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.

Abiotic Stress Responses and Microbe-Mediated Mitigation in Plants: The Omics Strategies

“…The proteomic experiments for Pseudomonas have been designed principally to focus on the recalcitrant, xenobiotic compounds in addition to the toxic organic pollutants ( Lupi et al, 1995 ; Reardon and Kim, 2002 ; Kim et al, 2007 ). Species of Pseudomonas have been well characterized for their PGP traits such as siderophore production ( Ferret et al, 2014 ; Cunrath et al, 2015 ), secretion of plant growth stimulating substances ( Pereira and Castro, 2014 ; Balcazar et al, 2015 ; Sorty et al, 2016 ), and biocontrol against phytopathogenic organisms ( Chet and Inbar, 1994 ; Natsch et al, 1994 ; Acebo-Guerrero et al, 2015 ; Wang et al, 2015 ). Characteristic versatile metabolic scope and unique biofilm forming ability of the members of this genus ( Kertesz et al, 1993 ; Sauer et al, 2002 , 2004 ; Arevalo-Ferro et al, 2005 ; VerBerkmoes et al, 2006 ) permits these species to thrive well under diverse environmental conditions, thus making them most effective inoculants for field application.…”

Bacterial Community Structures in Freshwater Polar Environments of Svalbard

“…These cold environments constitute an unexhausted source of vast metabolic potential that may be linked to the impact of climate change and used to exploit cold-active enzymes for biotechnological applications (5, 14). …”

Plant growth promoting traits of psychrotolerant bacteria: A boon for agriculture in hilly terrains

“…On the other hand, Verma et al (3) have identified as many as 35 bacterial strains with potential of siderophore production to varying extent. In another study, seven bacterial strains isolated from glacial ice by Balcazar et al (18) were tested positive for siderophore production.…”