Streptomyces- Bacterial Interaction: The Possible Control of Soft Rot Disease Of Melon by Streptomyces Species PDF

Keywords

filtrates, soft rot disease, bacteria

Abstract

Screening for the antimicrobial activity of the culture filtrates of Streptomyces venezuelae, S. rubiginosus and S. recifencis showed that the Gram positive bacterium, Clostridium acetobuttylicum was completely resistant whereas Bacillus subtilis, B. licheniformis and Mycobacterium phlei while insensitive to the filtrate of either S. venezuelae or S. rubiginosus were very sensitive to S. recifencis filtrate. Coupling the filtrates of S. venezuelae with S. recifencis reduced or even nullified the latter's potency whereas coupling S. rubiginosus with S. recifencis lowered the latter's effects. Of the Gram negative bacteria, Escherichia coli, Aerobacter sp., Shigella flexneri, Pseudomonas putida and Erwinia toxica were totally resistant to the antibiotics produced by the three Streptomyces species. Erwinia carotovora var. carotovora, E. carotovora var. citrullus and Serratia marcescens were sensitive only to the filtrate of S. recifencis. Salmonella typhimurium was sensitive only to S. venezuelae filtrate. The mixed culture filtrates of S. rubiginosus with S. recifencis were highly potent against E. coli and Pseudomonas putida. Growth of E. toxica was highly suppressed by the filtrate of the mixed culture of S. venezuelae and S. rubiginosus but the sensitivity of E. carotovora var. citrullus to S. recifencis was abolished by mixed cultures with the other two Streptomyces species whereas that of E. carotovora var. carotovora was only attenuated. Supplementation with nickel noticeably increased whereas supplementation with cadmium or lanthanum slightly decreased the sensitivity of E. carotovora var. carotovora to S. recifencis filtrate. Nickel-fed cultures of E. carotovora var. citrullus or E. toxica was completely resistant to S. recifencis and S. venezuelae + S. rubiginous filtrates respectively. Nickel-feeding, in combination with lanthanum and/or cadmium had the same effect on E. toxica but the sensitivity of nickel-treated E. carotovora var. carotovora to S. recifencis filtrate was abolished by addition of lanthanum and reduced by replacement or further addition of cadmium. The toxins produced by E. toxica had a broader spectrum than those of E. carotovora var. carotovora and E. carotovora var. citrillus; particularly on Gram positive bacteria. Of the tested Gram negative bacteria, only Serratia marcescens and Shigella flexneri were sensitive as well as E. carotovora var. carotovora and E. toxica