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Abstract
Photomixotrophic callus and suspension cultures of P. elliottii were established. The selective use of environmental pressures such as increased CO$\sb2$ and decreased O$\sb2$ in the inlet gas, a decrease in the medium sucrose and macro-nutrients, and an increased photoperiod to 24 h helped to develop these cell lines.
Electron micrographs showed that secondary metabolites and starch could exist in P. elliottii callus cell simultaneously. No secondary metabolites were observed in the HT callus, HT suspension, and PMT suspension. These micrographs served to document the physical structure of the cells at the time of subculture. Furthermore, inferences can be draw about the physical structures and the tissues physiological state.
Interest in bioreactor technology has been renewed with the advent of large scale suspension cultures of higher plant and animal cells. The bioreactor with all its control mechanisms offers a significant research tool to study the physiology of phototrophic cells that cannot be conducted in shake flasks. Results of this study have demonstrated that a stirred tank reactor equipped with a cell lift impeller can be used to effectively culture photomixotrophic P. elliottii and Glycine max suspensions. Optimum biomass production utilizing the cell life impeller occurred at 60 rpm and 0.3 vvm which produced a K$\sb{\rm L}$a value of 20 h$\sp{-1}$ and an OTR of 1.63 mmol L$\sp{-1}$h$\sp{-1}$. The cell lift impeller and the flat bladed turbine produced similar net biomass, but the average cell aggregate was 1.0 mm as compared to 3 to 5 mm respectively. Poor biomass yields were obtained with the marine impeller, due mostly to poor mixing characteristics which were a function of impeller diameter to tank diameter. Increased CO$\sb2$ to 2% in the inlet gas increased cell viability and reduced inoculum size. G. max cells produced net 0$\sb2$ during late exponential and early stationary phase. During similar periods, P. elliottii evolved O$\sb2$ at a rate just balancing out consumption. Maximum chlorophyll levels obtained during stationary phase exceed inoculum levels. Neither culture was able to develop fully autotrophic suspensions in the reactor.
