Growth rate and nutrient limitation affect the transport of Rhodococcus sp. strain DN22 through sand

Biodegradation. 2006 Dec;17(6):571-6. doi: 10.1007/s10532-005-9027-5. Epub 2006 Feb 14.

Abstract

Rhodococcus strain DN22 grows on the nitramine explosive RDX as a sole nitrogen source, and is potentially useful for bioremediation of explosives-contaminated soil. In order for strain DN22 to be effectively applied in situ, inoculum cells must reach zones of RDX contamination via passive transport, a process that is difficult to predict at field-scale. We examined the effect of growth conditions on the transport of DN22 cells through sand columns, using chemostat-grown cultures. Strain DN22 formed smaller coccoid cells at low dilution rate (0.02 h(-1)) and larger rods at high dilution rate (0.1 h(-1)). Under all nutrient limitation conditions studied, smaller cells grown at low dilution rate were retained more strongly by sand columns than larger cells grown at high dilution rate. At a dilution rate of 0.05, cells from nitrate-limited cultures were retained more strongly than cells from RDX-limited or succinate-limited cultures. Breakthrough concentrations (C/C (0)) from sand columns ranged from 0.04 (nitrate-limited, D=0.02 h(-1)) to 0.98 (succinate-limited, D=0.1 h(-1)). The observed strong effect of culture conditions on transport of DN22 cells emphasizes the importance of physiology studies in guiding the development of bioremediation technologies.

MeSH terms

  • Biodegradation, Environmental*
  • Biological Transport
  • Explosive Agents / metabolism*
  • Hydrophobic and Hydrophilic Interactions
  • Nitrates / metabolism
  • Rhodococcus / cytology
  • Rhodococcus / growth & development*
  • Rhodococcus / physiology*
  • Silicon Dioxide*
  • Soil Pollutants / metabolism*
  • Succinates / metabolism
  • Triazines / metabolism*

Substances

  • Explosive Agents
  • Nitrates
  • Soil Pollutants
  • Succinates
  • Triazines
  • Silicon Dioxide
  • cyclonite