Single-step ethanol production from lignocellulose using novel extremely thermophilic bacteria

Svetlitchnyi, Vitali; Kensch, Oliver; Falkenhan, Doris A.; Korseska, Svenja G; Lippert, Nadine; Prinz, Melanie; Sassi, Jamaleddine; Schickor, Anke; Curvers, Simon

doi:10.1186/1754-6834-6-31

Cited by 83 publications

(63 citation statements)

References 36 publications

(64 reference statements)

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“…This yield obtained can by compared with the yield by other wild type bacteria. Svetlitchnyi et al [54] reported maximum ethanol yield of 3.5 g/l from the wild type bacterium Caldicellulosiruptor DIB 004C. Sato et al [55] reported ethanol production of 4 g/l by wild type Clostridum thermocellum strain I-1-B and an improved 23.6 g/l ethanol by the same strain when grown in optimized medium.…”

Section: Discussionmentioning

confidence: 99%

Bioethanol Production by an Ethanol-Tolerant Bacillus cereus Strain GBPS9 Using Sugarcane Bagasse and Cassava Peels as Feedstocks

Ezebuiro¹,

Ogugbue²,

Oruwari³

et al. 2015

J Biotechnol Biomater

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Bioethanol production potential of ethanol-tolerant Bacillus cereus strain GBPS9 using sugarcane bagasse and cassava peels as feedstocks was investigated. The Bacillus cereus GBPS9 used in this study was isolated from agro-wastes impacted soil and classified based on phylogenetic analysis of its 16S rRNA gene. The sequence of the isolate has been deposited in GenBank under the accession number KT318371.1. The isolate was selected based on its cellulolytic ability, tolerance to ethanol concentration of 6% (v/v) and ability to ferment sugar to ethanol. The substrates employed in the study were cassava peels and sugarcane bagasse. Chemical composition analysis showed total carbohydrate and lignin contents (% dry weight) of 69.6 ± 1.2 and 13.9 ± 0.4 for cassava peels and 70.3 ± 1.9 and 16.2 ± 1.2 for sugarcane bagasse, respectively. The feedstocks were subjected to acid, alkali and steam explosion pretreatments to increase cellulose content and therefore, reduce lignin content. The best pretreatment methods (steam explosion for sugarcane bagasse and acid for cassava peels) increased total carbohydrate contents to 85.4 ± 2.33 and 80.4 ± 2.5 for sugarcane bagasse and cassava peels, respectively. The respective lignin contents after pretreatment were 4.2 ± 0.44 and 4.8 ± 0.8 for sugarcane bagasse and cassava peels. Cultural conditions (pH, temperature, nitrogen source, inoculum size and substrate concentration) of the bacterium were optimized to enhance cellulase production. The laboratory scale fermentation of the feedstocks to ethanol was carried out in 250 mL Erlenmeyer flasks. Gas Chromatography -Mass spectrometry (GC-MS) analysis of the fermentation broth of sugarcane bagasse and cassava peels substrates revealed ethanol contents of 18.40 and 17.80 g/L, respectively. The study has demonstrated efficient bioethanol production by Bacillus cereus GBPS9 using sugarcane bagasse and cassava peels as feedstocks.

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Section: Discussionmentioning

confidence: 99%

Bioethanol Production by an Ethanol-Tolerant Bacillus cereus Strain GBPS9 Using Sugarcane Bagasse and Cassava Peels as Feedstocks

Ezebuiro¹,

Ogugbue²,

Oruwari³

et al. 2015

J Biotechnol Biomater

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“…However, very few microorganisms able to grow at such temperatures are able to generate ethanol from sugar (8)(9)(10), and no bacterium growing above 70°C produces an alcohol other than ethanol. In addition, no member of the domain Archaea is known to produce any alcohol as a major product, regardless of growth temperature.…”

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Single gene insertion drives bioalcohol production by a thermophilic archaeon

