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81.
An overview of advances in acetone-butanol fermentation research is presented with specific reference to the history of acetone-butanol fermentation, genetic manipulation of the butanol-producing Clostridium beijerinckii NCIMB 8052, as well as upstream and downstream processing. Specific reference is made to the development of the hyperamylolytic, hyper-"butanolagenic" C. beijerinckii BA101 strain. Amylolytic enzyme production by C. beijerinckii BA101 was 1.8- and 2.5-fold greater than that of the C. beijerinckii NCIMB 8052 strain grown in starch and glucose, respectively. We confirmed the presence of a phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS) associated with cell extracts of C. beijerinckii BA101 by glucose phosphorylation by PEP and ATP-dependent glucose phosphorylation. It was found that C. beijerinckii BA101 was defective in PTS activity and that it compensates for this defect with enhanced glucokinase activity, resulting in an ability to transport and utilize glucose during the solventogenic stage. The principal problem associated with acetone-butanol fermentation by C. beijerinckii or C. acetobutylicum is butanol toxicity/inhibition to the culture. To solve this problem, we have attempted various alternative in situ/online techniques of butanol removal including membrane-based systems such as pervaporation, liquid-liquid extraction, and gas stripping. We found that gas stripping and pervaporation appear to be the most promising of the in situ acetone-butanol fermentation and recovery techniques but, in terms of cost-effective industrial applications, gas stripping appears to be the most promising. 相似文献
82.
M.C. McCarthyP. Thaddeus 《Journal of Molecular Spectroscopy》2002,211(2):235-240
The microwave rotational spectra of the carbon-13 isotopic species of H2C3, H2C4, and H2C5 have been observed in a pulsed supersonic molecular beam by Fourier transform microwave spectroscopy. At high resolution all of the rotational lines exhibit hyperfine structure produced by the magnetic interaction between the nuclear spin of 13C and the overall rotation of the molecule. The component of the nuclear spin-rotation tensor along the a-inertial axis is large for most isotopic species, especially at the carbene carbon; at this position Caa is two to three times larger than at other substituted positions along the chain. In contrast to both H2C3 and H2C3, in H2C4Caa exhibits a pronounced alternation along the carbon chain backbone. Following detection of the five carbon-13 isotopic species and D2C5, an experimental structure (r0) has been determined to high accuracy for H2C5. 相似文献
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