RAPISARDA Viviana Andrea
congresos y reuniones científicas
Microbiology Symposium - Bacteria responses to high environmental phosphate concentration: physiological aspects and potential biotechnological applications
Congreso; Joint LV Annual SAIB Meeting and XIV PABMB Congress; 2019
Institución organizadora:
In the last decade, our research has focused on the physiological changes associated with environmental phosphate (Pi) and intracellular polyphosphate (polyP) in bacteria of clinical, agronomic and biotechnological interest. PolyP, a polymer of orthophosphate residues, has a crucial role in bacteria survival, stress responses, biofilm formation and virulence factors production. We found that Escherichia coli grown in media with >37 mM Pi maintained a high polyP level in late stationary phase, which could account for changes in gene expression and enzyme 41 activities that enhance its stationary-phase fitness. Indeed, maintenance of high polyP levels in high Pi medium improved bacterial survival and tolerance to stress agents when compared to cells grown in sufficient Pi medium. Once accumulated in high Pi, polyP degradation by PPX (an exopolyphosphatase) mediated copper tolerance with the participation of the low-affinity inorganic phosphate transport system. Moreover, in 25 mM), polyP degradation during stationary phase triggered biofilm formation via LuxS quorum sensing system. Inmedia with sufficient Pi ( fact, PhoB was activated by acetyl phosphate when high polyP levels were maintained in the stationary phase, with the consequent repression of biofilm formation owing to inhibition of c-di-GMP synthesis and autoinducer-2 production. In uropathogenic E. coli isolates causative of prostatitis, environmental Pi differentially affected the virulence phenotypes (biofilm formation, curli, cellulose production, and expression of virulence factors). However, in spite of the complexity of UPEC responses to environmental Pi, polyP degradation induced biofilm formation in all the assayed clinical isolates. The plant growth-promoting bacterium Gluconacetobacter diazotrophicus accumulated polyP and degraded it in high Pi medium, thereby improving survival, tolerance to stressors, biofilm formation capacity, and competence as a promoter of plant growth. In Herbaspirillum seropedicae, another plant growth-promoting bacterium, Pi concentration changes intracellular polyP levels, generating differential expression of 620 genes, being 53% repressed and 43% induced in high Pi condition. In the lactic acid bacterium Lactobacillus paraplantarum, the proteins involved in glycolysis, pyruvate metabolism and pentose phosphate pathway were up-regulated in high Pi stationary phase cells, implying an active metabolism similar to that of exponential phase cells. Contrary, stress-related chaperones were repressed in high Pi medium, inferring that high polyP levels in stationary phase may provide chaperone capacity. Together, environmental Pi concentration modulates polyP levels in bacteria, affecting their gene expression profile, cellular fitness and biofilm formation. According, media Pi concentration results critical for some bacteria and should be considered in physiological studies and in the development of strategies to benefit their biotechnological potential.