Simplifying Production of Immobilized D-Allulose 3-Epimerase via Pichia pastoris Secretion: A New Approach

You don’t need a purification column to get a working immobilized allulose enzyme. A team used Pichia pastoris to secrete D-allulose 3-epimerase (DPEase) directly into the culture medium. That move combines purification and immobilization into one step. The work appears in Microbial Cell Factories (DOI: 10.1186/s12934-025-02763-4).

The enzyme bottleneck

DPEase converts D-fructose into D-allulose. It is the biocatalyst behind most allulose production. But enzyme costs can eat into margins. Free enzyme gets used once and thrown away. Immobilized enzyme can be reused, and that changes the economics.

Traditional immobilization usually starts with purified enzyme. You produce cells, break them open, purify the protein, and only then attach it to a support. Each step adds time and cost. This study cuts through that workflow.

What the study did

The researchers expressed recombinant DPEase in Pichia pastoris. Because the enzyme is secreted, it ends up outside the cells. That means no cell lysis and no complex protein cleanup. The culture broth itself becomes the enzyme source for immobilization.

One step gives you a reusable, solid-supported catalyst. That is a direct simplification of enzyme manufacturing.

Key findings

The data show a stable enzyme with real process potential.

Parameter	Finding
Expression host	Pichia pastoris, secreted
Purification and immobilization	One step
Reuse	5 cycles, retained 83.38% relative activity
pH stability	>80% relative activity from pH 5.0 to 11.0
Temperature stability	>80% relative activity from 35 to 70 °C
Optimal conditions	pH 6.0, 60 °C
Maximum conversion	17.03% from 10% D-fructose

The reuse number stands out. Five cycles with 83.38% relative activity means the enzyme can drive multiple batches before replacement. Broad stability across pH and temperature gives you process flexibility. You can operate near pH 6.0 at 60 °C without losing most of the activity. That opens the door for faster reaction rates and simpler syrup handling.

The 17.03% conversion came from a 10% fructose feed. That is a practical substrate concentration, not a dilute lab condition.

What it means for manufacturers

For ingredient buyers, the main effect is cost. Fewer purification steps usually mean lower capital expense and shorter production times. For formulators, the stability profile is the selling point. A DPEase that tolerates pH 5.0–11.0 and 35–70 °C will survive real-world variability in fructose syrups.

Reusability matters even more. If an enzyme can be reused five times with minimal loss, the enzyme cost per kilogram of allulose drops sharply. That helps make allulose more competitive as a bulk sweetener.

This is not a full-scale commercial rollout. The study does not report pilot reactor data. Scale-up work remains the next step. But the direction is obvious: make the enzyme cheaper and easier to produce, and the allulose supply chain gets simpler.

FAQ

Why Pichia pastoris for DPEase?

Pichia pastoris secretes recombinant proteins into the growth medium. That avoids cell disruption and gives a cleaner starting stream for direct immobilization.

Is 17.03% conversion enough?

The study used 10% D-fructose and reached a maximum conversion of 17.03%. Exact yield depends on enzyme loading, reaction time, and equilibrium. The value proves the enzyme works at a realistic substrate concentration.

Can I adopt this process now?

Not immediately. The evidence is bench-scale. You would need pilot testing with your chosen immobilization support and reactor type before production.

Enzyme manufacturing often fails on complexity. This secretion-based method removes complexity directly. Expect more allulose producers to look toward Pichia pastoris as a workhorse for DPEase. The next generation of allulose may come from a broth, not a purification suite.