Magnesium Sulphate and β-Alanine Enhanced the Ability of Kluyveromyces marxianus Producing Bioethanol Using Oil Palm Trunk Sap

The abundance of oil palm trunk waste generated each year has encouraged research in using its sap for fermentation to produce value-added products. One of these value-added products is bioethanol production using yeast strains. In this study, the ability of Kluyveromyces marxianus ATCC 46537 to produce bioethanol using oil palm trunk sap (OPTS) was examined. The nutrients (ammonium sulphate, di-ammonium hydrogen phosphate, magnesium sulphate, b-alanine, calcium chloride and potassium dihydrogen phosphate) required to enhance production were screened and optimised. The concentrations of bioethanol and sugars were monitored with high performance liquid chromatography. The results showed that K. marxianus could attain maximum bioethanol concentration at 16 h with a higher productivity as compared to S. cerevisiae. Magnesium sulphate and b-alanine were found to increase bioethanol production. When 7.93 g/L of magnesium sulphate and 0.90 g/L of b-alanine were supplemented to OPTS, bioethanol production increased 20% with a bioethanol yield of 0.47 g/g and a productivity of 2.22 g/L.h. Therefore, minimum supplementation of OPTS with inorganic nutrients could enhance the bioethanol production of Kluyveromyces marxianus

Improved bioethanol production from oil palm trunk sap

Renewable energy such as bioethanol produced from biomass waste is gaining a lot of interest worldwide due to depletion of fossil fuel reserve. The OPT felled for replanting is a suitable raw material to produce bioethanol because it is an abundant waste material produced by the palm oil industry in Malaysia. In order to utilize the felled OPT, fermentation by suitable microorganism can be performed to obtain bioethanol. Hence, this study was carried out to select the best microorganisms for bioethanol fermentation using OPT sap and to optimise nutrient supplementation in OPT sap for bioethanol fermentation. In this study, four microorganisms were tested for ethanol production at fixed temperature, pH, agitation and inoculum size which are Saccharomyces cerevisiae ATCC 9763, Saccharomyces cerevisiae CCT 0762, dry baker’s yeast and Kluyveromyces marxianus ATCC 46537. The parameters were set at inoculum size of 10 % (v/v), agitation speed of 150 rpm, incubation temperature of 30 ºC and fermentation time of 72 hours. Two types of analytical method were performed to analyse the data which are cell dry weight measurement and High Performance Liquid Chromatography (HPLC). The results showed that K. marxianus ATCC 46537 produced the highest ethanol yield (0.39 g/g) at a shorter fermentation time (16 h) compared to the other strains. Then, response surface methodology (RSM) was employed to optimise the nutrient supplementation in OPT sap. Using Two-level Factorial Design, six nutrients, namely ammonium sulphate, di-ammonium hydrogen phosphate, magnesium sulphate, β-alanine, calcium chloride and potassium dihydrogen phosphate were screened using K. marxianus ATCC 46537 and the selected significant nutrients were magnesium sulphate and β-alanine. Subsequently, the optimisation study using Central Composite Design found the optimum value of magnesium sulphate was 7.93 g/L and 0.90 g/L for β-alanine. Under optimum conditions, the predicted ethanol concentration was 0.46 g/g while the experimental value (0.47 g/g) was in agreement with the predicted value with 2.13 % error. As a conclusion, K. marxianus ATCC 46537 were able to improve ethanol production from 0.39 g/g without nutrient supplementation into 0.47 g/g with nutrient optimisation using RSM

Effects of castor oil on cellulase enzymatic activities on pure cellulose during simultaneous saccharification and fermentation (SSF)

Castor oil from castor (Ricinus communis) seed can be used as ethanol absorbent during simultaneous saccharification and fermentation (SSF). This study was performed to investigate the effect of castor oil on cellulase enzymatic activity on pure cellulose during SSF. In this experiment, SSFs were performed in a 150 ml working volume in media bottles after being aseptically inoculated with Saccharomyces cerevisiae. Carbomethyl cellulose (CMC) of 5% (w/v) and 10% (w/v) were used as feedstocks with 25 FPUlg CMC and 50 FPU/g CMC. Then, 15 ml castor oil was added into the fermentation broths. The fermentation broths were incubated at 37°C and agitated at 120 rpm under anaerobic conditions for 5 days. Data were obtained by High-Performance Liquid Chromatography (HPLC) and the respective graph were plotted. Cellulase activities were then investigated by performing enzyme assay. When castor oil was present in the fermentation broth, the ethanol concentration was reduced. However, both cellobiose and glucose were also reduced suggesting better utilization while having access ethanol absorbent into the castor oil layer. From this study, the data suggest that the effect of castor oil towards S. cerevisiae was not significant. Furthermore, cellulase enzymatic activities became better at 25 FPUlg CMC in the presence of castor oil. This result showed that castor oil can be selectively used as ethanol absorbent in the fermentation broth during SSF to increase ethanol yield

Influence of Nutrient Addition on the Bioethanol Yield from Oil Palm Trunk Sap Fermented by Saccharomyces Cerevisiae

This paper presents the influence of nutrient addition namely MgSO4, C3H7NO2, (NH4)2SO4 and Na2HPO4 to the bioethanol yield from oil palm trunk saps (OPTS) with fermentation carried out by Saccharomyces cerevisiae. The sugar and ethanol contents in the sample were determined using a high-performance liquid chromatography. Nutrient addition has improved the bioethanol yield markedly, with the average yield ranged from 58.50% to 77.12% compared to about 51.08% without nutrient addition. The highest bioethanol yield (81.89%) was achieved by adding MgSO4. The rank of nutrient influence on improving the bioethanol yield was MgSO4 > C3H7NO2 > (NH4)2SO4 > Na2HPO

Optimisation of Bioethanol Yield from Oil Palm Trunk Sap

This paper presents the effect of nutrients addition and fermentation microorganism on bioethanol yield from oil palm trunk sap. Six microorganisms namely, Saccharomyces cerevisiae ATCC 9763, Saccharomyces cerevisiae ATCC 26602, baker’s yeast, Kluyveromyces marxianus ATCC 46537, Zymomonas mobilis ATCC 29501 and Escherichia coli ATCC 10536 were screened for ethanol production at fixed temperature, pH, agitation and inoculum size. The sugar and ethanol content were determined using a high performance liquid chromatography (HPLC). The results showed that K. marxianus produced the highest ethanol yield (60.9%) at a shorter fermentation time (16h) compared to the other strains. Six nutrients, namely, ammonium sulphate, di-ammonium hydrogen phosphate, magnesium sulphate, β-alanine, calcium chloride and potassium dihydrogen phosphate were screened using this strain and the highest ethanol yield (98.62%) was achieved in fermentation supplemented by magnesium sulphate and β-alanine. Subsequently, the optimisation study using a reseponse surfae methodology found the optimum value of magnesium sulphate was 7.93 g/L and 0.90 g/L for β-alanine. Under the optimum conditions, the predicted ethanol concentration was 34.58 g/L while the experimental value (35.50 g/L) was in agreement with the predicted value with 2.66% error

Optimisation of Oil Palm Trunk Sap Fermentation to Bioethanol

Malaysia has an abundant amount oil palm biomass (approx. 15 million tons annually) arising from replanting activities involving old oil palm aged above 20 years-old which has lower productivity. In some cases, the outer hard portion of the oil palm trunk is utilised for plywood manufacturing, but the soft inner portion is normally discarded. This soft inner portion contains a huge amount of sugar-rich sap that can be fermented into bioethano