In-vitro solubilization of waste minerals and morphological characteristics of potassium and phosphorus solubilizing bacteria

Abstract

Soil potassium and phosphorus supplementation relies heavily on the use of chemical fertilizer, which has a considerable negative impact on the environment. There is a growing need to turn back to nature or sustainable agents that promote evergreen agriculture. Among such natural bio-agents, the potassium solubilizing bacteria (KSB), and phosphorus solubilizing bacteria (PSB) which solubilize fixed forms of potassium (K) and phosphorus (P) to plant available K and P vice versa by various mechanisms including acidolysis, chelation, exchange reactions, complexolysis, and production of organic acids are considered one such available viable alternative. In this research screening and characterization of ten KSB and PSB isolates which were evaluated for their ability to solubilize K and P from the waste muscovite (WM), waste biotite (WB), tri-calcium phosphate (TCP) and rock phosphate (RP) by analysing the soluble P and K content after 7, 14, 21 days after incubation (DAI) at 28±2 °C on MABs (Modified Aleksandrov Broths) and Pikovskaya's medium. The Zone of solubilization (cm), Colony size diameter (cm), Solubilization index of PSB40 at 7DAI and 14 DAI 2.83±0.01, 4.05±0.01, 1.26±0.01, 1.50±0.01, 2.61±0.02, 2.81±0.01 respectively. PSB40 showed superiority towards P solubilisation than rest of isolates. Overall, it can be concluded that the diversity of KSB and PSB as bioinoculants to release K and P provides a win-win situation under in vitro condition.