NCIMB’s multispecies microbial bioassay LumiMARA was recently used as part of a comprehensive ecotoxicity study that assessed the exposure of living organisms to the widely used antibiotic cephalosporin and its photoproducts. The results of study, undertaken by a group of Polish scientists, was published in the Journal of Photochemistry & Photobiology, A: Chemistry (Zandarek et al, 2023)
Endocrine and pharmaceutically active compounds have been found in municipal wastewaters and surface waters receiving treated wastewater. This has concerning potential implications with respect to ecotoxicity and antimicrobial resistance. Moreover, it is not only the impact of the compounds themselves that should be considered, but also their breakdown products. One of the most important important factors influencing the breakdown of chemicals in the environment is sunlight, and the products of photodegradation can have completely different ecotoxilogical effects from their parent compounds.
Zandarek et al, 2023 used LumiMARA alongside a number of higher order tests in their study. They noted that the benefit of selecting LumiMARA as a bacterial test, test in comparison to Microtox, is that it includes 11 different luminescent bacteria strains, rather than one. Microtox is based on testing using the an aliivibrio fischeri strain, and testing using this species is also described in ISO11348-32007(E). The LumiMARA test includes two strains of this species alongside 9 strains of other species.
Their lumiMARA results show phototransformation of the antibiotic cephalosporin results in increased toxicity. In other words, when the compound is released into the environment, the toxic effects are likely to increase over time.
Looking more closely at the results reported by Zandarek et al. (2023) highlights that at lower concentrations of the antibiotic, the aliivibrio fischeri strains within the LumiMARA test used did not show any increased inhibition with phototransformation, while results for the full array of lumiMARA strains shows a clear increase in the number of strains exhibiting 100% inhibition. Only two strains showed 100% inhibtion when exposed to the 0.01 ug/ml of the parent compound, whereas 3 showed 100% inhibition after 3h irradiation, and 4 showed 100% inhibition after 5h irradiation.
This illustrates the value of using a multispecies microbial test over single species testing with aliivibrio fischeri. Testing using vibrio fishcheri alone would have shown no toxicity when approximately one third of the strains within lumiMARA exhibit 100% toxicity when exposed to the same compounds.
NCIMB supplies LumiMARA bioassay kits and also provides a testing service. Visit our ecotoxicity testing page for more information.
“The main limitation of Microtox is that only one bacterial strain is used. To reduce such limitation, the LumiMARA multispecies microbial assay was developed”Zandarek et al, (2023) https://www.sciencedirect.com/science/article/pii/S1010603023004197