, Volume 19, Issue 6, pp 807–813 | Cite as

Microbial degradation of 7-ketocholesterol

  • Jacques Mathieu
  • John Schloendorn
  • Bruce E. Rittmann
  • Pedro J. J. AlvarezEmail author
Original Paper


7-Ketocholesterol (7KC) is an oxidized derivative of cholesterol suspected to be involved in the pathogenesis of atherosclerosis and possibly Alzheimer’s disease. While some oxysterols are important biological mediators, 7KC is generally cytotoxic and interferes with cellular homeostasis. Despite recent interest in preventing the accumulation of 7KC in a variety of matrices to avoid adverse biological effects, its microbial degradation has not been previously addressed in the peer-reviewed literature. Thus, the rate and extent of biodegradation of this oxysterol was investigated to bridge this gap. A wide variety of bacteria isolated from soil or activated sludge, including Proteobacterium Y-134, Sphingomonas sp. JEM-1, Nocardia nova, Rhodococcus sp. RHA1, and Pseduomonas aeruginosa, utilized 7KC as a sole carbon and energy source, resulting in its mineralization. Nocardia nova, which is known to produce biosurfactants, was the fastest degrader. This study supports the notion that microbial catabolic enzymes could be exploited to control 7KC levels in potential biotechnological applications for agricultural, environmental, or medical use.


7-Ketocholesterol Oxysterol Phytosterol 5-Cholesten-3β-ol-7-one 3β-Hydroxy-5-cholesten-7-one 7-Oxocholesterol 



Funding for this work has been provided by the Methuselah Foundation (Lorton, VA). We also greatly appreciate the help of Dr. William Mohn (University of British Columbia) for providing Rhodococcus sp. RHA1 and valuable advice.


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Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • Jacques Mathieu
    • 1
  • John Schloendorn
    • 2
  • Bruce E. Rittmann
    • 2
  • Pedro J. J. Alvarez
    • 1
    Email author
  1. 1.Department of Civil and Environmental EngineeringRice UniversityHoustonUSA
  2. 2.Department of Civil and Environmental EngineeringArizona State UniversityTempeUSA

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