Physiological signs of domestication in Saccharomyces uvarum

GONZÁLEZ FLORES, M.; RODRÍGUEZ M.E.; QUEROL A.; LOPES C.A.

Simposio; 34th International Specialised Symposium on Yeast; 2018

Four subpopulations of S. uvarum have been reported: Holartic and South America-A(SA-A) detected in both natural and fermentative environments and Australasian andSouth America-B (SA-B) only detected in natural environments. However, little is knownabout the phenotypic differences associated with either their phylogenetic origin ortheir ecological adaptions. We studied the response of 61 strains of S. uvarum includedin three subpopulations (Holartic, SA-A and SA-B) to the following stress conditions:temperature (13ºC to 30°C), ethanol (0 to 8% v/v) and nitrogen concentrations (20 to 300mg/L YAN) using microplate assays. The Holartic strains exhibited the greatestplasticity (ability to modify their performance in different conditions), being also themost cryotolerant. Regarding ethanol tolerance, very low plasticity was detected inpopulations from natural environments (independently from their genetic history),showing the lowest ethanol tolerance. Finally, strains from fermentative environmentsshowed the highest nitrogen requirement. One strain representing each subpopulationwas selected for competition assays in extreme conditions of temperature (13°C and25°C), ethanol (0 and 8%v/v) and YAN (40 and 300 mg/L). The implantation capacitywas evaluated by mtDNA-RFLP analysis. In extreme conditions (either 8% ethanol or13ºC), a significant implantation of the Holartic strain (more than 55%), versus SA-A(aprox. 25%) and SA-B (aprox. 20%) was observed. Either at 0% ethanol or at 25°C, thethree strains were detected in equal proportions. At 40mg/L YAN, South Americanstrains (both SA-A and SA-B) dominated over the Holartic strain (50% and 35% vs 15%,respectively). The SA-B strain was not able to grow at high YAN concentrations whilethe remaining strains showed similar implantation percentages. We evidenced differentphysiological adaptive mechanisms in S. uvarum that could be associated to itsdomestication, as well as a putative explanation about the absence of SA-Bsubpopulation in fermentative processes.