title: Novel cyanobacterial bioreporters of phosphorus bioavailability based on alkaline phosphatase and phosphate transporter genes of Anabaena sp. PCC 7120.
abstract: There is heterogeneity in the way cyanobacteria respond to P starvation and subsequently how they adapt to environments with low or fluctuating P concentrations. In this study, we have fused the promoterless lux operon luxCDABE to the promoter regions of Anabaena sp. PCC 7120 phoA genes putatively encoding alkaline phosphatases, phoA (all2843) and phoA-like (alr5291) and to the promoter region of one operon putatively encoding a high affinity phosphate transporter pst1 (all4575-4572). The self-bioluminescent strains constructed in this way, Anabaena AP (phoA promoter), Anabaena AP-L (phoA-like promoter), and Anabaena PST (pst1 promoter) have been used to study the expression of these genes in response to P starvation and P re-feeding with inorganic and organic phosphate sources. Our data showed that the pst1 promoter was activated at much higher level than the phoA-like promoter following P starvation; however, we did not observe activation of the phoA promoter. The P re-feeding experiments revealed that both strains, Anabaena (A.) PST and A. AP-L could be used as novel bioreporters of P availability in environmental samples. Both strains were used to estimate bioavailable P in environmental samples (fresh- and wastewaters) with a wide range of soluble P concentrations. The results indicated that most of the P in the water samples was in chemical forms available to the cyanobacterium; however there were some differences in the estimates given by both strains as A. PST appeared to be more adequate for the samples with the lowest P load while A. AP-L gave similar or even higher values of P concentrations than those chemically measured in samples with higher P load.
authors.affiliation: Department of Biology, Universidad Autónoma de Madrid, Madrid, Spain.
authors.forename: M Angeles
authors.initials: MA
authors.lastname: Muñoz-Martín
authors.forename: Pilar
authors.initials: P
authors.lastname: Mateo
authors.forename: Francisco
authors.initials: F
authors.lastname: Leganés
authors.forename: Francisca
authors.initials: F
authors.lastname: Fernández-Piñas
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D000469:Alkaline Phosphatase / Q000378:metabolism*; D017033:Anabaena / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000502:physiology; D001682:Biological Availability; D000458:Cyanobacteria / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D028061:Phosphate Transport Proteins / Q000235:genetics / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D011401:Promoter Regions, Genetic
chemical_list: D001426:Bacterial Proteins; D028061:Phosphate Transport Proteins; D010758:Phosphorus; D000469:Alkaline Phosphatase