Thraustochytrid protists degrade hydrocarbons

Although thraustochytrid protists are known to be of widespread occurrence in the sea, their hydrocarbon-degrading abilities have never been investiga ted. We isolated thraustochytrids from coastal waters and sediments of Goa coast by enriching MPN isolation tubes with crude oil. Three isolates teste d showed positive hydrophobicity of cell walls as judged by the Microbial A dhesion to Hydrocarbons (MATH) assay. Addition of Bombay High crude oil to nutrient broth slightly enhanced growth of the protists as compared to unen riched controls. Autoclaved crude oil added to sediments was degraded by 2 thraustochytrids to a much greater extent than non-autoclaved oil. Tarballs supported excellent growth of thraustochytrids when added to a peptone bro th. Inoculation of thraustochytrids to tarball-enriched sediment resulted i n a decrease of up to 71% of tarball contents after a month. Up to 30% of t arballs added to peptone broth was degraded by thraustochytrids in 7 days, as estimated by gravimetry and gas chromatography. Fractions above the rete ntion time for 20 degreesC aliphatics were degraded to a much greater degre e than those below 20 degreesC. Thraustochytrids appear to play a definite role in tar ball degradation in sediments.