▁obtained ▁industri ally ▁by ▁hydro ly s is ▁of ▁animal ▁materials , ▁such ▁as ▁p oul try ▁fe athers ▁or ▁h og ▁hair . ▁Despite ▁w ides p read ▁belief ▁otherwise , ▁little ▁evidence ▁shows ▁that ▁human ▁hair ▁is ▁used ▁as ▁a ▁source ▁material ▁and ▁its ▁use ▁is ▁explicitly ▁b anned ▁in ▁the ▁European ▁Union . ▁Syn th et ically ▁produced ▁- c yst e ine , ▁comp li ant ▁with ▁Jewish ▁k os her ▁and ▁Muslim ▁hal al ▁laws , ▁is ▁also ▁available , ▁al beit ▁at ▁a ▁higher ▁price . ▁ ▁The ▁synth etic ▁route ▁involves ▁fer ment ation ▁using ▁a ▁mut ant ▁of ▁E . ▁col i . ▁D eg uss a ▁introduced ▁a ▁route ▁from ▁subst it uted ▁th ia z ol ines . ▁ ▁Following ▁this ▁technology , ▁- c yst e ine ▁is ▁produced ▁by ▁the ▁hydro ly s is ▁of ▁rac em ic ▁ 2 - am ino - Δ 2 - th ia z oline - 4 - car box y lic ▁acid ▁using ▁Pseud omon as ▁th ia z olin oph il um . ▁ ▁B ios yn thesis ▁▁ ▁In ▁animals , ▁b ios yn thesis ▁begins ▁with ▁the ▁am ino ▁acid ▁ser ine . ▁ ▁The ▁sul fur ▁is ▁derived ▁from ▁m eth ion ine , ▁which ▁is ▁converted ▁to ▁hom oc yst e ine ▁through ▁the ▁intermediate ▁S - aden os yl m eth ion ine . ▁ ▁C yst ath ion ine ▁beta - syn th ase ▁then ▁comb ines