Mineralization of Dimethylsilanediol by Microorganisms Isolated From Soil

Abstract

Previous studies have shown that polydimethylsiloxane is hydrolyzed in soil to dimethylsilanediol and that dimethylsilanediol is biodegraded in soil. Previously, two soil microorganisms capable of biodegrading dimethylsilanediol were isolated and identified. In this paper, the extent of [ 14 C]dimethylsilanediol biodegradation by these two soil microorganisms, Fusarium oxysporum Schlechtendahl and an Arthrobacter species, is investigated. The silicon-containing products of dimethylsilanediol biodegradation in liquid culture were identified by high-performance liquid chromatography coupled to argon plasma emission spectrometry (HPLC-ICP). The biodegradation of [ 14 C]methylsilanetriol was investigated in liquid cultures and in soil by monitoring the production of 14 CO 2 . The sorption coefficient of [ 14 C]methylsilanetriol was determined, and the sorption coefficient of [ 14 C]dimethylsilanediol was estimated, by measuring the amount of 14 C counts in the water phase of a water-soil mixture. Methylsilanetriol was found to be mineralized in liquid cultures of F. oxysporum Schlecht. and the Arthrobacter sp. that were supplied with a primary carbon source. However, the production of 14 CO 2 from [ 14 C]methylsilanetriol in soil experiments never exceeded the level of possible [ 14 C]-containing impurities in the methylsilanetriol. Methylsilanetriol was found to be more strongly sorbed to soil, which might have reduced its bioavailability. Previous evidence has shown that polydimethylsiloxane is hydrolyzed in soil to the monomer dimethylsilanediol, which is biodegraded in soil. Now mineralization of dimethylsilanediol to inorganic silicate has been demonstrated.