Mbiriso, mumera kana mvuriro (yeast) idzinde risingaoneki nemeso risina ruvara rine cell imwe chete. Inowanikwa muchikwata cheAscomycetes murudzi rwemaFungi (anosanganisirawo chabvubvu). Mumbiriso munowanikwa maenzyme anoshanda, uye anoshandiswa mukubika doro nekuti chingwa chifute. Zviuru zvemadzinde aya zvinoumbana zvoomarara zvinotengeswa sembiriso. VaRwanda vanoti umusemburo (n. leaven) vachireva mbiriso. Mamwe mazwi gusembura (to leaven). VaGiryama vanoti ku-ira (v. ferment) vachireva kuvira. Njem vanoti ngwɛl (n. yeast) kureva mbiriso. Waalii vanoti biri; bira (v. mature; maturate - to ripen or develop). Mamwe mazwi bira (to ferment).