BACKGROUND: In this study, five microalgal species (Chlorella vulgaris, Chlorococcum sp. GD, Parachlorella kessleri TY, Scenedesmus quadricauda, and Scenedesmus obliquus) were cultivated in batch mode to evaluate their respective potential for the treatment of real aquaculture wastewater from a fishery. Subsequently, the microalga with the best performance was cultivated with different initial inoculation concentrations to evaluate the effect of initial inoculation on pollutant removal efficiency. RESULTS: When real aquaculture wastewater was inoculated with exogenous microalgae, the growth of both indigenous microalgae and bacteria was significantly inhibited. Pollutant removal was closely related to exogenous inoculationof microalgae. Parachlorella kessleri TY had high growth potential and pollutant removal capability in aquaculture wastewater, compared with the other four microalgae. When the wastewater was inoculated with low biomass concentrations of P. kessleri TY (50-100 mg L −1 ), it grew well and degraded most of the encountered pollutant. In particular, P. kessleri TY with 100 mg L −1 of inoculation concentration removed 94.4% of COD, 96.2% of ammonium, 99% of nitrite, 94.3% of nitrate, and 95.6% of phosphorus after 3 days of cultivation. CONCLUSIONS: Both the screening for microalgal species and the regulation of initial inoculation concentrations are promising approaches to enhance pollutant removal efficiency from real aquaculture wastewater. Determination of water qualityTo determine the water quality, the microalgal suspension was centrifuged at 5000 rpm for 5 min and the supernatant J Chem Technol Biotechnol 2019; 94: 900-910 /jctb up to 94.4%, 96.2%, 99%, 94.3%, and 95.6% for COD, ammonium, nitrite, nitrate, and total phosphorus, respectively. In the remaining tested inoculation concentrations (25, 50, 200, and 400 mg L −1 ), 77.8-88.9% of COD, 54.2-86.1% of ammonium, 64.1-91.7% of nitrite, 57.1-85.7% of nitrate, and 53-81.4% of total phosphorus were removed from the aquaculture wastewater J Chem Technol Biotechnol 2019; 94: 900-910

Freshwater representatives of Rhodophyta were sampled and the complete chloroplast and mitochondrial genomes were determined. Characteristics of the chloroplast and mitochondrial genomes were analyzed and phylogenetic relationship of marine and freshwater Rhodophyta were reconstructed based on the organelle genomes. The freshwater member Compsopogon caeruleus was determined for the largest chloroplast genome among multicellular Rhodophyta up to now. Expansion and subsequent reduction of both the genome size and GC content were observed in the Rhodophyta except for the freshwater Compsopogon caeruleus. It was inferred that the freshwater members of Rhodophyta occurred through diverse origins based on evidence of genome size, GC-content, phylogenomic analysis and divergence time estimation. The freshwater species Compsopogon caeruleus and Hildenbrandia rivularis originated and evolved independently at the inland water, whereas the Bangia atropurpurea, Batrachospermum arcuatum and Thorea hispida are derived from the marine relatives. The typical freshwater representatives Thoreales and Batrachospermales are probably derived from the marine relative Palmaria palmata at approximately 415–484 MYA. The origin and evolutionary history of freshwater Rhodophyta needs to be testified with more organelle genome sequences and wider global sampling.

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