Anaerobic biodegradation of phenol by <Emphasis Type="Italic">Candida albicans</Emphasis> PDY-07 in the presence of 4-chlorophenol

Biodegradation of phenol and 4-chlorophenol (4-cp) using pure culture of Candida albicans PDY-07 under anaerobic condition was studied. The results showed that the strain could completely degrade up to 1,800 mg/l phenol within 68 h. The capacity of the strain to degrade phenol was higher than that to degrade 4-cp. In the dual-substrate system, 4-cp intensely inhibited phenol biodegradation. Comparatively, low-concentration phenol from 25 to 150 mg/l supplied a carbon and energy source for Candida albicans PDY-07 in the early phase of biodegradation and accelerated the assimilation of 4-cp, which resulted in that 50 mg/l 4-cp was degraded within less time than that without phenol. While the biodegradation of 50 mg/l 4-cp was inhibited in the presence of 200 mg/l phenol. In addition, the intrinsic kinetics of cell growth and substrate degradation were investigated with phenol and 4-cp as single and dual substrates in batch cultures. The results demonstrated that the models adequately described the dynamic behaviors of biodegradation by Candida albicans PDY-07.     

Degradation of chlorobenzene by strain <Emphasis Type="Italic">Ralstonia pickettii</Emphasis> L2 isolated from a biotrickling filter treating a chlorobenzene-contaminated gas stream

A Ralstonia pickettii species able to degrade chlorobenzene (CB) as the sole source of carbon and energy was isolated from a biotrickling filter used for the removal of CB from waste gases. This organism, strain L2, could degrade CB as high as 220 mg/L completely. Following CB consumption, stoichiometric amounts of chloride were released, and CO₂ production rate up to 80.2% proved that the loss of CB was mainly via mineralization and incorporation into cell material. The Haldane modification of the Monod equation adequately described the relationship between the specific growth rate and substrate concentration. The maximum specific growth rate and yield coefficient were 0.26 h⁻¹ and 0.26 mg of biomass produced/mg of CB consumed, respectively. The pathways for CB degradation were proposed by the identification of metabolites and assay of ring cleavage enzymes in cell extracts. CB was degraded predominantly via 2-chlorophenol to 3-chlorocatechol and also partially via phenol to catechol with subsequent ortho ring cleavage, suggesting partially new pathways for CB-utilizing bacteria.     

Enhanced phenol degradation by immobilized Acinetobacter sp. strain AQ5NOL 1

A locally isolated Acinetobacter sp. Strain AQ5NOL 1 was encapsulated in gellan gum and its ability to degrade phenol was compared with the free cells. Optimal phenol degradation was achieved at gellan gum concentration of 0.75% (w/v), bead size of 3 mm diameter (estimated surface area of 28.26 mm²) and bead number of 300 per 100 ml medium. At phenol concentration of 100 mg l⁻¹, both free and immobilized bacteria exhibited similar rates of phenol degradation but at higher phenol concentrations, the immobilized bacteria exhibited a higher rate of degradation of phenol. The immobilized cells completely degrade phenol within 108, 216 and 240 h at 1,100, 1,500 and 1,900 mg l⁻¹ phenol, respectively, whereas free cells took 240 h to completely degrade phenol at 1,100 mg l⁻¹. However, the free cells were unable to completely degrade phenol at higher concentrations. Overall, the rates of phenol degradation by both immobilized and free bacteria decreased gradually as the phenol concentration was increased. The immobilized cells showed no loss in phenol degrading activity after being used repeatedly for 45 cycles of 18 h cycle. However, phenol degrading activity of the immobilized bacteria experienced 10 and 38% losses after the 46 and 47th cycles, respectively. The study has shown an increased efficiency of phenol degradation when the cells are encapsulated in gellan gum.     

Phenol degradation by Paenibacillus thiaminolyticus and Bacillus cereus in axenic and mixed conditions

In this study, seven aerobic bacterial strains were screened for phenol tolerance at different concentration of phenol. Bacterial strains were unable to utilize phenol in absence of glucose, indicated the phenomenon of co-metabolism. Among the seven isolated bacterial strains, only ITRC BK-4 and ITRC BK-7 found potential and identified as Paenibacillus thiaminolyticus (DQ435022) and Bacillus cereus (DQ435023), respectively. Phenol degradation was monitored routinely with spectrophotometer and further confirmed by HPLC analysis. ITRC BK-4, ITRC BK-7 and mixed culture degrade 700 ppm phenol up to 51.72, 70.00 and 84.57% respectively in mineral salt medium (MSM) at temperature 37 ± 1°C, pH 7.5 ± 0.2, 120 rpm in presence of 1% glucose (w/v) within 144 h incubation. The mix culture was found more potential for phenol degradation compared to axenic strains. Hence, the axenic and mixed strains of these bacteria would be useful for the removal/mineralization of phenol from industrial waste waters.     

