Effect of physicochemical parameters on inorganic phosphate solubilisation by serratia marcescens PH1 and organic acids production [electronic resource].

Includes references.

Phosphate solubilizing bacteria are capable to release inorganic phosphate and make it available to plants for growth enhancement.
In this study, Serratia marcescens PH1, which has been isolated from tomato plant rhizosphere, has been subjected to different physical
and chemical parameters for optimization of its phosphate solubilisation capacity. The best temperature, inoculum percentage, agitation rate,
incubation time, and pH value were found to be 30?, 1.5%, 150rpm, 5 days, and 7-8, respectively. The best carbon source for phosphate
solubilisation among 5 different sources, glucose, sucrose, galactose, maltose, and arabinose, was glucose which allows for releasing
797mg/L of P. Besides, casein was the best nitrogen source for phosphorus release (853mg/L) and Ca3(PO4)2 in Pikovskaya medium was the
best P source (855mg/L). The key factors affecting P release in the modified Pikovskaya medium were glucose, casein and inoculum percentage.
P concentration in the modified Pikovskaya culture medium was 853mg/ml comparing with only 749mg/L in the classical formula. For freeing of P,
Serratia marcescens PH1 produces organic acids such as citric, lactic, malic, and benzoic acids. Phosphorus yield was increased gradually with
organic acids production till reaching 861mg/ml in 5 days with pH drop to 1.1. pqqC (a gene responsible of PQQ production) gene fragment
of approx. 568 bp was successfully amplified in phosphate solubilizing bacteria. Detection of pqq genes is an evidence of gluconic acid
production capability. This acid is a well known biocontrol agent. Serratia marcescens PH1 is a strong phosphate solubilizer and we are planning
to conduct more wide-scale experiments in pots to optimize the utilization of such bacterium before conducting agricultural applications as a plant
growth promoter and a biocontrol agent

Summary in Arabic.