Maintenance of Ascomycete Fungus Strains

This study was conducted on a KU70Δ mutant [23 (link)] derived from the wild-type strain S. apiospermum IHEM 14462, originally isolated from sputum sample from a CF patient and previously used for whole-genome sequencing [25 (link)]. Strains were maintained at 37 °C by weekly passages on potato-dextrose-agar plus chloramphenicol (PDA from Condalab, containing in g/L: dextrose, 20; infusion extract from potatoes, 4; chloramphenicol, 0.5; and bacteriological agar, 15), supplemented with 20 µg/mL phleomycin or 50 µg/mL hygromycin, for maintenance of the KU70Δ mutant or the double mutant KU70Δ/SODDΔ, respectively. All strains were stored at −80 °C as conidial suspensions in 20% glycerol. Conidia processed into any experiment were collected from 9-day-old cultures grown in PDA or yeast extract-peptone-dextrose (YPD containing in g/L: yeast extract, 10; peptone, 20; glucose, 20; and chloramphenicol, 0.5%) and resuspended in sterile water or saline before to be enumerating by hematocytometer counts.