Phenol degradation by halophilic bacteria isolated from hypersaline environments

Area of Science:

• Environmental Microbiology
• Biotechnology
• Bioremediation

Background:

• Phenol is a toxic industrial pollutant frequently found in hypersaline wastewater.
• Dilution of hypersaline wastewater is often required for effective biotreatment, increasing costs and complexity.
• Halophilic microorganisms offer a potential solution for treating phenol in undiluted, high-salt environments.

Purpose of the Study:

• To investigate the ability of halophilic bacteria to degrade phenol in hypersaline media.
• To identify genes encoding key enzymes involved in phenol degradation in these bacteria.
• To analyze the genetic and protein sequence of a key enzyme from a selected strain.

Main Methods:

• Isolation and identification of three halophilic bacterial strains (Halomonas organivorans, Arhodomonas aquaeolei, Modicisalibacter tunisiensis).
• Cultivation of strains in hypersaline media (100 g/L salts) with phenol (3 mM).
• PCR amplification to detect genes for catechol 1,2 dioxygenase and protocatechuate 3,4-dioxygenase.
• Gene cloning and comparative protein sequence analysis of protocatechuate 3,4-dioxygenase from H. organivorans.

Main Results:

• All three isolated halophilic bacteria demonstrated growth on phenol in 100 g/L salt media.
• Genes for catechol 1,2 dioxygenase and protocatechuate 3,4-dioxygenase were detected in all strains.
• The protocatechuate 3,4-dioxygenase from H. organivorans showed conserved amino acid structures compared to other microbial enzymes.

Conclusions:

• Halophilic bacteria, including H. organivorans, A. aquaeolei, and M. tunisiensis, are capable of degrading phenol under hypersaline conditions.
• The presence of specific aromatic dioxygenase genes supports their role in phenol bioremediation.
• The conserved protein structure of protocatechuate 3,4-dioxygenase in H. organivorans suggests its functional significance in phenol metabolism.