Elucidating styrene tolerance mechanisms in Gluconobacter oxydans through adaptive laboratory evolution

Area of Science:

• Microbiology
• Environmental Biotechnology
• Bioremediation

Background:

• Styrene biodegradation by Gluconobacter oxydans (G. oxydans) is limited by styrene's toxicity.
• Wastewater containing styrene poses environmental challenges requiring effective treatment solutions.

Purpose of the Study:

• To develop G. oxydans mutants with enhanced tolerance to styrene.
• To elucidate the mechanisms underlying styrene tolerance in G. oxydans.

Main Methods:

• Evolution experiments were conducted at low styrene concentrations.
• Physiological and biochemical analyses were performed.
• Genetic analysis focused on mutations in flagellar protein FlgE and transcription factors MarR and HipB.

Main Results:

• Styrene negatively impacts G. oxydans cell growth, membrane function, and motility.
• Phenotypic heterogeneity and enhanced biofilm formation contribute to styrene tolerance.
• Mutations in FlgE affect motility and biofilm formation.
• Transcription factors MarR and HipB positively regulate styrene tolerance, with MarR being more critical.
• Mutants demonstrated tolerance up to 22 g·L⁻¹ styrene.

Conclusions:

• G. oxydans can be evolved for enhanced styrene tolerance.
• Mechanisms involve improved biofilm formation, altered motility, and regulation by MarR and HipB.
• These findings provide insights for applying G. oxydans in styrene-laden wastewater treatment.