Growth and uptake of sucrose and mineral ions by bulblets of Lilium Oriental Hybrid ‘Casablanca’ during bioreactor culture

Abstract

SummaryThe growth and changes in concentration of major nutrients and sugars in the media were investigated in Lilium bulblets cultured in vitro using a novel type bioreactor (Balloon Type Bubble Bioreactor) system. Bulblets of Lilium Oriental Hybrid ‘Casablana’ grew faster when the medium was exchanged frequently with new medium in a Balloon Type Bubble Bioreactor (Immerson type). More bulblets over 2.1.g were produced when the medium was replaced with new medium after 2, 6 and 12 weeks of bioreactor culture as compared with cultures where fresh medium was added every 2, 6 and 12 weeks. Uptake of sugar and other minerals indicate that for optimal bulblet growth, high sucrose levels are necessary. However in the addition method, it was not possible to maintain high sucrose level by adding fresh medium every 2, 6 and 12 weeks. Although high sucrose levels could be maintained by the exchange method, the sucrose supplied was rapidly hydrolysed into glucose and fructose when the medium was replaced with new medium every 2, 6 and 12 weeks of bioreactor culture. Mineral absorption also displayed variation, both in quantity and selectivity of the inorganic nutrients supplied. During the growth of bulblets, fast exhaustion of NH4–, NO3–, SO42– and H2PO4– occurred, whereas consumption of K+, Mg2+, Ca2+, Na+ and Cl– is very slow. There is also a rapid fall in the pH of the medium following the addition of, or exchange with, fresh medium during the bulblet growth. The change in pH may be attributed to the differential uptake or excretion of NO3–, and/or NH4+ ions.