P.J. Alvarez, J.M. Mathieu

Medical bioremediation is the proposed approach of augmenting human catabolic machinery with microbial enzymes in order to prevent the accumulation of deleterious intracellular substances associated with increasing age. It has been hypothesized that one of the substances of interest, 7-ketocholesterol (7KC), could at least be partially responsible for the progression of atherosclerosis. Although only found in small quantities in atherosclerotic lesions, oxidized sterols nevertheless have potent biological effects that are only partly understood at this time. 7KC is the major form of oxidized sterol, or oxysterol, present in LDL, and is thus a primary target for medical bioremediation. Here we report the isolation and characterization of numerous bacteria found to degrade 7KC and also give the results of a microarray study performed with one of those species, Rhodococcus sp. RHA1. Species were isolated through the use of enrichment cultures created from either activated sludge or soil samples, and degradation was confirmed through high performance liquid chromatography (HPLC). The absence of detectable byproducts in our HPLC analysis, and also CO2 accumulation as measured through respirometry, demonstrate mineralization of 7KC. From the 7KC degrading cultures, Pseudomonas aeruginosa, Aeromonas sp., Nocardia nova, gamma-Proteobacteria Y-134, and Sphingomonas sp. JEM-1 have all been identified through phylogenetic analysis using 16S rDNA.

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medical bioremediation