title: Organic acid production in vitro and plant growth promotion in maize under controlled environment by phosphate-solubilizing fluorescent Pseudomonas.
abstract: BACKGROUND
  Phosphorus deficiency is a major constraint to crop production due to rapid binding of the applied phosphorus into fixed forms not available to the plants. Microbial solubilization of inorganic phosphates has been attributed mainly to the production of organic acids. Phosphate-solubilizing microorganisms enhance plant growth under conditions of poor phosphorus availability by solubilizing insoluble phosphates in the soil. This paper describes the production of organic acids during inorganic phosphate solubilization and influence on plant growth as a function of phosphate solubilization by fluorescent Pseudomonas.
  
  
  RESULTS
  Nineteen phosphate-solubilizing fluorescent Pseudomonas strains of P. fluorescens, P. poae, P. trivialis, and Pseudomonas spp. produced gluconic acid, oxalic acid, 2-ketogluconic acid, lactic acid, succinic acid, formic acid, citric acid and malic acid in the culture filtrates during the solubilization of tricalcium phosphate, Mussoorie rock phosphate, Udaipur rock phosphate and North Carolina rock phosphate. The strains differed quantitatively and qualitatively in the production of organic acids during solubilization of phosphate substrates. Cluster analysis based on organic acid profiling revealed inter-species and intra-species variation in organic acids produced by Pseudomonas strains. The phosphate-solubilizing bacterial treatments P. trivialis BIHB 745, P. trivialis BIHB 747, Pseudomonas sp. BIHB 756 and P. poae BIHB 808 resulted in significantly higher or statistically at par growth and total N, P and K content over single super phosphate treatment in maize. These treatments also significantly affected pH, organic matter, and N, P, and K content of the soil.
  
  
  CONCLUSIONS
  The results implied that organic acid production by Pseudomonas strains is independent of their genetic relatedness and each strain has its own ability of producing organic acids during the solubilization of inorganic phosphates. Significant difference in plant growth promotion by efficient phosphate-solubilizing Pseudomonas strains point at the need for selecting potential strains in plant growth promotion experiments in conjunction with various phosphate substrates for their targeted application as bioinoculants.
authors.affiliation: Plant Pathology and Microbiology Laboratory, Institute of Himalayan Bioresource Technology (CSIR), Palampur (HP)-176 061, India. vyasp2000@yahoo.co.in
authors.forename: Pratibha
authors.initials: P
authors.lastname: Vyas
authors.forename: Arvind
authors.initials: A
authors.lastname: Gulati
mesh_terms: D000144:Acids, Acyclic / Q000378:metabolism*; D016000:Cluster Analysis; D010710:Phosphates / Q000378:metabolism*; D011549:Pseudomonas / Q000378:metabolism*; D012987:Soil / Q000032:analysis; D003313:Zea mays / Q000254:growth & development* / Q000378:metabolism / Q000382:microbiology*
chemical_list: D000144:Acids, Acyclic; D010710:Phosphates; D012987:Soil
references.citation: Curr Microbiol. 2003 Aug;47(2):87-92
references.pmid: 14506853
references.citation: Curr Microbiol. 2006 Jun;52(6):473-6
references.pmid: 16732458
references.citation: Curr Microbiol. 2008 Jan;56(1):73-9
references.pmid: 17909886
references.citation: Curr Microbiol. 2008 Feb;56(2):140-4
references.pmid: 18026795
references.citation: Biochem J. 1976 Mar 15;154(3):659-68
references.pmid: 821472
references.citation: Biotechnol Adv. 1999 Oct;17(4-5):319-39
references.pmid: 14538133
references.citation: Microb Ecol. 2009 Aug;58(2):425-34
references.pmid: 19319589
references.citation: Microbiol Res. 2004;159(4):371-94
references.pmid: 15646384
references.citation: Curr Microbiol. 2009 Apr;58(4):371-7
references.pmid: 19137371
references.citation: Naturwissenschaften. 2004 Nov;91(11):552-5
references.pmid: 15502903
references.citation: Microbiol Res. 2007;162(1):69-76
references.pmid: 17140781
references.citation: Curr Microbiol. 2008 Feb;56(2):168-74
references.pmid: 17965911
references.citation: Mycorrhiza. 1998 Feb;7(5):249-53
references.pmid: 24578050