Development of microalgal bioassay based on the community level physiological profiling (CLPP)

Microalgal bioassay was developed based on community level physiological profiling (CLPP) to assess the effect of environmental stressors such as micropollutants. ECO Biolog plates were used to determine the changes in substrate utilization patterns caused by external disturbances such as the presence of antibiotics (a mixture of streptomycin sulfate and penicillin GT sodium), hexadecyl trimethyl ammonium chloride (CTAC), a micropollutant, and their combination (antibiotics and CTAC). The performance of the bioassay was assessed using artificially defined communities made up of five freshwater algae strains (Chlorella vulgaris, Chlamydomonas reinhardtii, Desmodesmus subspicatus, Selenastrum capricornutum, and Scenedesmus obliquus) at five different compositions with varying ratios of the test algae. Differences in the response as indicated by substrate utilization patterns to induced stressor by five defined microalgal communities were quantified using principal component analysis (PCA). The changes in substrate utilization patterns are probably due to the changes in metabolic potentials of the individual strains. The effects were more pronounced for the treatments than that obtained by varying the initial composition of the defined algal communities. The effects of the external factors were found to be consistent in the highest cell density of 300,000 cells per well to the lowest of 25 cells per well.