A study on the mechanisms of ethanol-use in a chain elongation process

Controlling ethanol use in chain elongatio

A study on the mechanisms of ethanol-use in a chain elongation process

Controlling ethanol use in chain elongatio

A study on the mechanisms of ethanol-use in a chain elongation process

Controlling ethanol use in chain elongatio

Control strategies for ethanol-based chain elongation processes

Chain elongation with open cultures is an emerging biotechnological process for the conversion of residual biomass to precursors for fuels and chemicals. Like anaerobic digestion, chain elongation is catalyzed by an anaerobic open‑culture (i.e. reactor microbiome). The open culture chain elongation process upgrades low‑value volatile fatty acids (VFAs from e.g. acidified organic waste) with an electron donor (such as ethanol) into high‑value medium chain fatty acids (MCFAs), such as n‑caproate. Although fermenting with open‑cultures has many advantages, they do typically bring also undesired competing processes which degrade substrates and products. A selective control (i.e. inhibition) of these competing processes will lead to a more effective chain elongation process. The goal of this thesis was to control competing processes in ethanol‑based chain elongation. Special attention was given to control the competing process excessive ethanol oxidation (EEO). EEO degrades ethanol, which is a valuable substrate, but does not contribute directly to chain elongation. In this thesis, it was shown that EEO is dependent on hydrogenotrophic methanogenesis. The overall reaction can be referred to as syntrophic ethanol oxidation. By limiting the CO2 loading rate to a chain elongation process, syntrophic ethanol oxidation was also limited. Next to CO2 loading rate, it was found that a long HRT in a continuous chain elongation process also resulted in a limited rate of syntrophic ethanol oxidation. A major advantage of this strategy over a limited CO2 loading rate is that the n‑caproate concentration can become very high. Later on, with inhibition assays, it was shown that these high n‑caproate concentrations were inhibitory to syntrophic ethanol oxidation. As such, accumulation of n‑caproate in chain elongation bioreactors inhibits syntrophic ethanol oxidation which leads to a more selective and ethanol‑efficient chain elongation process. In this thesis, also the discovery of granular sludge formation in a chain elongation process was presented. The granules did contribute to MCFA production; though the formation of these granules seemed to coincide with high‑rate syntrophic ethanol oxidation. Although chain elongation can effectively produce n‑caproate from organic residues, ethanol and base use can be further reduced to lower operational costs and environmental impact. An outlook is provided, therefore, on how to further minimize ethanol‑use and base‑use to further increase the effectiveness of chain elongation processes.</p

Development of an effective chain elongation process from acidified food waste and ethanol into n-Caproate

Introduction: Medium chain fatty acids (MCFAs), such as n-caproate, are potential valuable platform chemicals. MCFAs can be produced from low-grade organic residues by anaerobic reactor microbiomes through two subsequent biological processes: hydrolysis combined with acidogenesis and chain elongation. Continuous chain elongation with organic residues becomes effective when the targeted MCFA(s) are produced at high concentrations and rates, while excessive ethanol oxidation and base consumption are limited. The objective of this study was to develop an effective continuous chain elongation process with hydrolyzed and acidified food waste and additional ethanol. Results: We fed acidified food waste (AFW) and ethanol to an anaerobic reactor while operating the reactor at long (4 d) and at short (1 d) hydraulic retention time (HRT). At long HRT, n-caproate was continuously produced (5.5 g/L/d) at an average concentration of 23.4 g/L. The highest n-caproate concentration was 25.7 g/L which is the highest reported n-caproate concentration in a chain elongation process to date. Compared to short HRT (7.1 g/L n-caproate at 5.6 g/L/d), long HRT resulted in 6.2 times less excessive ethanol oxidation. This led to a two times lower ethanol consumption and a two times lower base consumption per produced MCFA at long HRT compared to short HRT. Conclusions: Chain elongation from AFW and ethanol is more effective at long HRT than at short HRT not only because it results in a higher concentration of MCFAs but also because it leads to a more efficient use of ethanol and base. The HRT did not influence the n-caproate production rate. The obtained n-caproate concentration is more than twice as high as the maximum solubility of n-caproic acid in water which is beneficial for its separation from the fermentation broth. This study does not only set the record on the highest n-caproate concentration observed in a chain elongation process to date, it notably demonstrates that such high concentrations can be obtained from AFW under practical circumstances in a continuous process

