@article{mbs:/content/journal/micro/10.1099/00221287-14-2-440, author = "Stevenson, I. L.", title = "Antibiotic Activity of Actinomycetes in Soil and their Controlling Effects on Root-rot of Wheat", journal= "Microbiology", year = "1956", volume = "14", number = "2", pages = "440-448", doi = "https://doi.org/10.1099/00221287-14-2-440", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-14-2-440", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", abstract = "SUMMARY: A study has been made of conditions affecting the production of antibiotics in three soils by a number of unidentified Streptomyces spp. capable of inhibiting a variety of test organisms in vitro. In actinomycete-inoculated soils, antibiotic production was demonstrated only in sterile soils supplemented with a suitable organic source. The greatest accumulations of antibiotics were found in a neutral soil with added glucose (2ยท5%) while under similar conditions, no antibioties, or only traces were recovered from acid and alkaline soils. Antibiotics, however, could be recovered from inoculated acid soil, following neutralization and the addition of glucose. Fresh grass (3%), clover (3%) and soybean meal (2%) were also suitable supplements for antibiotic production by the majority of the actinomycetes, though the amounts of antibiotics were considerably less than in glucose-treated soils. In greenhouse experiments the assessment of root damage to wheat seedlings in sterile soil demonstrated that all the actinomycetes tested significantly reduced the degree of root-rot caused by Helminthosporium sativum. In the neutral and alkaline soils a relationship was evident between disease incidence and degree of antagonism exhibited by actinomycetes in vitro, suggesting that antibiotics were responsible. No such relationship was observed between disease control and the antibiotic-producing abilities of the actinomycetes in soil as determined by standard assay procedures.", }