Inactivation of
            <i>Ascaris suum</i>
            by Short-Chain Fatty Acids

Butkus, Michael A.; Hughes, Kelly T.; Bowman, Dwight D.; Liotta, Janice L.; Jenkins, Michael B.; Labare, Michael P.

doi:10.1128/aem.01675-10

Cited by 34 publications

(41 citation statements)

References 23 publications

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“…This resulted in a net average production rate of 0.125 mmol C·L −1 ·d −1 for n -octanol (Figure 4G), and occurred during Phase 3 at a reactor pH of 6.3, which stimulated C. kluyveri to chain elongate with available ethanol and carboxylates. The higher pH of 6.3 compared to 6.0 is advantageous for C. kluyveri due to two reasons: (1) the growth conditions are more optimum (Barker and Taha, 1942); and (2) the concentrations of undissociated medium-chain carboxylic acids are lower (pKa of ~4.9), resulting in a lower microbial inhibition (Butkus et al, 2011). The resulting n -octanol production was achieved at a low selectivity and specificity (mol carbon in product per mol carbon in all other liquid products).…”

Section: Resultsmentioning

confidence: 99%

A Narrow pH Range Supports Butanol, Hexanol, and Octanol Production from Syngas in a Continuous Co-culture of Clostridium ljungdahlii and Clostridium kluyveri with In-Line Product Extraction

et al. 2016

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Carboxydotrophic bacteria (CTB) have received attention due to their ability to synthesize commodity chemicals from producer gas and synthesis gas (syngas). CTB have an important advantage of a high product selectivity compared to chemical catalysts. However, the product spectrum of wild-type CTB is narrow. Our objective was to investigate whether a strategy of combining two wild-type bacterial strains into a single, continuously fed bioprocessing step would be promising to broaden the product spectrum. Here, we have operated a syngas-fermentation process with Clostridium ljungdahlii and Clostridium kluyveri with in-line product extraction through gas stripping and product condensing within the syngas recirculation line. The main products from C. ljungdahlii fermentation at a pH of 6.0 were ethanol and acetate at net volumetric production rates of 65.5 and 431 mmol C·L−1·d−1, respectively. An estimated 2/3 of total ethanol produced was utilized by C. kluyveri to chain elongate with the reverse β-oxidation pathway, resulting in n-butyrate and n-caproate at net rates of 129 and 70 mmol C·L−1·d−1, respectively. C. ljungdahlii likely reduced the produced carboxylates to their corresponding alcohols with the reductive power from syngas. This resulted in the longer-chain alcohols n-butanol, n-hexanol, and n-octanol at net volumetric production rates of 39.2, 31.7, and 0.045 mmol C·L−1·d−1, respectively. The continuous production of the longer-chain alcohols occurred only within a narrow pH spectrum of 5.7–6.4 due to the pH discrepancy between the two strains. Regardless whether other wild-type strains could overcome this pH discrepancy, the specificity (mol carbon in product per mol carbon in all other liquid products) for each longer-chain alcohol may never be high in a single bioprocessing step. This, because two bioprocesses compete for intermediates (i.e., carboxylates): (1) chain elongation; and (2) biological reduction. This innate competition resulted in a mixture of n-butanol and n-hexanol with traces of n-octanol.

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Section: Resultsmentioning

confidence: 99%

A Narrow pH Range Supports Butanol, Hexanol, and Octanol Production from Syngas in a Continuous Co-culture of Clostridium ljungdahlii and Clostridium kluyveri with In-Line Product Extraction

et al. 2016

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“…In the present study, product inhibition had restrained further increases in MCC productivities. When the OLR was increased, we observed increased concentrations of undissociated n -caprylic acid in the bioreactor broth ( Figure 2B ), which are known to inhibit microbial activity (Butkus et al, 2011). Importantly, average undissociated n -caprylic acid (C8) concentrations increased to 0.06–0.11 g COD/L (0.17–0.31 mM) during both the batch phase (Phase I) and in the phase of continuous substrate addition (Phase III) ( Figure 2B ; Supplementary Table S2).…”

Section: Resultsmentioning

confidence: 99%

Waste Conversion into n-Caprylate and n-Caproate: Resource Recovery from Wine Lees Using Anaerobic Reactor Microbiomes and In-line Extraction

