Large-scale production of bacterial consortia for remediation of chlorinated solvent-contaminated groundwater.

Chlorinated solvents such as perchloroethylene (PCE) and trichloroethylene (TCE) continue to be significant groundwater contaminants throughout the USA. In many cases efficient bioremediation of aquifers contaminated with these chemicals requires the addition of exogenous microorganisms, specifically members of the genus Dehalococcoides (DHC). This process is referred to as bioaugmentation. In this study a fed-batch fermentation process was developed for producing large volumes (to 3,200 L) of DHC-containing consortia suitable for treating contaminated aquifers. Three consortia enriched from three different sites were grown anaerobically with sodium lactate as an electron donor and PCE or TCE as an electron acceptor. DHC titers in excess of 10(11) DHC/L could be reproducibly obtained at all scales tested and with all three of the enrichment cultures. The mean specific DHC growth rate for culture SDC-9 was 0.036 +/- 0.005 (standard error, SE)/h with a calculated mean doubling time of 19.3 +/- 2.7 (SE) h. Finished cultures could be concentrated approximately tenfold by membrane filtration and stored refrigerated (4 degrees C) for more that 40 days without measurable loss of activity. Dehalogenation of PCE by the fermented cultures was affected by pH with no measurable activity at pH <5.0.