Diversity and characteristics of yeasts from water sources in the North West Province, South Africa

Yeasts form an important part of ecosystems. Yeast biodiversity in the North West Province, South Africa, remains largely unexplored. The purpose of this study was to determine the diversity and characteristics of yeasts from water sources in the North West Province. Yeasts were isolated from four rivers and an inland lake. Various parameters were measured to determine the physico-chemical quality of the water. Isolation was done on yeast-malt-extract (YM) agar and identified using biological methods. Physico-chemical parameters were within a target water quality range for various water uses. Yeasts were detected at 22 of the 23 sampling sites. Levels ranged from 3 to 8,680 cfu/L and were broadly divided into pigmented and non-pigmented yeasts. Pigmented yeasts could potentially be an indication of pollution, while non-pigmented yeasts could potentially be pathogenic species. Levels of yeasts could be statistically associated with some physico-chemical parameters. A large percentage of isolated yeasts could grow at temperatures ranging from 4 to 40 °C. Candida spp., Cryptococcus spp., Rhodotorula spp. and Zygosaccharomyces spp. were identified. Our results provide preliminary information on the distribution and diversity of yeasts in water sources in the North West Province.