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1.
Bone Joint J ; 102-B(7_Supple_B): 52-56, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32600208

RESUMO

AIMS: Of growing concern in arthroplasty is the emergence of atypical infections, particularly Cutibacterium (formerly Propionibacterium) sp. infections. Currently, the dermal colonization rate of Cutibacterium about the hip is unknown. Therefore, the aim of this study was to investigate colonization rates of Cutibacterium sp. at locations approximating anterior and posterolateral approaches to the hip joint. METHODS: For this non-randomized non-blinded study, 101 adult patients scheduled for hip or knee surgery were recruited. For each, four 3 mm dermal punch biopsies were collected after administration of anaesthesia, but prior to antibiotics. Prebiopsy skin preparation consisted of a standardized preoperative 2% chlorhexidine skin cleansing protocol and an additional 70% isopropyl alcohol mechanical skin scrub immediately prior to biopsy collection. Two skin samples 10 cm apart were collected from a location approximating a standard direct anterior skin incision, and two samples 10 cm apart were collected from a lateral skin incision (suitable for posterior, direct-lateral, or anterolateral approaches). Samples were cultured for two weeks using a protocol optimized for Cutibacterium. RESULTS: A total of 23 out of 404 cultures (collected from 101 patients) were positive for a microorganism, with a total of 22 patients having a positive culture (22%). Overall, 15 of the cultures in 14 patients were positive for Cutibacterium sp. (65%), of which Cutibacterium acnes comprised the majority (n = 13; 87%). Other isolated microorganisms include coagulase-negative Staphylococcus (n = 6), Clostridium (n = 1), and Corynebacterium (n = 1). Of all positive cultures, 15 were obtained from the anterior location (65%), of which seven (60%) were from the most proximal biopsy location. However, these findings were not statistically significant (anterior vs lateral, p = 0.076; proximal vs distal, p =0.238). CONCLUSION: Approximately 14% (14/101) of the patients demonstrated a positive Cutibacterium colonization about the hip, the majority anteriorly. Given the high colonization rate of Cutibacterium, alternative skin preparations for total hip arthroplasty should be considered. Cite this article: Bone Joint J 2020;102-B(7 Supple B):52-56.


Assuntos
Quadril/microbiologia , Propionibacteriaceae/isolamento & purificação , Pele/microbiologia , Coxa da Perna/microbiologia , Adulto , Idoso , Artroplastia de Quadril , Biópsia , Clostridium/isolamento & purificação , Corynebacterium/isolamento & purificação , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Staphylococcus/isolamento & purificação
3.
Bioresour Technol ; 312: 123532, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32502888

RESUMO

Furan aldehydes and phenolic compounds generated during biomass pretreatment can inhibit fermentation for biofuel production. Efflux pumps actively transport small molecules out of cells, thus sustaining normal microbial metabolism. Pseudomonas putida has outstanding tolerance to butanol and other small molecules, and we hypothesize that its efflux pump could play essential roles for such robustness. Here, we overexpressed efflux pump genes from P. putida to enhance tolerance of hyper-butanol producing Clostridium saccharoperbutylacetonicum to fermentation inhibitors. Interestingly, overexpression of the whole unit resulted in decreased tolerance, while overexpression of the subunit (srpB) alone exerted significant enhanced robustness of the strain. Compared to the control, the engineered strain had enhanced capability to grow in media containing 17% more furfural or 50% more ferulic acid, and produced ~14 g/L butanol (comparable to fermentation under regular conditions without inhibitors). This study provided valuable reference for boosting microbial robustness towards efficient biofuel production from lignocellulosic materials.


Assuntos
Pseudomonas putida , Biomassa , Butanóis , Clostridium , Fermentação , Lignina
4.
Sheng Wu Gong Cheng Xue Bao ; 36(6): 1190-1197, 2020 Jun 25.
Artigo em Chinês | MEDLINE | ID: mdl-32597068

