A Pathway for Isethionate Dissimilation in Bacillus krulwichiae

Area of Science:

• Microbiology
• Environmental Science
• Biochemistry

Background:

• Hydroxyethyl sulfonate (isethionate) is a widespread environmental compound from industrial and biotic sources.
• Known aerobic isethionate dissimilation pathways were limited to Gram-negative bacteria, involving membrane-bound enzymes.

Purpose of the Study:

• To investigate alternative isethionate dissimilation pathways in Gram-positive bacteria.
• To characterize the novel pathway and its key enzymes.

Main Methods:

• Bioinformatic analysis of gene clusters in Gram-positive bacteria.
• Biochemical characterization of recombinant IseD enzyme.
• Demonstration of bacterial growth using isethionate as a sole carbon source.

Main Results:

• A novel aerobic pathway for isethionate dissimilation in Gram-positive bacteria was identified.
• This pathway utilizes a cytosolic, NAD+-dependent alcohol dehydrogenase (IseD) for isethionate oxidation.
• Bacillus krulwichiae demonstrated growth on isethionate, excreting sulfite.

Conclusions:

• The IseD-dependent pathway is the first described mechanism for isethionate dissimilation in Gram-positive bacteria.
• This finding highlights metabolic diversity in organosulfonate degradation.
• The pathway likely contributes to organosulfur mineralization and the environmental sulfur cycle.