Nutrient uptake and accumulation by sugarcane cell cultures in relation to the growth cycle

Abstract

Growth characteristics and nutrient changes in medium and cells of batch-grown sugarcane cultures were investigated over a period of 14 days. Amino acids, PO 4 3− and K+ were substantially removed from the medium during the first seven days of culture; a strong preference for uptake of organic nitrogen over inorganic nitrogen was observed. Sodium uptake increased during the time when K+ was becoming deficient in the medium. The main anions taken up were SO 4 2− and PO 4 3− . Strong acidification and a virtually total extracellular hydrolysis of sucrose in the medium during the first seven days of culture were also observed. Tapering off of the rapid growth phase was accompanied by an increase of intra-cellular sucrose and a decrease of intracellular protein. As cells went from rapid growth into stationary phase, cytoplasmic space of the cells decreased slightly in favor of vacuolar space. Overall cell volume stayed constant throughout the growth cycle, except during a short period before onset of rapid growth. Transport of the glucose analog 3-O-methyl glucose remained constant in terms of Km value but the Vmax was slightly higher in rapidly growing cells.