Isolation, Screening, and Characterization of Plant-Growth-Promoting Bacteria from Durum Wheat Rhizosphere to Improve N and P Nutrient Use Efficiency

• Main Authors: Nilde Antonella Di Benedetto, Daniela Campaniello, Antonio Bevilacqua, Mariagrazia Pia Cataldi, Milena Sinigaglia, Zina Flagella, Maria Rosaria Corbo
• Format: Article
• Language: English
• Published: MDPI AG 2019-11-01
• Series: Microorganisms
• Subjects: plant-growth-promoting bacteria; durum wheat; phenotypic and genotypic characterization; multivariate approach; nutrient-use efficiency
• Online Access: https://www.mdpi.com/2076-2607/7/11/541

The main goal of this paper was to select promising microorganisms which could potentially act as plant-growth-promoting bacteria (PGPB) for durum wheat of Foggia County. At this scope, a new statistical framework, based on multivariate analyses and the evaluation of the statistical distribution of each trait, was used. Four hundred and seventy-four isolates were isolated from the rhizosphere of durum wheat in Foggia County and preliminarily screened as a function of four target indices (ammonium production, siderophores production, P-solubilization, and nitrification). After this step, the number of strains was reduced and the remaining isolates were tested through a quantitative approach, to assess the production of IAA (indole acetic acid), P-mineralization, and nitrification. In this second step, the cut-off was based on the whole population trend by evaluating for each trait the medians and quartiles. As a result, 16 promising isolates were selected and identified by 16S rDNA sequencing (<i>Bacillus</i>, <i>Pseudomonas</i>, <i>Stenotrophomonas</i>, and <i>Lysinibacillus</i>). The last step of this research was a preliminary validation in a growth chamber on eight strains. As screening and simple indices, two quantitative measures were chosen. The main result was the selection of at least three isolates (6P, 20P, and 25A) for a future field validation. They increased biomass and height by respectively 50% and 25%.