Polyketide synthase; part of the gene cluster that mediates the biosynthesis of bikaverin, a red pigment also considered as a mycotoxin (PubMed:12409099, PubMed:17696354, 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:12409099, PubMed:17696354, 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 during the growth phase, but is induced as the growth rate decreases due to nitrogen depletion of the culture medium (PubMed:12409099). Highly expressed only under acidic culture conditions (PubMed:12409099, PubMed:19400779). Also induced by salt starvation (PubMed:19838698). Expression is repressed by regulatory gene, areA, a transcriptional regulator responsible for the activation of nitrogen assimilation genes (PubMed:12409099). Expression is also negatively regulated by vel1 (PubMed:20572938). Multidomain protein; including a starter unit:ACP transacylase (SAT) that selects the starter unit; a ketosynthase (KS) that catalyzes repeated decarboxylative condensation to elongate the polyketide back- bone; a malonyl-CoA:ACP transacylase (MAT) that selects and transfers the extender unit malonyl-CoA; a product template (PT) domain that controls the immediate cyclization regioselectivity of the reactive polyketide backbone; and an acyl-carrier protein (ACP) that serves as the tether of the growing and completed polyketide via its phosphopantetheinyl arm (By similarity). Impairs the production of bikaverin and its intermediate oxo-pre-bikaverin (PubMed:12409099, PubMed:19400779, PubMed:26382642).