Effects of cultivation conditions on the CO2 fixation rate and production of phycocyanin by Thermosynechococcus sp CL-1

Abstract

Carbon dioxide (CO2) has increased dramatically due to fossil fuels burning associated with increased population and industrialization Photosynthesis in microalgae and cyanobacteria has long been recognized to absorb CO2 from atmosphere Cyanobacteria produces nutraceutical product phycocyanin and simultaneously mitigates CO2 emission during its growth In this study the growth characteristics of cyanobacteria Thermosynechococcus sp CL-1 (TCL-1) in an 1 L photobioreactor with 1 5 cm light path has been conducted to find the optimal condition for production of biomass and phycocyanin Two illumination processes single-side illumination with intensity 500 1 000 and 2 000 μmol m?2 s?1 and double-side illumination with intensity 250 /250 500 /500 and 1 000 /1 000 μmol m?2 s?1 have been performed The red LED with 620 nm wavelength was also mixed with white LED to examine the effect of light color The results show that cultivation by double-side of illumination with 500 /500 μmol m-2 s-1 has the maximum biomass productivity 3 324 ± 0 mg L-1 day-1 The cultures of double-side illumination with 1 000 /1 000 μmol m-2 s-1 has the maximum CO2 fixation rate at 124 40 ± 6 40 mM day-1 The culture with DIN concentration of 14 6 mM has the highest phycocyanin productivity 201 6 ± 40 4 mg L-1 day-1 (12 hour) or 97 6 ± 11 7 mg L-1 day-1 (24 hour) DIN concentration increased could alleviate oxidative damage High light with high DIN concentration MDA content higher than high light with DIN starvation Further cultivating with different wavelength light intensity and temperature the maximum phycocyanin productivity 281 4 ± 10 0 mg L-1 day-1 can be obtained by double-side illumination of 250 Mix /250 W μmol m-2 s-1 using the modified Su and Chu’s medium with a 14 6 mM DIN at 50 oC Therefore TCL-1 cultivated in the mixed red – white LED has a great potential in biomass productivity CO2 fixation and phycocyanin productivity

Date of Award	2015 Jul 23
Original language	English
Supervisor	Hsin Chu (Supervisor)