Effect of pH and inoculum size on pentachlorophenol degradation by Pseudomonas sp. (original) (raw)
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Effect of pH and inoculum size on pentachlorophenol degradation by <i>Pseudomonas sp.</i>
Water SA, 2007
Pentachlorophenol (PCP) is a toxic compound which is used as a fungicide, bactericide, herbicide and chemical intermediate. Because of its toxicity, there is a need to decontaminate the PCP-laden soils and bioremediation is a very useful alternative to conventional clean-up methods. The success of this depends on finding strains able to degrade PCP in a changeable environment. The aim of this work was to study the influence of pH of the medium and the effect of inoculum size on pentachlorophenol degradation by Pseudomonas sp. A study of PCP degradation kinetics was performed to assess such effects. PCP was degraded rapidly at pH values from 6.3 to 8, but the maximum rate of PCP degradation by Pseudomonas sp. was at pH 6.3. In contrast, the PCP degradation kinetics at pH 5.5 were significantly lower, although PCP was totally depleted. These results show the broad range of pHs for PCP degradation for this strain. PCP was degraded at every inoculum size tested and PCP degradation increased with the increasing inoculum size, but cultures inoculated with the lowest inoculum showed the highest specific consumption rate. This reveals a lower consumption of PCP per CFU at a high population density. These results are useful to understand the physiological and biochemical properties of Pseudomonas sp. before its optimum use in environmental application and these data will assist in choosing the right PCP-degrader for a changeable environment.
Microbial Treatment of Soil to Remove Pentachlorophenol
Applied and Environmental Microbiology, 1983
Direct inoculation of bacteria capable of degrading pentachlorophenol (PCP) into PCP-contaminated soil was investigated as a prophylactic measure to reduce the hazards of runoffs when spills occur or when wooden poles freshly treated with PCP-containing preservatives are located near streams and lakes. In laboratory tests at 30°C, the direct addition of 10 6 PCP-utilizing Arthrobacter cells per g of dry soil reduced the half-life of the pesticide from 2 weeks to <1 day. Soil inoculation also was shown to be an effective way to increase the PCP disappearance rate in a test conducted in an outdoor shed.
Involvement of Plasmid in Degradation of Pentachlorophenol by Pseudomonas sp. from a Chemostat
Biochemical and Biophysical Research Communications, 2001
Pseudomonas sp. strain IST103 obtained from a stable bacterial consortium was capable of utilizing pentachlorophenol (PCP) as sole carbon and energy source. The consortium was developed by continuous enrichment in a chemostat. The degradation of PCP by bacterial strain proceeded through an oxidative route as indicated by accumulation of tetrachloro-p-hydroquinone and chlorohydroquinone determined by high performance liquid chromatography (HPLC), and chloride molecules released in culture medium. Two different molecular size plasmids, of approximately 80 and 4 kilobase, were found to be responsible for carrying genes for degradation of PCP. This was evidenced by mutants produced by curing of plasmid by treatment of ethidium bromide. The derivatives were not able to utilize PCP, however, transformation of low molecular size plasmid of Pseudomonas sp. strain 103 into E. coli JM109 utilized PCP, indicated a possible involvement of plasmid in degradation of pentachlorophenol.
Bulletin of Japanese Society of Microbial Ecology, 1993
In a pure culture of Pseudomonas sp. strain DP-4, a 2, 4-dichlorophenol (DCP)-assimilator, 102 cell/ml of DP-4 increased to 106 cell/mi at the early stationary phase in a mineral salts medium to which no organic substrates were deliberately added. This increase was attributable to the expense of ca. 2 pg C/ml of contaminated organic substrates in the medium. In the culture of DP-4 with ca. 106 cell/ml of the heterotrophic microorganisms which were no DCP-degraders, the density of DP-4 did not increase in the mineral salts medium without DCP, and when DCP was added the density of DP-4 increased with the the concentration of DCP. In the DP-4 culture with the heterotrophic microorganisms, the specific growth rates (1u) of DP-4 were measured at various concentrations of DCP in the range 0.01-10pg C/ml, and p of DP-4 was fitted to Monod's equation. The maximum specific growth rate (3.2/day) and the half saturation constant (0.11 pg DCP-C/ml) were considered as kinetic parameters when DP-4 assimilated DCP as a sole source of carbon.
