Influence of inorganic phosphate sources on protein expression of a phosphate solubilizing wild bacterium from La Comarca Lagunera

Introduction : The aim of this work was to identify the proteins involved in solubilization of inorganic phosphates (Pi) of Klebsiella aerogenes and to evaluate the solubilization capacity of Pi under the influence of different carbon (C) and nitrogen (N) sources of bacteria isolated from La Comarca Lagunera. Method : Eihgt strains, isolated from La Comarca Lagunera forage crops and conserved in glycerol at -20° C, were used. The Solubilization Index (SI) was determined in solid medium PVK and the solubilization of Pi was quantified in liquid medium with different C, N and Phosphorus (P) sources. Bacteria with highest capacity to solubilize phosphate was identified by molecular methods. For protein expression studies, bacterial cultures were done by duplicate in two Pi sources {(calcium phosphate (CP) and aluminum phosphate (AP)} using PVK liquid medium. Proteins were precipitated with trichloroacetic acid (TCA), quantified with BCA TM Protein assay kit and run on 12 % polyacrylamide gel. A tryptic digestion was done and the peptides obtained were analyzed by HPLC-mass spectrometry. Proteins and their function were identified with bioinformatic tools. Results : K. aerogenes showed the greatest capacity to solubilize CP (2.31 y 2.59) in solid medium PVK with Glucose (G)-Urea (U), G-Ammonium Nitrate (AN) respectively, CP (1.97 ppm) and AP (1.36 ppm) in PVK liquid medium with G-U. Two hundred sixteen proteins were identified in both bacterial cultures, among which were found ABC transporter, Pho kinase histidine and Phosphate-specific transport system accessory protein Pho U, involved with the use of P. Discussion or Conclusion : The sources of C y N influence the solubilization capacity of Pi in native bacteria from La Comarca Lagunera . The best solubilization results were found when G and U were in the medium as source of C and N respectively . Under the conditions in this study, K. aerogenes did not express unique proteins to solubilize FC and FA. The expression levels of some proteins were different in some identified proteins.