Basen

Schut

Nguyen

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Bioethanol production is achieved by only two metabolic pathways and only at moderate temperatures. Herein a fundamentally different synthetic pathway for bioalcohol production at 70°C was constructed by insertion of the gene for bacterial alcohol dehydrogenase (AdhA) into the archaeon Pyrococcus furiosus. The engineered strain converted glucose to ethanol via acetate and acetaldehyde, catalyzed by the host-encoded aldehyde ferredoxin oxidoreductase (AOR) and heterologously expressed AdhA, in an energy-conserving, redox-balanced pathway. Furthermore, the AOR/AdhA pathway also converted exogenously added aliphatic and aromatic carboxylic acids to the corresponding alcohol using glucose, pyruvate, and/or hydrogen as the source of reductant. By heterologous coexpression of a membrane-bound carbon monoxide dehydrogenase, CO was used as a reductant for converting carboxylic acids to alcohols. Redirecting the fermentative metabolism of P. furiosus through strategic insertion of foreign genes creates unprecedented opportunities for thermophilic bioalcohol production. Moreover, the AOR/AdhA pathway is a potentially game-changing strategy for syngas fermentation, especially in combination with carbon chain elongation pathways.Archaea | metabolic engineering | hyperthermophile | carbon monoxide | aldehydes

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“…Examples of strictly anaerobic thermophiles that have been studied for biofuel production are Clostridium thermocellum (14,15), several Caldicellulosiruptor spp. (16)(17)(18), as well as Thermoanaerobacterium spp. and Thermoanaerobacter spp.…”

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confidence: 99%

Isolation and Screening of Thermophilic Bacilli from Compost for Electrotransformation and Fermentation: Characterization of Bacillus smithii ET 138 as a New Biocatalyst

Bosma

Weijer

Daas

et al. 2015

Appl Environ Microbiol

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b Thermophilic bacteria are regarded as attractive production organisms for cost-efficient conversion of renewable resources to green chemicals, but their genetic accessibility is a major bottleneck in developing them into versatile platform organisms. In this study, we aimed to isolate thermophilic, facultatively anaerobic bacilli that are genetically accessible and have potential as platform organisms. From compost, we isolated 267 strains that produced acids from C 5 and C 6 sugars at temperatures of 55°C or 65°C. Subsequently, 44 strains that showed the highest production of acids were screened for genetic accessibility by electroporation. Two Geobacillus thermodenitrificans isolates and one Bacillus smithii isolate were found to be transformable with plasmid pNW33n. Of these, B. smithii ET 138 was the best-performing strain in laboratory-scale fermentations and was capable of producing organic acids from glucose as well as from xylose. It is an acidotolerant strain able to produce organic acids until a lower limit of approximately pH 4.5. As genetic accessibility of B. smithii had not been described previously, six other B. smithii strains from the DSMZ culture collection were tested for electroporation efficiencies, and we found the type strain DSM 4216 T and strain DSM 460 to be transformable. The transformation protocol for B. smithii isolate ET 138 was optimized to obtain approximately 5 ؋ 10 3 colonies per g plasmid pNW33n. Genetic accessibility combined with robust acid production capacities on C 5 and C 6 sugars at a relatively broad pH range make B. smithii ET 138 an attractive biocatalyst for the production of lactic acid and potentially other green chemicals. Green chemicals are sustainable bio-based alternatives for chemicals based on fossil resources. Biomass is considered an attractive renewable resource for the production of such green chemicals. Major challenges for using biomass are to develop costeffective production processes and to convert substrates that go beyond first-generation pure sugars. From this perspective, the use of microbial fermentation processes that convert lignocellulosic sugars is gaining considerable attention. For particular products natural producers can be used, but often Escherichia coli and Saccharomyces cerevisiae are used as platform organisms because of their well-known physiology and ease of engineering for the production of many different products (1, 2).In general, most organisms used for the production of green chemicals and fuels are mesophiles, and current processes still are based mainly on first-generation feedstocks, i.e., sucrose from sugar beet or sugarcane or glucose derived from starches from corn or tapioca. Although the engineering of platform organisms broadens the spectrum of possible substrates (3), the efficiency of the process could be increased by the use of organisms naturally capable of degrading lignocellulose-derived sugars (4). To further increase the efficiency and reduce the costs of the microbial production of green chemicals, modera...

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Single-step ethanol production from lignocellulose using novel extremely thermophilic bacteria

Cited by 83 publications

References 36 publications

Bioethanol Production by an Ethanol-Tolerant Bacillus cereus Strain GBPS9 Using Sugarcane Bagasse and Cassava Peels as Feedstocks

Bioethanol Production by an Ethanol-Tolerant Bacillus cereus Strain GBPS9 Using Sugarcane Bagasse and Cassava Peels as Feedstocks

Single gene insertion drives bioalcohol production by a thermophilic archaeon

Isolation and Screening of Thermophilic Bacilli from Compost for Electrotransformation and Fermentation: Characterization of Bacillus smithii ET 138 as a New Biocatalyst

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