Microbial Degradation Of Phenol Research Articles

Microbial Degradation of Phenols by “Bacillus Brevis”

Industrial wastewater containing phenols causes significant environmental and ecological problems. Various methods such as chlorination, flocculation, adsorption etc. have been used for the degradation of phenol. But microbial degradation methods have proved to be the most effective and economical approach for the mineralization of toxic chemicals. A soil microbial strain Bacillus brevis, capable of utilizing phenol as a sole carbon source was isolated from the phenol bearing soil suspension of Briquetting and Carbonization Plant of NeyveliLignite Corporation Limited, (Tamil Nadu) and tested for its capacity to grow and degrade phenol. Based on it’s morphological, physiological and biochemical characteristics, the organism was found to be a Gram-positive, motile, mesophilic and rod-shaped endospore bacterium. The results indicate that the growth of the organism decreases at very high concentration of phenol. The efficiency of the organism in the degradation of substituted phenols such as o & p chlorophenols and o & p nitrophenols were compared and discussed. The degradation was highly efficient in the pH range 8 – 10. The biocatalyst obtained by immobilizing the Bacillus brevis cells on alginate beads and lignite carbon are more effective in degrading phenols.

Vetiver plantlets in aerated system degrade phenol in illegally dumped industrial wastewater by phytochemical and rhizomicrobial degradation.

This research evaluated the feasibility of using vetiver plantlets (Vetiveria zizanioides (L.) Nash) on a floating platform with aeration to degrade phenol (500mg/L) in illegally dumped industrial wastewater (IDIWW). The IDIWW sample was from the most infamous illegal dumping site at Nong Nae subdistrict, Phanom Sarakham district, Chachoengsao province, Thailand. Laboratory results suggested that phenol degradation by vetiver involves two phases: Phase I, phytopolymerization and phyto-oxidation assisted by root-produced peroxide (H2O2) and peroxidase (POD), followed by phase II, a combination of phase I with enhanced rhizomicrobial degradation. The first 360-400h of phenol degradation were dominated by phytopolymerization and phyto-oxidation yielding particulate polyphenols (PPP) or particulate organic matter (POM) as by-products, while phenol decreased to around 145mg/L. In Phase II, synergistically, rhizomicrobial growth was ∼100-folds greater on the roots of the vetiver plantlets than in the IDIWW and participated in the microbial degradation of phenol at this lower phenol concentration, increasing the phenol degradation rate by more than three folds. This combination of phytochemical and rhizomicrobiological processes eliminated phenol in IDIWW in less than 766h (32days), while without the vetiver plantlets, phenol degradation by aerated microbial degradation alone may require 235days. To our knowledge, this is the first that systematically reveals the complete phenol degradation mechanism by vetiver plantlets in real aerated wastewater.

Enhanced degradation of phenol by Sphingomonas sp. GY2B with resistance towards suboptimal environment through adsorption on kaolinite

The effects of clay minerals on microbial degradation of phenol under unfavorable environmental conditions were investigated. Degradation of phenol by Sphingomonas sp. GY2B adsorbed on kaolinite, montmorillonite, and vermiculite were evaluated in comparison with free bacteria under optimal conditions. Kaolinite was found to be the most effective in accelerating degradation rate (reducing the degradation time) as well as improving degradation efficiency (increasing the percentage of phenol degraded), with GY2B/kaolinite complex achieving a degradation efficiency of 96% within 6 h. GY2B adsorbed on kaolinite was more competent than free GY2B in degradation under conditions with high phenol concentrations and at alkaline pH. Kaolinite reduced the time required for degradation by 8–12 h and improved the degradation efficiency by as much as 82% at high phenol concentrations. Meanwhile, the GY2B/kaolinite complex reduced the degradation time by 24 h and improved the degradation efficiency by 46% at pH 12. The improvement was partially due to the buffering effects of kaolinite. It was also shown that Cr(VI) and kaolinite synergistically enhanced the degradation by GY2B, with Cr(VI) and kaolinite both increasing the degradation rate and kaolinite being primarily responsible for enhanced degradation efficiency. These results showed one of the common clay minerals, kaolinite, is able to significantly improve the microbial degradation performance, and protect microorganisms against unfavorable environment. Kaolinite can collaborate with Cr(VI) to further improve the microbial degradation performance. It is implied that clay minerals have great potential to be applied in enhancing the biodegradation of phenol.

