Chain elongation of acetate and ethanol in an upflow anaerobic filter for high rate MCFA production

Grootscholten, T.I.M.; Steinbusch, K.J.J.; Hamelers, H.V.M.; Buisman, Cees J.N.

doi:10.1016/j.biortech.2012.10.165

Cited by 155 publications

(153 citation statements)

References 17 publications

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“…[5][6][7][8][9][10][11][12][13][14][15] In addition to hydrogen, other high-value intermediates are also recoverable from wastewater treated anaerobically, such as medium chain fatty acids (MCFA), which are used to produce biokerosene and biodiesel. [16][17][18] Conventional resource recovery systems tend to mimic and intensify natural anaerobic systems, and hence, can be limited. State-of-the-art technologies, such as granulation, attached growth systems, and anaerobic membrane bioreactors, retain biomass, separating the solids (or biomass) retention time (SRT) from the hydraulic retention time (HRT); this reduces the risk of biomass washout and enables more flexible process control.…”

Section: Introductionmentioning

confidence: 99%

Achieving high-rate hydrogen recovery from wastewater using customizable alginate polymer gel matrices encapsulating biomass

Zhu

Arnold

Sakkos

et al. 2018

Environ. Sci.: Water Res. Technol.

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aIn addition to methane gas, higher-value resources such as hydrogen gas are produced during anaerobic wastewater treatment. They are, however, immediately consumed by other organisms. To recover these high-value resources, not only do the desired phenotypes need to be retained in the anaerobic reactor, but the undesired ones need to be washed out. In this study, a well-established alginate-based polymer gel, with and without a coating layer, was used to selectively encapsulate hydrogen-producing biomass in beads to achieve high-rate recovery of hydrogen during anaerobic wastewater treatment. , as well as a composite coating on the beads, consisting of alternating layers of polyethylenimine and silica hydrogel, were investigated with respect to their performance, specifically, their mass transfer characteristics and their differential ability to retain the encapsulated biomass. Although the coating reduced the escape rate of encapsulated biomass from the beads, all alginate polymer matrices without coating effectively retained biomass. Fast diffusion of dissolved organic carbon (DOC) through the polymer gel was observed in both Ca-alginate and Sr-alginate without coating. The coating, however, decreased either the diffusivity or the permeability of the DOC depending on whether the DOC was from synthetic wastewater (more lipids and proteins) or real brewery wastewater (more sugars). Consequently, the encapsulation system with coating became diffusion limited when brewery wastewater with high chemical oxygen demand was fed, resulting in a lower hydrogen production rate than the uncoated encapsulation systems. In all cases the encapsulated biomass was able to produce hydrogen, even at a hydraulic residence time of 45 min. Although there are limitations to this system, the used of encapsulated biomass for resource recovery from wastewater shows promise, particularly for highrate systems in which the retention of specific phenotypes is desired.

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Section: Introductionmentioning

confidence: 99%

Achieving high-rate hydrogen recovery from wastewater using customizable alginate polymer gel matrices encapsulating biomass

Zhu

Arnold

Sakkos

et al. 2018

Environ. Sci.: Water Res. Technol.

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“…In all these cases, LAB and lactic acid are added together with the substrate to the reactor, but the mechanisms for the formation of metabolic periods still remain unclear. Biochemical mechanisms for carbon chain elongation of organic acids occur in anaerobic fermentation systems and are exploited for the production of carboxylate platform chemicals from biomass (Agler et al 2011;Grootscholten et al 2013). For chain elongation, the presence of energyrich reduced compounds such as ethanol or lactic acid is required (Spirito et al 2014).…”

Section: Discussionmentioning

confidence: 99%

Metabolic and microbial community dynamics during the anaerobic digestion of maize silage in a two-phase process

Sträuber

Lucas

Kleinsteuber

2015

Appl Microbiol Biotechnol

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Two-phasic anaerobic digestion processes (hydrolysis/acidogenesis separated from acetogenesis/methanogenesis) can be used for biogas production on demand or a combined chemicals/bioenergy production. For an effective process control, detailed knowledge about the microbial catalysts and their correlation to process conditions is crucial. In this study, maize silage was digested in a two-phase process and interrelationships between process parameters and microbial communities were revealed. In the first-phase reactor, alternating metabolic periods were observed which emerged independently from the feeding frequency. During the L-period, up to 11.8 g L(-1) lactic acid was produced which significantly correlated to lactic acid bacteria of the genus Lactobacillus as the most abundant community members. During the alternating G-period, the production of volatile fatty acids (up to 5.3, 4.0 and 3.1 g L(-1) for propionic, n-butyric and n-caproic acid, respectively) dominated accompanied by a high gas production containing up to 28 % hydrogen. The relative abundance of various Clostridiales increased during this metabolic period. In the second-phase reactor, the metabolic fluctuations of the first phase were smoothed out resulting in a stable biogas production as well as stable bacterial and methanogenic communities. However, the biogas composition followed the metabolic dynamics of the first phase: the hydrogen content increased during the L-period whereas highest CH4/CO2 ratios (up to 2.8) were reached during the G-period. Aceticlastic Methanosaeta as well as hydrogenotrophic Methanoculleus and Methanobacteriaceae were identified as dominant methanogens. Consequently, a directed control of the first-phase stabilizing desired metabolic states can lead to an enhanced productivity regarding chemicals and bioenergy.

