Aerobic Mineralization of 2,6-Dichlorophenol by Ralstonia sp. Strain RK1

Abstract

A new aerobic bacterium was isolated from the sediment of a freshwater pond close to a contaminated site at Amponville (France). It was enriched in a fixed-bed reactor fed with 2,6-dichlorophenol (2,6-DCP) as the sole carbon and energy source at pH 7.5 and room temperature. The degradation of 2,6-DCP followed Monod kinetics at low initial concentrations. At concentrations above 300 μM (50 mg · liter−1), 2,6-DCP increasingly inhibited its own degradation. The base sequence of the 16S ribosomal DNA allowed us to assign the bacterium to the genus Ralstonia (formerlyAlcaligenes). The substrate spectrum of the bacterium includes toluene, benzene, chlorobenzene, phenol, and all fourortho- and para-substituted mono- and dichlorophenol isomers. Substituents other than chlorine prevented degradation. The capacity to degrade 2,6-DCP was examined in two fixed-bed reactors. The microbial population grew on and completely mineralized 2,6-DCP at 2,6-DCP concentrations up to 740 μM in continuous reactor culture supplied with H2O2as an oxygen source. Lack of peroxide completely stopped further degradation of 2,6-DCP. Lowering the acid-neutralizing capacity of the medium to 1/10th the original capacity led to a decrease in the pH of the effluent from 7 to 6 and to a significant reduction in the degradation activity. A second fixed-bed reactor successfully removed low chlorophenol concentrations (20 to 26 μM) with hydraulic residence times of 8 to 30 min.

Isolation and characterization of Cupriavidus basilensis HMF14 for biological removal of inhibitors from lignocellulosic hydrolysate

“…Strain HMF14 could be cultured at temperatures up to 41°C and did not show anaerobic nitrate respiration. As both the 16S rDNA sequencing and the phenotypic characteristics best matched the type species of C. basilensis (DSMZ 11853 T ) (Steinle et al. , 1998; Goris et al.…”

“…The resulting sequences were assigned GenBank accession numbers GU220488, GU220489, GU220490. Results of 16S rDNA sequencing were confirmed as indicated, by phenotypic characterization tests based on Bergey's Manual of Systematic Bacteriology (Holt, 1984) and Steinle and colleagues (1998).…”

Cupriavidus pampae sp. nov., a novel herbicide-degrading bacterium isolated from agricultural soil

“…Strains of Cupriavidus species have been isolated from environmental and human clinical sources. C. necator (Makkar & Casida, 1987), Cupriavidus oxalaticus (Sahin et al, 2000), Cupriavidus basilensis (Steinle et al, 1999), Cupriavidus campinensis (Goris et al, 2001), Cupriavidus metallidurans (Goris et al, 2001), Cupriavidus pinatubonensis and Cupriavidus laharis (Sato et al, 2006) were isolated initially from environmental sources and several strains of the species have been recognized as potential agents for bioremediation of soil and water contaminated with heavy metals or chlorinated organic compounds (Steinle et al, 1998;Goris et al, 2001;Vandamme & Coenye, 2004). Other species, such as Cupriavidus gilardii, Cupriavidus pauculus, Cupriavidus respiraculi and Cupriavidus taiwanensis, have been isolated from both human clinical samples and environmental sources (Coenye et al, 1999;Vandamme et al, 1999;Chen et al, 2001;Wauters et al, 2001).…”

Association between fertilizer-mediated changes in microbial communities and Aedes albopictus growth and survival

“…Moreover, members of the genus Ralstonia have considerable importance as potential agents for the bioremediation of soil and water contaminated with heavy metals or chlorinated organic compounds due to their capability to thrive under low concentration of nutrients (Goris et al 2001;Steinle et al 1998). Further studies are needed to determine the role of these indicator species on fertilizer degradation as well as on mosquito growth and survival.…”