Microbial Degradation of Phenol by Isolation and Molecular Identification Wastewater Bacteria

Microbial Degradation of Phenol by Isolation and Molecular Identification Wastewater Bacteria

Characterization of phenol and cresol biodegradation by compound-specific stable isotope analysis

Microbial degradation of phenol and cresols can occur under oxic and anoxic conditions by different degradation pathways. One recent technique to take insight into reaction mechanisms is compound-specific isotope analysis (CSIA). While enzymes and reaction mechanisms of several degradation pathways have been characterized in (bio)chemical studies, associated isotope fractionation patterns have been rarely reported, possibly due to constraints in current analytical methods. In this study, carbon enrichment factors and apparent kinetic isotope effects (AKIEc) of the initial steps of different aerobic and anaerobic phenol and cresols degradation pathways were analyzed by isotope ratio mass spectrometry connected with liquid chromatography (LC-IRMS). Significant isotope fractionation was detected for aerobic ring hydroxylation, anoxic side chain hydroxylation, and anoxic fumarate addition, while anoxic carboxylation reactions produced small and inconsistent fractionation. The results suggest that several microbial degradation pathways of phenol and cresols are detectable in the environment by CSIA.

Importance of soil organic matter for the diversity of microorganisms involved in the degradation of organic pollutants

Many organic pollutants are readily degradable by microorganisms in soil, but the importance of soil organic matter for their transformation by specific microbial taxa is unknown. In this study, sorption and microbial degradation of phenol and 2,4-dichlorophenol (DCP) were characterized in three soil variants, generated by different long-term fertilization regimes. Compared with a non-fertilized control (NIL), a mineral-fertilized NPK variant showed 19% and a farmyard manure treated FYM variant 46% more soil organic carbon (SOC). Phenol sorption declined with overall increasing SOC because of altered affinities to the clay fraction (soil particles <2 mm in diameter). In contrast, DCP sorption correlated positively with particulate soil organic matter (present in the soil particle fractions of 63-2000 μm). Stable isotope probing identified Rhodococcus, Arthrobacter (both Actinobacteria) and Cryptococcus (Basidiomycota) as the main degraders of phenol. Rhodococcus and Cryptococcus were not affected by SOC, but the participation of Arthrobacter declined in NPK and even more in FYM. (14)C-DCP was hardly metabolized in the NIL variant, more efficiently in FYM and most in NPK. In NPK, Burkholderia was the main degrader and in FYM Variovorax. This study demonstrates a strong effect of SOC on the partitioning of organic pollutants to soil particle size fractions and indicates the profound consequences that this process could have for the diversity of bacteria involved in their degradation.

Isolation and characterization of phenol utilizing bacteria from industrial effluent-contaminated soil and kinetic evaluation of their biodegradation potential

Microbial degradation of phenol by pure bacterial species is a well-known approach towards alleviation of environmental pollution. In this study, five phenol-degrading bacterial species designated as CUPS-1 to CUPS-5 were isolated from the oil-effluent dumped sites of Haldia Industrial area of West Bengal, India. Detailed morphological, biochemical and molecular characterization identified CUPS-3 as a novel strain- Stenotrophomonas maltophilia (GU358076), while the others could be identified as Pseudomonas (CUPS-2, 5), Delftia (CUPS-1) and Micrococcus (CUPS-4) genera, respectively. Although all of these strains utilized phenol as their sole carbon source supporting growth, three among them, CUPS-2, CUPS-3 and CUPS-5 proved potential phenol degraders and hence used for further biodegradation studies. Degradation experiments were carried out for several initial phenol concentrations of 500 mg/L, 750 mg/L, 1000 mg/L, 1250 mg/L and 1500 mg/L. The novel strain, CUPS-3 could completely degrade 500 mg/L phenol within 48 h, with 0.0937/h substrate degradation rate and 16.34 mg/L/h substrate consumption rate. The strains degraded phenol via meta-cleavage pathway. Prediction of kinetic parameters of the biodegradation was accomplished Haldane model using the experimental data of degradation rate and phenol concentration as function of time.

