title: Effect of mineral phosphates on growth and nitrogen  fixation of diazotrophic cyanobacteria Anabaena variabilis  and Westiellopsis prolifica.
abstract: The nitrogen fixing cyanobacterial strains namely Anabaena variabilis (Nostocales, Nostocaceae) and Westiellopsis prolifica (Nostocales, Hapalosiphonaceae) were evaluated for their nitrogen fixation and growth potential in response to different concentrations (10, 20 and 30 mg P) of the alternate insoluble P-sources Mussorie Rock Phosphate and Tricalcium Phosphate. Distinct and significant intergeneric differences were observed with respect to nitrogen fixation measured as Acetylene Reduction Activity (ARA) and growth potential as soluble proteins, total carbohydrate content, dry weight and total chlorophyll content in response to different concentrations of Mussorie Rock Phosphate and Tricalcium Phosphate. Both the strains showed higher soluble protein content at 20 mg P (Mussorie Rock Phosphate) that increased with time of incubation in A. variabilis. Both cyanobacteria recorded maximum Acetylene Reduction Activity at 20 mg P (Tricalcium Phosphate) followed by activity in presence of soluble phosphate (K2HPO4). The mean activity at all concentrations of insoluble phosphate (Mussorie Rock Phosphate and Tricalcium Phosphate) was more than in the presence of soluble phosphate.
authors.affiliation: National Bureau of Agriculturally Important Microorganisms, Kushmaur, Mau Nath Bhanjan, Uttar Pradesh 275101, India. micromahesh@gmail.com
authors.forename: Mahesh S
authors.initials: MS
authors.lastname: Yandigeri
authors.forename: Arvind K
authors.initials: AK
authors.lastname: Yadav
authors.forename: Kamlesh Kumar
authors.initials: KK
authors.lastname: Meena
authors.forename: Sunil
authors.initials: S
authors.lastname: Pabbi
mesh_terms: D000114:Acetylene / Q000378:metabolism; D046870:Anabaena variabilis / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism; D001426:Bacterial Proteins / Q000032:analysis; D018533:Biomass; D002241:Carbohydrates / Q000032:analysis; D002734:Chlorophyll / Q000032:analysis; D000458:Cyanobacteria / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism*; D009586:Nitrogen Fixation; D010710:Phosphates / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002241:Carbohydrates; D010710:Phosphates; D002734:Chlorophyll; D000114:Acetylene