Degradation of 1,4-dichlorobenzene by Alcaligenes sp. strain A175

Triclosan is a broad-spectrum antimicrobial agent that has been incorporated into many household and medical products. Bacteria with high levels of triclosan resistance were isolated from compost, water, and soil samples. Two of these bacteria, Pseudomonas putida TriRY and Alcaligenes xylosoxidans subsp. denitrificans TR1, were able to use triclosan as a sole carbon source and clear particulate triclosan from agar. A decrease in triclosan concentration was measured by HPLC within 6 h of inoculation with strain TriRY and 24 h with strain TR1. Bioassays demonstrated that triclosan was inactivated in liquid cultures and/or embedded in plastic by the growth of strain TriRY and strain TR1, permitting the growth of triclosan-sensitive bacteria. ß

Section: Resultsmentioning

confidence: 99%

Soil bacteria Pseudomonas putida and Alcaligenes xylosoxidans subsp. denitrificans inactivate triclosan in liquid and solid substrates

Meade

2001

“…strain P51 was taken from the laboratory culture collection [3]. Strain P51 was grown in a 300 ml batch culture on mineral medium Z3 with 250 mg l 3I 1,2,4-TCB as sole carbon and energy source in a 3 l gas-tight Erlenmeyer £ask [5]. Growth was followed spectrophotometrically at 578 nm and by plate counts of colony form-ing units on nutrient broth (NB) medium (Biolife, Italy).…”

Section: Growth Of Bacteriamentioning

confidence: 99%

Quantification of bacterial mRNA involved in degradation of 1,2,4-trichlorobenzene by Pseudomonas sp. strain P51 from liquid culture and from river sediment by reverse transcriptase PCR (RT/PCR)

Meckenstock

1998

Competitive reverse transcriptase polymerase chain reaction (RT/PCR) was used to quantify the mRNA of the tcbC gene of Pseudomonas sp. strain P51. The tcbC gene encodes the enzyme chlorocatechol-1,2-dioxygenase involved in 1,2,4-trichlorobenzene (TCB) degradation. The mRNA content per cell was monitored in a batch culture growing on 1,2,4-TCB. No mRNA could be detected in the first 2 days of the lag phase. mRNA production became maximal with 20 molecules per cell in the early exponential growth phase but then decreased to less than 10 molecules per cell. When TCB was depleted and the cells entered the stationary phase, the mRNA content decreased slowly below the detection limit within 4 days. In order to compare detection of tcbC mRNA in pure culture and in river sediment, cells of strain P51 pregrown on TCB were added to sediment and RNAs extracted. In sediment samples containing 5U10V cells per gram the tcbC mRNA was quantifiable by RT/PCR. The mRNA recovery was about 3% as compared to the inoculum. The detection limit of the RT/PCR method was about 10 U mRNA molecules per gram sediment or 10 T copies per ml culture medium which corresponded in our case to 10 S molecules per reaction vial. z

“…An Alcaligenes sp., which could utilize benzene, chlorobenzene, and 1,3-and 1,4-dichlorobenzene, oxidized 1,3-dichlorobenzene via the dihydrodioi to 3,5-dichlorocatechol, which was degraded by ortho-cleavage to 2,4-dichloromuconate [277]. Similarly, degradation of 1,4-dichlorobenzene by strains of Alcali-genes and Pseudomonas has been demonstrated to proceed via the corresponding dihydrodiol to 3,6-dichlorocatechol, with subsequent ring-cleavage yielding 2,5-dichloromuconate [28, 278,279]. para-Chlorotoluene was degraded via an analogous pathway to 3-chloro-6-methylcatechol and 2-chloro-5-methylmuconate [280].…”

Section: Aerobic Degradation Of Halobenzenesmentioning

confidence: 99%

Microbial breakdown of halogenated aromatic pesticides and related compounds

Häggblom

1992

363

132

Considerable progress has been made in the last few years in understanding the mechanisms of microbial degradation of halogenated aromatic compounds. Much is already known about the degradation mechanisms under aerobic conditions, and metabolism under anaerobiosis has lately received increasing attention. The removal of the halogen substituent is a key step in degradation of halogenated aromatics. This may occur as an initial step via reductive, hydrolytic or oxygenolytic mechanisms, or after cleavage of the aromatic ring at a later stage of metabolism. In addition to degradation, several biotransformation reactions, such as methylation and polymerization, may take place and produce more toxic or recalcitrant metabolites. Studies with pure bacterial and fungal cultures have given detailed information on the biodegradation pathways of several halogenated aromatic compounds. Several of the key enzymes have been purified or studied in cell extracts, and there is an increasing understanding of the organization and regulation of the genes involved in haloaromatic degradation. This review will focus on the biodegradation and biotransformation pathways that have been established for halogenated phenols, phenoxyalkanoic acids, benzoic acids, benzenes, anilines and structurally related halogenated aromatic pesticides. There is a growing interest in developing microbiological methods for clean‐up of soil and water contaminated with halogenated aromatic compounds.