Efficient ethanol production from separated parenchyma and vascular bundle of oil palm trunk.

For efficient utilization of both starchy and cellulosic materials, oil palm trunk was separated into parenchyma (PA) and vascular bundle (VB). High solid-state simultaneous saccharification and fermentation (HSS-SSF) using 30% (w/v) PA, containing 46.7% (w/w) starch, supplemented with amylases and Saccharomyces cerevisiae K3, produced 6.1% (w/v) ethanol. Subsequent alkali-pretreatment using sodium hydroxide was carried out with starch-free PA (sfPA) and VB. Enzymatic digestibility of 5% (w/v) pretreated sfPA and VB was 92% and 97%, respectively, using 18 FPU of commercial cellulase supplemented with 10 U of Novozyme-188 per gram of substrate. Likewise, HSS-SSF using 30% (w/v) alkali-pretreated sfPA and VB, with cellulases and yeast, resulted in high ethanol production (8.2% and 8.5% (w/v), respectively). These results show that HSS-SSF using separated PA and VB is a useful fermentation strategy, without loss of starchy and cellulosic materials, for oil palm trunk.

Ethanol and lactic acid production using sap squeezed from old oil palm trunks felled for replanting.

Old oil palm trunks that had been felled for replanting were found to contain large quantities of high glucose content sap. Notably, the sap in the inner part of the trunk accounted for more than 80% of the whole trunk weight. The glucose concentration of the sap from the inner part was 85.2g/L and decreased towards the outer part. Other sugars found in relatively low concentrations were sucrose, fructose, galactose, xylose, and rhamnose. In addition, oil palm sap was found to be rich in various kinds of amino acids, organic acids, minerals and vitamins. Based on these findings, we fermented the sap to produce ethanol using the sake brewing yeast strain, Saccharomyces cerevisiae Kyokai no.7. Ethanol was produced from the sap without the addition of nutrients, at a comparable rate and yield to the reference fermentation on YPD medium with glucose as a carbon source. Likewise, we produced lactic acid, a promising material for bio-plastics, poly-lactate, from the sap using the homolactic acid bacterium Lactobacillus lactis ATCC19435. We confirmed that sugars contained in the sap were readily converted to lactic acid with almost the same efficiency as the reference fermentation on MSR medium with glucose as a substrate. These results indicate that oil palm trunks felled for replanting are a significant resource for the production of fuel ethanol and lactic acid in palm oil-producing countries such as Malaysia and Indonesia.