced by different concentrations of culture supernatant of a thermotolerant phosphate-solubilizing bacterium isolated from RP mines having Fe-P- and Al-P-solubilizing ability to make an environmentally clean SP. Increases in water soluble and citrate soluble P were observed by the treatment of RP with culture supernatant. Organic acid secretion along with decrease in pH was observed and was found to be the major cause in solubilization of RP. HPLC analysis of the culture supernatant showed the presence of citric, malic, and acetic acids. Phylogenetic analysis of the culture showed it to belong to the genus Bacillus.
Isolation and Characterization of Thermo-tolerant Phosphate-Solubilizing Bacteria From a Phosphate Mine and Their Rock Phosphate Solubilizing Abilities H. Yadav, R. K. Gothwal, P. S. Solanki, S. Nehra, S. Sinha-roy, et al. Geomicrobiology Journal, 2015 A study of rock phosphate (RP) mines, rich in R2O3 (Fe2O3 and Al2O3) contents, was done to explore the possibilities of isolating and characterizing thermo-tolerant phosphate solubilizing bacteria (PSB) having the ability to solubilize ferric phosphate (Fe-P) and aluminium phosphate (Al-P) efficiently. One hundred and ten thermo-tolerant PSB were isolated employing Pikovskaya (PVK) broth amended with RP, and six of these isolates were selected for further study. The phosphate solubilizing efficiency (PSE) was determined in PVK broth containing tri-calcium phosphate (TCP), hydroxyapatite (Hy-P), Fe-P, Al-P or RP. These isolates showed solubilization of all the phosphorus (P) sources used in this study, particularly Fe-P, Al-P and RP. The main mechanism of P-solubilization seemed to be mediated by the production of organic acids leading to medium acidification. HPLC analysis revealed production of multiple organic acids (oxalic, citric, malic, succinic, formic, acetic and gluconic acids) in the culture supernatant along with some unknown acids. Based on the partial sequence analysis of 16S rRNA genes, these thermo-tolerant isolates were found to belong to two bacterial genera, Brevibacillus and Bacillus.
