Résumé
Abstract The aerobic degradation of aromatic compounds by bacteria is performed by dioxygenases. To show some characteristic patterns of the dioxygenase genotype and its degradation specificities, twenty-nine gram-negative bacterial cultures were obtained from sediment contaminated with phenolic compounds in Wuhan, China. The isolates were phylogenetically diverse and belonged to 10 genera. All 29 gram-negative bacteria were able to utilize phenol, m-dihydroxybenzene and 2-hydroxybenzoic acid as the sole carbon sources, and members of the three primary genera Pseudomonas, Acinetobacter and Alcaligenes were able to grow in the presence of multiple monoaromatic compounds. PCR and DNA sequence analysis were used to detect dioxygenase genes coding for catechol 1,2-dioxygenase, catechol 2,3-dioxygenase and protocatechuate 3,4-dioxygenase. The results showed that there are 4 genotypes; most strains are either PNP (catechol 1,2-dioxygenase gene is positive, catechol 2,3-dioxygenase gene is negative, protocatechuate 3,4-dioxygenase gene is positive) or PNN (catechol 1,2-dioxygenase gene is positive, catechol 2,3-dioxygenase gene is negative, protocatechuate 3,4-dioxygenase gene is negative). The strains with two dioxygenase genes can usually grow on many more aromatic compounds than strains with one dioxygenase gene. Degradation experiments using a mixed culture representing four bacterial genotypes resulted in the rapid degradation of phenol. Determinations of substrate utilization and phenol degradation revealed their affiliations through dioxygenase genotype data.
Sujets)
Phénol/métabolisme , Dioxygenases/génétique , Dioxygenases/métabolisme , Bactéries à Gram négatif/enzymologie , Bactéries à Gram négatif/métabolisme , Phylogenèse , Pseudomonas , Polluants du sol/métabolisme , Acinetobacter , ADN bactérien/génétique , ADN bactérien/composition chimique , ADN ribosomique/génétique , ADN ribosomique/composition chimique , Carbone/métabolisme , ARN ribosomique 16S/génétique , Biotransformation , Analyse de regroupements , Chine , Réaction de polymérisation en chaîne , Analyse de séquence d'ADN , Sédiments géologiques/microbiologie , Alcaligenes , Pollution de l'environnement , Bactéries à Gram négatif/classification , Bactéries à Gram négatif/génétiqueRésumé
The study was designed to observe the impact of moderate surgical trauma on substrate utilization in 39patients(men,n=1 9;women,n=2 0 ) undergoing elective cholecystectomy. The utilization rate of carbohydrate,fat and protein was estimated on the day before operation and on the1 st,4th and7th post operative day by indirect calorimetry.The result showed that the postoperative utilization rate of carbohydrate was declined,and that of fat elevated significantly when compared with the preoperative values(P0 .0 5 ) .It suggested that the main energy source after moderate surgical trauma be from the oxidation of fat,which might be related to the change of metabolic hormone and the insulin resistance.