Microalgae have been considered for biological carbon capture and sequestration to offset carbon emissions from fossil fuel combustion. This study shows that mixed biodiverse microalgal communities can be selected for and adapted to tolerate growth in 100% flue gas from an unfiltered coal-fired power plant that contained 11% CO. The high SOx and NOx emissions required slow adaptation of microalgae over many months, with step-wise increases from 10% to 100% flue gas supplementation and phosphate buffering at higher concentrations. After a rapid decline in biodiversity over the first few months, community profiling revealed Desmodesmus spp. as the dominant microalgae. To the authors' knowledge this work is the first to demonstrate that up 100% unfiltered flue gas from coal-fired power generation can be used for algae cultivation. Implementation of serial passages over a range of photobioreactors may contribute towards the development of microalgal-mediated carbon capture and sequestration processes.

Purpose: To isolate thymoquinone (TQ) from Nigella sativa L. and Thymus vulgaris L., and investigate its anti-proliferative effect on HeLa cancer cells. Method: Pulverized dried samples of N. sativa seed (100 g) and aerial parts of T. vulgaris (1000 g) were subjected to Soxhlet extraction using methanol and n-hexane combined in different proportions. Thymoquinone (TQ) was then isolated from the extracts using high performance liquid chromatography (HPLC). The isolated TQ was further subjected to Fourier Transform Infrared (FTIR) spectroscopy to identify its functional groups. The anti-proliferative effect of TQ on HeLa cancer cells was evaluated using 3-[4, 5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. Results: Extract yield from N. sativa was significantly higher than from T. vulgaris, and also increased with increase in the proportion of methanol in the extraction solvent (p < 0.05). Methanol and n-hexane (4:1, v:v) yielded the highest amount of oil, with yields of 15.8 and 9.7 ml/25 g dry weight (d.wt.) from N. sativa and T. vulgaris, respectively. The results obtained from HPLC showed that the concentration of TQ isolated from N. sativa (388.61 µg/ml) was significantly higher than that from T. vulgaris (357.03 µg/ml, p < 0.05). The anti-proliferative effects of TQ standard and TQ isolated from N. sativa on HeLa cancer cells were dose-dependent, and was highest at the lowest concentration. The number of viable cells significantly decreased with increase in TQ concentration (p < 0.01). TQ from N. sativa significantly reduced the number of viable cells even at the lowest concentration when compared to TQ standard (p < 0.05). Cell death was significantly higher in TQ-treated groups than in untreated cancer cells. Conclusion: The results obtained in this study show that N. sativa is a potential source of TQ, with the yield enhanced by modifying the extraction procedure or solvent used. Furthermore, TQ isolated from N. sativa exerts a dose-dependent anti-proliferative effect on HeLa cancer cells.

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