O-methyltransferase; part of the gene cluster that mediates the biosynthesis of bikaverin, a red pigment also considered as a mycotoxin (PubMed:19400779). The first stage is catalyzed by the polyketide synthase bik1, which catalyzes the formation of the intermediate SMA76a also knowm as pre-bikaverin (PubMed:19400779). FAD-dependent monooxygenase bik2 might then be responsible for the oxidation of pre-bikaverin to oxo-pre-bikaverin which is in turn methylated by the O-methyltransferase bik3 to me-oxo-pre-bikaverin (PubMed:26382642). A further cycle of oxydation and methylation by bik2 and bik3 leads to the final product of bikaverin, via a nor-bikaverin intermediate (PubMed:19400779, PubMed:26382642). Secondary metabolite biosynthesis. Expression is repressed by glutamine and at alkaline ambient pH and highly induced under nitrogen starvation and acidic pH conditions (PubMed:19400779). Impairs the production of bikaverin (PubMed:19400779). Leads to the accumulation of the intermediate oxo-pre-bikaverin (PubMed:26382642). Belongs to the class I-like SAM-binding methyltransferase superfamily. Cation-independent O-methyltransferase family. COMT subfamily.