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Front Microbiol ; 11: 416, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32256473


Both CO and H2 can be utilized as energy sources during the autotrophic growth of Clostridium ljungdahlii. In principle, CO is a more energetically and thermodynamically favorable energy source for gas fermentation in comparison to H2. Therefore, metabolism may vary during growth under different energy sources. In this study, C. ljungdahlii was fed with CO and/or CO2/H2 at pH 6.0 with a gas pressure of 0.1 MPa. C. ljungdahlii primarily produced acetate in the presence of H2 as an energy source, but produced alcohols with CO as an energy source under the same fermentation conditions. A key enzyme activity assay, metabolic flux analysis, and comparative transcriptomics were performed for investigating the response mechanism of C. ljungdahlii under different energy sources. A CO dehydrogenase and an aldehyde:ferredoxin oxidoreductase were found to play important roles in CO utilization and alcohol production. Based on these findings, novel metabolic schemes are proposed for C. ljungdahlii growing on CO and/or CO2/H2. These schemes indicate that more ATP is produced during CO-fermentation than during H2-fermentation, leading to increased alcohol production.

Microbiology (Reading) ; 153(Pt 5): 1556-1565, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17464070


Nicotine and some related alkaloids in tobacco and tobacco wastes are harmful to health and the environment, and a major environmental requirement is to remove them from tobacco and tobacco wastes. In this study, an isolated strain, S16, identified as Pseudomonas putida biotype A, was used to investigate nicotine degradation. Possible intermediates were identified based on the results of NMR, Fourier-transform (FT)-IR and UV spectroscopy, GC-MS and high-resolution MS (HR-MS) analysis. The pathway of nicotine degradation in P. putida was proposed to be from nicotine to 2,5-dihydroxypyridine through the intermediates N-methylmyosmine, 2'-hydroxynicotine, pseudooxynicotine, 3-pyridinebutanal,C-oxo, 3-succinoylpyridine and 6-hydroxy-3-succinoylpyridine. N-Methylmyosmine, 2,5-dihydroxypyridine and succinic acid were detected and satisfactorily verified for the first time as intermediates of nicotine degradation. In addition, an alcohol compound, 1-butanone,4-hydroxy-1-(3-pyridinyl), was found to be a novel product of nicotine degradation. These findings provide new insights into the microbial metabolism of nicotine and the environmentally friendly route of nicotine degradation.

Nicotina/metabolismo , Pseudomonas putida/metabolismo , Microbiologia do Solo , Biodegradação Ambiental , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Resíduos Industriais , Espectroscopia de Ressonância Magnética , Redes e Vias Metabólicas , Modelos Biológicos , Dados de Sequência Molecular , Estrutura Molecular , Nicotina/química , Pseudomonas putida/química , Pseudomonas putida/genética , Pseudomonas putida/isolamento & purificação , Piridinas/química , Piridinas/metabolismo , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Ácido Succínico/análise
Environ Sci Technol ; 39(17): 6877-80, 2005 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-16190252


A new technology for 6-hydroxy-3-succinoyl-pyridine (HSP) production from (S)-nicotine in tobacco waste by whole cells of a Pseudomonas sp. has been developed. When deionized water was used in the transformation reaction as a medium and the initial pH value of reaction mixture was adjusted to 7.0, 1.45 g/L HSP was produced from 3 g/L of nicotine in 5 h with 3.4 g/L of cells in a 5-L flask at 30 degrees C. HSP could be easily purified from the reaction without perplexing separation steps. A quantity of 1.3 g of HSP was recovered without impurity, and the overall yield of HSP was 43.8% (w/w), based on an initial concentration of 3.0 g/L of nicotine in reaction. This biotransformation made it possible to convert nicotine in tobacco wastes with high nicotine content into valuable compounds.

Nicotina/metabolismo , Pseudomonas/metabolismo , Piridinas/metabolismo , Succinatos/metabolismo , Poluição por Fumaça de Tabaco/prevenção & controle , Tabaco/química , Biotransformação , Cromatografia em Camada Delgada , Concentração de Íons de Hidrogênio , Resíduos Industriais , Nicotina/química , Pseudomonas/citologia , Piridinas/química , Succinatos/química , Temperatura , Fatores de Tempo , Água/química