## 3 Results  
Effect of Perfluorocarbon Compounds on the Growth and ATP Concentration of Phototrophic Microorganisms  
The biomass accumulation and ATP concentration of the cells growing in media with PFCs were studied. The microalgae C. _vulgaris_ C-1 and cyanobacteria (_A. (Spirulina) platensis_ (Nordst.) Geitl. rsemsu 1/02 and _Nostoc_ sp. _resmsu_ Nss-14/11) cells were investigated for 3 days under standard conditions for each microorganism when 0.5% or 1% (\(v/v\)) of a certain PFC (perfluorohexane, polyether I, perfluorodecalin or polyether II) was introduced into the cell growth medium (Table 1, Figure 1). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Microalgae**} & \multicolumn{6}{c}{**PFC (\% v/v)**} \\ \cline{2-9}  & **Control \({}^{**}\)** & **Perfluorohexane** & \multicolumn{2}{c}{**Polyether I**} & \multicolumn{2}{c}{**Perfluorodecalin**} & \multicolumn{2}{c}{**Polyether II**} \\ \cline{2-9}  & **0** & **0.5** & **1** & **0.5** & **1** & **0.5** & **1** & **0.5** & **1** \\ \hline _C. vulgaris_ & 33 \(\pm\) 1 & 22 \(\pm\) 1 & 24 \(\pm\) 1 & 18 \(\pm\) 0.9 & 26 \(\pm\) 1 & 30 \(\pm\) 1 & 24 \(\pm\) 1 & 26 \(\pm\) 1 & 22 \(\pm\) 1 \\ _C. vulgaris_ *** & 57 \(\pm\) 2 & 32 \(\pm\) 1 & 57 \(\pm\) 2 & 37 \(\pm\) 1 & 66 \(\pm\) 3 & 57 \(\pm\) 2 & 55 \(\pm\) 2 & 62 \(\pm\) 3 & 89 \(\pm\) 4 \\ _Arthospira_ & 27 \(\pm\) 1 & 17 \(\pm\) 1 & 18 \(\pm\) 1 & 15 \(\pm\) 1 & 21 \(\pm\) 1 & 26 \(\pm\) 1 & 20 \(\pm\) 1 & 20 \(\pm\) 1 & 18 \(\pm\) 1 \\ _Nostoc_ sp. & 63 \(\pm\) 3 & 40 \(\pm\) 2 & 41 \(\pm\) 2 & 33 \(\pm\) 1 & 50 \(\pm\) 2 & 60 \(\pm\) 3 & 44 \(\pm\) 2 & 48 \(\pm\) 2 & 42 \(\pm\) 2 \\ \hline \hline \end{tabular}  
* The initial concentration of ATP (nmol/g CDW) was as follows in the cells: it was 11 \(\pm\) 1 in C. _vulgaris_, 19 \(\pm\) 1 in _A. platensis_ and 59 \(\pm\) 1 in _Nostoc_ sp.;
* Growth was without PFCs; *
* Cultivation was with the addition of 1 g/L of glycerol to the culture medium.  
\end{table} 
Table 1: Concentration of ATP (nmol/g DCW) * after 3 days of their cultivation in the culture media with various concentrations of different PFCs. Figure 1: Dependence of the concentration of accumulated biomass of phototrophic microorganisms (**(A)**_C. vulgaris_ cells in Tamiya medium, **(B)**_C. vulgaris_ cells in Tamiya medium with 1 g/L glycerol, **(C)**_A. platensis_ cells in Zarrouk medium, **(D)**_Nostoc_ sp. cells in the medium BG-11) on the concentrations of different PFCs. Control: the concentration of accumulated cell biomass of phototrophic microorganisms when concentration of PFC was 0.0%. The concentration of the suspended cell inoculum was the same in all variants of cells (1.2 g DCW/L), and it was high enough compared to most of the known studies [30; 47; 48]. The choice of such a cell concentration was based on the data previously obtained by the authors [13], when it was revealed that a high rate of cell growth of phototrophic cultures can be achieved in a short period of time with a high density of the cell population in the inoculum. High cell population density and growth rates of phototrophs, among other things, stimulated the process of \"blooming\" of the reservoirs. Because the rate of biomass accumulation began to decrease after 3 days, experiments were carried out for no more than 3 days in order to analyze the process according to the initial growth rates. For all the studied cultures, a positive effect was noted from the presence of perfluorohexane, polyether I or polyether II in the growth medium, manifested in an increased average rate of biomass accumulation in comparison to the parameter value in the control (without PFC) (Figures 1 and 2). The most pronounced effect was observed when perfluorohexane or polyether II was introduced into the growth medium. These results were generally consistent with the data obtained earlier regarding the accumulation of _E. coli_ cell biomass in the presence of PFCs [31]. Figure 2: The average rate of biomass accumulation (g DCW/L/d) for 3 days: C. _vulgaris_ cells in Tamiya medium (**A**), _A.