A novel, nature-based alternative for photobioreactor decontaminations

Area of Science:

• Biotechnology
• Microbiology
• Environmental Science

Background:

• Large-scale microalgae cultivation is vital for producing animal feed, supplements, and bioproducts.
• Contamination by other microorganisms is a frequent challenge in industrial photobioreactors, impacting yield and purity.

Purpose of the Study:

• To investigate the efficacy of 5-isobutyl-2,3-dimethylpyrazine as a novel agent for removing contaminating microalgae from industrial photobioreactors.
• To assess the susceptibility of common microalgae genera found in contaminated bioreactors to this pyrazine compound.

Main Methods:

• Reactor samples from a multi-stage cultivation process were analyzed using 18S rRNA gene sequencing to identify dominant microalgae genera.
• Representative isolates of Haematococcus, Chlorella, and Scenedesmus were cultured.
• Susceptibility tests were performed using varying concentrations of 5-isobutyl-2,3-dimethylpyrazine, including vaporized forms.

Main Results:

• Haematococcus, Chlorella, and Scenedesmus were identified as the most frequent microalgae contaminants.
• All tested microalgae isolates demonstrated high susceptibility to 5-isobutyl-2,3-dimethylpyrazine.
• Scenedesmus vacuolatus exhibited the highest tolerance, requiring 1.66% (v/v) of the compound for deactivation. Vaporized pyrazine also reduced microalgae viability.

Conclusions:

• 5-isobutyl-2,3-dimethylpyrazine is a promising, nature-based solution for controlling microalgae contamination in industrial photobioreactors.
• This compound offers a potential alternative to existing methods for maintaining culture purity in large-scale microalgae production.