RESUMO

Clostridia inhabiting in jiupei and pit mud plays key roles in the formation of flavour during the fermentation process of Luzhou-flavour baijiu. However, the differences of Clostridial communities between jiupei and pit mud remains unclear. Here, the species assembly, succession, and metabolic capacity of Clostridial communities between jiupei and pit mud were analysed by high-throughput sequencing and pure culture approaches. The ratio of Clostridial biomass to bacterial biomass in the pit mud was relatively stable (71.5%-91.2%) throughout the fermentation process. However, it varied widely in jiupei (0.9%-36.5%). The dominant Clostridial bacteria in jiupei were Clostridium (19.9%), Sedimentibacter (8.8%), and Hydrogenispora (7.2%), while Hydrogenispora (57.2%), Sedimentibacter (5.4%), and Caproiciproducens (4.9%) dominated in the Clostridial communities in pit mud. The structures of Clostridial community in pit mud and jiupei were significantly different (P=0.001) throughout fermentation. Isolated Clostridial strains showed different metabolic capacities of volatile fatty acids in pure culture. Spatial and temporal heterogeneity of Clostridial communities existed in the baijiu fermentation pit, which was closely related to the main flavour components of Luzhou-flavour baijiu.


Assuntos
Bebidas Alcoólicas , Clostridium , Microbiologia de Alimentos , Bebidas Alcoólicas/microbiologia , Bactérias/classificação , Bactérias/metabolismo , Clostridium/fisiologia , Ácidos Graxos Voláteis/metabolismo , Fermentação
5.
Int J Syst Evol Microbiol ; 70(5): 2988-2997, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32369000

RESUMO

A novel, Gram-stain-positive, rod-shaped, non-motile, non-spore-forming, obligately anaerobic bacterium, designated strain ZHW00191T, was isolated from human faeces and characterized by using a polyphasic taxonomic approach. Growth occurred at 25-45 °C (optimum, 37-42 °C), at pH 5.5-10.0 (optimum, pH 6.5-7.0) and with 0-2 % (w/v) NaCl (optimum, 0 %). The end products of glucose fermentation were acetic acid, isobutyric acid and isovaleric acid and a small amount of propionic acid. The dominant cellular fatty acids (>10 %) of strain ZHW00191T were C16 : 0, C18 : 1 ω9с and C18 : 2ω6,9с. Its polar lipid profile comprised diphosphatidylglycerol, phosphatidylglycerol, three unidentified phospholipids and ten unidentified glycolipids. Respiratory quinones were not detected. The cell-wall peptidoglycan contained meso-2,6-diaminopimelic acid, and the whole-cell sugars were ribose and glucose. The genomic DNA G+C content was 32.8 mol%. Analysis of the 16S rRNA gene sequence indicated that ZHW00191T was most closely related to Clostridium hiranonis TO-931T (95.3 % similarity). Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) analyses with closely related reference strains indicated that reassociation values were both well below the thresholds of 95-96% and 70 % for species delineation, respectively. Based on phenotypic, chemotaxonomic and genetic studies, a novel genus, Peptacetobacter gen. nov., is proposed. The novel isolate ZHW00191T (=JCM 33482T=GDMCC 1.1530T) is proposed as the type strain of the type species Peptacetobacter hominis gen. nov., sp. nov. of the proposed new genus. Furthermore, it is proposed that Clostridium hiranonis be transferred to this novel genus, as Peptacetobacter hiranonis comb. nov.


Assuntos
Clostridium/classificação , Fezes/microbiologia , Bacilos Gram-Positivos Formadores de Endosporo/classificação , Filogenia , Adulto , Técnicas de Tipagem Bacteriana , Composição de Bases , China , DNA Bacteriano/genética , Ácido Diaminopimélico/química , Ácidos Graxos/química , Glicolipídeos/química , Bacilos Gram-Positivos Formadores de Endosporo/isolamento & purificação , Humanos , Masculino , Hibridização de Ácido Nucleico , Peptidoglicano/química , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
6.
PLoS One ; 15(5): e0229889, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32396555

RESUMO

The purpose of the study involves the development of an anaerobic, thermophilic microbial consortium TERIK from the high temperature reservoir of Gujarat for enhance oil recovery. To isolate indigenous microbial consortia, anaerobic baltch media were prepared and inoculated with the formation water; incubated at 65°C for 10 days. Further, the microbial metabolites were analyzed by gas chromatography, FTIR and surface tension. The efficiency of isolated consortia towards enhancing oil recovery was analyzed through core flood assay. The novelty of studied consortia was that, it produces biomass (600 mg/l), bio-surfactant (325 mg/l), and volatile fatty acids (250 mg/l) at 65°C in the span of 10 days, that are adequate to alter the surface tension (70 to 34 mNm -1) and sweep efficiency of zones facilitating the displacement of oil. TERIK was identified as Clostridium sp. The FTIR spectra of biosurfactant indicate the presence of N-H stretch, amides and polysaccharide. A core flooding assay was designed to explore the potential of TERIK towards enhancing oil recovery. The results showed an effective reduction in permeability at residual oil saturation from 2.14 ± 0.1 to 1.39 ± 0.05 mD and 19% incremental oil recovery.


