scholarly journals Microbial Communities Performing Hydrogen Solventogenic Metabolism of Volatile Fatty Acids

2021 ◽  
Author(s):  
Gustavo Mockaitis ◽  
Guillaume Bruant ◽  
Eugenio Foresti ◽  
Marcelo Zaiat ◽  
Serge Guiot
Keyword(s):  
Fatty Acids ◽  
Bacterial Community ◽  
Partial Pressure ◽  
Microbial Communities ◽  
Metabolic Pathways ◽  
Thermodynamic Data ◽  
Volatile Fatty Acids ◽  
Thermal Pretreatment ◽  
Alcohol Production ◽  
Acidic Pretreatment

Abstract Four different physicochemical pretreatments on an anaerobic inoculum used for alcohol production from acetate and butyrate are evaluated. Experiments were conducted in single batches using acetate and butyrate as substrates at 30°C and with a pressurized headspace of pure H2 at 2.15 atm (218.2 MPa). Thermal and acidic-thermal pretreatments lead to higher production of both ethanol and butanol. Modelling shows that the highest attainable concentrations of ethanol and butanol produced were 122 mg L−1 and 97 mg L−1 for the thermal pretreatment (after 17.5 days) and 87 mg L−1 and 143 mg L−1 for the acidic-thermal pretreatment (after 18.9 days). Thermodynamic data indicated that a high H2 partial pressure favoured solventogenic metabolic pathways. Acidic-thermal pretreatment selected a bacterial community more adapted to the conversion of acetate and butyrate into ethanol and butanol, respectively. Thermal-acidic pretreatment was unstable, showing significant variability between replicates. Acidic pretreatment showed the lowest alcohol production.

scholarly journals Effect of Inoculum Pretreatment on Alcohol Production from Volatile Fatty Acids through an Anaerobic Solventogenic Process

2021 ◽  
Author(s):  
Gustavo Mockaitis ◽  
Guillaume Bruant ◽  
Eugenio Foresti ◽  
Marcelo Zaiat ◽  
Serge R. Guiot
Keyword(s):  
Fatty Acids ◽  
Volatile Fatty Acids ◽  
Liquid Fuels ◽  
Biological Processes ◽  
Thermal Pretreatment ◽  
Sequencing Data ◽  
Balance Study ◽  
Alcohol Production ◽  
Acidic Pretreatment ◽  
Mass Balance Study

1AbstractBackgroundProduction of alcohols from wastes through biological processes is environmentally and economically interesting, since they can be valorized as drop-in liquid fuels, which have a high market value. Using microbial mixed cultures in such processes is of great interest since it confers more stability, a higher resistance to both toxicity and contamination, and an increased substrate flexibility. However, there is still a lack of fundamental knowledge on such microbial populations used as inoculum in solventogenic processes. This work evaluates the effect of four different physicochemical pretreatments (acidic, thermal, acidic-thermal and thermal-acidic) on an anaerobic inoculum used for alcohols production from volatile fatty acids.ResultsAll experiments were conducted in single batches using acetate and butyrate as substrates, at 30°C and with a pressurized headspace of pure H2 at 2182 mBar. Higher productions of both ethanol and butanol were achieved with both thermal and acidic-thermal pretreatments of the inoculum. The highest concentrations of ethanol and butanol produced were respectively of 122 mg.L−1 and 97 mg.L−1 for the thermal pretreatment (after 710 hours), and of 87 mg.L−1 and 143 mg.L−1 for the acidic-thermal pretreatment (after 210 hours). Butyrate was consumed and acetate was produced in all assays. A mass balance study indicated that the inoculum provided part of the substrate. Thermodynamic data indicated that a high H2 partial pressure favored solventogenic metabolic pathways. Finally, sequencing data showed that both thermal and acidic-thermal pretreatments selected mainly the bacterial genera Pseudomonas, Brevundimonas and Clostridium.ConclusionThe acidic-thermal pretreatment selected a bacterial community more adapted to the conversion of acetate and butyrate into ethanol and butanol, respectively. A higher production of ethanol was achieved with the thermal pretreatment, but at a slower rate. The thermal-acidic pretreatment was unstable, showing a huge variability between replicates. The acidic pretreatment showed the lowest alcohol production, almost negligible as compared to the control assay.

