Non-reducing polyketide synthase; part of the gene cluster that mediates the biosynthesis of the tropolone class of fungal maleic anhydrides (PubMed:22508998, PubMed:24863423). The pathway begins with the synthesis of 3-methylorcinaldehyde by the non-reducing polyketide synthase (PKS) tropA (PubMed:22508998). 3-methylorcinaldehyde is the substrate for the FAD-dependent monooxygenase tropB to yield a dearomatized hydroxycyclohexadione (PubMed:22508998, PubMed:24863423). The 2-oxoglutarate-dependent dioxygenase tropC then performs the oxidative ring expansion to provide the first tropolone metabolite stipitaldehyde (PubMed:22508998, PubMed:24863423). Trop D converts stipitaldehyde into stipitacetal which is in turn converted to stipitalide by the short-chain dehydrogenase/reductase tropE (PubMed:24863423). The next steps involve tropF, tropG, tropH, tropI and tropJ to form successive tropolone maleic anhydrides including stipitaldehydic, stipitatonic and stipitatic acids (PubMed:24863423). Secondary metabolite biosynthesis. 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 backbone; 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. The release of the polyketide chain from the non-reducing polyketide synthase is mediated by the thioesterase (TE) domain localized at the C-ter of the protein. Impairs the production of tropolones (PubMed:22508998).