Assuntos
Archaea/metabolismo , Microbiologia Industrial , Consórcios Microbianos , Campos de Petróleo e Gás/microbiologia , Clostridium/metabolismo , Temperatura Alta , Humanos , Petróleo/microbiologia , Tensão Superficial , Tensoativos/farmacologia
7.
Z Gastroenterol ; 58(5): 456-460, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32392607

RESUMO

Clostridium (C.) ventriculi (known as Sarcina ventriculi) is a ubiquitous gram-positive, anaerobic, acidophilic coccus found in patients with gastric motility disorders. The microorganisms can be identified histologically by their characteristic presentation in tetrads or packets of 8 in hematoxylin and eosin stains. Severe cases of emphysematous gastritis or gastric perforation have been described. Nevertheless, the significance of C. ventriculi in an upper gastrointestinal tract and its pathogenic character remain unclear. We present a 67-year-old woman who underwent hiatoplasty with gastropexy. After 3 months, she underwent a gastroscopy showing gastroesophageal reflux. Biopsies showed ulcerative reflux esophagitis with presence of C.ventriculi, subsequently confirmed by 16S ribosomal RNA gene amplicon sequencing. The barium swallow study revealed an atonic stomach with delayed gastric emptying. The patient was treated with PPI and domperidone. On follow up, 15 months post-operatively, a control gastroscopy showed a stomach with food residues and reflux-associated small erosions. The Clostridium organisms were detected only in oxyntic mucosa biopsies without erosions or ulcerations. We speculate that the recognition of the organisms in the biopsy material is important and suggests dysmotility disorder. However, in our opinion, the presence of C. ventriculi, even in combination with mucosal damage, does not necessarily prompt antibiotic treatment since no complications occurred and inflammation as well as gastric function improved under PPI and prokinetic therapy in our patient. Larger study groups with long-term follow-up are needed to understand whether these organisms could behave as pathogens or are only bystanders in the setting of delayed gastric emptying.


Assuntos
Clostridium/isolamento & purificação , Domperidona/uso terapêutico , Esofagite Péptica/tratamento farmacológico , Esofagite Péptica/microbiologia , Refluxo Gastroesofágico/complicações , Complicações Pós-Operatórias/microbiologia , Idoso , Antibacterianos/uso terapêutico , Antieméticos/uso terapêutico , Infecções por Clostridium/diagnóstico , Infecções por Clostridium/tratamento farmacológico , Infecções por Clostridium/microbiologia , Esofagite Péptica/diagnóstico , Feminino , Refluxo Gastroesofágico/diagnóstico por imagem , Gastropexia , Gastroscopia , Humanos , Inibidores da Bomba de Prótons/uso terapêutico , Estômago/cirurgia
8.
Proc Natl Acad Sci U S A ; 117(23): 13168-13175, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32471945

RESUMO

Living biological systems display a fascinating ability to self-organize their metabolism. This ability ultimately determines the metabolic robustness that is fundamental to controlling cellular behavior. However, fluctuations in metabolism can affect cellular homeostasis through transient oscillations. For example, yeast cultures exhibit rhythmic oscillatory behavior in high cell-density continuous cultures. Oscillatory behavior provides a unique opportunity for quantitating the robustness of metabolism, as cells respond to changes by inherently compromising metabolic efficiency. Here, we quantify the limits of metabolic robustness in self-oscillating autotrophic continuous cultures of the gas-fermenting acetogen Clostridium autoethanogenum Online gas analysis and high-resolution temporal metabolomics showed oscillations in gas uptake rates and extracellular byproducts synchronized with biomass levels. The data show initial growth on CO, followed by growth on CO and H2 Growth on CO and H2 results in an accelerated growth phase, after which a downcycle is observed in synchrony with a loss in H2 uptake. Intriguingly, oscillations are not linked to translational control, as no differences were observed in protein expression during oscillations. Intracellular metabolomics analysis revealed decreasing levels of redox ratios in synchrony with the cycles. We then developed a thermodynamic metabolic flux analysis model to investigate whether regulation in acetogens is controlled at the thermodynamic level. We used endo- and exo-metabolomics data to show that the thermodynamic driving force of critical reactions collapsed as H2 uptake is lost. The oscillations are coordinated with redox. The data indicate that metabolic oscillations in acetogen gas fermentation are controlled at the thermodynamic level.


