Mineralization of dimethylsilanediol by microorganisms isolated from soil

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 dimethylsilaned iol were isolated and identified. In this paper, the extent of [C-14]dimeth ylsilanediol biodegradation by these two soil microorganisms, Fusarium oxys porum Schlechtendahl and an Arthrobacter species, is investigated. The sili con-containing products of dimethylsilanediol biodegradation in liquid cult ure were identified by high-performance liquid chromatography coupled to ar gon plasma emission spectrometry (HPLC-ICP). The biodegradation of [C-14]me thylsilanetriol was investigated in liquid cultures and in soil by monitori ng the production of (CO2)-C-14. The sorption coefficient of [C-14]methylsi lanetriol was determined, and the sorption coefficient of [C-14]dimethylsil anediol was estimated, by measuring the amount of C-14 counts in the water phase of a water-soil mixture. Methylsilanetriol was found to be mineralize d in liquid cultures of F. oxysporum Schlecht. and the Arthrobacter sp. tha t were supplied with a primary carbon source. However, the production of (C O2)-C-14 from [C-14]methylsilanetriol in soil experiments never exceeded th e level of possible [C-14]-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 polydim ethylsiloxane is hydrolyzed in soil to the monomer dimethylsilanediol, whic h is biodegraded in soil. Now mineralization of dimethylsilanediol to inorg anic silicate has been demonstrated.