Variation in antibiotic inhibitory abilities among streptomycetes from south Texas agricultural soils

Effective control of soilborne pathogens remains a challenge in agricultural systems. As part of an integrated pest management strategy, one approach to increase disease control is the active management of indigenous pathogen antagonists found in soil microbial communities. The focus of this study was the in vitro characterization of streptomycetes, bacteria commonly found in soil and known antibiotic-producers. Streptomycete isolates from watermelon and sorghum fields in south Texas were evaluated for their inhibitory activity and diversity of inhibitory phenotypes against a well characterized reference collection of streptomycetes isolated from Minnesota agricultural soils. Higher streptomycete densities, zones of inhibition and diversity of inhibitory phenotypes were found for isolates from sorghum fields compared to watermelon fields. These results suggest that increasing the density and activity of the indigenous microbes may provide additional disease control in these agricultural systems.