title: Bioprospecting glacial ice for plant growth promoting bacteria.
abstract: Glaciers harbor a wide diversity of microorganisms, metabolically versatile, highly tolerant to multiple environmental stresses and potentially useful for biotechnological purposes. Among these, we hypothesized the presence of bacteria able to exhibit well-known plant growth promoting traits (PGP). These kinds of bacteria have been employed for the development of commercial biofertilizers; unfortunately, these biotechnological products have proven ineffective in colder climates, like the ones prevailing in mountainous ecosystems. In the present work, we prospected glacial ice collected from two small tropical glaciers, located above 4.900 m in the Venezuelan Andes, for cold-active PGP bacteria. The initial screening strategy allowed us to detect the best inorganic-P solubilizers at low temperatures, from a sub-sample of 50 bacterial isolates. Solubilization of tricalcium phosphate, aluminum- and iron-phosphate, occurred in liquid cultures at low temperatures and was dependent on medium acidification by gluconic acid production, when bacteria were supplied with an appropriate source of carbon. Besides, the isolates were psychrophilic and in some cases exhibited a broad range of growth-temperatures, from 4 °C to 30 °C. Additional PGP abilities, including phytohormone- and HCN production, siderophore excretion and inhibition of phytopathogens, were confirmed in vitro. Nucleotidic sequence analysis of 16S rRNA genes allowed us to place the isolates within the Pseudomonas genus. Our results support the possible use of these strains to develop cold-active biofertilizers to be used in mountainous agriculture.
authors.affiliation: Laboratorio de Microbiología Molecular y Biotecnología, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela.
authors.forename: Wilvis
authors.initials: W
authors.lastname: Balcazar
authors.affiliation: Laboratorio de Microbiología Molecular y Biotecnología, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela.
authors.forename: Johnma
authors.initials: J
authors.lastname: Rondón
authors.affiliation: Laboratorio de Microbiología Molecular y Biotecnología, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela.
authors.forename: Marcos
authors.initials: M
authors.lastname: Rengifo
authors.affiliation: Laboratorio de Microbiología Molecular y Biotecnología, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela.
authors.forename: María M
authors.initials: MM
authors.lastname: Ball
authors.affiliation: Centro de Física Fundamental, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Melfo
authors.affiliation: Laboratorio de Microbiología Molecular y Biotecnología, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela.
authors.forename: Wileidy
authors.initials: W
authors.lastname: Gómez
authors.affiliation: Laboratorio de Microbiología Molecular y Biotecnología, Facultad de Ciencias, Universidad de Los Andes, Mérida, Venezuela; Instituto Antártico Ecuatoriano, Blvd. 9 de Octubre 416 y Chile, Ed. Citibank, 4th Piso, Guayaquil, Ecuador. Electronic address: yluis@ula.ve.
authors.forename: Luis Andrés
authors.initials: LA
authors.lastname: Yarzábal
mesh_terms: D000898:Antibiosis; D065132:Bioprospecting; D016000:Cluster Analysis; D003080:Cold Temperature; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D007053:Ice; D046448:Ice Cover / Q000382:microbiology*; D008969:Molecular Sequence Data; D010710:Phosphates / Q000378:metabolism; D010802:Phylogeny; D063245:Plant Development; D010937:Plant Growth Regulators / Q000378:metabolism; D010944:Plants / Q000382:microbiology*; D011549:Pseudomonas / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014687:Venezuela
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D007053:Ice; D010710:Phosphates; D010937:Plant Growth Regulators; D012336:RNA, Ribosomal, 16S
keywords: Andes mountains; Bacteria; Plant growth promotion; Psychrophiles; Tropical glaciers