Process-integrated nanozyme-assisted bioconversion and fermentation of agar-rich red macroalgae to...

Area of Science:

• Marine biotechnology
• Biopolymer production
• Microbial engineering

Background:

• Red macroalgae like Gelidium amansii are a sustainable source for biopolymers.
• Challenges include slow polysaccharide hydrolysis and microbial sugar uptake mismatches.
• Nanozymes offer potential but their integration with microbial processes is unclear.

Purpose of the Study:

• To develop a nanozyme-assisted bioconversion strategy for direct polyhydroxyalkanoate (PHA) production from G. amansii.
• To investigate the role of nanozymes in modulating biomass hydrolysis and sugar release.
• To optimize PHA production using controlled feeding strategies.

Main Methods:

• Utilized redox-active CeFe3O4 nanozymes to influence early-stage sugar release from G. amansii.
• Implemented pulse-feeding strategies to regulate carbon availability during fermentation.
• Systematically evaluated effects of biomass loading, nanozyme concentration, and feeding regime on PHA production at flask and stirred-tank scales.

Main Results:

• Moderate nanozyme concentrations increased transient soluble sugar levels but not necessarily PHA production.
• Pulse-feeding stabilized sugar availability and more than doubled maximum PHA productivity compared to single-pulse feeding.
• PHA productivity correlated with temporal coordination between substrate release and microbial metabolic capacity.

Conclusions:

• Nanozyme-assisted hydrolysis modulation combined with controlled feeding enhances PHA production from red macroalgae.
• Temporal coordination, not just total carbon input, is key for efficient PHA bioconversion.
• This strategy offers a process-level improvement for producing PHA from marine biomass.