Assuntos
Reatores Biológicos/microbiologia , Clostridium/metabolismo , Metabolismo Energético , Fermentação , Processos Autotróficos , Biomassa , Monóxido de Carbono/metabolismo , Hidrogênio/metabolismo , Metabolômica , Oxirredução , Proteômica , Termodinâmica
10.
Bioresour Technol ; 308: 123318, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32278998

RESUMO

Caproate production by mixed culture fermentation (MCF) is economically attractive. Xylose is known as the second most abundant sugar in nature, however, producing caproate from xylose is never reported. In this study, caproate production from xylose by mesophilic MCF was firstly investigated. The results showed that as pH decreasing to 5.0, the caproate concentration was 2.06 g/L in a batch reactor and was between 0.45 and 1.07 g/L in a continuously stirred reactor. Microbial analysis illustrated that Caproiciproducens and Clostridium_sensu_stricto_12, as two main identified caproate producers, occupied over 50% and around 10% of mixed culture, respectively. Thus, caproate production from xylose was proposed via the fatty acid biosynthesis pathway, not the well-known reverse ß-oxidation pathway. These unexpected differences from literatures gains more understanding about caproate production from organic substrates via MCF.


Assuntos
Caproatos , Xilose , Clostridium , Fermentação , Glucose
11.
Environ Sci Technol ; 54(9): 5864-5873, 2020 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-32267683

RESUMO

Chain elongation is a process that produces medium chain fatty acids such as caproic acid, which is one of the promising products of the carboxylate platform. This study analyzed the impact of bioaugmentation of heat-treated anaerobic digester sludge with Clostridium kluyveri (AS + Ck) on caproic acid production from a mixed substrate (lactose, lactate, acetate, and ethanol). It was compared with processes initiated with non-augmented heat-treated anaerobic digester sludge (AS) and mono-culture of C. kluyveri (Ck). Moreover, stability of the chain elongation process was evaluated by performing repeated batch experiments. All bacterial cultures demonstrated efficient caproate production in the first batch cycle. After 18 days, caproate concentration reached 9.06 ± 0.43, 7.86 ± 0.38, and 7.67 ± 0.37 g/L for AS, Ck, and AS + Ck cultures, respectively. In the second cycle, AS microbiome was enriched toward caproate production and showed the highest caproate concentration of 11.44 ± 0.47 g/L. On the other hand, bioaugmented culture showed the lowest caproate production in the second cycle (4.10 ± 0.30 g/L). Microbiome analysis in both AS and AS + Ck culture samples indicated strong enrichment toward the anaerobic order of Clostridia. Strains belonging to genera Sporanaerobacter, Paraclostridium, Haloimpatiens, Clostridium, and Bacillus were dominating in the bioreactors.


Assuntos
Clostridium kluyveri , Reatores Biológicos , Caproatos , Carbono , Clostridium , Fermentação
12.
World J Microbiol Biotechnol ; 36(3): 48, 2020 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-32152786

RESUMO

The search for gasoline substitutes has grown in recent decades, leading to the increased production of ethanol as viable alternative. However, research in recent years has shown that butanol exhibits various advantages over ethanol as a biofuel. Furthermore, butanol can also be used as a chemical platform, serving as an intermediate product and as a solvent in industrial reactions. This alcohol is naturally produced by some Clostridium species; however, Clostridial fermentation processes still have inherent problems, which focuses the interest on Saccharomyces cerevisiae for butanol production, as an alternative organism for the production of this alcohol. S. cerevisiae exhibits great adaptability to industrial conditions and can be modified with a wide range of genetic tools. Although S. cerevisiae is known to naturally produce isobutanol, the n-butanol synthesis pathway has not been well established in wild S. cerevisiae strains. Two strategies are most commonly used for of S. cerevisiae butanol production: the heterologous expression of the Clostridium pathway or the amino acid uptake pathways. However, butanol yields produced from S. cerevisiae are lower than ethanol yield. Thus, there are still many challenges needed to be overcome, which can be minimized through genetic and evolutive engineering, for butanol production by yeast to become a reality.


