Topic
Fermentation
About: Fermentation is a research topic. Over the lifetime, 68865 publications have been published within this topic receiving 1251939 citations. The topic is also known as: fermentation (metabolism).
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TL;DR: Itaconic acid could be efficiently produced from liquefied corn starch by overexpressing the glucoamylase gene in A. terreus, which will be helpful for constructing a highly efficient microbial cell factory for itaconate production and for further lowering the production cost of itaconic Acid.
Abstract: Background: Itaconic acid is on the DOE (Department of Energy) top 12 list of biotechnologically produced building block chemicals and is produced commercially by Aspergillus terreus. However, the production cost of itaconic acid is too high to be economically competitive with the petrochemical-based products. Itaconic acid is generally produced from raw corn starch, including three steps: enzymatic hydrolysis of corn starch into a glucose-rich syrup by α-amylase and glucoamylase, fermentation, and recovery of itaconic acid. The whole process is very time-consuming and energy-intensive. Results: In order to reduce the production cost, saccharification and fermentation were integrated into one step through overexpressing the glucoamylase gene in A. terreus under the control of the native PcitA promoter. The transformant XH61-5 produced higher itaconate titer from liquefied starch than WT. To further increase the titer by enhancing the secretion capacity of overexpressed glucoamylase, a stronger signal peptide was selected based on the major secreted protein ATEG_02176 (an acid phosphatase precursor) by A. terreus under the itaconate production conditions. Under the control of the stronger signal peptide, the transformant XH86-8 showed higher itaconate production level than XH61-5 from liquefied starch. The itaconate titer was further enhanced through a two-step process involving the vegetative and production phase, and the transformant XH86-8 produced comparable itaconate titer from liquefied starch to current one (~80 g/L) from saccharified starch hydrolysates in industry. The effects of the new signal peptide and the two-step process on itaconate production were investigated and discussed.
39 citations
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TL;DR: Environmental samples showed higher yeast diversity compared to the fermentations, included the most frequent fermentation species, whereas the most frequently isolated environmental species were Candida carpophila, Candida conglobata, and Candida quercitrusa.
39 citations
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TL;DR: In this article, the authors investigated the cogeneration of hydrogen and methane from protein-mixed food waste by two-phase anaerobic fermentation for the first time, and the hydrogen-producing bacteria derived from activated sludge were used to produce hydrogen from defatted milk powder (DMP) in the first stage.
39 citations
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TL;DR: Investigation of the effect of process stream recirculation on ethanol production from steam- pretreated softwood based on simultaneous saccharification and fermentation was investigated, resulting in a decrease in ethanol yield while hydrolysis seemed unaffected.
Abstract: The effect of process stream recirculation on ethanol production from steam- pretreated softwood based on simultaneous saccharification and fermentation (SSF) was investigated for two process configurations. In the first configuration, a part of the stillage stream after distillation was recycled and, in the second configuration, the liquid after SSF was recycled. The aim was to minimize the energy consumption in the distillation of the fermentation broth and in the evaporation of the stillage, as well as the use of fresh water. However, recirculation leads to an increased concentration of nonvolatiles in the first configuration, and of both volatiles and nonvolatiles in the second configuration. These substances might be inhibitory to the enzymes and the yeast in SSF. When 60% of the fresh water was replaced by stillage, the ethanol yield and the productivity were the same as for the configuration without recirculation. The ethanol production cost was reduced by 17%. In the second configuration, up to 40% of the fresh water could be replaced without affecting the final ethanol yield, although the initial ethanol productivity decreased. The ethanol production cost was reduced by 12%. At higher degrees of recirculation, fermentation was clearly inhibited, resulting in a decrease in ethanol yield while hydrolysis seemed unaffected.
39 citations
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TL;DR: Washed suspensions of Saccheromyces cerevisiae and Saccharomyces uvarum reduce dimethyl sulphide (DMS) but there is no correlation between DMS formation in fermentation and DMSO reduction in whole cells.
Abstract: The ability to produce dimethyl sulphide (DMS) during fermentation of wort is apparently a general characteristic of Saccheromyces cerevisiae and Saccharomyces uvarum. Washed suspensions of these yeasts reduce dimethyl sulphoxide (DMSO) but there is no correlation between DMS formation in fermentation and DMSO reduction in whole cells. Although different strains vary widely in their ability to reduce DMSO they all contain similar levels of NADPH—dependent DMSO reductase. This enzyme is a multi-protein system which closely resembles methionine sulphoxide reductase. Spoilage bacteria including Enterobacter cloacae can reduce DMSO more efficiently than can yeast probably because a different enzyme system is involved.
39 citations