Media and reagents

The media used in these experiments included yeast extract-peptone-dextrose (YPD) medium, YPD medium containing 200 μg/ml of nourseothricin (Werner BioAgents, Jena, Germany), and Spider medium, and they were prepared as previously described [⁶⁰]. In YPG medium, dextrose was replaced with 3% glycerol. The base RPMI 1640 liquid medium, RPMI 1640 medium supplemented with 0.2% acetic acid (final pH 6.3, buffer control medium), and chitosan medium prepared from RPMI 1640 supplemented with 0.2% chitosan dissolved in 0.2% acetic acid (experimental medium) were prepared as previously described [^56,61,62]. The chitosan used in this study was purchased from Shin Era Technology (Taipei, Taiwan). The molecular weight (MW) of chitosan is approximately 20–35 kDa, and its degree of deacetylation is approximately 90% [⁵⁶]. All chemicals were purchased from Sigma-Aldrich Chemical unless stated otherwise.