Simultaneous Production of Cellulase and β-Carotene in the Filamentous Fungus <i>Trichoderma reesei</i>

Abstract

β-Carotene is an indispensable additive in beverage, cosmetic, feed, and pharmaceutical production. The fermentation industry annually generates abundant waste mycelia from <i>Trichoderma reesei (T. reesei)</i>, a pivotal industrial strain for cellulase and heterologous protein production. In this study, we constructed a <i>T. reesei</i> cell factory for β-carotene production for the first time. Four key enzymes, CarRP, CarB, GGS1/CrtE, and HMG1, were overexpressed in <i>T. reesei</i>. The concentrations of medium components, including tryptone and glucose, were optimized. The modified strain accumulated β-carotene at a titer of 218.8 mg/L in flask culture. We achieved cellulase production (FPase, 22.33 IU/mL) with the concomitant production of β-carotene (286.63 mg/L) from <i>T. reesei</i> in a jar. Overall, this study offers a novel and unique approach to address the costly waste mycelium management process using <i>T. reesei</i> industrial strains that simultaneously produce proteins and carotenoids.