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“…A recent development is the production of fatty acids by processes using microbial chain elongation from organic waste material, yielding both odd-and even-chain-length fatty acids ranging from C 4 to C 9 (5,6).…”

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confidence: 99%

Application of AlkBGT and AlkL from Pseudomonas putida GPo1 for Selective Alkyl Ester ω-Oxyfunctionalization in Escherichia coli

Nuland

Eggink

Weusthuis

2016

Appl Environ Microbiol

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The enzyme system AlkBGT from Pseudomonas putida GPo1 can efficiently -functionalize fatty acid methyl esters. Outer membrane protein AlkL boosts this -functionalization. In this report, it is shown that whole cells of Escherichia coli expressing the AlkBGT system can also -oxidize ethyl nonanoate (NAEE). Coexpression of AlkBGT and AlkL resulted in 1.7-fold-higher -oxidation activity on NAEE. With this strain, initial activity on NAEE was 70 U/g (dry weight) of cells (g cdw ), 67% of the initial activity on methyl nonanoate. In time-lapse conversions with 5 mM NAEE the main product was 9-hydroxy NAEE (3.6 mM), but also 9-oxo NAEE (0.1 mM) and 9-carboxy NAEE (0.6 mM) were formed. AlkBGT also -oxidized ethyl, propyl, and butyl esters of fatty acids ranging from C 6 to C 10 . Increasing the length of the alkyl chain improved the -oxidation activity of AlkBGT on esters of C 6 and C 7 fatty acids. From these esters, application of butyl hexanoate resulted in the highest -oxidation activity, 82 U/g cdw . Coexpression of AlkL only had a positive effect on -functionalization of substrates with a total length of C 11 or longer. These findings indicate that AlkBGT(L) can be applied as a biocatalyst for -functionalization of ethyl, propyl, and butyl esters of medium-chain fatty acids. IMPORTANCEFatty acid esters are promising renewable starting materials for the production of -hydroxy fatty acid esters (-HFAEs).-HFAEs can be used to produce sustainable polymers. Chemical conversion of the fatty acid esters to -HFAEs is challenging, as it generates by-products and needs harsh reaction conditions. Biocatalytic production is a promising alternative. In this study, biocatalytic conversion of fatty acid esters toward -HFAEs was investigated using whole cells. This was achieved with recombinant Escherichia coli cells that produce the AlkBGT enzymes. These enzymes can produce -HFAEs from a wide variety of fatty acid esters. Medium-chain-length acids (C 6 to C 10 ) esterified with ethanol, propanol, or butanol were applied. This is a promising production platform for polymer building blocks that uses renewable substrates and mild reaction conditions. T he global demand for polymers is expected to grow in the coming years (1) and thus also the need for sustainable polymer production processes. -Hydroxy fatty acids (-HFAs) and dicarboxylic acids (DCAs) are building blocks of polymers such as polyesters and polyamides (1-3). These compounds can be produced from medium-chain-length fatty acids (MCFAs) by oxidation of the terminal methyl group, a reaction called -oxidation (4).A recent development is the production of fatty acids by processes using microbial chain elongation from organic waste material, yielding both odd-and even-chain-length fatty acids ranging from C 4 to C 9 (5, 6).Chemical -oxidation of nonactivated terminal methyl groups remains challenging due to the inert nature of these bonds. This results in poor selectivity (7,8). Biocatalytic -oxidation can be a solution for the terminal activation of fatty acid (est...

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Chain elongation of acetate and ethanol in an upflow anaerobic filter for high rate MCFA production

Cited by 155 publications

References 17 publications

Achieving high-rate hydrogen recovery from wastewater using customizable alginate polymer gel matrices encapsulating biomass

Achieving high-rate hydrogen recovery from wastewater using customizable alginate polymer gel matrices encapsulating biomass

Metabolic and microbial community dynamics during the anaerobic digestion of maize silage in a two-phase process

Application of AlkBGT and AlkL from Pseudomonas putida GPo1 for Selective Alkyl Ester ω-Oxyfunctionalization in Escherichia coli

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