Application of Multiple Strategies to Improve the Production of the Potential Cancer Drug 4-Acetylantroquinonol B (4-AAQB) by the Rare Fungus Antrodia cinnamomea

4-Acetylantroquinonol B (4-AAQB) was identified in the rare fungus Antrodia cinnamomea and has been proven to be a potential therapeutic agent for cancer treatment. But the extraction of 4-AAQB from the fruit body led to a low yield and limited its further application in the pharmaceutical field. In this work, 4-AAQB production was enhanced in the submerged fermentation by the combination of exogenous additives, surfactants with the in situ extractive fermentation. 4-Methylbenzoic acid was proven to be an efficient additive for the accumulation of 4-AAQB by Antrodia cinnamomea, while 2% (w/v) Tween-80 added on the first day as surfactant and 30% (w/v) oleic acid added on the sixteenth day as extractant were the most available couples for 4-AAQB production in the in situ extractive fermentation. The combination of these multiple strategies resulted in the yield of 4-AAQB to 17.27 mg/g dry cell weight with a titer of 140 mg/L, which was the highest titer of 4-AAQB reported so far. It showed that the combination of these strategies had a significant promotion on 4-AAQB production by A. cinnamomea, which laid a good foundation for its large-scale production and also provided a viable method for the cultivation of other rare fungi.