Microbial degradation of phenol and phenolic derivatives

Phenol and its derivatives are one of the largest groups of environmental pollutants due to their presence in many industrial effluents and broad application as antibacterial and antifungal agents. A number of microbial species possess enzyme systems that are applicable for the decomposition of various aliphatic and aromatic toxic compounds. Intensive efforts to screen species with high‐degradation activity are needed to study their capabilities of degrading phenol and phenolic derivatives. Most of the current research has been directed at the isolation and study of microbial species of potential ecological significance. In this review, some of the best achievements in degrading phenolic compounds by bacteria and yeasts are presented, which draws attention to the high efficiency of strains of Pseudomonas, Candida tropicalis, Trichosporon cutaneum, etc. The unique ability of fungi to maintain their degradation potential under conditions unfavorable for other microorganisms is outstanding. Mathematical models of the microbial biodegradation dynamics of single and mixed aromatic compounds, which direct to the benefit of the processes studied in optimization of modern environmental biotechnology are also presented.

Isolation and characterization of a Rhodococcus strain with phenol-degrading ability and its potential use for tannery effluent biotreatment

Wastewater derived from leather production may contain phenols, which are highly toxic, and their degradation could be possible through bioremediation technologies. In the present work, microbial degradation of phenol was studied using a tolerant bacterial strain, named CS1, isolated from tannery sediments. This strain was able to survive in the presence of phenol at concentrations of up to 1,000 mg/L. On the basis of morphological and biochemical properties, 16S rRNA gene sequencing, and phylogenetic analysis, the isolated strain was identified as Rhodococcus sp. Phenol removal was evaluated at a lab-scale in Erlenmeyer flasks and at a bioreactor scale in a stirred tank reactor. Rhodococcus sp. CS1 was able to completely remove phenol in a range of 200 to 1,000 mg/L in mineral medium at 30 ± 2 °C and pH 7 as optimal conditions. In the stirred tank bioreactor, we studied the effect of some parameters, such as agitation (200-600 rpm) and aeration (1-3 vvm), on growth and phenol removal efficiency. Faster phenol biodegradation was obtained in the bioreactor than in Erlenmeyer flasks, and maximum phenol removal was achieved at 400 rpm and 1 vvm in only 12 h. Furthermore, Rhodococcus sp. CS1 strain was able to grow and completely degrade phenols from tannery effluents after 9 h of incubation. Based on these results, Rhodococcus sp. CS1 could be an appropriate microorganism for bioremediation of tannery effluents or other phenol-containing wastewaters.

Model-based design of different fedbatch strategies for phenol degradation in acclimatized activated sludge cultures

Microbial degradation of phenol was studied using batch and fedbatch cultures of acclimatized activated sludge under a wide range of phenol (0–793mgl−1) and biomass (0.74–6.7gl−1) initial concentrations. As cell growth continued after total phenol removal, the production and later consumption of a main metabolic intermediate was considered the step governing the biodegradation kinetics. A model that takes explicitly into account the kinetics of the intermediate was developed by introducing a specific growth rate model associated with its consumption and the incorporation of a dual-substrate inhibitory effect on phenol degradation. Biomass growth and phenol removal were adequately predicted in all the cultures. Moreover, the model-based design of the fedbatch feeding strategies allowed driving separately the phenol degradation under substrate-limitation and substrate-inhibition modes. A sensitivity analysis was also performed in order to establish the importance of the parameters in the accuracy of model predictions.

Phenol degradation by Bacillus cereus: Pathway and kinetic modeling

The microbial degradation of phenol by pure cultures Bacillus cereus MTCC 9817 strain AKG1 and B. cereus MTCC 9818 strain AKG2 is studied in batch mode for several initial concentrations of phenol in the range of 100–2000 mg/L with an interval of 100 mg/L. Degradation pathways are investigated at initial phenol concentrations of 100, 500, 1000, 1500, and 2000 mg/L. The bacteria are able to degrade phenol of concentration as high as 2000 mg/L. The maximum degradation rate is obtained at an initial phenol concentration of about 800 mg/L for the strain AKG1 and about 200 mg/L for the strain AKG2. Both the strains degrade phenol via meta-cleavage pathway through formation of 2-hydroxymuconic semialdehyde (2-HMSA) as an intermediate product. Modeling of the biodegradation of phenol indicates that the Haldane inhibitory model predicts the experimental data fairly well for both the strains.

