Potential use of cyclodextrins in soil bioremediation (original) (raw)
Related papers
Biodegradation of cyclodextrins in soil
Chemosphere, 2005
Cyclodextrins, especially random methylated bCD (RAMEB) and hydroxypropyl bCD (HPbCD), are becoming common enhancing additives in the bioremediation of soils formerly contaminated by hydrocarbons and/or other poorly bioavailable organic pollutants. Therefore, their degradation in the soil, particularly the most persistent RAMEB, has been of great concern. Like oil contaminants, these additives should be biodegradable via an environmentally safe technology. Hence, in this paper, the biodegradability of eight different cyclodextrins (CDs) in four different soils was examined under various treatment conditions in laboratory and pilot scale field experiments. This paper is the first report on the potential biological fate of CDs studied under a large variety of environmental conditions and in different soil ecosystems. Data on the potential relationship between CD biodegradation and the biological removal of hydrocarbons in the CD-amended contaminated soils are also given. All CDs were found to be more or less biodegradable; even the most persistent RAMEB was depleted from soils under favourable conditions. In the field experiments, the depletion of RAMEB to about 40% of its initial level was observed for a period of 2 years in hydrocarbon-contaminated soils of high organic matter and cell concentration.
Development of an innovative soil remediation: “Cyclodextrin-enhanced combined technology
Science of The Total Environment, 2008
This paper introduces an in situ "Cyclodextrin-enhanced soil bioremediation technology" which is a combination of 1. in situ bioventilation for biodegradation in the unsaturated soil zone; 2. physico-chemical treatment of the pumped ground water; 3. impulsive flushing for the three-phase soil. For enhancement of biodegradation and solubilization randomly methylated β-cyclodextrin (RAMEB) was used.
Enzyme and Microbial Technology, 2000
In general the biodegradation of nonchlorinated aliphatic and aromatic hydrocarbons is influenced by their bioavailability. Hydrocarbons are very poorly soluble in water. They are easily adsorbed to clay or humus fractions in the soil, and pass very slowly to the aqueous phase, where they are metabolised by microorganisms. Surfactants that increase their solubility and improve their bioavailability can thereby accelerate degradation. Cyclodextrins are natural compounds that form soluble complexes with hydrophobic molecules. They are widely used in medicine and harmless to microorganisms and enzymes. This paper describes their in vitro effect on the biodegradative activity of a microbial population isolated from a petroleum-polluted soil, as shown by the decrease of dodecane (C12), tetracosane (C24) anthracene and naphthalene added individually as the sole carbon source to mineral medium liquid cultures. -cyclodextrin accelerated the degradation of all four hydrocarbons, particularly naphthalene, and influenced the growth kinetics as shown by a higher biomass yield and better utilization of hydrocarbon as a carbon and energy source. Its low cost, biocompatibility and effective acceleration of degradation make -cyclodextrin an attractive option for bioremediation.
Water, Air, & Soil Pollution: Focus, 2003
Bioavailability is one main factor that influences the extent of biodegradation of hydrocarbons. They are very poorly soluble in water and easily adsorbed to clay or humus fractions, so they pass very slowly to the aqueous phase where they are metabolised by microorganisms. Cyclodextrins are natural compounds that form soluble inclusion complexes with hydrophobic molecules and increase degradation rate of hydrocarbons in vitro. In the perspective of an in situ application, we previously checked that β-cyclodextrin does not increase eluviation of hydrocarbons through the soil and consequently does not increase the risk of groundwater pollution. The results of an in situ application of β-cyclodextrin for bioremediation of a hydrocarbon polluted site are presented. We stated that the combination of bioaugmentation and enhanced bioavailability due to β-cyclodextrin was effective for a full degradation.
