Microbial production of the building block p-Coumaric Acid: unleashing the potential of Kluyveromyces marxianus

Abstract

The interest in several plant secondary metabolites, such as naringenin or resveratrol, for their known biological functions, is growing at a fast pace. These properties encompass antioxidant, antiinflammatory, and anti-microbial, among many other activities. The phenolic acid p-coumaric acid is naturally produced by plants, being a key precursor of many of these secondary metabolites. Nevertheless, p-coumaric acid is currently extracted from plants, which poses several drawbacks for its industrial production including low efficiency and dependence on plant availability. On the other hand, microbial production of p-coumaric acid has been emerging as a sustainable and economically viable alternative. The unconventional yeast Kluyveromyces marxianus is garnering increasing interest as an alternative cell platform to produce ethanol and high-value compounds with a span of applications across industries [1]. This is due to its distinctive attributes, such as rapid growth rate, thermotolerance, and the capacity to metabolize different sugars [2]. Due to its Crabtree-negative metabolism, this yeast produces acetyl-coenzyme A in the presence of oxygen and high sugar concentration. As such, it could be an interesting chassis to produce aromatic compounds derived from p-coumaric since some of them require malonyl-CoA (derived from acetyl-CoA) as a precursor. For that, in yeast, the expression of heterologous enzymes involved in the conversion of aromatic amino acids into p-coumaric acid is required. Building upon this knowledge, here, two K. marxianus strains were engineered and screened for their capacity for p-coumaric acid production. Initially, a heterologous enzyme, tyrosine ammonia lyase (TAL), which converts tyrosine to p-coumaric acid, was integrated into both strains. Further, the effects of different carbon sources and agitation conditions on p-coumaric acid production and yeast primary metabolism were evaluated. Overall, this work shows the potential of K. marxianus for p-coumaric acid production and its derivatives through an integrated process.