Degradation of chlorophenol mixtures in a fed-batch system by two soil bacteria
Water SA, 2011
This work was undertaken to investigate the effect of variations of the feed rate on a fed-batch set-up used to degrade xenobiotics. The mixture of substrates was composed of PCP, 2, 4, 6 TCP and 2, 3, 5, 6 TeCP (pentachlorophenol, 2, 4, 6 trichlorophenol and 2, 3, 5, 6 tetrachlorophenol respectively). Two acclimated bacteria isolated from soil were used: Pseudomonas aeruginosa and Achromobacter sp. nov. The different flow rates tested were: I: 0.5 m· ℓmin 1, II: 1.67 m· ℓmin 1 and III: 2.00 m· ℓmin-1. Our results show that during fed- ...
Microbial degradation of pentachlorophenol
Biodegradation, 1996
Pentachlorophenol (PCP) was the most prevalent wood preservative for many years worldwide. Its widespread use had led to contamination of various environments. Traditional methods of PCP clean-up include storage in land-fill sites, incineration and abiotic degradation processes such as photodecomposition. Some aerobic and anaerobic microorganisms can degrade PCP under a variety of conditions. Axenic bacterial cultures, Flavobacterium sp., Rhodococcus sp., Arthrobacter sp., Pseudomonas sp., Sphingomonas sp., and Mycobacterium sp., and fungal cultures, Phanerochaete sp. and Trametes sp. exhibit varying rates and extent of PCP degradation. This paper provides some general information on properties of PCP and reviews the influence of nutrient amendment, temperature and pH on PCP degradation by various aerobic and anaerobic microorganisms. Where information is available, proposed degradation pathways, intermediates and enzymes are reviewed.
Use of a pentachlorophenol degrading bacterium to bioremediate highly contaminated soil
Applied Biochemistry and Biotechnology, 1995
A Sphingomonas species that mineralizes high concentrations of pentachlorophenol (PCP) was isolated from a PCP-contaminated EPA Superfund site. This bacterium, identified as Sphingomonas sp. strain RA2, is able to degrade PCP at concentrations of up to 300/~g/mL in liquid culture. This organism was tested for its ability to degrade high concentrations of PCP in a soil that did not contain organisms capable of degrading high concentrations of PCP. When inoculated into contaminated soil, Sphingomonas sp. RA2 mineralized PCP at concentrations of 300, 600, 900, and 1200/~g PCP/g of soil, but was unable to mineralize 1500 ~g PCP/g of soil. Only very minimal loss of PCP was seen in uninoculated soils. The results of this study demonstrate that Sphingomonas sp. RA2 may be a useful organism for remediation of sites contaminated with high concentrations of PCP.
Journal of Environmental Sciences, 2010
A pentachlorophenol (PCP) mineralizing bacterium was isolated from the secondary sludge of pulp and paper mill and identified as Pseudomonas stutzeri strain CL7. This isolate used PCP as its sole source of carbon and energy and was capable of degrading this compound as indicated by stoichiometric release of chloride and biomass formation. P. stutzeri (CL7) was able to mineralize a high concentration of PCP (600 mg/L) than any previously reported Pseudomonad with PCP as sole carbon source. As the concentration of PCP increased from 50 to 600 mg/L, the reduction in the cell growth was observed and the PCP degradation was more than 90% in all studied concentrations. This isolate was able to remove 66.8% of PCP from the secondary sludge of pulp and paper mill when supplemented with 100 mg/L of PCP and grown for two weeks. This study showed that the removal efficiency of PCP by CL7 was found to be very effective and can be used in PCP remediation of pulp paper mill waste in the environment.
Bangladesh Journal of Microbiology, 2010
The phenol and monochlorophenols-degrading bacteria were isolated from the soil samples adjacent to textile, pharmaceuticals, industries and automobile workshops. Twenty seven isolates were recovered including twelve phenol, four 2-chlorophenol (2-CP) and eleven 4-chlorophenol (4-CP) degrading organisms. Among them five isolates were chosen as potential monochlorophenol-degrader; four of them were identified as species of Pseudomonas and one as Aeromonas. The biodegradability of phenol and monochlorophenol followed the order: phenol > 4-chlorophenol > 2-chlorophenol. Pseudomonas sp. AP2, Pseudomonas sp. AP3, Pseudomonas sp. AP4 and Aeromonas sp. PP3 degraded 400 and 600 ppm phenol within 48 and 72 h, and Pseudomonas sp. A4-CP2 degraded 600 and 800 ppm phenol in 48 and 72 h respectively. Pseudomonas sp. A4-CP2 also degraded 200 ppm 2-chlorophenol within 96 h and 200 and 350 ppm 4-chlorophenol within 48 and 75 h respectively. Bacterial isolates grew well in liquid culture contai...