Cycloheximide resistance in the Lipomycetaceae revisited

Abstract

Cycloheximide (CYH) is a heterocyclic, glutarimide antibiotic that is a potent inhibitor of protein biosynthesis in most eukaryotes. This study demonstrated that yeasts from all species of the Lipomycetaceae, with the exception of Dipodascopsis spp., can grow in the presence of up to 5 g.L(-1) CYH -- a concentration that is five times higher than the accepted "highest" concentration of 1 g.L(-1) used in physiological tests for yeast identification. Lipomycetaceous yeasts are known to utilize heterocyclic nitrogen-containing compounds such as thymine as sole nitrogen source. CYH contains a glutarimide ring, which is chemically similar to thymine. We investigated the possibility that CYH resistance in the Lipomycetaceae might be due to an ability to degrade CYH and use it as the sole nitrogen source. However, we were unable to demonstrate significant growth on CYH as sole nitrogen source. When thymine was used as positive control, we could demonstrate its utilization as sole nitrogen source.

Cryptococcus cyanovorans sp. nov., a basidiomycetous yeast isolated from cyanide-contaminated soil

“…The ability of these novel strains, as well as other strains isolated from cyanide-contaminated soil and Cryptococcus curvatus CBS 570 T and Cryptococcus humicolus CBS 2042, to grow in the presence of NaCN as sole nitrogen source in liquid media was assessed as follows. Cells from strains were starved by cultivation in yeast nitrogen base (YNB) without ammonium sulphate and amino acids (per litre 1.7 g YNB and 10 g glucose) following the procedure of Müller et al (2007). After this period, cells were tested for nitrogen source assimilation using minimal medium (containing, per litre, 4.3 g K 2 HPO 4 , 3.4 g KH 2 PO 4 and 0.3 g MgCl 2 ) containing 10 g l −1 glucose and 10 mM NaCN.…”