Microbial degradation of 7-ketocholesterol

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Jacques Mathieu1, John Schloendorn, Bruce E Rittmann

  • 1Department of Civil and Environmental Engineering, Rice University, Houston, TX, USA.

Biodegradation
|March 18, 2008
PubMed

Insights

Microbial degradation of 7-ketocholesterol (7KC), a cholesterol derivative linked to diseases, was investigated. Several soil bacteria, including Nocardia nova, efficiently mineralized 7KC, suggesting biotechnological applications.

Area of Science:

  • Microbiology
  • Biochemistry
  • Environmental Science

Background:

  • 7-Ketocholesterol (7KC) is an oxidized cholesterol derivative implicated in atherosclerosis and Alzheimer's disease pathogenesis.
  • While some oxysterols are bioactive, 7KC exhibits cytotoxicity and disrupts cellular homeostasis.
  • Preventing 7KC accumulation is of interest, but its microbial degradation remains uncharacterized.

Purpose of the Study:

  • To investigate the rate and extent of 7-ketocholesterol (7KC) biodegradation by microorganisms.
  • To identify bacterial species capable of utilizing 7KC as a sole carbon and energy source.
  • To explore potential biotechnological applications for microbial 7KC degradation.

Main Methods:

  • Screening of diverse bacterial isolates from soil and activated sludge for 7KC degradation.
  • Culturing bacteria with 7KC as the sole carbon and energy source.
  • Monitoring 7KC mineralization by identified bacterial strains.

Main Results:

  • Multiple bacterial strains, including Proteobacterium Y-134, Sphingomonas sp. JEM-1, Nocardia nova, Rhodococcus sp. RHA1, and Pseudomonas aeruginosa, effectively degraded 7KC.
  • These bacteria utilized 7KC as their sole source of carbon and energy, leading to its complete mineralization.
  • Nocardia nova demonstrated the highest degradation rate among the tested species.

Conclusions:

  • Microbial communities possess the capability to degrade 7-ketocholesterol (7KC).
  • Specific bacterial strains, notably Nocardia nova, can efficiently mineralize 7KC.
  • Microbial catabolic enzymes offer potential for biotechnological control of 7KC levels in various applications.

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