NCIMB’s MARA and LumiMARA multispecies bioassays use microorganisms to provide a rapid, highly reproducible analysis of toxicity.
The tests have been used to assess a wide variety of samples from a diverse range of industry sectors, including building, food manufacturing and oil and gas. Samples tested have included complex industrial effluents, leachates, ballast waters and potable water. MARA and LumiMARA have also been employed to examine the efficacy of disinfectants, biocides and bioremediation processes.
We offer a MARA and LumiMARA testing service at our Aberdeen laboratories.
Increased genetic diversity
Using MARA and LumiMARA multispecies bioassays as an alternative to toxicity testing with a single species of bacteria is a very quick, simple and cost effective means of increasing the breadth and genetic diversity of toxicity testing. The tests include not only bacteria, which have been carefully selected for their genetic diversity, but also one yeast species.
The MARA test includes ten genetically diverse bacterial species and one yeast, freeze-dried in a micro-titre plate. The micro-organisms are exposed to a concentration gradient of the test sample and incubated for 18hrs along with growth media and a redox dye. Growth of the micro-organisms is then measured by assessing reduction of the redox dye through the use of a flatbed scanner and image analysis software.
LumiMARA uses 11 species of naturally occurring bioluminescent bacteria. When these bacteria are exposed to toxins, their luminescence is reduced and this can be used as a rapid and direct measure of toxicity. The bacteria are exposed to a concentration gradient of test sample and incubated for 15 minutes before the plate is read using a luminometer.
Plate readings from MARA and LumiMARA are used to calculate the microbial toxic concentration (MTC).
MTC is a measure of inhibition equivalent to an EC50 value. It is used for MARA and LumiMARA because it has a number of benefits including elimination of interpolation errors of classic EC50 determination.
Whole effluent assessment
MARA and LumiMARA can be used for whole effluent testing as part of a risk based approach to effluent management. Following successful trials the tests were recommended by the UK’s Department of Energy and Climate Change as part of their preferred approach to the implementation of a risk based approach to the management of produced water from offshore oil and gas production. For more information about our produced water ecotoxicity testing service is available on our oil and gas industry pages.