Establishment of Oil Palm Suspension Culture in the Sixfors Bioreactor

In vitro propagation is an important part of the oil palm industry’s approach towards clonal propagation of high-yielding materials. Oil palm suspension cultures have been established using the shake flask system which was developed for production of a reliable supply of regenerable plant tissues. However, this system is inefficient for fast large scale proliferation of embryogenic suspension cultures. Bioreactors have been used for the industrial production of microbial, animal and plant metabolites. However, it’s used was not well known in oil palm suspension culture. During the development of oil palm suspension culture in the sixfors multibioreactor, nutrients and extra cellular metabolites were monitored where kinetic parameters and nutrients to biomass conversion yield were calculated to better characterise the behaviour of oil palm suspension culture. It was observed that the amount of biomass of all the cell lines was at an average of 2-3 fold higher than the original inoculums weight with an incubation period of 30 to 60 days. The carbon source, which is sucrose, was hydrolysed to glucose and fructose in the first 10 days and both were completely utilised after the 25th day. The sugar to biomass conversion yield was low and the mainly linear growth showed that the growth of the cell was limited by the culture conditions. Nitrogen sources from the MS media remained in excess until the end of the growth period where only 30% of ammonia and 15% of nitrates were utilised which resulted in the cell being toxic and thus limiting cell growth. The growth was exponential in the first 10 days with a maximum specific growth rate of 0.07 day-1 which corresponded to a doubling time of 10 days. The cells then entered a period of linear growth until Day 25 to reach the maximum dry weight of 4 g/l, after which the cells began to die off causing the dry weight to fall to 2.8 g/l at Day 45. The pH profile was an indication of the nitrogen and sugar uptake by the cells. The pH decreased rapidly from 5.6 to 4.0 in the first 9 days and then increased gradually to 4.4 at the 25th day. At this point, the cell growth had stagnated, and the pH quickly increased to 5.5 before declining again to the end of the culture at Day 45. The initial pH decrease was partly due to the uptake of ammonium. After this, however, the great increase was due to the uptake of nitrate ions to the ammonium stored in the vacuoles of the cell