Developing Kluyveromyces marxianus chassis strains for production of bio-based chemicals

Promovendus/a: Jolien Smets

Promotor(en): Prof. dr. ir. Kevin Verstrepen

Plastic is everywhere, but traditional plastics harm the environment. A promising alternative is PLA (polylactic acid), a bioplastic that’s strong, biodegradable, and has a smaller ecological footprint. PLA is made from lactic acid, which can be produced by microbes instead of petrochemicals. This biological route is more sustainable, but still expensive, because it needs costly raw materials and chemicals to keep the process stable. To make lactic acid production cheaper and greener, we need microbes that can handle tough industrial conditions. Today, most companies use baker’s yeast (Saccharomyces cerevisiae), but it’s not perfect for every process. My research explored a different yeast: Kluyveromyces marxianus. This yeast can tolerate heat, acidic environments, and use various sugars, ideal traits for industrial fermentation. I studied 168 strains of K. marxianus to find the best candidates, then genetically engineered 10 of them to produce lactic acid. The top performer was further evolved to withstand lactic acid stress, boosting production by 18% and reaching impressive yields in bioreactor tests. It even converted plant-based sugars efficiently, while needing fewer chemicals for pH control. Genome analysis revealed a key mutation that explained this improvement. This work shows how combining cutting-edge genetic tools with microbial diversity can create powerful “microbial factories”. These organisms could help us produce bioplastics and other green chemicals sustainably, paving the way for a cleaner future.