Grease trap waste, a renewable resource for biosynthesis of long-chain dicarboxylic acids using Candida tropicalis ATCC 20962.

Long-chain dicarboxylic acids (LCDAs) are valuable chemicals with a variety of industrial applications. However, since they are typically fossil-derived, there is a need for renewable feedstocks. This study investigated grease trap waste (GTW), an underutilised waste stream, for LCDA production using Candida tropicalis. Several experiments optimised glucose and GTW feed rates and pH, resulting in a final titre of 34.7 g/L LCDAs with a productivity of 0.42 g/(L·h) and a yield of 76 % after 140 h. Optimal conditions included a glucose feed rate of 0.38 g/(L·h), as lower feed rates resulted in glucose deficiency, while higher glucose feed rates promoted excessive growth. The optimal GTW feed rate was 0.5 g/(L·h), as higher rates had inhibitory effects on yeast growth and LCDA production. However, maintaining a pH of 7 was essential to limit foaming, deviating from typical alkaline conditions. This work demonstrated GTW's potential for sustainable LCDA biosynthesis, supporting circular bioeconomy goals.