Degradation of phenol by aerobic granules and isolated yeast Candida tropicalis

Aerobic granules effectively degrade phenol at high concentrations. This work cultivated aerobic granules that can degrade phenol at a constant rate of 49 mg-phenol/g x VSS/h up to 1,000 mg/L of phenol. Fluorescent staining and confocal laser scanning microscopy (CLSM) tests demonstrated that an active biomass was accumulated at the granule outer layer. A strain with maximum ability to degrade phenol and a high tolerance to phenol toxicity isolated from the granules was identified as Candida tropicalis via 18S rRNA sequencing. This strain degrades phenol at a maximum rate of 390 mg-phenol/g x VSS/h at pH 6 and 30 degrees C, whereas inhibitory effects existed at concentrations >1,000 mg/L. The Haldane kinetic model elucidates the growth and phenol biodegradation kinetics of the C. tropicalis. The fluorescence in situ hybridization (FISH) and CLSM test suggested that the Candida strain was primarily distributed throughout the surface layer of granule; hence, achieving a near constant reaction rate over a wide range of phenol concentration. The mass transfer barrier provided by granule matrix did not determine the reaction rates for the present phenol-degrading granule.     

Biotransformation of 2,4,6-Trinitrotoluene by Pure Culture Ruminal Bacteria

Twenty-one ruminal bacteria species were tested for their ability to degrade 2,4,6-trinitrotoluene (TNT) within 24 h. Butyrivibrio fibrisolvens, Fibrobacter succinogenes, Lactobacillus vitulinus, Selenomonas ruminantium, Streptococcus caprinus, and Succinivibrio dextrinosolvens were able to completely degrade 100 mg/L TNT, with <5% of the original TNT recovered as diaminonitrotoluene metabolites. Eubacterium ruminantium, Lactobacillus ruminis, Ruminobacter amylophilus, Streptococcus bovis, and Wolinella succinogenes were able to completely degrade 100 mg/L TNT, with 23–60% of the TNT recovered as aminodinitrotoluene and/or diaminonitrotoluene metabolites. Clostridium polysaccharolyticum, Megasphaera elsdenii, Prevotella bryantii, Prevotella ruminicola, Ruminococcus albus, and Ruminococcus flavefaciens were able to degrade 80–90% of 100 mg/L TNT. Desulfovibrio desulfuricans subsp. desulfuricans, Prevotella albensis, and Treponema bryantii degraded 50–80% of the TNT. Anaerovibrio lipolytica was completely inhibited by 100 mg/L TNT. These results indicate that a variety of rumen bacteria is capable of transforming TNT.     

Process development for degradation of phenol by Pseudomonas putida in hollow-fiber membrane bioreactors

The degradation of phenol (100-2800 mg/L) by cells Pseudomonas putida CCRC14365 in an extractive hollow-fiber membrane bioreactor (HFMBR) was studied, in which the polypropylene fibers were prewetted with ethanol. The effects of flow velocity, the concentrations of phenol, and the added dispersive agent tetrasodium pyrophosphate on phenol degradation and cell growth were examined. It was shown that about 10% of phenol was sorbed on the fibers at the beginning of the degradation process. The cells P. putida fully degraded 2000 mg/L of phenol within 73 h when the cells were immobilized and separated by the fibers. Even at a level of 2800 mg/L, phenol could be degraded more than 90% after 95-h operation. At low phenol levels (< 400 mg/L) where substrate inhibition was not severe, it was more advantageous to treat the solution in a suspended system. At higher phenol levels (> 1000 mg/L), however, such HFMBR-immobilized cells could degrade phenol to a tolerable concentration with weak substrate-inhibition effect, and the degradation that followed could be completed by suspended cultures due to their larger degradation rate. The process development in an HFMBR system was also discussed.     

