FIGURE 4.

Screening of a mutagenized population of S. eubayanus CBS 12357. (A) Survival after UV exposure of CBS 12357 spores. Plated spores were mutagenized using a UVC-lamp, 36W, MSC-Advantage Biological Safety Cabinet, Thermo Fisher Scientific. Plates were subjected to UV for different periods ranging from 45–120 s. Surviving germinated spores were quantified after 5 days of incubation at 20°C in the dark. Spores sample exposed to UV for 80 s were further processed. (B) Principal component analysis (PCA) two-dimensional score plot of parental strains CBS 12357, UV mutagenized strains, and culture medium from cultivations in 96-well microtiter plates. About 1000 picked colonies were arrayed in 96 MTP format. The mutagenized population was further inoculated in SWM, SWM-ca and SWM-fa. Principal Component Analysis (PCA) was performed on a dataset comprising CASI readouts as determined by final OD_660nm values after 72 h growth on SWM and SWM-ca, and FACI readouts as determined by discrete UV-Vis absorbance values from 280–360 nm with 10 nm intervals of SMW-fa culture supernatants after 72 h of cultivation. Ellipses were drawn to include 68% of the particular subgroup of cultures. The 80 replicates of the parental strain S. eubayanus CBS 12357 were shown in green, the blank culture replicates (no cells) were shown in blue, the UV-mutagenized variants were shown in black and the UV mutagenized strains exhibiting a fitness reduction were shown in red.