Assuntos
1-Butanol/metabolismo , Biocombustíveis , Proteínas Fúngicas/metabolismo , Saccharomyces cerevisiae/metabolismo , Vias Biossintéticas , Butanóis/metabolismo , Clostridium/metabolismo , Tolerância a Medicamentos , Etanol/metabolismo , Fermentação , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica , Microbiologia Industrial , Engenharia Metabólica , Saccharomyces cerevisiae/genética , Solventes
15.
Proc Natl Acad Sci U S A ; 117(13): 7516-7523, 2020 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-32170009

RESUMO

Among CO2-fixing metabolic pathways in nature, the linear Wood-Ljungdahl pathway (WLP) in phylogenetically diverse acetate-forming acetogens comprises the most energetically efficient pathway, requires the least number of reactions, and converts CO2 to formate and then into acetyl-CoA. Despite two genes encoding glycine synthase being well-conserved in WLP gene clusters, the functional role of glycine synthase under autotrophic growth conditions has remained uncertain. Here, using the reconstructed genome-scale metabolic model iSL771 based on the completed genome sequence, transcriptomics, 13C isotope-based metabolite-tracing experiments, biochemical assays, and heterologous expression of the pathway in another acetogen, we discovered that the WLP and the glycine synthase pathway are functionally interconnected to fix CO2, subsequently converting CO2 into acetyl-CoA, acetyl-phosphate, and serine. Moreover, the functional cooperation of the pathways enhances CO2 consumption and cellular growth rates via bypassing reducing power required reactions for cellular metabolism during autotrophic growth of acetogens.


Assuntos
Aminoácido Oxirredutases/metabolismo , Aminometiltransferase/metabolismo , Processos Autotróficos/fisiologia , Complexos Multienzimáticos/metabolismo , Acetilcoenzima A/metabolismo , Aminoácido Oxirredutases/genética , Aminometiltransferase/genética , Proteínas de Bactérias/metabolismo , Ciclo do Carbono , Dióxido de Carbono/metabolismo , Monóxido de Carbono/metabolismo , Clostridium/metabolismo , Redes e Vias Metabólicas , Complexos Multienzimáticos/genética , Família Multigênica , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase/metabolismo
16.
J Vet Diagn Invest ; 32(2): 239-245, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32052697

RESUMO

Enteric disease in horses may be caused by a variety of microorganisms, including several clostridial species. Paeniclostridium sordellii (previously Clostridium sordellii) has been frequently associated with gas gangrene in humans and several animal species, including horses. However, its role in enteric diseases of animals has not been fully determined. We describe herein 7 cases of enteric disease in horses associated with P. sordellii infection. Grossly, the small and/or large intestines were necrotic, hemorrhagic, and edematous. Microscopically, there was severe mucosal necrosis and hemorrhage of the small and/or large intestine of all horses. P. sordellii was isolated and/or demonstrated by immunohistochemistry and/or PCR in the intestine of all horses. All other known causes of enteric disease in horses were ruled out in these 7 cases. P. sordellii should be considered among the differential diagnoses in cases of enteric disease in horses.


Assuntos
Infecções por Clostridium/veterinária , Clostridium/fisiologia , Enterocolite/veterinária , Doenças dos Cavalos/diagnóstico , Animais , Infecções por Clostridium/diagnóstico , Infecções por Clostridium/microbiologia , Clostridium sordellii , Diagnóstico Diferencial , Enterocolite/diagnóstico , Enterocolite/microbiologia , Doenças dos Cavalos/microbiologia , Cavalos , Intestino Grosso/patologia , Intestino Delgado/patologia
17.
J Vet Diagn Invest ; 32(2): 175-183, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32081096

RESUMO

Gas gangrene is a necrotizing infection of subcutaneous tissue and muscle that affects mainly ruminants and horses, but also other domestic and wild mammals. Clostridium chauvoei, C. septicum, C. novyi type A, C. perfringens type A, and C. sordellii are the etiologic agents of this disease, acting singly or in combination. Although a presumptive diagnosis of gas gangrene can be established based on clinical history, clinical signs, and gross and microscopic changes, identification of the clostridia involved is required for confirmatory diagnosis. Gross and microscopic lesions are, however, highly suggestive of the disease. Although the disease has a worldwide distribution and can cause significant economic losses, the literature is limited mostly to case reports. Thus, we have reviewed the current knowledge of gas gangrene in mammals.