Concurrent Sessions A: Passage Effectiveness Monitoring in Small Streams I - Alternatives to Direct Detection for Assessing the Effectiveness of Aquatic Organism Passage

Direct detection of individuals is often considered the most reliable indicator of the effectiveness of aquatic organism passage efforts, but given spatial and temporal variation in movement along with other logistical constraints this detection can be difficult and expensive to obtain, with a high probability of false negatives (concluding no passage when passage is possible). However, the ultimate goal of these projects is to restore population connectivity and increase population resilience. Therefore, we expect that effective aquatic organism passage should be manifest in predictable changes in abundance and genetic structure, which can at the same time serve as indicators of individual movement. Towards this goal we focused on two approaches. First, we used patterns of abundance and diversity above and below road crossings to test whether these patterns could be used to infer passage and connectivity. Second we took advantage of the discrete spawning location strategy used by most stream-dwelling species combined with new tools to assess local genetic structure (via parentage and sibling assignment) to determine whether relatedness structure was consistent with movement and successful dispersal across a potential barrier. For each of these approaches we employed two methods 1) simulation models which define sensitivity, power, and accuracy and 2) field applications which directly test performance. These approaches have been rigorously evaluated in simulations and successfully tested in the field in several locations in the northeastern US and these efforts have helped to define which species, which situations, and which sampling regimes where these techniques will and will not be effective. We are currently working to incorporating these models into assessment frameworks at both site and landscape scales

Effect of n-Caproate Concentration on Chain Elongation and Competing Processes

Chain elongation is an open-culture fermentation process that facilitates conversion of organic residues with an additional electron donor, such as ethanol, into valuable n-caproate. Open-culture processes are catalyzed by an undefined consortium of microorganisms which typically also bring undesired (competing) processes. Inhibition of competing processes, such as syntrophic ethanol oxidation, will lead to a more selective n-caproate production process. In this study, we investigated the effect of n-caproate concentration on the specific activity of chain elongation and competing processes using batch inhibition assays. With "synthetic medium sludge" (originally operating at 3.4 g/L n-caproate), syntrophic ethanol oxidation was proportionally inhibited by n-caproate until 45% inhibition at 20 g/L n-caproate. Hydrogenotrophic methanogenesis was for 58% inhibited at 20 g/L n-caproate. Chain elongation of volatile fatty acids (volatile fatty acid upgrading; the desired process), was completely inhibited at 20 g/L n-caproate with all tested sludge types. "Adapted sludge" (operating at 23.2 g/L n-caproate) showed a 10 times higher volatile fatty acid upgrading activity at 15 g/L n-caproate compared to "nonadapted sludge" (operating at 7.1 g/L n-caproate). This shows that open cultures do adapt to perform chain elongation at high n-caproate concentrations which likely inhibits syntrophic ethanol oxidation through hydrogenotrophic methanogenesis. As such, we provide supporting evidence that the formation of n-caproate inhibits syntrophic ethanol oxidation which leads to a more selective medium chain fatty acid production process.</p

Inflammatory Biomarker Profiles in Very Preterm Infants within the Context of Preeclampsia, Chorioamnionitis, and Clinically Diagnosed Postnatal Infection

Preterm delivery can be precipitated by preeclampsia or infection, and preterm infants are at heightened risk of postnatal infection. Little is known about the ontogeny of inflammatory biomarkers in extremely preterm infants. We hypothesized that suspected prenatal infection (clinical chorioamnionitis or spontaneous preterm labor) and clinically diagnosed postnatal infection would be associated with unique biomarker signatures, and those patterns would be influenced by the degree of prematurity. Venous blood was collected daily for the first week and weekly for up to 14 additional weeks from 142 neonates born at 22–32 weeks gestation. A custom array was utilized to measure monocyte chemoattractant protein-1 (MCP-1) and interleukin-6 (IL-6). C-reactive protein (CRP) levels were obtained from the electronic medical record. Independent of gestational age, MCP-1 was significantly increased (p p p < 0.01) in the presence of chorioamnionitis with funisitis. IL-6 and CRP were both increased in infants diagnosed with postnatal infection, with peak levels observed on days 2 and 3, respectively. In conclusion, suspected prenatal and postnatal infections and non-infectious complications of pregnancy are associated with unique biomarker profiles, independent of gestational age, including over a 2-fold increase in MCP-1 among newborns of mothers with preeclampsia. Further, in those clinically diagnosed with a postnatal infection in the absence of antenatal infection concerns, IL-6 increases before CRP, emphasizing a potential role for expanded biomarker screening if antibiotics are initially avoided in infants delivered for maternal indications

