Isolating Fistulifera pelliculosa from the northern Bohai Sea and analyzing biochemical composition, antibacterial and nutrient removal potential

The microalgae located near the estuary of the Liaohe River along the coast of Panjin have long been in an area with large fluctuations in salinity, temperature, and nutrients, and have high-quality alternatives for high-value metabolites. Three strains of microalgae were screened and the biomass of microalgae could be optimized 0.313-0.790 g L-1 in 10 L bioreactor. The determination results of bioactive substances in these three microalgae showed that, the amount of fucoxanthin in the growth phase II (14 days) was maximum, at 5.354, 6.284 and 14.837 mg g-1 respectively. The diatoxanthin of Dut-wj-J1 in growth phase III (21 days) could reach 5.158 mg g-1. Dut-wj-J4 had the highest lipid pro-duction efficiency (9.45 mg L-1 d-1) followed by Dut-wj-J2 (8.49 mg L-1 d-1) and Dut-wj-J1 (8.18 mg L-1 d-1) re-spectively. These bioactive substances have inhibition zones of 7-13 mm against all four strains of bacteria ie., Acetobacter, Rhodococcus erythropolis, Escherichia coli and Bacillus subtilis Cohn respectively. In addition, these microalgae can play a potential role in nutrient enrichment in eutrophic seawater. The NO3- degradation rates of these three algae in the first 14 days were 75.0 %, 45.8 % and 100 % respectively, as well as the PO4- degradation rates in the first 7 days were 94.8 %, 100 % and 80.9 % respectively. This work manifests the plasticity of algae isolated from the Bohai Sea and provides useful insights for further joint production of bioactive substances.