Studies on the production of volatile fatty acids from grass by rumen liquor in an artificial rumen: II. The volatile fatty acid production from dried grass

1957 ◽  
Vol 49 (2) ◽  
pp. 171-179 ◽  
Author(s):  
A. John ◽  
G. Barnett ◽  
R. L. Reid
Keyword(s):  
Fatty Acids ◽  
Acetic Acid ◽  
Propionic Acid ◽  
Metabolic Pathways ◽  
Volatile Fatty Acid ◽  
Volatile Fatty Acids ◽  
Water Soluble ◽  
Fatty Acid Production ◽  
Growing Seasons ◽  
Titration Curves

1. A study has been made of the production of volatile fatty acids obtainable from dried grass and its gross water-soluble and water-insoluble separates, in the artificial rumen, over two growing seasons.2. In contradistinction to fresh grass, the dried grass gives a consistent production of acetic acid proportionately greater than propionic acid, at all stages of maturity, but when aqueous extracts of the dried grass, and the resultant extracted grass, respectively, are examined separately in the artificial rumen, it is found that the former yield preponderating amounts of acetic acid while the latter give amounts of propionic acid equal to, or exceeding, the corresponding productions of acetic acid.3. An examination of the titration curves for the total acids obtained from the dried grass, extracted grass and grass extract runs, indicates an approach to an incomplete relationship between the residual carbohydrate in the extracted grass and cellulose, while the grass extract reveals itself as the chief source of acetic acid in the whole dried grass, the acid being formed very speedily at the start of the run.4. The suggested sources and some of the possible metabolic pathways involved in the formation of v.f.a. from grass are discussed in the text.

scholarly journals Similar PAH Fate in Anaerobic Digesters Inoculated with Three Microbial Communities Accumulating Either Volatile Fatty Acids or Methane

PLoS ONE ◽  
2015 ◽  
Vol 10 (4) ◽  
pp. e0125552 ◽  
Author(s):  
Florence Braun ◽  
Jérôme Hamelin ◽  
Anaïs Bonnafous ◽  
Nadine Delgenès ◽  
Jean-Philippe Steyer ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Microbial Communities ◽  
Volatile Fatty Acids ◽  
Anaerobic Digesters

Bacterial community structure in maximum volatile fatty acids production from alginate in acidogenesis

2014 ◽  
Vol 157 ◽  
pp. 22-27 ◽  
Author(s):  
Jiyun Seon ◽  
Taeho Lee ◽  
Seong Chan Lee ◽  
Hong Duc Pham ◽  
Hee Chul Woo ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Community Structure ◽  
Bacterial Community ◽  
Bacterial Community Structure ◽  
Volatile Fatty Acids

scholarly journals Age-Related Changes in the Ruminal Microbiota and Their Relationship With Rumen Fermentation in Lambs

2021 ◽  
Vol 12 ◽  
Author(s):  
Xuejiao Yin ◽  
Shoukun Ji ◽  
Chunhui Duan ◽  
Peizhi Tian ◽  
Sisi Ju ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Bacterial Community ◽  
Growth Performance ◽  
Volatile Fatty Acids ◽  
Rumen Fermentation ◽  
Rumen Bacteria ◽  
Ruminal Fermentation ◽  
Rumen Microbiota ◽  
Age Related ◽  
Age Related Changes

The rumen microbiota is vital for the health and growth performance of the host animal, mainly due to its role in the fermentation of ingested feed within the rumen. Attaining a better understanding of the development of the bacterial community and fermentation in the rumen can provide the theoretical basis for regulating feed utilization. This study analyzed the development of rumen bacteria in lambs from birth to 4 months of age using 16S-rRNA amplicon sequencing data and studied its relationship with ruminal fermentation. Serum levels of metabolites were monitored at 30, 60, 90, and 120 days of age, and the RandomForest approach was used to determine age-related changes in rumen bacteria. Levels of blood metabolites, ruminal fermentation, the rumen bacterial community and its functions were all affected by the age of the lambs (P < 0.05). Based on the Bray-Curtis distance within the age groups of the rumen microbiota, the similarity increased sharply after the lambs were weaned at 60 days of age (P < 0.05). The similarity between the samples collected from birth to 90 days of age and those collected at 120 days of age, increased after 20 days of age, reaching a maximum at 90 days vs. 120 days (P < 0.05). Some age-associated changes in the microbial genera were correlated with changes in the concentrations of volatile fatty acids and the levels of microbial crude protein in the rumen, including positive correlations between main volatile fatty acids and the genera of Prevotella 1, Lachnospiraceae NK3A20 group, Ruminococcus gauvreauii group, Ruminococcaceae UCG-014, and Ruminococcus 2 (P < 0.05). These results indicated that the microbial community and the function of rumen was not well-established before 20 days of age, so there is a degree of plasticity in the rumen bacterial community during the first 20 days of post-natal development in lambs, and this might provide an opportunity for interventions to improve rumen fermentation and, thus, increase their growth performance.

