Efficient Production of the Recombinant Human Lactoferrin in an Engineered <i>Trichoderma reesei</i>

Recombinant human lactoferrin (rhLF) was efficiently produced in <i>Trichoderma reesei</i> (<i>T. reesei</i>). An efficient and cost-effective Indirect ELISA was developed for detection. Using microcrystalline cellulose, the rhLF titer reached 184.76 mg/L. Overexpressing <i>pdi1</i> increased rhLF titer 1.25-fold, and deleting <i>pea1</i> enhanced it 1.30-fold. Combining these modifications in <i>T. reesei</i> CJ2095 Δ<i>pea1</i>::<i>pdi1</i> achieved 306.31 mg/L. Further optimization with 1% bran and 1.5 g/L Tween-80 boosted the titer to 368.47 mg/L. Scaling up to a 5 L fermenter yielded 1349.5 mg/L, a 1.93 × 10⁴-fold improvement over initial levels. The purified rhLF exhibited a secondary structure and antibacterial activity comparable to those of commercial rice-expressed lactoferrin. To our knowledge, this is the first report demonstrating the efficient production of rhLF using <i>T. reesei</i> as an expression host. This study highlights the potential of <i>T. reesei</i> as a robust platform for the industrial-scale production of human lactoferrin.