Confirmation of COS-5.44 resistance in the Arl1 overexpressing strain and sensitivity of the corresponding heterozygous deletion strain. The overexpression of ARL1 does confer resistance to COS-5.44 (112.5 μg/ml) compared with the wild type (vector control) that is not able to grow at this concentration. The heterozygous deletions strain (arl1 Δ) shows sensitivity to COS-5.44 (91.1 μg/ml). A) Growth curves of ARL1 and wild type (vector control) growth in the vehicle. B) Growth curves of Arl1 overexpressing and wild type strains growth with COS-5.44 (112.5 μg/ml). C) Growth curves of the heterozygous deletion (arl1 Δ) and wild type strain grown with the vehicle. D) Growth curves of heterozygous deletion (arl1 Δ) and wild type strains grown with COS-5.44 (91.1 μg/ml). Optical density readings were taken every 15 min over 20 hrs using a Tecan Genios reader. Tecan ODs were converted to conventional 1 mm path length cuvette ODs using a calibration function provided by Ericson et al. 2010, . Similar behaviour was observed for the rest of the selected overexpressing strains (Bck2, Erg24, Msg5 and Rba50) deduced to be resistant to chitosan oligosaccharide COS-5.44 from the MSP screen. The heterozygous deletion strains from these genes (bck2 Δ, erg24 Δ, msg5 Δ and rba50 Δ) were also individually tested for sensitivity to COS-5.44 (91.1 μg/ml). Three colonies of each strain were grown in triplicate and compared with the wild type in the presence of the COS-5.44 and the vehicle (1% DMSO).