A hybrid approach utilising adaptive laboratory evolution and gene expression analysis: How adaptive evolution...

Area of Science:

• Environmental Science
• Microbiology
• Biotechnology

Background:

• Polycyclic aromatic hydrocarbons (PAHs) are persistent environmental contaminants with significant ecological and health risks.
• Microbial biodegradation is a sustainable remediation strategy, but its effectiveness is limited by environmental stressors like salinity, temperature, and pH.
• Enhancing microbial stress tolerance and functional performance is crucial for effective bioremediation.

Purpose of the Study:

• To develop an integrated approach using adaptive laboratory evolution (ALE), transcriptomic analysis, and bioreactor validation to enhance microbial degradation of PAHs.
• To improve the stress tolerance and degradation efficiency of bacterial strains under challenging environmental conditions.
• To investigate the synergistic interactions and metabolic pathways involved in enhanced PAH degradation by an evolved microbial consortium.

Main Methods:

• Adaptive Laboratory Evolution (ALE) was employed on three bacterial strains (Pseudomonas stutzeri MP6, Stutzerimonas stutzeri MP15, and Stutzerimonas frequens MP37) under progressively increasing temperature, salinity, and acidic pH.
• Transcriptomic analysis was performed to identify changes in gene expression related to PAH metabolism and stress response.
• Bioreactor validation was conducted in a soil-slurry system to assess the degradation efficiency of the evolved microbial consortium under simulated environmental conditions.

Main Results:

• The evolved microbial consortium exhibited improved polycyclic aromatic hydrocarbon (PAH) degradation efficiency compared to individual strains, indicating synergistic interactions.
• Transcriptomic analysis revealed increased expression of genes involved in aromatic compound metabolism, including oxygenases and ring-cleavage enzymes.
• The evolved consortium achieved 85.65% PAH degradation within 90 days in a soil-slurry system under simulated environmental stress conditions.

Conclusions:

• Adaptive laboratory evolution (ALE) effectively enhances microbial resilience and functional performance for polycyclic aromatic hydrocarbon (PAH) bioremediation.
• The integrated approach of ALE, transcriptomics, and bioreactor validation provides a robust strategy for developing enhanced microbial consortia.
• This study supports the potential application of ALE-driven adapted microbial communities for sustainable and efficient bioremediation of contaminated environments.