3.4. The effect of light in different wavelength ranges on the synthesis of phycocyanin
Figure 8 shows the effects of adding nanoparticles on the intracellular accumulation of phycocyanin in FACHB-314 under different wavelength conditions. The addition of rGO-TiO2composite nanoparticles has a significant increase compared to other white light conditions. Table 1 shows the changes of rGO-TiO2 composite nanoparticles on phycocyanin-related indicators of FACHB-314 under white light. The growth curve ofFACHB-314 shows that the control group without nanoparticle culture has the highest phycocyanin content of 75.1 mg/g and the phycocyanin production of 81.86 mg/L on the sixth day of culture. In theFACHB-314 experimental group cultured with TiO2nanoparticles, the maximum phycocyanin content was 55.7 mg/g. Compared with the control group, the phycocyanin content decreased by 25.8%, and the intracellular phycocyanin production under this condition is 81.88 mg/L. FACHB-314 cultured with rGO-TiO2nanoparticles had a maximum phycocyanin content of 80.3 mg/g on the seventh day of culture. Compared with the control group, the phycocyanin content increased by 6.9%. The intracellular phycocyanin production of algae was 97.16 mg/L. Compared with the control group, the production of phycocyanin also increased by 18.7%. Compared with the FACHB-314cultured with TiO2 nanoparticles, the phycocyanin content increased by 24.6 mg/g compared with the experimental group with TiO2 nanoparticles, and the content increased by 44.2%. The production of phycocyanin also increased by 15.28 mg/g, an increase of 18.7%.
For FACHB-314 cultured without nanoparticles, the intracellular phycocyanin content of FACHB-314 was lower than the initial value (39.0 mg/g) under this condition, and it was gradually consumed. The maximum phycocyanin content of FACHB-314 cultured under red light was 39.0 mg/g, and the maximum phycocyanin yield was 6.24 mg/L. Compared with white light, the phycocyanin content is reduced by 48.1%.FACHB-314 with nanoparticles maintains a higher phycocyanin content and phycocyanin production. Among them, the rGO-TiO2 nanoparticle FACHB-314 has the highest phycocyanin content.