Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Tham khảo tài liệu 'biodiesel quality emissions and by products part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 314 Biodiesel - Quality Emissions and By-Products entails the formation of unwanted byproducts such as acetic acid lactic acid formic acid succinic acid butyric acid 2 3-butanediol and ethanol. The main byproducts of K. pneumoniae strains are 2 3-butanediol acetic acid ethanol and lactic acid Menzel et al. 1997 Zhang et al. 2006 Kretschmann et al. 1993 whereas C. butyricum and metabolically engineered C. acetobutylicum strains mainly accumulate byproducts acetic acid and butyric acid during 1 3-PDO production Papanikolaou et al. 2000 Papanikolaou et al. 2004 Saintamans et al. 1994 Gonzalez-Pajuelo et al. 2005 Soucaille 2008 Sarcabal et al. 2007 . With C. pasteurianum butanol but not 1 3-PDO is the main fermentation product from glycerol and ethanol acetic acid butyric acid and lactic acid are formed as further byproducts Biebl 2001 . Metabolically engineered E. coli were reported to accumulate formic acid acetic acid lactic acid and pyruvic acid as the major byproducts Tong et al. 1991 Skraly et al. 1998 and accumulate growth inhibiting metabolites glycerol-3-phosphate and methylglyoxylate Tkac et al. 2001 Zhu et al. 2001 . A major concern in 1 3-PDO production is the fact that the substrate glycerol the intermediate 3-HPA the product 1 3-PDO and several byproducts inhibit growth and production. In K. pneumoniae 1 3-PDO yields decrease with increasing glycerol concentrations and metabolic flux analyses revealed a higher carbon flux via the oxidative glycerol utilization pathway to the loss of 1 3-PDO Xiu et al. 2011 . In C. butyricum growth is completely inhibited at 1 3-PDO concentrations higher than 60 g l-1. Also the byproducts acetic acid 27 g l-1 and butyric acid 19 g l-1 abolished growth of this bacterium as did glycerol concentrations of 80 g l-1 or more Biebl 1991 Colin et al. 2000 . Growth of K. pneumoniae is inhibited at glycerol concentrations above 110 g l-1 under aerobic and above 133 g l-1 under anaerobic conditions. Also the byproducts acetic acid 15
