Isolation and characteristics of yeasts able to grow at low concentrations of nutrients

Seven oligotrophic yeasts, which can grow in a 104‐fold dilution of malt–yeast–glucose–peptone medium (10−4 YM), were mainly isolated from soil. These yeasts belong to the Cryptococcaceae. When inoculated at about 102 cells/ml in 10−4 YM, the isolates grew to 1·4×103–2·4×105 cells/ml after 3 days. Some culture collection yeasts fell into three groups according to their growth characteristics in 10−4 YM, one group showing characteristics of the oligotrophic yeasts. The half‐saturation values of uptake by the five isolated oligotrophic yeasts for D‐glucose, L‐leucine and L‐amino acids were 6·0–25·0, 1·7–43·3 and 3·5–21·6 μM, respectively. The oligotrophic yeasts suspended in 10 mM‐phosphate buffer (pH 6·0) had high tolerances for starvation, and remained more than 15% viable after 90 days of starvation. © 1998 John Wiley & Sons, Ltd.