Optimization of Enzymatic Saccharification of Alkali Pretreated Parthenium sp. Using Response Surface Methodology

Abstract

Parthenium sp. is a noxious weed which threatens the environment and biodiversity due to its rapid invasion. This lignocellulosic weed was investigated for its potential in biofuel production by subjecting it to mild alkali pretreatment followed by enzymatic saccharification which resulted in significant amount of fermentable sugar yield (76.6%). Optimization of enzymatic hydrolysis variables such as temperature, pH, enzyme, and substrate loading was carried out using central composite design (CCD) in response to surface methodology (RSM) to achieve the maximum saccharification yield. Data obtained from RSM was validated using ANOVA. After the optimization process, a model was proposed with predicted value of 80.08% saccharification yield under optimum conditions which was confirmed by the experimental value of 85.80%. This illustrated a good agreement between predicted and experimental response (saccharification yield). The saccharification yield was enhanced by enzyme loading and reduced by temperature and substrate loading. This study reveals that under optimized condition, sugar yield was significantly increased which was higher than earlier reports and promises the use of Parthenium sp. biomass as a feedstock for bioethanol production.

Optimization of the Enzymatic Saccharification Process of Empty Fruit Bunch Pretreated with Laccase Enzyme

“…Different cellulase enzymes vary in their tolerance to pH and temperature. However, the observations from this study are consistent with the findings of Pandiyan et al (2014), who studied the combined effects of pH and temperature on the enzymatic saccharification of alkali-pretreated Parthenium spp. using response surface methodology.…”

“…This was believed to be due to the progressive thermal denaturation of the enzymes at 60 and 70 o C. Studies previously conducted on the effect of temperature on the rate of enzymatic reactions confirmed that when the temperature was higher than the tolerance limit of an enzyme system, the protein structures that maintain the shape and function of the enzyme will become denatured, and this will result in the loss of the enzyme activity (Martinek 1969). Pandiyan et al (2014) optimized the enzymatic saccharification of alkali-pretreated Parthenium spp. using response surface methodology and achieved 83.27% saccharification efficiency at 50 o C, which was higher than 22.16% saccharification efficiency recorded at 60 o C. These were indications that the temperature of 50 o C was the most favored temperature for the enzymatic saccharification of different lignocellulosic biomass.…”

Conversion of rice husk into fermentable sugar by two stage hydrolysis

“…This might be due to the adaptability of cellulase complex for the temperature range from 30˚C to 60˚C which was selected in this study. However, there was slightly decreased in enzymatic hydrolysis efficiency at temperature beyond 50˚C, this could partially be explained by the loss of enzyme activity due to thermal inactivation [19]. It is observed that the highest sugar concentration was produced at the range of pH 6 to pH 7 and 40˚C to 50˚C, where this result is also found in study of Ong et al (2012) by using rice straw as substrate [20].…”

Expression of novel glucose tolerant β-glucosidase on cell surface by Rhodotorula glutinis isolate

“…RSM has also been used to optimise factors (temperature, pH, enzyme, and substrate loading) affecting enzymatic hydrolysis of Parthenium sp. (Pandiyan et al, 2014). Other tools like Taguchi have been used to optimise culture conditions for production of cellulases and xylanases by Phoma exigua on varying pH, surfactant, carbon and nitrogen sources (Tiwari et al, 2013).…”