Chemosphere, 2018
The phenylurea herbicide diuron is persistent in soil, water and groundwater and is considered 16 to be a highly toxic molecule. The principal product of its biodegradation, 3,4-dichloroaniline, 17 exhibits greater toxicity than diuron and is persistent in the environment. Five diuron degrading 18 microbial consortia (C1-C5), isolated from different agricultural soils, were investigated for 19 diuron mineralization activity. The C2 consortium was able to mineralize 78.6% of the diuron in 20 solution, while consortium C3 was only able to mineralize 22.9%. Isolated consortia were also 21 tested in soil slurries and in all cases, except consortium C4, DT 50 (the time required for the 22 diuron concentration to decline to half of its initial value) was drastically reduced, from 700 23 days (non-inoculated control) to 546, 351, and 171 days for the consortia C5, C2, and C1, 24 respectively. In order to test the effectiveness of the isolated consortium C1 in a more realistic 25 scenario, soil diuron mineralization assays were performed under static conditions (40% of the 26 soil water-holding capacity). A significant enhancement of diuron mineralization was observed 27 after C1 inoculation, with 23.2% of the herbicide being mineralized in comparison to 13.1% for 28 the control experiment. Hydroxypropyl-β-cyclodextrin, a biodegradable organic enhancer of 29 pollutant bioavailability, used in combination with C1 bioaugmentation in static conditions, 30 resulted in a significant decrease in the DT 50 (214 days; 881 days, control experiment). To the 31 best of our knowledge, this is the first report of the use of soil-isolated microbial consortia in 32 combination with cyclodextrins proposed as a bioremediation technique for pesticide 33 contaminated soils.
Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2007
In situ bioremediation of polycyclic aromatic hydrocarbons (PAH) polluted soils can be improved by the augmentation of degrading microbial populations and by the increase of hydrocarbon bioavailability. b-cyclodextrin (b-CD) significantly accelerate the induction of hydrocarbon biodegradation, but it is not still clear its effectiveness during final, slower stages of degradation. Moreover, it is yet not known if the PAH uptake from plants is influenced by the presence of CD. A field study was carried out by creating two plots (A and B). Diesel fuel was spread on the surface, and on plot B a commercial microbial consortium and b-CD were spread. Soybean was seeded in both plots. Soil samples were withdrawn every 10 cm layers from 0 to 60 cm depth, before fuel spreading, immediately after seeding and after soya harvesting. Chemical and microbial analyses were carried out throughout the process to characterize the soil and to determine residual PAHs. Soybean seeds were analyzed for PAH content. It was observed that b-CD induced a significant increase of PAH degradation rate. The microbial inoculum did not improve the degradation; biodegradation activity was strong in superficial layers, and some PAH leaching was observed, that was reduced by CD. The analysis of PAH in soyabeans revealed that an uptake of hydrocarbons occurred, and that it was more significant in plot B. This suggests that the b-CDenhanced bioremediation process can further be improved by phytoremediation, that could also allow to simultaneously reach an additional profit from a non-food yield for biofuel production.
Biodegradation of hydrocarbons in the presence of cyclodextrins
World Journal of Microbiology & Biotechnology, 2010
Aliphatic hydrocarbons are one of the main components of oil contamination. Bioremediation is considered to be a cost-effective treatment option among the conventional treatment methods with bioavailability being the limitation. Chemical surfactants could be used to increase the bioavailability of the hydrocarbons but they showed marked toxicity and environmental pollution. Cyclodextrins are cyclic oligosaccharides which can alter the solubility of the hydrocarbons by incorporating suitably sized hydrophobic molecules into their hydrophobic cavities. This paper focuses on studying the degradation of hydrocarbons by Pseudomonas like species named as Vid1 isolated previously from bilge oil contaminated waters in the presence of cyclodextrins. Among the three cyclodextrins (α, β and γ) tested at different concentrations, 2.5 mM of β-cyclodextrin showed higher amount of biodegradation when n-hexadecane was used as a model hydrocarbon compound. The percentage of residual hexadecane remaining in the 2.5 mM β-cyclodextrin supplied medium at 120 h was found to be 15% in comparison with the biotic control which was 43%. In the next experimental setup, degradation of mixture of hydrocarbons (tetradecane, hexadecane and octadecane) by Vid1 (Pseudomonas like species) was studied at a concentration of 2.5 mM β-cyclodextrin. The residual percentage of tetradecane, hexadecane and octadecane at 120 h was found to be 32, 43 and 61% in comparison with the biotic control 50, 58 and 67%, respectively. Our studies show that among a mixture of hydrocarbons (tetradecane, hexadecane and octadecane) in the presence of β-cyclodextrin, the highest concentration of hydrocarbon degradation was found in tetradecane, hexadecane and octadecane, respectively.