Phosphorus is an important macronutrient, but its availability in soil is limited. Many soil microorganisms improve the bioavailability of phosphate by releasing it from various organic compounds, including phytate. To investigate the diversity of phytate-hydrolyzing bacteria in soil, we sampled soils of various ecological habitats, including forest, private homesteads, large agricultural complexes, and urban landscapes. Bacterial isolate Pantoea sp. strain 3.5.1 with the highest level of phytase activity was isolated from forest soil and investigated further. The Pantoea sp. 3.5.1 agpP gene encoding a novel glucose-1-phosphatase with high phytase activity was identified, and the corresponding protein was purified to apparent homogeneity, sequenced by mass spectroscopy, and biochemically characterized. The AgpP enzyme exhibits maximum activity and stability at pH 4.5 and at 37°C. The enzyme belongs to a group of histidine acid phosphatases and has the lowest K _m values toward phytate, glucose-6-phosphate, and glucose-1-phosphate. Unexpectedly, stimulation of enzymatic activity by several divalent metal ions was observed for the AgpP enzyme. High-performance liquid chromatography (HPLC) and high-performance ion chromatography (HPIC) analyses of phytate hydrolysis products identify dl - myo -inositol 1,2,4,5,6-pentakisphosphate as the final product of the reaction, indicating that the Pantoea sp. AgpP glucose-1-phosphatase can be classified as a 3-phytase. The identification of the Pantoea sp. AgpP phytase and its unusual regulation by metal ions highlight the remarkable diversity of phosphorus metabolism regulation in soil bacteria. Furthermore, our data indicate that natural forest soils harbor rich reservoirs of novel phytate-hydrolyzing enzymes with unique biochemical features.

Phosphate solubilizing microorganisms (PSMs) in soil have been shown to reduce mineral phosphate fertilizer supplementation and promote plant growth. Nevertheless, only several P-solubilizing microorganisms capable of solubilizing both organic and mineral sources of soil phosphorus have been identified up to now. The aim of this study was to evaluate the inorganic soil phosphate solubilizing activity of phytate-hydrolyzing Pantoea brenneri soil isolates. We showed that the strains efficiently solubilize a variety of inorganic phosphates. We optimized the media composition and culturing conditions to improve the solubilization efficiency of the strains and investigated the mechanisms of their phosphate solubilization. Through HPLC analysis, it was determined that P. brenneri produce oxalic, malic, formic, malonic, lactic, maleic, acetic, and citric acids as well as acid and alkaline phosphatases while growing on insoluble phosphate sources. Finally, we analyzed the influence of P. brenneri strains with multiple PGP-treats on plant growth in greenhouse experiments and showed their ability to promote growth of potato.

Replenishing of the stores of inorganic phosphate is among the most urgent environmental problems. In soil, phosphorus within inorganic compounds is mostly (over 80%) present as insoluble, phytic acid-based conglomerates. Phytates are strong chelating agents, binding the cations of bivalent metals, as well as peptides and low-molecular metabolites into resilient poorly degradable compounds. Their hydrolysis in nature is carried out by microbial phytases, which may potentially be used for an innovative microbial technology. The review deals with microbial degradation of the derivatives of phytic acid. Bacterial species capable of phytase synthesis for stepwise specific cleaving of phytates and their derivatives are discussed. Information analysis was carried out in order to search for the genes encoding phytases in bacterial genomes. Directional modification of the genes of bacterial phytases in order to develop new biotechnologies for agriculture and forage industry is considered. Application of microbial enzymes in agriculture and medicine is analyzed. Bacteria phytases are concluded to have a high practical potential. Microbiology is capable of providing the theoretical and experimental basis for development of the new biotechnology.

Plants synthetize a large spectrum of secondary metabolites with substantial structural and functional diversity, making them a rich reservoir of new biologically active compounds. Among different plant lineages, the evolutionarily ancient branch of non-vascular plants (Bryophytes) is of particular interest as these organisms produce many unique biologically active compounds with highly promising antibacterial properties. Here, we characterized antibacterial activity of metabolites produced by different ecotypes (strains) of the model mosses Physcomitrium patens and Sphagnum fallax. Ethanol and hexane moss extracts harbor moderate but unstable antibacterial activity, representing polar and non-polar intracellular moss metabolites, respectively. In contrast, high antibacterial activity that was relatively stable was detected in soluble exudate fractions of P. patens moss. Antibacterial activity levels in P. patens exudates significantly increased over four weeks of moss cultivation in liquid culture. Interestingly, secreted moss metabolites are only active against a number of Gram-positive, but not Gram-negative, bacteria. Size fractionation, thermostability and sensitivity to proteinase K assays indicated that the secreted bioactive compounds are relatively small (less than <10 kDa). Further analysis and molecular identification of antibacterial exudate components, combined with bioinformatic analysis of model moss genomes, will be instrumental in the identification of specific genes involved in the bioactive metabolite biosynthesis.

Bacillus subtilis is traditionally classified as a PGPR that colonizes plant roots through biofilm formation. The current study focused on investigating the influence of various factors on bacilli biofilm formation. In the course of the study, the levels of biofilm formation by the model strain B. subtilis WT 168 and on its basis created regulatory mutants, as well as strains of bacilli with deleted extracellular proteases under conditions of changes in temperature, pH, salt and oxidative stress and presence of divalent metals ions. B. subtilis 168 forms halotolerant and oxidative stress-resistant biofilms at a temperature range of 22 °C–45 °C and a pH range of 6–8.5. The presence of Ca²⁺, Mn²⁺ and Mg²⁺ upsurges the biofilm development while an inhibition with Zn²⁺. Biofilm formation level was higher in protease-deficient strains. Relative to the wild-type strain, degU mutants showed a decrease in biofilm formation, abrB mutants formed biofilms more efficiently. spo0A mutants showed a plummeted film formation for the first 36 h, followed by a surge after. The effect of metal ions and NaCl on the mutant biofilms formation is described. Confocal microscopy indicated that B. subtilis mutants and protease-deficient strains differ in matrix structure. The highest content of amyloid-like proteins in mutant biofilms was registered for degU-mutants and protease-deficient strains.

Telomeres cap the physical ends of eukaryotic chromosomes to ensure complete DNA replication and genome stability. Heritable natural variation in telomere length exists in yeast, mice, plants and humans at birth; however, major effect loci underlying such polymorphism remain elusive. Here, we employ quantitative trait locus (QTL) mapping and transgenic manipulations to identify genes controlling telomere length set point in a multi-parent Arabidopsis thaliana mapping population. We detect several QTL explaining 63.7% of the total telomere length variation in the Arabidopsis MAGIC population. Loss-of-function mutants of the NOP2A candidate gene located inside the largest effect QTL and of two other ribosomal genes RPL5A and RPL5B establish a shorter telomere length set point than wild type. These findings indicate that evolutionarily conserved components of ribosome biogenesis and cell proliferation pathways promote telomere elongation.