Common Plant Compound Supercharges Fungal Enzyme Factory in Surprising Trade-Off

A humble molecule found in countless plants has been shown to dramatically boost the output of one of industry’s most versatile fungal enzymes, and researchers have now traced exactly how the trick works. In a study published in Biotechnology for Biofuels and Bioproducts, a team at Inner Mongolia University reports that adding a precisely calibrated dose of p-coumaric acid to submerged cultures of the white-rot fungus Funalia trogii raised extracellular laccase activity to a maximum of 9.82 units per milliliter, without suppressing the accumulation of fungal biomass. That last detail matters enormously for biotechnology, because many inducers that push enzyme yields do so at the cost of starving the producing organism, forcing engineers to choose between more cells or more enzyme. Here, the fungus appears to have both.

Laccases are multicopper oxidases that catalyze the one-electron oxidation of a remarkably broad range of substrates, typically phenolic compounds and aromatic amines, while reducing oxygen to water. That chemistry has made them prized for applications ranging from delignifying lignocellulosic biomass for biofuels, to detoxifying industrial effluents, to degrading synthetic dyes, pharmaceuticals, and even certain persistent organic pollutants. White-rot fungi such as F. trogii are among nature’s most prolific laccase producers, since their ecological role involves dismantling the lignin polymer that gives wood its rigidity. The challenge for industry has always been yield: wild-type fermentation titers are rarely economical, and boosting them usually requires either genetic engineering, which carries regulatory and stability burdens, or empirical feeding of inducers whose mechanisms remain poorly understood.

The Inner Mongolia team, led by Chao Lv and Peiyao Wang as co-first authors, with Dejian Zhang, Wei Wang, Huiting Xue, and Guanhua Li rounding out the group, focused on p-coumaric acid, or pCA, a hydroxycinnamic acid that is abundant in plant cell walls and released during the degradation of lignocellulose. From the fungus’s perspective, pCA is a meaningful ecological signal: it is a phenolic compound that white-rot organisms routinely encounter as they colonize wood and leaf litter. The researchers systematically screened inducer candidates and found that supplementing the culture medium with 0.026 percent weight per volume of pCA delivered the strongest response, pushing extracellular laccase activity to that 9.82 U/mL peak while leaving biomass accumulation intact.

To understand what was happening inside the cells, the team turned to comparative RNA sequencing, profiling the transcriptomes of induced and control cultures with four biological replicates per treatment. The sequencing data passed rigorous quality control, with high proportions of clean reads, strong Q20 and Q30 base-quality scores, and low error rates across all eight libraries. Principal component analysis showed clean separation between the induced and control expression profiles, confirming that pCA produced a coherent, reproducible transcriptional shift rather than random noise. The scale of the response, however, was strikingly selective, and that selectivity turned out to be the study’s central discovery.

Among the differentially expressed genes, exactly two laccase-encoding transcripts stood out: Cluster-205.3418 and Cluster-205.4519. These were selectively upregulated in the pCA-treated cultures, while a third laccase-associated gene, Cluster-205.2285, showed no significant differential expression between the groups. In other words, pCA did not simply crank up every laccase gene in the genome; it acted as a specific transcriptional activator of a particular pair of transcripts. This specificity suggests that the fungus possesses a targeted regulatory circuit responsive to hydroxycinnamic acid signals, one that channels resources into the enzyme isoforms most relevant to oxidizing phenolic compounds in the environment rather than into a blanket upregulation of all secreted oxidases.

The transcriptomic rewiring extended well beyond the laccase genes themselves. The RNA-seq analysis revealed repression of DNA replication and cell-cycle pathways, indicating that induced cells were throttling back on proliferation. At the same time, the data showed altered expression in genes associated with cytochrome P450 metabolism, ABC transporter activity, and a suite of redox-related processes. Cytochrome P450 enzymes and ABC transporters are classic components of microbial detoxification machinery: P450s chemically modify xenobiotic compounds, while ABC transporters pump them out of the cell. Their involvement paints a picture of a fungus that has detected a phenolic challenge in its surroundings and is mobilizing both its oxidative arsenal and its export machinery to cope with it.

Biochemical measurements corroborated the transcriptional story. The team observed transient increases in the intracellular activities of catalase and superoxide dismutase, two enzymes that jointly neutralize reactive oxygen species by converting superoxide radicals into hydrogen peroxide and then into water and oxygen. These spikes were confined to the early induction phase, indicating a moderate oxidative-stress response rather than a sustained crisis. The interpretation is elegant: pCA, being a phenolic compound susceptible to oxidation, likely triggers a burst of reactive oxygen chemistry at the cell surface, and the fungus responds by both reinforcing its antioxidant defenses and ramping up laccase secretion, the very enzyme that can oxidize and thereby disarm the offending molecule.

Taken together, the results support what the authors describe as a dual-action mechanism. On one hand, pCA functions as a specific transcriptional activator, directly switching on the two laccase genes that matter most for the fungus’s oxidative repertoire. On the other hand, it elicits a broader stress-associated transcriptional reprogramming, consistent with a shift from growth-oriented programs toward defense and secretion. This is a textbook growth–defense trade-off, a concept well established in plant biology and increasingly recognized in fungi: an organism cannot simultaneously maximize proliferation and defense, so it reallocates resources when threat signals appear. In F. trogii, the trade-off manifests as suppressed cell-cycle activity paired with boosted enzyme production, and the practical consequence is that the fungus channels its metabolic budget into secreting laccase without actually producing fewer cells.

The implications for industrial biotechnology are considerable. Because the strategy relies on a cheap, plant-derived, food-safe aromatic acid rather than genetic modification, it could be integrated into existing fermentation processes with minimal regulatory friction. The identification of the two responsive laccase genes also gives strain engineers concrete targets: future work could overexpress Cluster-205.3418 and Cluster-205.4519, or edit their promoters to mimic the pCA response constitutively, potentially decoupling enzyme yield from inducer dosing altogether. Moreover, the finding that biomass was preserved suggests that the growth–defense trade-off here is finely balanced rather than severe, hinting that optimization of inducer timing and concentration could push titers further before the trade-off bites.

There are also deeper ecological questions worth asking. The specificity of the pCA response implies that F. trogii has evolved to read hydroxycinnamic acids as information about its environment, likely as a cue that lignocellulose is being broken down and that phenolic substrates are available. Understanding this signaling axis could illuminate how white-rot fungi coordinate lignin degradation in nature, and it may reveal additional inducer molecules that trigger complementary enzyme suites, including the peroxidases that work alongside laccases in complete ligninolysis. For now, the study stands as a satisfying piece of mechanistic biotechnology: a simple additive, a measurable yield gain, and a transcriptomic explanation that connects the two, all resting on the ancient negotiation between a fungus and the plants it decomposes.

Subject of Research: Enhancement of laccase production in the fungus Funalia trogii using p-coumaric acid as an inducer

Article Title: Enhanced laccase production from Funalia trogii by addition of p-coumaric acid via a specific mechanism of gene activation and a growth–defense trade-off

Article References: Enhanced laccase production from Funalia trogii by addition of p-coumaric acid via a specific mechanism of gene activation and a growth–defense trade-off. (n.d.). https://doi.org/10.1186/s13068-026-02828-5

Image Credits: AI Generated

DOI: 10.1186/s13068-026-02828-5

Keywords: laccase, Funalia trogii, p-coumaric acid, white-rot fungus, transcriptomics, RNA-seq, oxidative stress, growth-defense trade-off, submerged fermentation, lignin degradation, biocatalysis, industrial enzymes