Microbial Degradation of Phenol in a Modified Three‐Stage Airlift Packing‐Bed Reactor

Phenol degradation was carried out by using a modified three-stage airlift packing-bed bioreactor. A laboratory-scale airlift packing-bed reactor, with hydrodynamic flexible packing material in the three-stage bioreactor, was constructed and operated for phenol removal from synthetic wastewater. The airlift packing-bed reactor successfully degraded phenol and lowered the chemical oxygen demand (COD) of wastewater. High COD removal was observed, and much lower sludge effluent was obtained in this investigation. This airlift bioreactor showed a superior hydrodynamics performance and broad operating conditions for phenolic material removal. Different operating modes were discussed to obtain the optimal condition for phenol degradation (i.e., hydraulic retention time [HRT] and gas flowrate of airlift). The HRT and feed phenol concentration of wastewater dominated the removal efficiency of phenol and COD. In this bioreactor, surface loading up to 2.84 g phenol/ m2 x d, almost 100% phenol removal, and over 90% COD removal was achieved. The lower operating cost combined with higher phenol-removal efficiency and a low sludge effluent concentration can be achieved by using this reactor for phenol wastewater treatment.

Optimisation of process variables for microbial degradation of phenol by binary mixed culture of Pseudomonas aeruginosa and Pseudomonas fluorescens using response surface methodology

The removal efficiency of phenol from aqueous solutions was measured using an indigenous freely suspended binary mixed culture of Pseudomonas aeruginosa and Pseudomonas fluorescens. Experiments were performed as a function of temperature (25?45°C), aeration (1.0?3.5 vvm) and agitation (200?600 rpm). Optimisation of these three process parameters for phenol biodegradation was studied. Statistically designed experiments using response surface methodology were used to get more information about the significant effects and the interactions between the three parameters. A 2³ full-factorial central composite design followed by multistage Monte Carlo optimisation technique was employed for experimental design and analysis of the results. The optimum process conditions of temperature 30°C, aeration 3.0 vvm and agitation 300 rpm were recognised for maximising phenol degradation (removal). Maximum removal efficiency of phenol was achieved (100%) at the optimum process conditions.

Modeling the biodegradation of phenolic compounds by microalgae

Phenols represent a group of organic pollutants frequently found in many near-shore marine systems. The microbial degradation of phenols, mainly by bacteria and fungi, has been extensively studied both experimentally and theoretically, but only relatively recently the capabilities of some algae for phenols biodegradation gained interest. The biodegradation of phenols by microalgae occurs only under aerobic conditions. In this paper, a dynamic energy budget model is proposed for describing aerobic biodegradation of phenolic compounds by microalgae and qualitatively validated against experimental data. A microalgal cell has the ability to produce biomass via the autotrophic assimilation (uptake of light and dissolved inorganic carbon), the heterotrophic assimilation (uptake of dissolved organic carbon) and, to a lesser extend, via the biodegradation of phenols. The rules of synthesizing units are used for the uptake and interactions of substrates and for the merging of assimilates. The model is capable of making predictions under oxygen and carbon (inorganic and organic) limiting conditions. Model predictions cover a wide range of experimental evidence, but also give a possible explanation for the inhibition of bioremoval of phenols in the presence of glucose. The dissolved oxygen profiles numerically observed show low oxygen concentration during the intermediate phase of the biodegradation process and a rapid increase after the consumption of the phenolic compound, indicating that lack of oxygen could be a limiting factor for the biodegradation of phenols. The presence of glucose increases the specific growth rate but decreases the specific biodegradation rate of the phenolic compound. Model analysis suggests that this inhibition may be due to the competition for oxygen between glucose and phenol assimilation. In general, the balance between the benefits and costs of the different types of assimilation determines the microalgal growth rates as well as the phenol biodegradation rates. Being based on general assumptions, the model can be applied to the biodegradation of a wide variety of aromatic compounds.

Microbial degradation of phenols: a review

The microbial degradation of phenols has been reviewed including the phenol-degrading microbes, factors affecting degradability, and the use of biotechnology with emphasis on degradation mechanisms and their kinetics. The mechanism of microbial degradation depends on aerobic and anaerobic conditions. Under aerobic conditions, degradation of phenol was shown to be initiated by oxygenation into catechols as intermediates followed by a ring cleavage at either the ortho or meta position, depending on the type of strain. Anaerobic biodegradation of phenol occurs by carboxylation followed by dehydroxylation (reducing reaction) and dearomatisation. It was also clear that the parameters used in the Haldane model are not constants but vary, hence it may never be possible to describe the kinetic properties of a microbial cell with a single set of constants.

