Optimal temperature and photoperiod for the cultivation of Agardhiella subulata microplantlets in a bubble-column photobioreactor.
The optimal temperature and illumination photoperiod requirements for the phototrophic growth of a novel microplantlet suspension culture derived from the macrophytic marine red alga Agardhiella subulata were determined. The optimal growth temperature was 24 degrees C. The effects of illumination light-dark (LD) photoperiod (hour of light:hours of darkness within a 24 h cycle) on biomass production was studied within a bubble-column photobioreactor. The 4.5 cm diameter photobioreactor was maintained at near-saturation conditions with respect to light flux (38 mciromol photons m(-2) s(-1)), nutrient medium delivery (20% nutrient replacement per day), and CO(2) delivery (0.35 mmol CO(2) L(-1) h(-1)) so that the cumulative effects of photodamage on the cell density versus time curve at photoperiods approaching continuous light could be observed. Biomass production was maximized at 16:8 LD, where biomass densities exceeding 3.6 g dry cell mass L(-1) were achieved after 60 days in culture. Biomass production was proportional to photoperiod at low fractional photoperiods (< or =10:14 LD), but high fractional photoperiods approaching continuous light (> or = 20:4 LD) shut down biomass production. Biomass production versus time profiles under resource-saturated cultivation conditions were adequately described by a cumulative photodamage growth model, which coupled reversible photodamage processes to the specific growth rate. Under light-saturated growth conditions, the rate constant for photodamage was kd = 1.17 +/- 0.28 day(-1) (+/-1.0 SE), and the rate constant for photodamage repair was kr = 5.12 +/- 0.95 day(-1) (+/-1.0 SE) at 24 degrees C.
Department of Chemical Engineering, Oregon State University, Corvallis, Oregon 97331, USA.
Yao-Ming
YM
Huang
Gregory L
GL
Rorrer
D018533:Biomass; D019149:Bioreactors; D002245:Carbon Dioxide / Q000378:metabolism; D018929:Cell Culture Techniques / Q000379:methods; D002478:Cells, Cultured / Q000378:metabolism; D002940:Circadian Rhythm; D003198:Computer Simulation; D008027:Light; D008954:Models, Biological; D010100:Oxygen / Q000378:metabolism; D018462:Photobiology; D017440:Photoperiod; D010788:Photosynthesis; D011786:Quality Control; D015203:Reproducibility of Results; D000461:Rhodophyta / Q000254:growth & development* / Q000378:metabolism*; D012680:Sensitivity and Specificity; D013696:Temperature; D014871:Water Microbiology
D002245:Carbon Dioxide; D010100:Oxygen