Engineering bacterial processes for cellulosic ethanol production

Kambam, Pavan Kumar Reddy; Henson, Michael A.

doi:10.4155/bfs.10.46

Cited by 10 publications

(5 citation statements)

References 157 publications

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“…To this end, microbes other than the widely used model organisms, such as Escherichia coli and Saccharomyces cerevisiae, are being evaluated for their prospective abilities to act as production hosts. Thermophilic organisms are of particular interest due to their multiple advantages over mesophilic organisms when being used as production hosts. − For example, their ability to grow and ferment at thermophilic temperatures reduces the cooling costs, , and increase substrate and product solubility, it reduces the contamination risk with mesophiles, − and there are examples of using thermophiles for nonsterilized fermentations which would reduce sterilization costs, , additionally, the fermentation process runs at the optimum temperature for enzymatic lignocellulose degradation, allowing for efficient simultaneous saccharification and fermentation. , However, the use of nonmodel thermophiles as production hosts is generally hampered by the lack of well-developed genome editing tools compared to those available for currently used mesophilic model organisms. , …”

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confidence: 99%

Efficient Genome Editing of a Facultative Thermophile Using Mesophilic spCas9

et al. 2017

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Well-developed genetic tools for thermophilic microorganisms are scarce, despite their industrial and scientific relevance. Whereas highly efficient CRISPR/Cas9-based genome editing is on the rise in prokaryotes, it has never been employed in a thermophile. Here, we apply Streptococcus pyogenes Cas9 (spCas9)-based genome editing to a moderate thermophile, i.e., Bacillus smithii, including a gene deletion, gene knockout via insertion of premature stop codons, and gene insertion. We show that spCas9 is inactive in vivo above 42 °C, and we employ the wide temperature growth range of B. smithii as an induction system for spCas9 expression. Homologous recombination with plasmid-borne editing templates is performed at 45–55 °C, when spCas9 is inactive. Subsequent transfer to 37 °C allows for counterselection through production of active spCas9, which introduces lethal double-stranded DNA breaks to the nonedited cells. The developed method takes 4 days with 90, 100, and 20% efficiencies for gene deletion, knockout, and insertion, respectively. The major advantage of our system is the limited requirement for genetic parts: only one plasmid, one selectable marker, and a promoter are needed, and the promoter does not need to be inducible or well-characterized. Hence, it can be easily applied for genome editing purposes in both mesophilic and thermophilic nonmodel organisms with a limited genetic toolbox and ability to grow at, or tolerate, temperatures of 37 and at or above 42 °C.

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confidence: 99%

Efficient Genome Editing of a Facultative Thermophile Using Mesophilic spCas9

et al. 2017

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“…E. coli has been genetically altered to produce ethanol since 1987 [57]. In 2010, E. coli was genetically modified to express the Vitreoscilla hemoglobin for direct fermentation of sugar to ethanol [58].…”

Section: Other Fermentation Organismsmentioning

confidence: 99%

Whey to Vodka

Hughes¹,

Risner²,

Meunier-Goddik³

2019

Whey - Biological Properties and Alternative Uses

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Whey production can be an economic and environmental problem for small creameries and acid whey producers. The fermentation and distillation of whey not only eliminates the cost of disposing whey as waste while minimizing environmental impact but adds a revenue option through production of a value-added product. Kluyveromyces marxianus is typically utilized to ferment the pasteurized and pretreated whey. The fermented product contains approximately 3% ethanol v/v. Various options for distilling may be utilized such as a simple two-pot system or a more complex four-stage system to assure production of a neutral spirit. Quality of the distilled spirit is impacted by whey source, whey pretreatment, fermentation conditions, and the distilling process.

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“…Also, Z. mobilis is amply considered since it has been genetically modified to obtain ethanol by cofermentation of several substrates like glucose, xylose and arabinose. This topics have been reviewed elsewhere (Kambam & Henson, 2010;Vinuselvi et al, 2011). For the production of liquid biofuels, mainly ethanol, sequential or simultaneous operational configurations between the hydrolysis or saccharification and fermentation stages have been adopted.…”

Section: Biotransformation Of Lignocellulosic Materials Into Alternatimentioning

confidence: 99%