Phytate-hydrolyzing rhizobacteria: abiotic stress tolerance and antimicrobial activity

Abstract

Phytate-hydrolyzing bacteria Pantoea sp. 3.1, 3.2, 3.5.2, 3.6.1 and Bacillus ginsengihumi M2.11 were previously isolated from the soil samples of the Republic of Tatarstan. The effect of cultivation conditions on the growth dynamics as well as antimicrobial activity was determined. All four Pantoea strains showed optimum growth at 26 ºC and 28 ºC and pH 6.0-7.0. The optimum conditions for the growth of B. ginsengihumi M2.11 strain was determined to be 26 ºC, 28 ºC and 37 ºC and alkaline pH 7 and 8. Salt concentration in the range of 0 to 1000 mM did not significantly affect the growth of the strains. Antagonistic activity of Pantoea sp. 3.5.2 was studied against phytopathogenic micromycetes, identified as Alternaria alternata and Bipolaris sorokiniana. In the presence of bacterial isolate growth of A. alternata was inhibited by 57% and growth of B. sorokiniana – by 85%. Minor growth inhibition by Pantoea sp. 3.5.2 of gram-negative bacteria from Enterobacteriaceae family was observed. The presence of fungicidal activity in the Pantoea strain together with its ability to hydrolyze soil phytates and overcome abiotic stress factors in soil can possibly serve as the basis for the new fungicide of microbial origin.