(138d) Identification and Functional Analysis of ?-Carotene Ketolase (BKT) Variants for Enhanced Astaxanthin Biosynthesis in Haematococcus

Astaxanthin is a valuable carotenoid with a range of applications in the food, pharmaceutical, and cosmetic industries due to its potent antioxidant properties. While it is naturally produced by certain microorganisms and flowering plants, slow growth rates and difficulties in extraction limit their utility. Therefore, there is demand for more efficient production methods. The green alga Haematococcus accumulates large amounts of astaxanthin in its immobile (akinete) stage. The biosynthesis of astaxanthin in Haematococcus is comprised of at least seven enzymatic steps with the β-carotene ketolase (bkt) enzyme . Recent genome sequencing of Haematococcus pluvialis has uncovered up to six distinct copies of the bkt gene in the nuclear genome. It is hypothesized that these variant copies may have unique functional roles in astaxanthin production. In our preliminary analyses of various isolates of Haematococcus, have revealed up to a ten-fold variation in astaxanthin accumulation among the isolates. We selected six of these isolates and cloned the bkt variants within each to determine if and how they contribute to variation in astaxanthin production. We plan to assay bkt activity in E. coli through co-expressed with a heterologous zeaxanthin biosynthesis pathway and measurement of the resulting astaxanthin products. Our study offers an opportunity to identify specific bkt variants with the enhanced catalytic activity and facilitate the development of more efficient strategies for industrial-scale production of this high-value pigment.