Microbiological Laboratory Assays

Serves as a litmus test to determine if bioremediation is a realistic treatment approach at a specific site..

• Gather background information via review of historical laboratory results and
   remedial investigations
     -chemistry (organic and inorganic)
     -geology (soil type and hydrogeological characteristics)

• Microbial enumeration   to evaluate current total culturable and   contaminant-utilizing microbial populations.   The populations are evaluated by:      • Plate Counts, or      • Most Probable Number Tubes.

• Nutrient concentrations are evaluated to determine if nutrients may be a limiting factor
   of bioremediation.
     • Nitrate.
     • Phosphate.
     • Ammonia.

Determines the potential for in situ or ex situ aerobic bioremediation of contaminants of concern using laboratory kinetics studies.

• Enrichment cultures of native bacteria are developed using the contaminant(s) of
   concern (COC) or cosubstrate as a carbon and energy source.

• Contaminant removal over time is evaluated in a minimum of 4 treatment groups
   (Kinetics Study). Treatments are prepared with site matrix material. The method of
   chemical analysis will vary based on contaminant, contaminant concentration and site    conditions. -more...
     • Gas chromatography (GC)
     • High pressure liquid chromatography (HPLC), or
     • Radiotracer techniques (utilize ¹⁴C-labeled organic compound of interest to quantify        daughter product formation and complete biological mineralization to ¹⁴C-CO₂, )

• Microbial physiological assays are conducted to evaluate key system factors.
     • Culture growth.
     • Respirometry.

Are used to evaluate microbial populations present in site samples.

• Heterotrophic Plate Counts represent total culturable aerobic population.

• Contaminant-Degrader Plate Counts represent the culturable aerobic population
   capable of utilizing the contaminant of concern as sole carbon and energy source.

• Most Probable Number (MPN) Tubes represent statistically based aerobic populations.

• Nitrate and phosphate concentrations are evaluated to determine if macro nutrients
   are limited at the site.
     • General carbon to nutrient ratio is 100:10:1 (carbon:nitrogen:phosphate).
     • Micronutrients, trace elements (metals) and vitamins are also vital to bacterial        metabolism.

• 5-Day Biological Oxygen Demand (BOD) can evaluate 6-variables per study to
   determine the effect of amendment on oxygen demand. Amendment assays
   may involve nutrients, bacterial culture, cosubstrate, contaminant, or other.

• Chemical Oxygen Demand (COD).

• Oxygen addition requirements for a treatment system can be estimated utilizing BOD
   data.

Selective and differential growth media are utilized to identify the presence of common pathogens.

• DNA fingerprinting methodologies are    used to identify and monitor:          • Culturable bacterial isolates, and / or     • Microbial communities.

These methods can be used to track bacterial isolates or overall bacterial community structure within a treatment system or matrix.

Are used to characterize the metabolic capabilities of bacterial isolates.

• Catalase.
• Oxidase.
• Litmus Milk.
• Nitrate Reduction.