Diversity and relationships among strains of culturable yeasts in agricultural soils in Cameroon

Abstract

Yeasts are unicellular fungi; they are found in a diverse range of natural habitats, including soil, aquatic environments, the surface of plants, and the skin and mucosal surfaces of animal hosts. A variety of yeasts have been found in the soil environment. However, most studies of soil yeasts have come from developed countries, and there is a dearth of research on soil yeasts in Africa. In this study, we analyzed 493 soil samples from nine geographical locations in Cameroon for yeasts, using a culture - based method. A total of 110 yeast isolates were obtained. Based on their sequences at the fungal barcode locus, the Internal Transcribed Spacer (ITS) regions of the nuclear ribosomal RNA gene cluster, the 110 yeast isolates were putatively identified as belonging to 16 yeast species, including 15 Ascomycetes and one Basidiomycete. Differences in yeast species distribution were observed among the analyzed geographic regions. PCR fingerprinting analyses identified a large number of genotypes among strains within each of the obtained yeast species. Significantly, there was little evidence of geographic clustering among yeast strains from any of the yeast species. Our results suggest that Cameroon contains significant yeast diversity and that gene flow is common among local and regional soil yeast populations.

Global Patterns in Culturable Soil Yeast Diversity

“…in a previous study (Aljohani et al 2018). Overall, we observed a slightly negative correlation between the number of soil samples and the yeast isolation rate (p < 0.05), as countries with more soil samples did not necessarily yield more yeast isolates.…”

“…As shown in the study by Aljohani et al (2018) for the Cameroonian soil samples, all but one of the 19 yeast species recovered from Cameroonian soil were ascomycetes.…”

Global patterns in culturable soil yeast diversity

“…The yeast isolation rate varied among countries, ranging from 17% in Saudi Arabia to 87% in Canada. The yeast isolation rate and species distribution data from Cameroon soils have been reported in a previous study ( Aljohani et al., 2018 ). Overall, we observed a slightly negative correlation between the number of soil samples and the yeast isolation rate (p < 0.05), as countries with more soil samples did not necessarily yield more yeast isolates.…”

Analyses of the Global Multilocus Genotypes of the Human Pathogenic Yeast Candida tropicalis

“…The second area of future research is to integrate natural ecological studies of C. tropicalis into clinical investigations and global population genetic analyses. C. tropicalis has been found in a diversity of ecological niches, including multiple anatomical sites in humans (Supplementary Table 1), soil (Yang et al, 2012; Aljohani et al, 2018), trees (Carvalho et al, 2014), aquatic environments (Vogel et al, 2007), and animals such as wild birds (Lord et al, 2010), horses (Cordeiro et al, 2013), rheas (Brilhante et al, 2013) as well as in tortoises and sea turtles (Brilhante et al, 2015). However, as seen in Supplementary Table 1, most geographic populations (at either the regional or national levels) in the current database had only a limited number of analyzed ecological niches (mostly in humans) and that most body sites had relatively few strains of C. tropicalis each.…”