Peroxisomal β-oxidation cycle or import of peroxisomal proteins is dispensable for biotin synthesis in S. cerevisiae. A, strains transformed with either empty vector p416 or a plasmid carrying the BIO6/BIO1 gene cluster (BIO) were grown on medium containing biotin (right) or on biotin-depleted medium supplemented with avidin (left). The strain/plasmid combinations were BY4742/p416 (sector 1), BY4742/BIO (sector 2), pox1Δ0/p416 (sector 3), pox1Δ0/BIO (sector 4), fox2Δ0/p416 (sector 5), fox2Δ0/BIO (sector 6), pot1Δ0/p416 (sector 7), pot1Δ0/BIO (sector 8), pex5Δ0/p416 (sector 9), pex5Δ0/BIO (sector 10), pex7Δ0/p416 (sector 11), and pex7Δ0/BIO (sector 12). B, growth kinetics of strains BY4742/BIO (WT), pox1Δ0/BIO, and fox2Δ0/BIO in liquid biotin-depleted medium supplemented with avidin. Absorbance at 600 nm (OD 600; 0.6-cm light path) was recorded. Error bars represent S.E. (n = 6).