i ▁cells ▁can ▁be ▁stored ▁fro zen , ▁and ▁th aw ed ▁before ▁use , ▁whereas ▁P ich ia ▁cells ▁have ▁to ▁be ▁produced ▁immediately ▁before ▁use . Expression ▁yields ▁in ▁P ich ia ▁vary ▁between ▁different ▁cl ones , ▁so ▁that ▁a ▁large ▁number ▁of ▁cl ones ▁has ▁to ▁be ▁screen ed ▁for ▁protein ▁production , ▁to ▁find ▁the ▁best ▁producer . ▁The ▁biggest ▁advantage ▁of ▁P ich ia ▁over ▁E . ▁col i ▁is ▁that ▁P ich ia ▁is ▁capable ▁of ▁forming ▁dis ulf ide ▁b onds ▁and ▁g ly cos yl ations ▁in ▁prote ins , ▁but ▁E . ▁col i ▁cannot . ▁ ▁E . ▁col i ▁might ▁produce ▁a ▁mis fold ed ▁protein ▁when ▁ ▁dis ulf ides ▁are ▁included ▁in ▁final ▁product , ▁leading ▁to ▁in active ▁or ▁ins ol ub le ▁forms ▁of ▁prote ins . ▁ ▁The ▁well - stud ied ▁Sac char omy ces ▁c ere vis iae ▁is ▁also ▁used ▁as ▁an ▁expression ▁system ▁with ▁similar ▁advantages ▁over ▁E . ▁col i ▁as ▁P ich ia . ▁However ▁P ich ia ▁has ▁two ▁main ▁advantages ▁over ▁S . ▁c ere vis iae ▁in ▁labor atory ▁and ▁industrial ▁settings : P ich ia , ▁as ▁mentioned ▁above , ▁is ▁a ▁m eth yl ot roph , ▁meaning ▁that ▁it ▁can ▁grow ▁with ▁the ▁simple ▁m eth an ol , ▁as ▁the ▁only ▁source ▁of ▁energy ▁— ▁P ich ia ▁can ▁grow ▁fast ▁in ▁cell ▁susp ension ▁with ▁reason ably ▁strong ▁m eth an ol