et al. 2016

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To convert wastes into sustainable liquid fuels and chemicals, new resource recovery technologies are required. Chain elongation is a carboxylate-platform bioprocess that converts short-chain carboxylates (SCCs) (e.g., acetate [C2] and n-butyrate [C4]) into medium-chain carboxylates (MCCs) (e.g., n-caprylate [C8] and n-caproate [C6]) with hydrogen gas as a side product. Ethanol or another electron donor (e.g., lactate, carbohydrate) is required. Competitive MCC productivities, yields (product vs. substrate fed), and specificities (product vs. all products) were only achieved previously from an organic waste material when exogenous ethanol had been added. Here, we converted a real organic waste, which inherently contains ethanol, into MCCs with n-caprylate as the target product. We used wine lees, which consisted primarily of settled yeast cells and ethanol from wine fermentation, and produced MCCs with a reactor microbiome. We operated the bioreactor at a pH of 5.2 and with continuous in-line extraction and achieved a MCC productivity of 3.9 g COD/L-d at an organic loading rate of 5.8 g COD/L-d, resulting in a promising MCC yield of 67% and specificities of 36% for each n-caprylate and n-caproate (72% for both). Compared to all other studies that used complex organic substrates, we achieved the highest n-caprylate-to-ncaproate product ratio of 1.0 (COD basis), because we used increased broth-recycle rates through the forward membrane contactor, which improved in-line extraction rates. Increased recycle rates also allowed us to achieve the highest reported MCC production flux per membrane surface area thus far (20.1 g COD/m2-d). Through microbial community analyses, we determined that an operational taxonomic unit (OTU) for Bacteroides spp. was dominant and was positively correlated with increased MCC productivities. Our data also suggested that the microbiome may have been shaped for improved MCC production by the high broth-recycle rates. Comparable abiotic studies suggest that further increases in the broth-recycle rates could improve the overall mass transfer coefficient and its corresponding MCC production flux by almost 30 times beyond the maximum that we achieved. With improved in-line extraction, the chain-elongation biotechnology production platform offers new opportunities for resource recovery and sustainable production of liquid fuels and chemicals.

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“…Importantly, antimicrobial activity requires protonation of the carboxyl group (Butkus et al . ). For example, inactivation of Ascaris eggs required a pH less than the pK a for each fatty acid tested (Butkus et al .…”

Section: Introductionmentioning

confidence: 97%

“…For example, inactivation of Ascaris eggs required a pH less than the pK a for each fatty acid tested (Butkus et al . ). This ease of neutralization, combined with its proclivity for biodegradation (Sheridan et al .…”

Section: Introductionmentioning

confidence: 97%

“…However, this is likely an overgeneralization as comparisons between studies are difficult due to contrasting methodological approaches, limited solubility of longer chain acids and the variety of species tested. Importantly, antimicrobial activity requires protonation of the carboxyl group (Butkus et al 2011). For example, inactivation of Ascaris eggs required a pH less than the pK a for each fatty acid tested (Butkus et al 2011).…”

Section: Introductionmentioning

confidence: 99%

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Inactivation of the bacterial pathogens Staphylococcus pseudintermedius and Acinetobacter baumannii by butanoic acid

et al. 2019

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Aims This study was performed to evaluate the efficacy of butanoic acid against bacterial pathogens including Acinetobacter baumannii and Staphylococcus pseudintermedius. Methods and Results Vegetative bacteria were exposed to butanoic acid in vitro and log reduction was quantified using viable count assays. The maximum (8 and 9) log inactivation was determined by qualitatively assaying for growth/no‐growth after a 48‐h incubation (37°C). Membrane integrity after exposure to butanoic acid was determined by propidium iodide staining, scanning electron microscopy, membrane depolarization and inductively coupled plasma analysis. Cytosolic pH was measured by 5‐(6‐)carboxyfluorescein succinimidyl ester. Conclusions Inhibitory concentrations of butanoic acid ranged between 11 and 21 mmol l−1 for Gram‐positive and Gram‐negative species tested. The maximum log reduction of A. baumannii was achieved with a 10‐s exposure of 0·50 mol l−1 of butanoic acid. Staphylococcus pseudintermedius required 0·40 mol l−1 of butanoic acid to achieve the same level of reduction in the same time period. Inactivation was associated with membrane permeability and acidification of the cytosol. Significance and Impact of the Study Antibiotic resistance among bacterial pathogens necessitates the utilization of novel therapeutics for disinfection and biological control. These results may facilitate the development of butanoic acid as an effective agent against a broad‐spectrum of antibiotic‐resistant bacterial pathogens.

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Inactivation of Ascaris suum by Short-Chain Fatty Acids

Cited by 34 publications

References 23 publications

A Narrow pH Range Supports Butanol, Hexanol, and Octanol Production from Syngas in a Continuous Co-culture of Clostridium ljungdahlii and Clostridium kluyveri with In-Line Product Extraction

A Narrow pH Range Supports Butanol, Hexanol, and Octanol Production from Syngas in a Continuous Co-culture of Clostridium ljungdahlii and Clostridium kluyveri with In-Line Product Extraction

Waste Conversion into n-Caprylate and n-Caproate: Resource Recovery from Wine Lees Using Anaerobic Reactor Microbiomes and In-line Extraction

Inactivation of the bacterial pathogens Staphylococcus pseudintermedius and Acinetobacter baumannii by butanoic acid

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