|FISHMAN, MAXWELL - Cornell University|
|GIGLIO, KRISTA - Former ARS Employee|
|FAY, DAVID - Cornell University|
Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2018
Publication Date: 7/5/2018
Citation: Fishman, M., Giglio, K., Fay, D., Filiatrault, M.J. 2018. Physiological and genetic characterization of calcium phosphate precipitation by Pseudomonas species. Scientific Reports. 8:10156.
Interpretive Summary: Formation of calcium minerals is a result of the environment and interactions with bacterial cells. Many bacteria can induce formation from calcium carbonate precipitates in the environment and/or in vitro culture conditions. However, it is unknown whether the plant pathogen Pseudomonas syringae possesses the ability to precipitate calcium carbonates. We discovered that when P. syringae is grown in a high calcium environment it produces calcium precipitates. Further characterization revealed that the precipitate formed on the colonies and in the area surrounding the colonies changed over time. Screening multiple Pseudomonas species showed distinctive differences in the morphology and type of calcium precipitates produced by the various bacteria, suggesting a relationship between species and habitat. This is the first report of calcium precipitation mediated by P. syringae. The results improve our understanding of bacterial induced calcium precipitation and provide characterization of calcium precipitates formed by Pseudomonads. Moreover the results could be of importance to bioremediation efforts and have implications in bacterial plant pathogenesis.
Technical Abstract: Microbial biomineralization is a widespread phenomenon. The ability to induce calcium precipitation around bacterial cells has been reported in several Pseudomonas species but has not been thoroughly tested. We assayed 14 Pseudomonas strains representing five different species for the ability to precipitate calcium. Calcium phosphate precipitated adjacent to the colonies of all the Pseudomonas strains tested and also precipitated on the surface of colonies for several of the Pseudomonas strains assayed. The precipitate was commonly precipitated as amorphous calcium phosphate, however seven of the 14 Pseudomonas strains tested precipitated amorphous apatite in agar adjacent to the colonies. Out of the seven Pseudomonas strains that precipitated amorphous apatite, six are plant pathogenic. The formation of amorphous apatite was commonly observed in the area of the agar where amorphous calcium phosphate had previously formed. A transposon mutagenesis screen in Pseudomonas syringae pv. tomato DC3000 revealed genes involved in general metabolism, lipopolysaccharide and cell wall biogenesis, and in regulation of virulence play a role in calcium precipitation. These results shed light on the common ability of Pseudomonas species to perform calcium precipitation and the underlying genetic regulation involved in biomineralization.