Expression of the inulinase gene from the marine-derived Pichia guilliermondii in Saccharomyces sp. W0 and ethanol production from inulin.
Bottom Line: It has been confirmed that Saccharomyces sp.It was found that 15.2 U of inulinase activity per one gram of inulin was suitable for inulin hydrolysis and ethanol production by the transformant Inu-66.During the 2 l fermentation, 14.9% (v/v) of ethanol was produced from inulin and 99.5% of the added inulin was converted into ethanol, CO₂ and cell mass.
Affiliation: Unesco Chinese Center of Marine Biotechnology, Ocean University of China, Yushan Road, No. 5, Qingdao, China.Show MeSH
Related in: MedlinePlus
Mentions: During ethanol fermentation by Saccharomyces spp., 1 mol of glucose is converted to 2 mol of CO2, and 2 mol of CH3‐CH2OH and CO2 will be released from the fermentation system. The molecular weight (44) of CO2 is almost the same as that (46) of CH3‐CH2OH. Therefore, the lost weight (CO2) was used to estimate the weight of ethanol produced in the closed fermentation system. This was the basis of carbon dioxide quantification in this study and CO2 evolved was monitored by the decrease in weight of the whole culture. Different volumes of the culture of the transformant Inu‐66 grown in the inulinase production medium for 72 h were inoculated into 150 ml of the ethanol fermentation medium and CO2 liberation (weight loss) during the fermentation was monitored. The results in Fig. 4 reveal that when the inoculation size was increased from 5 ml to 20 ml, CO2 liberation was also continuously increased. However, when the inoculation size was increased from 20 to 25 ml, CO2 liberation was not further increased. This means that the optimal inoculation size was 20 ml of the culture per 150 ml of the ethanol fermentation medium. This also indicates that 15.2 U of inulinase activity per one gram of inulin was suitable for inulin hydrolysis and ethanol production by the transformant Inu‐66 as 20 ml of the culture contained 684 U of inulinase activity and the total grams of inulin in 150 ml of the fermentation medium were 45. However, growth of Saccharomyces sp. W0 in the ethanol fermentation medium only caused a small amount of weight loss because it had no inulinase activity (Table 1 and Figs 3 and 4).
Affiliation: Unesco Chinese Center of Marine Biotechnology, Ocean University of China, Yushan Road, No. 5, Qingdao, China.