Microbial degradation of phenol in high-salinity solutions in suspensions and hollow fiber membrane contactors

A microporous polypropylene (PP) hollow fiber membrane contactor was used as a bioreactor to degrade phenol in aqueous solutions by Pseudomonas putida BCRC 14365 at 30 °C. The fibers were pre-wetted by ethanol to make them more hydrophilic. The initial cell density was fixed at 0.025 g l −1. The effects of added NaCl concentration (0–1.78 M) and pH (3–8) in substrate solution on the biodegradation were studied. The experimental results by suspended cells were discussed. It was shown that the cells in microporous hollow fibers were unable to tolerate substrate solution pH to a larger range than those in suspensions. The suspended cells grew well on 100 mg l −1 of phenol only at NaCl concentrations below 0.44 M. However, the cells in microporous hollow fibers could completely degrade 500 mg l −1 of phenol in solutions containing NaCl concentration up to 1.52 M, which was due to the enhanced tolerance limit to salinity effect by the membrane-attached biofilms and the sufficiently slow mass transfer of NaCl through the membrane pores.

Role of photochemical and microbial degradation of phenol in water

The present work is aimed at spectroscopic and luminescent investigations of the microbial cleavage efficiency of phenol in the water solution upon expose to UV light. With increasing time of irradiation of phenol in the saline solution,the absorption intensity increases throughout the spectrum. The efficiency of photoalteration of phenol in the saline solution is higher compared to that in water. The results obtained have shown that the efficiency of complex photobiological phenol destruction increases sharply compared to the photochemical or microbial destruction.

Microbial degradation of aromatic and polyaromatic toxic compounds adsorbed on powdered activated carbon

The microbial degradation of phenol (300–1300 mg l −1), p-nitrophenol (50–500 mg l −1), and phenanthrene (50–300 mg l −1) adsorbed on powdered activated carbon (PAC) was studied. The combination of physical sorption and biological degradation on PAC, which serves as adsorbent carrier, was compared with the degradation performance of suspended cells and cultures attached to sand, which serves as an example of an inert support. Almost similar profiles of degradation were obtained in the cultures with PAC for the three compounds studied, over the entire concentration range. However, at the higher concentrations, degradation was dramatically inhibited, or even ceased completely, in suspended or sand-attached cultures, even though specialized mixed bacterial cultures adapted to high toxicant concentrations were used in each case. Degradation with PAC assumes an intrinsic relationship between the activated carbon and bacteria in the same environment, thus regenerating the surface of the adsorbent/ carrier as diffusion and degradation proceed. The adsorbed material desorbs, diffuses out of the carbon and can then be metabolized. Our results highlight the applicability of activated carbon, in either powdered or granular form, to achieve a steady-state operation in continuous process, for the treatment of toxic chemicals, even with specialized bacteria.

Identification of metabolic intermediates in microbial degradation of phenol using laser desorption time-of-flight mass spectrometry

Laser desorption time-of-flight (LD-TOF) mass spectrometry was utilized to determine the metabolic intermediates in microbial degradation of phenol. The identified components were in good agreement with the well-documented pathway. This technique also demonstrated excellent precision. Analytical merits, instrumentation and methodology are discussed.

Microbial degradation of phenols and aromatic hydrocarbons in creosote-contaminated groundwater under nitrate-reducing conditions

Batch experiments were carried out to investigate the biodegradation of phenols and aromatic hydrocarbons under anaerobic, nitrate-reducing conditions in groundwater from a creosote-contaminated site at Fredensborg, Denmark. The bacteria in the creosote-contaminated groundwater degraded a mixture of toluene, phenol, the cresols ( o-, m- and p-cresol) and the dimethylphenols 2,4-DMP and 3,4-DMP at both 10° and 20°C. Benzene, the xylenes, napthalene, 2,3-DMP, 2,5-DMP, 2,6-DMP and 3,5-DMP were resistant to biodegradation during 7–12 months of incubation. It was demonstrated that the degradation of toluene, 2,4-DMP, 3,4-DMP and p-cresol depended on nitrate or nitrite as electron acceptors. 40–80% of the nitrate consumed during degradation of the aromatic compounds was recovered as nitrite, and the consumption of nitrate was accompanied by a production of ATP. Stoichiometric calculations indicated that in addition to the phenols are toluene other carbon sources present in the groundwater contributed to the consumption of nitrate. If the groundwater was incubated under anaerobic conditions without nitrate, sulphate-reducing conditions evolved after ∼ 1 month at 20°C and ∼2 months at 10°C. In the sulphate-reducing batches disappearance of toluene, phenol, o-cresol and o-cresol was observed, whereas no removal of benzene, the xylenes, naphthalane, 2,3-DMP, 2,4-DMP, 2,5-DMP and 3,5-DMP was detected during 7 months of incubation.