Project description:Phosphate-solubilizing bacteria (PSB) have the ability to dissolve insoluble phosphate and enhance soil fertility. However, the growth and mineral phosphate solubilization of PSB could be affected by exogenous soluble phosphate and the mechanism has not been fully understood. In the present study, the growth and mineral phosphate-solubilizing characteristics of PSB strain Burkholderia multivorans WS-FJ9 were investigated at six levels of exogenous soluble phosphate (0, 0.5, 1, 5, 10 and 20 mM). The WS-FJ9 strain showed better growth at high levels of soluble phosphate. The phosphate-solubilizing activity of WS-FJ9 reduced as the soluble phosphate concentration increased, as well as the production of pyruvic acid. Transcriptome profiling of WS-FJ9 at three levels of exogenous soluble phosphate (0, 5 and 20 mM) identified 446 differentially expressed genes, among which 44 genes were continuously up-regulated when soluble phosphate concentration increased and 81 genes were continuously down-regulated. Some genes related to cell growth were continuously up-regulated which would account for the better growth of WS-FJ9 at high levels of soluble phosphate. Genes involved in glucose metabolism, including glycerate kinase, 2-oxoglutarate dehydrogenase, and sugar ABC-type transporter were continuously down-regulated which indicates that metabolic channeling of glucose towards phosphorylative pathway was negatively regulated by soluble phosphate.
Project description:ADDITION OF COMPOST AND PHOSPHATE SOLUBILIZING BACTERIA IMPROVES SUGARCANE MACRONUTRIENT CONTENTS AND CHANGES THE SOIL BACTERIAL COMMUNITY
Project description:In bacteria, the availability of environmental inorganic phosphate is typically sensed by the conserved PhoRB two-component signaling pathway, which uses the flux through the Pst phosphate transporter as a readout of the extracellular phosphate level to control a variety of phosphate-responsive genes. While the sensing of environmental phosphate is well-established, the regulatory effects of cytoplasmic phosphate are still unclear. Here, we disentangle the physiological and transcriptional responses of Caulobacter crescentus to changes in the environmental and cytoplasmic phosphate levels. To this end, we are uncoupling phosphate uptake from the activity of the Pst system by producing an additional, heterologous phosphate transporter. This approach reveals a bi-pronged response of C.crescentus to phosphate limitation, in which the PhoRB signaling mostly facilitates the utilization of alternative phosphate sources, whereas the cytoplasmic phosphate level controls the morphological and physiological adaptation of cells to growth in conditions of global phosphate limitation. These findings open the door to a more comprehensive understanding of phosphate signaling in bacteria.
