scholarly journals Direct Conversion of Food Waste Extract into Caproate: Metagenomics Assessment of Chain Elongation Process

2021 ◽  
Vol 9 (2) ◽  
pp. 327
Author(s):  
Simona Crognale ◽  
Camilla M. Braguglia ◽  
Agata Gallipoli ◽  
Andrea Gianico ◽  
Simona Rossetti ◽  
...  
Keyword(s):  
Food Waste ◽  
Direct Conversion ◽  
Added Value ◽  
Chain Elongation ◽  
Continuous Reactor ◽  
Organic Loading Rate ◽  
Ferredoxin Oxidoreductase ◽  
Pyruvate Ferredoxin Oxidoreductase ◽  
Elongation Process ◽  
Waste Extract

In a circular economy strategy, waste resources can be used for the biological production of high added-value substances, such as medium chain fatty acids (MCFAs), thus minimising waste and favouring a sustainable process. This study investigates single-stage fermentation processes for the production of MCFAs in a semi-continuous reactor treating the extract of real food waste (FW), without the addition of external electron donors. Two sequential acidogenic fermentation tests were carried out at an organic loading rate (OLR) of 5 and 15 gCOD L−1d−1 with a hydraulic retention time of 4 days and pH controlled at 6 ± 0.2. The highest level of caproate (4.8 g L−1) was observed at OLR of 15 gCOD L−1d−1 with a microbiome mainly composed by lactate-producing Actinomyces, Atopobium, and Olsenella species and caproate-producing Pseudoramibacter. Metagenomic analysis revealed the presence of key enzymes for the production of lactate, such as lactate dehydrogenase and pyruvate ferredoxin oxidoreductase, as well as several enzymes involved in the reverse β-oxidation pathway, thus suggesting the occurrence of a lactate-based chain elongation process.

scholarly journals Adjusting Organic Load as a Strategy to Direct Single-Stage Food Waste Fermentation from Anaerobic Digestion to Chain Elongation

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1487
Author(s):  
Vicky De Groof ◽  
Marta Coma ◽  
Tom C. Arnot ◽  
David J. Leak ◽  
Ana B. Lanham
Keyword(s):  
Anaerobic Digestion ◽  
Food Waste ◽  
Loading Rate ◽  
Biogas Production ◽  
Single Stage ◽  
Stirred Tank ◽  
Chain Elongation ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Operating Strategy

Production of medium chain carboxylic acids (MCCA) as renewable feedstock bio-chemicals, from food waste (FW), requires complicated reactor configurations and supplementation of chemicals to achieve product selectivity. This study evaluated the manipulation of organic loading rate in an un-supplemented, single stage stirred tank reactor to steer an anaerobic digestion (AD) microbiome towards acidogenic fermentation (AF), and thence to chain elongation. Increasing substrate availability by switching to a FW feedstock with a higher COD stimulated chain elongation. The MCCA species n-caproic (10.1 ± 1.7 g L−1) and n-caprylic (2.9 ± 0.8 g L−1) acid were produced at concentrations comparable to more complex reactor set-ups. As a result, of the adjusted operating strategy, a more specialised microbiome developed containing several MCCA-producing bacteria, lactic acid-producing Olsenella spp. and hydrogenotrophic methanogens. By contrast, in an AD reactor that was operated in parallel to produce biogas, the retention times had to be doubled when fed with the high-COD FW to maintain biogas production. The AD microbiome comprised a diverse mixture of hydrolytic and acidogenic bacteria, and acetoclastic methanogens. The results suggest that manipulation of organic loading rate and food-to-microorganism ratio may be used as an operating strategy to direct an AD microbiome towards AF, and to stimulate chain elongation in FW fermentation, using a simple, un-supplemented stirred tank set-up. This outcome provides the opportunity to repurpose existing AD assets operating on food waste for biogas production, to produce potentially higher value MCCA products, via simple manipulation of the feeding strategy.

scholarly journals Development of an Effective Chain Elongation Process From Acidified Food Waste and Ethanol Into n-Caproate

2018 ◽  
Vol 6 ◽  
Author(s):  
Mark Roghair ◽  
Yuchen Liu ◽  
David P. B. T. B. Strik ◽  
Ruud A. Weusthuis ◽  
Marieke E. Bruins ◽  
...  
Keyword(s):  
Food Waste ◽  
Chain Elongation ◽  
Elongation Process

scholarly journals Pyruvate-Ferredoxin Oxidoreductase

1971 ◽  
Vol 246 (10) ◽  
pp. 3120-3125
Author(s):  
Kosaku Uyeda ◽  
Jesse C. Rabinowitz
Keyword(s):  
Ferredoxin Oxidoreductase ◽  
Pyruvate Ferredoxin Oxidoreductase

scholarly journals Zeolite addition to improve biohydrogen production from dark fermentation of C5/C6-sugars and Sargassum sp. biomass

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. M. Silva ◽  
A. A. Abreu ◽  
A. F. Salvador ◽  
M. M. Alves ◽  
I. C. Neves ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Anaerobic Bacteria ◽  
Dark Fermentation ◽  
Inorganic Materials ◽  
Biohydrogen Production ◽  
High Rate ◽  
Continuous Reactor ◽  
Organic Loading Rate ◽  
Fermentation Products ◽  
Zeolite Type

