Isolation and characterization of potent antifungal strains of the Streptomyces violaceusniger clade active against Candida albicans |
| |
Authors: | Min J Kang Janice L Strap Donald L Crawford |
| |
Institution: | (1) Department of Chemistry and Biochemistry, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0358, USA;(2) Faculty of Science, University of Ontario Institute of Technology, Oshawa, ON, L1K 2Z1, Canada;(3) Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, ID 83844-3052, USA |
| |
Abstract: | Streptomyces strains were isolated from a sagebrush rhizosphere soil sample on humic acid vitamin (HV) agar and water yeast extract (WYE)
agar supplemented with 1.5% (w/w) phenol as a selective medium. Acidic, neutral and alkaline pH conditions were also used
in the isolation procedures. The phenol treatment reduced the numbers of both actinomycetes and non-actinomycetes on plates
under all three pH conditions. From phenol-amended HV and WYE agar, 16 strains were isolated in pure culture; 14 from the
HV agar and two from the WYE agar. All the isolates were tested for their antifungal activities against Pythium ultimum P8 and five yeast strains, including two antifungal drug-resistant Candida albicans strains. HV isolates that showed broad-spectrum antifungal antibiotic activities were all found to be members of the Streptomyces violaceusniger clade, while those that did not were non-clade members. The phenol treatment was not selective for S. violaceusniger clade members. Therefore, we tested the spores of both S. violaceusniger clade and non-clade members using two biocides, phenol and hydrogen peroxide, as selection agents. Spores of non-clade members,
such as S. coelicolor M145 and S. lividans TK 21, survived these two biocides just as well as S. violaceusniger clade members. Thus, in our hands, biocide resistance was not S. violaceusniger clade specific as previously reported. However, isolates showing broad-spectrum antifungal and antiyeast activity were all
members of the clade. We conclude that screening of isolates for broad-spectrum antifungal/antiyeast activity is the preferred
method of isolating S. violaceusniger clade strains rather than biocide-based selection. Phylogenetic analysis of the phenol-resistant isolates revealed that the
HV isolates that exhibited broad-spectrum antifungal antibiotic activity were all clustered and closely related to the S. violaceusniger clade, while the isolates that did not exhibit antifungal antibiotic activity were all non-clade members. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|