Long-Term Nitrogen Amendment Leads to Increased Intensity of Antibiotic Production Among Streptomyces Community Members
Diseases caused by plant pathogens reduce the global food-crop up to 40% annually. While the effectiveness of chemical-based disease control is decreasing, antibiotic-mediated disease suppression by soil microbes presents a promising biological-based tool towards more sustainable disease control. Antibiotics produced by Streptomyces, a ubiquitous genus of soil bacteria, has been shown to increase natural disease suppression, however, there is little known about how agricultural practices alter the antibiotic production among naturally occurring Streptomyces populations. This study examines how long term nutrient amendment, and competition among microbiome community members influence overall antibiotic production intensity among Streptomyces. Twenty Streptomyces isolates were collected from plots under two distinct long-term nutrient management strategies and antibiotic production intensity was measured for each isolate alone, and in pairwise competition with 5 other community members. Overall, Streptomyces isolates from nitrogen amended plots were found to have significantly greater inhibition intensity than isolates taken from non-amended plots. Furthermore, when isolates from the nitrogen amended plot were grown with other community members, greater frequency of increased antibiotic production intensity was found than among pairings of non-amended isolates. These results suggest that nutrient management could act as a strategy for increasing the natural disease suppression capacities among native soil microbes.