Culturable bacteria of the maize rhizosphere: conserving Mexican potential biotechnological resources

Rhizospheric microbiota diversity of crops in agroecosystems is understudied in Mexico and worldwide. The aim of the present work was to explore the diversity of culturable bacteria in maize fields. A bacterial collection consisting of 11,520 purified isolates was created from the rhizosphere of maize plants. Genomic DNA was obtained from each isolate and a region of 16S rDNA was sequenced. The 16S rDNA amplicon sequences were analyzed and grouped into Operational Taxonomic Units (OTUs), allowing the assemblage of 7,077 bacterial isolates into 185 non-singleton OTUs. OTUs belonged to 19 bacterial genera within Firmicutes, Proteobacteria, Actinobacteria and Bacteroidetes Phyla; with Firmicutes as the richest Phylum comprising 146 OTUs and 6 genera, and being Bacillus the richest genus. The soil core-community of 28 OTUs belonging to Firmicutes and 1 OTU from Proteobacteria was identified. The work discusses the role that the different bacterial populations identified within the maize rhizosphere may play, their potential use for biotechnological purposes, and the importance of conservation of microbiological resources using bacterial collections.