scholarly journals Effect of Inoculum Pretreatment on the Composition of Microbial Communities in Anaerobic Digesters Producing Volatile Fatty Acids

2020 ◽  
Vol 8 (4) ◽  
pp. 581 ◽  
Author(s):  
Lucia Blasco ◽  
Minna Kahala ◽  
Elina Tampio ◽  
Markku Vainio ◽  
Satu Ervasti ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Microbial Communities ◽  
Volatile Fatty Acids ◽  
Cost Effective ◽  
Added Value ◽  
Methane Formation ◽  
Anaerobic Digesters ◽  
Formation Pathway ◽  
Fuels And Chemicals ◽  
Relationship Of

Volatile fatty acids (VFAs) are intermediates in the methane formation pathway of anaerobic digestion and can be produced through the fermentation of organic wastes. VFAs have become an anticipated resource- and cost-effective way to replace fossil resources with higher added value and more versatile fuels and chemicals. However, there are still challenges in the production of targeted compounds from diverse and complex biomasses, such as urban biowastes. In this study, the aim was to modulate the microbial communities through inoculum treatment to enhance the production of green chemicals. Thermal and freeze-thaw treatments were applied to the anaerobic digester inoculum to inhibit the growth of methanogens and to enhance the performance of acidogenic and acetogenic bacteria. VFA fermentation after different inoculum treatments was studied in batch scale using urban biowaste as the substrate and the process performance was assessed with chemical and microbial analyses. Inoculum treatments, especially thermal treatment, were shown to increase VFA yields, which were also correlating with the dynamics of the microbial communities and retention times of the test. There was a strong correlation between VFA production and the relative abundances of the microbial orders Clostridiales (families Ruminococcaceae, Lachnospiraceae and Clostridiaceae), and Lactobacillales. A syntrophic relationship of these taxa with members of the Methanobacteriales order was also presumed.

scholarly journals Acidogenesis of dairy wastewater at various pH levels

2002 ◽  
Vol 45 (10) ◽  
pp. 201-206 ◽  
Author(s):  
H.-Q. Yu ◽  
H.H.P. Fang
Keyword(s):  
Fatty Acids ◽  
Chemical Oxygen Demand ◽  
Volatile Fatty Acids ◽  
Biomass Yield ◽  
Oxygen Demand ◽  
Dairy Wastewater ◽  
Alcohol Production ◽  
Mixed Liquor ◽  
Influence Of Ph ◽  
Fatty Acids And Alcohols

Continuous experiments were conducted to study the influence of pH in the range 4.0–6.5 on the acidification of dairy wastewater at 37°C with 12 hours of hydraulic retention in an upflow reactor. Results showed that degradation of dairy pollutants increased with pH from pH 4.0 to 5.5. At pH 5.5, 95% of carbohydrate, 82% of protein and 41% of lipid were degraded. Based on chemical oxygen demand (COD), 48.4% of dairy pollutants were converted into volatile fatty acids and alcohols in the mixed liquor, 6.1% into hydrogen and methane in biogas, and the remaining 4.9% into biomass. The biomass yield at pH 5.5 was estimated as 0.32 mg-VSS/mg-COD. Further increase of pH, up to 6.5, increased degradation of carbohydrate, protein and lipid only slightly, but resulted in the lowering of overall acid and alcohol production due to their increased conversion into methane. Acetate, propionate, butyrate and ethanol are the main products of acidogenesis. Productions of propionate and ethanol were favored at pH 4.0−4.5, whereas productions of acetate and butyrate were favored at pH 6.0−6.5.

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