Comparison of Ethanol Fermentation Efficiency: Syngases versus Microorganisms
The anaerobic fermentation required for ethanol production from syngas appears to be a promising and competitive engineering application technology. The main challenge facing for syngas fermentation is the fact that it is often limited by low ethanol productivity. To evaluate the ability of different syngases and microorganisms to ferment ethanol and screen those efficient syngases and microorganisms, three simulative syngas mixtures and eight strains were investigated in 300 ml bottle fermentations. The results show that, both syngases and cultures affected ethanol production at a highly significant level (p<0.01). The maximum net ethanol concentrations (28.001, 23.871, 22.909 and 19.726 mg/L) were obtained with strains LP-fm4, C. carboxidivorans P7, B-fm4 and C. ljungdahlii using biomass-generated syngas, which yielded approximately two and three times more ethanol compared with strains C. ljungdahlii, B-fm4 (11.734, 10.300 mg/L) using corex-gas and strains C. carboxidivorans P7, C. ragsdalei P11 (9.937, 8.318 mg/L) using blast furnace gas, respectively. So, using biomass-generated syngas and strains LP-fm4ãC. carboxidivorans P7ãB-fm4 and C. ljungdahlii represented the best combination for fermenting ethanol efficiently compared with the other two. In addition, the maximum ethanol production per unit cell of both strains LP-fm4 and B-fm4 with biomass-generated syngas, C. ragsdalei P11 with blast furnace gas and B-fm4 with corex-gas were 1000.036, 881.103, 519.854 and 468.030 mg/L, respectively. This indicates that strains LP-fm4 and B-fm4 are the most promising for biomass-generated syngas fermentation, strains C. ragsdalei P11 and B-fm4 are potential candidates for blast furnace gas and corex-gas fermentations respectively.
Feng-Qin Wang, Yan-da Zhang, Bing-bing Sun, Hui Xie, Da-jiao Yang, Sen -Yang, Tian-bao Ren, Sheng Yang, An-Dong Song