Thermophilic ethanol fermentation from lignocellulose hydrolysate by genetically engineered Moorella thermoacetica

2017 ◽  
Vol 245 ◽  
pp. 1393-1399 ◽  
Author(s):  
Farida Rahayu ◽  
Yuto Kawai ◽  
Yuki Iwasaki ◽  
Koichiro Yoshida ◽  
Akihisa Kita ◽  
...  
Author(s):  
Anli Geng ◽  
Zhankun Wang ◽  
Kok Soon Lai ◽  
Mark Wei Yi Tan

There are various kinds of stresses during the process of ethanol fermentation and more inhibitory factors are produced when lignocelluloses hydrolysate is used as the substrate. The pretreatment of lignocelluloses biomass causes the increase in the amount of acids and thus the decrease in pH. Low-molecular weight aliphatic acids, furaldehydes and a broad range of aromatic compounds are produced during the pretreatment process. They are the inhibitors for the ethanol producers, e.g. Saccharomyces cerevisiae. Furthermore, besides glucose, lignocellulose hydrolysate contains other sugars, such as xylose, arabinose, galactose and mannose etc., among which xylose is taking the major proportion. Stress tolerance and xylose utilization are therefore essential for Saccharomyces cerevisiae strains to get high-efficiency fermentation and high-yield ethanol production from lignocellulosic materials. In this study, a few laboratory and industrial Saccharomyces cerevisiae strains were selected for the evaluation of their potentials in pH tolerance, inhibitor resistance, temperature and ethanol tolerance, and xylose resistance. The results revealed that strains ATCC 96581 and ATCC 24860 are the most stress tolerant S. cerevisiae strains for ethanol fermentation. Such strains will be improved for inhibitor resistance and xylose utilization in the future by metabolic engineering and directed evolution.


2017 ◽  
Vol 83 (8) ◽  
Author(s):  
Yuki Iwasaki ◽  
Akihisa Kita ◽  
Koichiro Yoshida ◽  
Takahisa Tajima ◽  
Shinichi Yano ◽  
...  

ABSTRACT For the efficient production of target metabolites from carbohydrates, syngas, or H2-CO2 by genetically engineered Moorella thermoacetica, the control of acetate production (a main metabolite of M. thermoacetica) is desired. Although propanediol utilization protein (PduL) was predicted to be a phosphotransacetylase (PTA) involved in acetate production in M. thermoacetica, this has not been confirmed. Our findings described herein directly demonstrate that two putative PduL proteins, encoded by Moth_0864 (pduL1) and Moth_1181 (pduL2), are involved in acetate formation as PTAs. To disrupt these genes, we replaced each gene with a lactate dehydrogenase gene from Thermoanaerobacter pseudethanolicus ATCC 33223 (T-ldh). The acetate production from fructose as the sole carbon source by the pduL1 deletion mutant was not deficient, whereas the disruption of pduL2 significantly decreased the acetate yield to approximately one-third that of the wild-type strain. The double-deletion (both pduL genes) mutant did not produce acetate but produced only lactate as the end product from fructose. These results suggest that both pduL genes are associated with acetate formation via acetyl-coenzyme A (acetyl-CoA) and that their disruption enables a shift in the homoacetic pathway to the genetically synthesized homolactic pathway via pyruvate. IMPORTANCE This is the first report, to our knowledge, on the experimental identification of PTA genes in M. thermoacetica and the shift of the native homoacetic pathway to the genetically synthesized homolactic pathway by their disruption on a sugar platform.


2019 ◽  
Vol 273 ◽  
pp. 634-640 ◽  
Author(s):  
Meilin Zhao ◽  
Dingchang Shi ◽  
Xinyao Lu ◽  
Hong Zong ◽  
Bin Zhuge ◽  
...  

Author(s):  
Gary Genosko

While Deleuze explored the temporalities of alcoholism in American literature in The Logic of Sense, and Jean Clet Martin, among others, has extended this inquiry by further extracting the alcoholic’s lines of flight from the same literature, this chapter breaks the mould by understanding alcohol, distilled and in its pure form of ethanol, as well as its imbibition, as a question of a component that passes through anthropocentric, and across multiple non-anthropocentric assemblages. The exploitation of ethanol fermentation, for example, exists across species. Indeed, as we entertain more overtly human cultural examples, such as ‘wine’ for cats, a recent Japanese pet trend, the metabolic communion of interspecies companionship requires that the material expressivity of the substance is overcoded because the ‘wine’ is not only non-alcoholic but liquid catnip in a ‘wine’ bottle. Indeed, theorization of the pursuit of shared pleasures – using Guattari’s ethological terms, we might say deterritorializing from deterministic biological factors yet also modifying these in some measure as well (Machinic Unconscious) – and engaging multiple species is this chapter’s goal, achievable by plotting the passages of alcohol and its related components across assemblages and their material and socio-cultural expressive trajectories beyond strictly anthropocentric and Western prerogatives.


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