Assessment of yeast diversity in different soil types under various management regimes in Moldavia region, Romania

Abstract

This study examined the diversity and abundance of yeasts population isolated from soils sample under different agricultural regimes (permanent grassland, arable land under agricultural rotation, forest land etc) from Moldavia region located in northeastern Romania, which covers an area of 35,806 km2 and has a population of approximately 4.3 million inhabitants. Twenty sites were common to the two samplings in May and September, 2015 and 2016. Soil samples were represented by typical chernozem, greic chernozem, psamic chernozem, cambic chernozem, faeoziom chernozem, preluvosoil, albic luvosoil, psamic luvosoil, solonchak, solonetz, planosoil, molic saline aluviosoil, vertosoil and gleiosoil. At each site, five replicate bulk samples were taken, consisting of 10 randomly collected sub-samples from the surface soil (10-15 cm horizon). The samples were transported to the laboratory, stored overnight at 4°C, air-dried at room temperature and sieved (2-mm mesh) prior to further use in the experiment. The soils pH values covered a range between 5.6 (planosoil) and 8.7 (solonchak). Yeast isolation and obtaining of the pure cultures was done mainly through inoculums dissemination and loop exhaustion techniques on solid nutrient media. We isolated and identified molecularly a total of 33 yeast species, including several possible new species. Occurrence and distribution of yeasts isolated from these soils provide new insights into ecology and niche specialization of several soil-borne species. Species composition of different localities was very heterogeneous and many of the species were found in a single site only.