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Degrading Microorganisms (degrading + microorganism)
Selected AbstractsA strain isolated from gas oil-contaminated soil displays chemotaxis towards gas oil and hexadecaneENVIRONMENTAL MICROBIOLOGY, Issue 10 2003Mariana P. Lanfranconi Summary In this report we describe the isolation of a strain from soil contaminated with gas oil by taking bacteria from a chemotactic ring on gas oil-containing soft agar plates. Partial 16 S rDNA sequencing of the isolated strain showed 99.1% identity with Flavimonas oryzihabitans. It was not only able to degrade different aliphatic hydrocarbons but it was also chemotactic towards gas oil and hexadecane, as demonstrated by the use of three different chemotaxis methods, such as agarose plug and capillary assays and swarm plate analysis. In addition, the strain was chemotactic to a variety of carbon sources that serve as growth substrates, including glucose, arabinose, mannitol, glycerol, gluconate, acetate, succinate, citrate, malate, lactate and casaminoacids. This is the first report on chemotaxis of a hydrocarbon-degrading bacterium towards a pure alkane, such as hexadecane. The fact that environmental isolates show chemotaxis towards contaminant/s present in the site of isolation suggests that chemotaxis might enhance biodegradation by favouring contact between the degrading microorganism and its substrate. [source] Monitoring of Desulfitobacterium frappieri PCP-1 in pentachlorophenol-degrading anaerobic soil slurry reactorsENVIRONMENTAL MICROBIOLOGY, Issue 6 2000M. Lanthier Anaerobic biodegradation of pentachlorophenol (PCP) was studied in rotative bioreactors containing 200 g of PCP-contaminated soil and 250 ml of liquid medium. Reactors were bioaugmented with cells of Desulfitobacterium frappieri strain PCP-1, a bacterium able to dehalogenate PCP to 3-chlorophenol. Cells of strain PCP-1 were detected by quantitative PCR for at least 21 days in reactors containing 500 mg of PCP per kg of soil but disappeared after 21 days in reactors with 750 mg of PCP per kg of soil. Generally, PCP was completely removed in less than 9 days in soils contaminated with 189 mg of PCP per kg of soil. Sorption of PCP to soil organic matter reduced its toxicity and enhanced the survival of strain PCP-1. In some non-inoculated reactors, the indigenous microorganisms of some soils were also able to degrade PCP. These results suggest that anaerobic dechlorination of PCP in soils by indigenous PCP-degrading bacteria, or after augmentation with D. frappieri PCP-1, should be possible in situ and ex situ when the conditions are favourable for the survival of the degrading microorganisms. [source] Rhizoremediation of lindane by root-colonizing SphingomonasMICROBIAL BIOTECHNOLOGY, Issue 1 2008Dietmar Böltner Summary We used a two-step enrichment approach to isolate root-colonizing hexachlorocyclohexane (HCH)-degrading microorganisms. The first step consists of the use of classical liquid enrichment to isolate ,-HCH degraders. The ,-HCH-degrading microbes were attached in mass to corn seeds sown in soil with ,-HCH, and after plant development we rescued bacteria growing on root tips. Bacteria were then subjected to a second enrichment round in which growth on liquid medium with ,-HCH and inoculation of corn seeds were repeated. We then isolated bacteria on M9 minimal medium with ,-HCH from root tips. We were able to isolate four Sphingomonas strains, all of which degraded ,-, ,-, ,- and ,-HCH. Two of the strains were particularly good colonizers of corn roots, reaching high cell density in vegetated soil and partly removing ,-HCH. In contrast, these bacteria performed poorly in unplanted soils. This study supports the hypothesis that the removal of persistent toxic chemicals can be accelerated by combinations of plants and bacteria, a process generally known as rhizoremediation. [source] The biodegradation of poly(3-hydroxy-butyrate- co -3-hydroxyvalerate) (PHB/V) and PHB/V-degrading microorganisms in soil,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3-5 2003Cunjiang Song Abstract To assess the polyhydroxyalkanoate (PHA)-biodegrading capacity of soil, numbers of aerobic poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB/V)-degrading microorganisms (degraders) were estimated by the film-MPN method. The numbers of PHB/V degraders were estimated to be 4.3,×,105 per gram of dry garden soil, 5.06,×,105 per gram of dry paddy-field soil, and 3.87,×,105 per gram of dry river-bank soil. The degradations of PHB/V in suspensions of the three kinds of soil were investigated. It was found that the PHB/V-biodegrading capacity of the soil increased as the number of PHB/V degraders in the soil increased. The relationship between weight loss of PHB/V and proliferation rate of PHB/V degraders in garden soil suspension was investigated. The effect of glucose on the biodegradation of PHB/V in garden soil was also studied. The weight loss after one week in garden soil suspension supplemented with 20,mM of glucose (GSS-20G) was 2.60%, which was lower than that in garden soil suspension (GSS) (7.14%). After five weeks, the weight loss had increased to 24.97% in GSS-20G but only to 18.26% in GSS. The results showed that glucose played important roles in inhibition and acceleration of different biodegrading phases and finally accelerated the PHB/V biodegradation in soil suspension. Copyright © 2003 John Wiley & Sons, Ltd. [source] Anaerobic mineralization of pentachlorophenol (PCP) by combining PCP-dechlorinating and phenol-degrading culturesBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2009Suyin Yang Abstract The dechlorination and mineralization of pentachlorophenol (PCP) was investigated by simultaneously or sequentially combining two different anaerobic microbial populations, a PCP-dechlorinating culture capable of the reductive dechlorination of PCP to phenol and phenol- degrading cultures able to mineralize phenol under sulfate- or iron-reducing conditions. In the simultaneously combined mixture, PCP (about 35 µM) was mostly dechlorinated to phenol after incubation for 17 days under sulfate-reducing conditions or for 22 days under iron-reducing conditions. Thereafter, the complete removal of phenol occurred within 40 days under both conditions. In the sequentially combined mixture, most of the phenol, the end product of PCP dechlorination, was degraded within 12 days of inoculation with the phenol degrader, without a lag phase, under both sulfate- and iron-reducing conditions. In a radioactivity experiment, [14C,U],PCP was mineralized to 14CO2 and 14CH4 by the combined anaerobic microbial activities. Analysis of electron donor and acceptor utilization and of the production and consumption of H2, CO2, and CH4 suggested that the dechlorinating and degrading microorganisms compete with other microorganisms to perform PCP dechlorination and part of the phenol degradation in complex anoxic environments in the presence of electron donors and acceptors. The presence of a small amount of autoclaved soil slurry in the medium was possibly another advantageous factor in the successful dechlorination and mineralization of PCP by the combined mixtures. This anaerobic,anaerobic combination technology holds great promise as a cost-effective strategy for complete PCP bioremediation in situ. Biotechnol. Bioeng. 2009;102: 81,90. © 2008 Wiley Periodicals, Inc. [source] | ||||||||||