## 4 Discussion
Previously, it was found that in the combined systems of algae-bacteria, an excess of AHLs can restrain the initial growth of _Chlorophyta_ sp., thereby having a negative effect on the characteristics of microalgae [67]. The results obtained in this work clearly indicate that the variants of combinations of bacteria and _Chorella_ that were experimentally created in this study turned out to be successful, and this should be taken into account by researchers who work in this field. The concentration of intracellular ATP is a marker of the metabolic activity of cells and the level of their viability [13]. The analysis of this biochemical characteristic of cells by bioluminescent ATP-metry makes it possible to quickly assess with high selectivity and sensitivity the effects of various conditions of cultivation of various cells on their functional activity [68]. In this work, data on the concentration of intracellular ATP were used to monitor the state of cells, both in the presence of xenobiotics and in the formation of consortia of _Chorella_ cells with bacteria. ATP-metry proved to be indispensable, especially when assessing the state of immobilized cells in granules (Table 2), as it was impossible to isolate them without damage. It was found that an increase in the level of ATP in the analyzed cell samples clearly corresponds to an increase in the level of accumulated biomass in them. Such an analysis of cellular systems by two parameters (ATP and biomass accumulation) allowed us to discuss the positive relationships that developed between cells of different cultures as a part of formed artificial consortia when the cells were combined at certain ratios. The analysis of the results obtained in this work suggests that if PFCs enter various water bodies, we should expect an intensification of the growth of some microorganisms, in particular a number of microalgae and primarily _C. vulgaris_ microalgae cells. The question remains open about the possibility of using PFCs in biotechnological processes to intensify the growth of microalgae. In our opinion, special use of chemically and biologically inert substances should be carried out in closed systems to avoid their accumulation in the environment. Interestingly, the ability of some phototrophic microorganisms to utilize OPCs was recently explained as a possible result of the plasmid transfer of necessary genes from bacteria due to the co-existence of microalgae and bacterial cells in native consortia [69; 70; 71; 72]. Thus, the results obtained in this work have practical significance for researchers in the field of developing new biocatalytic approaches to the treatment of wastewaters of complex composition containing OPCs and PFCs while simultaneously obtaining valuable renewable raw materials--biomass of phototrophic microorganisms. Additionally the results of this work indicate that with a combination of factors such as the presence of various nutrition sources and the presence of PFCs in the medium of microalgae and bacteria capable of regulating the QS of phototrophs, an active increase in microalgae biomass can be registered in environmental objects, which can change the equilibrium in such ecosystems. A recent study of the interaction of PFCs and microorganisms present in the aquatic environment showed that green microalgae _Desmodesmus subspicatus_ cells are not capable of growing in presence of perfluorohexane, perfluorooctane or perfluorooctane phosphonic acids [73]. For these microorganisms, a decrease in the intensity of green coloration in the presence of PFCs was noted, which indirectly indicates a negative effect of PFCs on microalgae chlorophyll, resulting in cell fluorescence being lost. The fact that _Chlorella_ cells were completely resistant to the possible negative effects of PFCs in this study is significant for predicting the viability of these microalgae in vivo under similar conditions.