Biodegradation of dimethylsilanediol in soils

Area of Science:

• Environmental Science
• Microbiology
• Biochemistry

Background:

• Polydimethylsiloxane (PDMS) hydrolysis in soil yields dimethylsilanediol.
• The environmental fate and biodegradation pathways of dimethylsilanediol are not fully understood.

Purpose of the Study:

• To investigate the biodegradation potential of [14C]dimethylsilanediol in various soil types.
• To identify microorganisms capable of degrading dimethylsilanediol and to develop methods for isolating them.
• To explore the use of primary substrates for enhancing dimethylsilanediol cometabolism.

Main Methods:

• Radiolabeling of dimethylsilanediol with Carbon-14 ([14C]) to track degradation.
• Incubation of [14C]dimethylsilanediol in diverse soil samples and monitoring 14CO2 evolution.
• Development of a method to select for primary substrates supporting cometabolism.
• Isolation and cultivation of microorganisms in liquid culture using selected substrates.
• Identification of isolated microbial species (fungus: Fusarium oxysporum, bacterium: Arthrobacter sp.).

Main Results:

• Dimethylsilanediol was biodegraded in all tested soils, evidenced by 14CO2 production.
• Addition of 2-propanol as a carbon source significantly increased 14CO2 production, indicating enhanced cometabolism.
• Fusarium oxysporum and an Arthrobacter species were isolated and confirmed to cometabolize dimethylsilanediol.
• The isolated Arthrobacter species demonstrated the ability to utilize dimethylsulfone as a primary carbon source, a novel finding.

Conclusions:

• Dimethylsilanediol is biodegradable in soil environments.
• Cometabolism, supported by suitable primary substrates, is an effective mechanism for dimethylsilanediol degradation.
• Specific microbial species, including Fusarium oxysporum and Arthrobacter sp., play a role in breaking down dimethylsilanediol.
• The discovery of a microorganism utilizing dimethylsulfone as a sole carbon source opens new avenues for bioremediation research.