Growth rate and nutrient limitation affect the transport of Rhodococcus sp. strain DN22 through sand.
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.
Priestley
James T
JT
School of Molecular and Microbial Biosciences, University of Sydney, Building G08, 2006, Maze Crescent, Australia. jpri5223@mail.usyd.edu.au
Coleman
Nicholas V
NV
Duxbury
Trevor
T
D001673:Biodegradation, Environmental; D001692:Biological Transport; D053834:Explosive Agents / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D009566:Nitrates / Q000378:metabolism; D012240:Rhodococcus / Q000166:cytology / Q000254:growth & development* / Q000502:physiology*; D012822:Silicon Dioxide; D012989:Soil Pollutants / Q000378:metabolism*; D013386:Succinates / Q000378:metabolism; D014227:Triazines / Q000378:metabolism*
D053834:Explosive Agents; D009566:Nitrates; D012989:Soil Pollutants; D013386:Succinates; D014227:Triazines; D012822:Silicon Dioxide; C009160:cyclonite