Berdicevsky I, Grossowicz N
Antimicrob Agents Chemother. 1972 Jul;2(1):1-7. doi: 10.1128/AAC.2.1.1.
Only Debaryomyces nicotianae strain 77, of seven different yeast strains tested, was found to be resistant to heptamycin and other antifungal heptaenes when grown in a rich medium. This strain, however, like the other six, was completely susceptible to these antibiotics in a minimal medium. Addition of yeast extract to the minimal medium abolished the heptamycin effect; calcium ions fully duplicated the effect of yeast extract; Mg(2+) and Mn(2+) were also effective but less so than Ca(2+). Ca(2+) also counteracted the activity of the heptaenes ascosin and trichomycin. Complete reversal of the polyene inhibition by Ca(2+) was obtained if the cation was added simultaneously with the antibiotic; addition of Ca(2+) 2 hr after the polyene was without effect. Addition of Ca(2+) in the absence of the polyene caused a slight, if any, growth stimulation of D. nicotianae 77. Cholesterol also counteracted polyene activity; this was due to the formation of a complex with the antibiotic which prevented the polyene from reaching the site of action-the cytoplasmic membrane. No evidence for complex formation between heptamycin and calcium was found. The importance of Ca(2+) in membrane structure, as evidenced from heptaene studies, is discussed.
在七种不同的酵母菌株中，只有德巴利酵母属烟草酵母菌株77在丰富培养基中生长时，被发现对七霉素和其他抗真菌七烯类抗生素具有抗性。然而，该菌株与其他六种菌株一样，在基本培养基中对这些抗生素完全敏感。向基本培养基中添加酵母提取物可消除七霉素的作用；钙离子可完全重现酵母提取物的作用；镁离子（Mg(2+)）和锰离子（Mn(2+)）也有效果，但不如钙离子（Ca(2+)）显著。钙离子（Ca(2+)）还可抵消七烯类抗生素阿斯科辛和曲古霉素的活性。如果在添加抗生素的同时加入钙离子（Ca(2+)），则可完全逆转多烯类抗生素的抑制作用；在多烯类抗生素加入2小时后添加钙离子（Ca(2+)）则没有效果。在没有多烯类抗生素的情况下添加钙离子（Ca(2+)），对烟草酵母菌株77的生长有轻微的促进作用（如果有促进作用的话）。胆固醇也可抵消多烯类抗生素的活性；这是由于与抗生素形成了复合物，阻止了多烯类抗生素到达作用位点——细胞质膜。未发现七霉素与钙之间形成复合物的证据。文中讨论了从七烯类抗生素研究中得出的钙离子（Ca(2+)）在膜结构中的重要性。