AbstractThermophilic biohydrogen production by dark fermentation from a mixture (1:1) of C5 (arabinose) and C6 (glucose) sugars, present in lignocellulosic hydrolysates, and from Sargassum sp. biomass, is studied in this work in batch assays and also in a continuous reactor experiment. Pursuing the interest of studying interactions between inorganic materials (adsorbents, conductive and others) and anaerobic bacteria, the biological processes were amended with variable amounts of a zeolite type-13X in the range of zeolite/inoculum (in VS) ratios (Z/I) of 0.065–0.26 g g−1. In the batch assays, the presence of the zeolite was beneficial to increase the hydrogen titer by 15–21% with C5 and C6-sugars as compared to the control, and an increase of 27% was observed in the batch fermentation of Sargassum sp. Hydrogen yields also increased by 10–26% with sugars in the presence of the zeolite. The rate of hydrogen production increased linearly with the Z/I ratios in the experiments with C5 and C6-sugars. In the batch assay with Sargassum sp., there was an optimum value of Z/I of 0.13 g g−1 where the H2 production rate observed was the highest, although all values were in a narrow range between 3.21 and 4.19 mmol L−1 day−1. The positive effect of the zeolite was also observed in a continuous high-rate reactor fed with C5 and C6-sugars. The increase of the organic loading rate (OLR) from 8.8 to 17.6 kg m−3 day−1 of COD led to lower hydrogen production rates but, upon zeolite addition (0.26 g g−1 VS inoculum), the hydrogen production increased significantly from 143 to 413 mL L−1 day−1. Interestingly, the presence of zeolite in the continuous operation had a remarkable impact in the microbial community and in the profile of fermentation products. The effect of zeolite could be related to several properties, including the porous structure and the associated surface area available for bacterial adhesion, potential release of trace elements, ion-exchanger capacity or ability to adsorb different compounds (i.e. protons). The observations opens novel perspectives and will stimulate further research not only in biohydrogen production, but broadly in the field of interactions between bacteria and inorganic materials.

Pyruvate:ferredoxin oxidoreductase in Campylobacter species

1995 ◽  
Vol 41 (2) ◽  
pp. 198-201 ◽  
Author(s):  
James A. Daucher ◽  
Noel R. Krieg
Keyword(s):  
Clostridium Pasteurianum ◽  
Benzyl Viologen ◽  
Minimal Inhibitory Concentrations ◽  
Ferredoxin Oxidoreductase ◽  
Crude Extracts ◽  
Reducing Activity ◽  
Pyruvate Ferredoxin Oxidoreductase ◽  
Pyruvate:Ferredoxin Oxidoreductase ◽  
Campylobacter Species

Twelve strains representing 11 Campylobacter species were tested by two methods to see whether pyruvate:ferredoxin oxidoreductase, which occurs mainly in anaerobes, was also present in these oxygen-respiring microaerophiles. Crude extracts exhibited a pyruvate-dependent reduction of benzyl viologen and, to a lesser extent, metronidazole. Addition of Clostridium pasteurianum ferredoxin enhanced the metronidazole-reducing activity. All strains were inhibited by metronidazole, with minimal inhibitory concentrations ranging from 3 to 25 μg/mL. The results suggest that pyruvate: ferredoxin oxidoreductase is characteristic of the genus.Key words: Campylobacter, microaerophilic, metronidazole, pyruvate.

Aerobic resistance of Trichomonas vaginalis to metronidazole induced in vitro

Parasitology ◽  
1993 ◽  
Vol 106 (1) ◽  
pp. 31-37 ◽  
Author(s):  
J. Tachezy ◽  
J. Kulda ◽  
E. Tomková
Keyword(s):  
Parent Strain ◽  
Trichomonas Vaginalis ◽  
Drug Resistant ◽  
Ferredoxin Oxidoreductase ◽  
Low Concentrations ◽  
Percent Concentration ◽  
Resistant Strains ◽  
Pyruvate Ferredoxin Oxidoreductase

SUMMARYAerobic resistance of Trichomonas vaginalis to metronidazole was induced in vitro by anaerobic cultivation of drug-susceptible trichomonads with low concentrations of the drug (2–3 μg/ml) for 50 days. Minimal lethal concentrations (MLC) for metronidazole of the resistant derivatives were high in aerobic susceptibility assays (MLC = 216–261.5 μg/ml) but low in anaerobic assays (MLC = 4.2–6.3 μg/ml), surpassing MLC values of their parent strain approximately 50-fold and 3-fold under aerobiosis and anaerobiosis, respectively. Sensitivity to metronidazole under anaerobic conditions and activity of the hydrogenosomal enzyme pyruvate: ferredoxin oxidoreductase indicated that the resistance was of the aerobic type. Dependence of the resistance manifestation on O2 was further confirmed by susceptibility assays in vitro performed in defined gas mixtures of different oxygen content (1–20%). Five percent concentration of O2 proved to be the threshold required for resistance demonstration and the MLC values further increased with increasing O2 concentrations. The in vitro-induced resistance was also demonstrated in vivo by subcutaneous mouse assay. The dose of metronidazole needed to cure 50% of infected mice (DC50) was 223 mg/kg × 3 for resistant derivative MR-3a but 6.6 mg/kg × 3 only for its drug-susceptible parent strain. The metronidazole – resistant strains developed in this study correspond by their properties to drug-resistant T. vaginalis strains isolated from patients refractory to treatment, and promise to be a useful tool in the study of 5-nitroimidazole aerobic resistance.

scholarly journals Development of an enhanced chain elongation process for caproic acid production from waste-derived lactic acid and butyric acid

2020 ◽  
Author(s):  
Corine Nzeteu
Keyword(s):  
Lactic Acid ◽  
Butyric Acid ◽  
Acid Production ◽  
Caproic Acid ◽  
Chain Elongation ◽  
Elongation Process ◽  
The Right

Contribution to the International Chain Elongation Conference 2020 | ICEC 2020. An abstract can be found in the right column.

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