Summary of bacteria cultured from surface sterilized roots and shoots of Zea plants grown in sand, Canadian soil or Mexican soil. Top panel: Examples of R2A plate cultures of extracts from roots and shoots of Parviglumis when grown on different substrates. Botton panel: Taxonomic identification of cultured microbes based on sequencing of 16S rDNA from each colony. A black box indicates successful culturing of that genus. To enable comparisons to TRFLP results, the 16S rDNA sequences were virtually digested and the peak sizes are shown in the right column (predicted 16S rDNA DdeI 6FAM labelled cleavage product fragment sizes). The white scale bar on the left equals 10 mm. More details on bacterial isolates are found in Additional file 3: Table S2.