RESUMEN
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.
Asunto(s)
Fenol/metabolismo , Dioxigenasas/genética , Dioxigenasas/metabolismo , Bacterias Gramnegativas/enzimología , Bacterias Gramnegativas/metabolismo , Filogenia , Pseudomonas , Contaminantes del Suelo/metabolismo , Acinetobacter , ADN Bacteriano/genética , ADN Bacteriano/química , ADN Ribosómico/genética , ADN Ribosómico/química , Carbono/metabolismo , ARN Ribosómico 16S/genética , Biotransformación , Análisis por Conglomerados , China , Reacción en Cadena de la Polimerasa , Análisis de Secuencia de ADN , Sedimentos Geológicos/microbiología , Alcaligenes , Contaminación Ambiental , Bacterias Gramnegativas/clasificación , Bacterias Gramnegativas/genéticaRESUMEN
Ralstonia metallidurans CH34 was isolated from the deposit of a znic factory .The degradation of phenol by R .metallidurans CH34 was investigated. The results showed that R . metallidurans CH34 possesses high ability to degrade phenol with the biodegradation rate constant of 0.33 . The optimal pH , temperature and volume of medium for phenol degradation are pH 7.0 , 30℃ , and 20%(v/v), respectively . In addition , this strain retains its ability to degrade phenol in the presence of high concentration of heavy metal ion .The sodium citrate , sodium succinate can enhance the degradation of phenol.
RESUMEN
A strain ph 16 , that could effectively degrade phenol,was isolated from sewer sludge of printing and dyeing plant. The preliminary identification sugg ested that the strain belongs to Micrococcus sp. The strain could resist to phenol up to 1.5 g/L. The efficient biodegradation of phenol occurred when th e strain was cultured in the medium (pH 7.0) containing 1.0 g/L phenol under 35℃, wh er e the highest degradation rate reach 99.6% after 36 hours. This strain, when t re ated with some heavy metal ions such as Hg +、Co 2+ and Ag 2+ , showe d the significant inhibition of phenol degradation by 74.2%～100%. The kinetic s of phenol degradation during culture of the strain was also explored.