Assuntos
Animais Domésticos , Clostridium/fisiologia , Gangrena Gasosa/veterinária , Mamíferos , Animais , Infecções por Clostridium , Gangrena Gasosa/diagnóstico , Gangrena Gasosa/microbiologia
18.
Int J Syst Evol Microbiol ; 70(4): 2463-2466, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32068529

RESUMO

Clostridium diolis shares high similarity based on 16S rRNA gene sequences and fatty acid composition with Clostridium beijerinckii. In this study, the taxonomic status of C. diolis was clarified using genomic and phenotypic approaches. High similarity was detected among C. diolis DSM 15410T, C. beijerinckii DSM 791T and NCTC 13035T, showing average nucleotide identity on blast and in silico DNA-DNA hybridization values over 97 and 85 %, respectively. Results of investigations for substrate utilization and enzyme activity displayed no striking differences between C. diolis DSM 15410T and C. beijerinckii JCM 1390T. Based on the results, we propose the reclassification of Clostridium diolis as a later heterotypic synonym of Clostridium beijerinckii. The type strain is ATCC 25752T (=CIP 104308T=DSM 791T=JCM 1390T=LMG 5716T=NCTC 13035T).


Assuntos
Clostridium beijerinckii/classificação , Clostridium/classificação , Filogenia , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Hibridização de Ácido Nucleico , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
19.
Chemosphere ; 250: 126105, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32092562

RESUMO

The effect of trace metals, namely tungsten and selenium, on the production of acids and alcohols through gas fermentation by a CO-enriched anaerobic sludge in a continuous gas-fed bioreactor was investigated. The CO-enriched sludge was first supplied with a tungsten-deficient medium (containing selenium) and in a next assay, a selenium-deficient medium (containing tungsten) was fed to the bioreactor, at a CO gas flow rate of 10 mL/min. In the absence of tungsten (tungstate), an initial pH of 6.2 followed by a pH decrease to 4.9 yielded 7.34 g/L acetic acid as the major acid during the high pH period. Subsequently, bioconversion of the acids at a lower pH of 4.9 yielded only 1.85 g/L ethanol and 1.2 g/L butanol in the absence of tungsten (tungstate). A similar follow up assay in the same bioreactor with two consecutive periods at different pH values (i.e., 6.2 and 4.9) with a selenium deficient medium yielded 6.6 g/L acetic acid at pH 6.2 and 4 g/L ethanol as well as 1.88 g/L butanol at pH 4.9. The results from the microbial community analysis showed that the only known CO fixing microorganism able to produce alcohols detected in the bioreactor was Clostridium autoethanogenum, both in the tungsten and the selenium deprived media, although that species has so far not been reported to be able to produce butanol. No other solventogenic acetogen was detected.


Assuntos
Microbiota , Selênio/química , Tungstênio/química , Eliminação de Resíduos Líquidos/métodos , 1-Butanol , Ácido Acético , Anaerobiose , Reatores Biológicos , Butanóis , Clostridium , Etanol , Fermentação , Esgotos
20.
Chemosphere ; 248: 126055, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32018108

RESUMO

This study investigated the effects of three different intermittent mixing modes (top, middle and bottom) on the performance of solid state anaerobic digestion (SS-AD) process of pig manure, corn stover and cucumber residues in a stirred tank reactor (STR). Results showed the cumulative methane yields of reactors had similar values (P > 0.05) except for the unmixed reactor (CK), which had a very low methane production. Reactors of top-mixed (T1) had shortest technical digestion time (T80) and more stable physicochemical characteristics than the other treatments. These findings indicated the three mixing modes had almost no effect on the cumulative methane yields, but affected the digestion process. The main bacteria in T1 reactor was Clostridium_sensu_stricto_1. However, Caldicoprobacter accounted for a relatively large proportion of the bacteria in middle-mixed (T2) and bottom-mixed (T3) which was consistent with the later methane production than T1. Methanosarcina was the dominant archaea in T1 reactor. Methanoculleus and Methanosarcina were the main microorganisms in top and bottom area of T2 and T3 reactor. Acidogenic (top area) and methanogenic zones (bottom area) were formed in all reactors respectively, by combining the physicochemical properties and microorganisms. Overall, T1 showed more advantages for methane production during SS-AD.


Assuntos
Agricultura , Eliminação de Resíduos Líquidos/métodos , Anaerobiose , Animais , Archaea , Bactérias , Biocombustíveis , Reatores Biológicos , Clostridium , Esterco , Metano/biossíntese , Suínos , Zea mays/química
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