Vascular nitric oxide and superoxide anion contribute to sex-specific programmed cardiovascular physiology in mice

Intrauterine environmental pertubations have been linked to the development of adult hypertension. We sought to evaluate the interrelated roles of sex, nitric oxide, and reactive oxygen species (ROS) in programmed cardiovascular disease. Programming was induced in mice by maternal dietary intervention (DI; partial substitution of protein with carbohydrates and fat) or carbenoxolone administration (CX, to increase fetal glucocorticoid exposure). Adult blood pressure and locomotor activity were recorded by radiotelemetry at baseline, after a week of high salt, and after a week of high salt plus nitric oxide synthase inhibition (by l-NAME). In male offspring, DI or CX programmed an elevation in blood pressure that was exacerbated by Nω-nitro-l-arginine methyl ester administration, but not high salt alone. Mesenteric resistance vessels from DI male offspring displayed impaired vasorelaxation to ACh and nitroprusside, which was blocked by catalase and superoxide dismutase. CX-exposed females were normotensive, while DI females had nitric oxide synthase-dependent hypotension and enhanced mesenteric dilation. Despite the disparate cardiovascular phenotypes, both male and female DI offspring displayed increases in locomotor activity and aortic superoxide production. Despite dissimilar blood pressures, DI and CX-exposed females had reductions in cardiac baroreflex sensitivity. In conclusion, both maternal malnutrition and fetal glucocorticoid exposure program increases in arterial pressure in male but not female offspring. While maternal DI increased both superoxide-mediated vasoconstriction and nitric oxide mediated vasodilation, the balance of these factors favored the development of hypertension in males and hypotension in females

Data_Sheet_1_Development of an Effective Chain Elongation Process From Acidified Food Waste and Ethanol Into n-Caproate.pdf

<p>Introduction: Medium chain fatty acids (MCFAs), such as n-caproate, are potential valuable platform chemicals. MCFAs can be produced from low-grade organic residues by anaerobic reactor microbiomes through two subsequent biological processes: hydrolysis combined with acidogenesis and chain elongation. Continuous chain elongation with organic residues becomes effective when the targeted MCFA(s) are produced at high concentrations and rates, while excessive ethanol oxidation and base consumption are limited. The objective of this study was to develop an effective continuous chain elongation process with hydrolyzed and acidified food waste and additional ethanol.</p><p>Results: We fed acidified food waste (AFW) and ethanol to an anaerobic reactor while operating the reactor at long (4 d) and at short (1 d) hydraulic retention time (HRT). At long HRT, n-caproate was continuously produced (5.5 g/L/d) at an average concentration of 23.4 g/L. The highest n-caproate concentration was 25.7 g/L which is the highest reported n-caproate concentration in a chain elongation process to date. Compared to short HRT (7.1 g/L n-caproate at 5.6 g/L/d), long HRT resulted in 6.2 times less excessive ethanol oxidation. This led to a two times lower ethanol consumption and a two times lower base consumption per produced MCFA at long HRT compared to short HRT.</p><p>Conclusions: Chain elongation from AFW and ethanol is more effective at long HRT than at short HRT not only because it results in a higher concentration of MCFAs but also because it leads to a more efficient use of ethanol and base. The HRT did not influence the n-caproate production rate. The obtained n-caproate concentration is more than twice as high as the maximum solubility of n-caproic acid in water which is beneficial for its separation from the fermentation broth. This study does not only set the record on the highest n-caproate concentration observed in a chain elongation process to date, it notably demonstrates that such high concentrations can be obtained from AFW under practical circumstances in a continuous process.</p