Community analysis and metabolic pathway of halophilic bacteria for phenol degradation in saline environment

A moderately halophilic bacterial enrichment was able to degrade 120 mg/L of phenol in the presence of 1–2 M of NaCl within 3 d or 2.5–3 M of NaCl within 6 d. The optimal degradation was achieved at 1.5 M of NaCl and 350 mg/L of phenol. PCR-DGGE profile of the enrichment showed that the Acidobacterium sp. and Chloroflexus sp. dominated the community. The phenol-biodegradation pathways consisted of an initial oxidative attack by phenol hydroxylase, and subsequent ring fission by catechol 1,2-dioxygenase and catechol 2,3-dioxygenase. Nuclear magnetic resonance (NMR) spectroscopy profiles showed that ectoine and hydroxyectoine were the main compatible solutes to adjust the bacterial osmotic pressure. This study provides further information on the understanding of phenol-degradation over a wide range of salinity and remediation of phenol as a pollutant in the environment.     

Resorcinol degradation by a <Emphasis Type="Italic">Penicillium chrysogenum</Emphasis> strain under osmotic stress: mono and binary substrate matrices with phenol

A phenol-degrading Penicillium chrysogenum strain previously isolated from a salt mine was able to grow at 1,000 mg l⁻¹ of resorcinol on solid medium. The aerobic degradation of resorcinol by P. chrysogenum CLONA2 was studied in batch cultures in minimal mineral medium with 58.5 g l⁻¹ of sodium chloride using resorcinol as the sole carbon source. The fungal strain showed the ability to degrade up to 250 mg l⁻¹ of resorcinol. Resorcinol and phenol efficiency degradation by P. chrysogenum CLONA2 was compared. This strain removes phenol faster than resorcinol. When phenol and resorcinol were in binary substrate matrices, phenol enhanced resorcinol degradation, and organic load decreased with respect to the mono substrate matrices. The acute toxicity of phenol and resorcinol, individually and in combination, to Artemia franciscana larvae has been verified before and after the bioremediation process with P. chrysogenum CLONA2. The remediation process was effective in mono and binary substrate systems.     

Biodegradation of phenol and 4-chlorophenol by the yeast <Emphasis Type="Italic">Candida tropicalis</Emphasis>

Biodegradation of phenol and 4-chlorophenol (4-cp) using a pure culture of Candida tropicalis was studied. The results showed that C. tropicalis could degrade 2,000 mg l⁻¹ phenol alone and 350 mg l⁻¹ 4-cp alone within 66 and 55 h, respectively. The capacity of the strain to degrade phenol was obviously higher than that to degrade 4-cp. In the dual-substrate system, 4-cp intensely inhibited phenol biodegradation. Phenol beyond 800 mg l⁻¹ could not be degraded in the presence of 350 mg l⁻¹ 4-cp. Comparatively, low-concentration phenol from 100 to 600 mg l⁻¹ supplied a sole carbon and energy source for C. tropicalis in the initial phase of biodegradation and accelerated the assimilation of 4-cp, which resulted in the fact that 4-cp biodegradation velocity was higher than that without phenol. And the capacity of C. tropicalis to degrade 4-cp was increased up to 420 mg l⁻¹ with the presence of 100–160 mg l⁻¹ phenol. In addition, the intrinsic kinetics of cell growth and substrate degradation were investigated with phenol and 4-cp as single and mixed substrates in batch cultures. The results illustrated that the models proposed adequately described the dynamic behaviors of biodegradation by C. tropicalis.     

Study of phenol biodegradation using Bacillus amyloliquefaciens strain WJDB-1 immobilized in alginate–chitosan–alginate (ACA) microcapsules by electrochemical method

An aerobic microorganism with an ability to utilize phenol as sole carbon and energy source was isolated from phenol-contaminated wastewater samples. The isolate was identified as Bacillus amyloliquefaciens strain WJDB-1 based on morphological, physiological, and biochemical characteristics, and 16S rDNA sequence analysis. Strain WJDB-1 immobilized in alginate–chitosan–alginate (ACA) microcapsules could degrade 200 mg/l phenol completely within 36 h. The concentration of phenol was determined using differential pulse voltammetry (DPV) at glassy carbon electrode (GCE) with a linear relationship between peak current and phenol concentration ranging from 2.0 to 20.0 mg/l. Cells immobilized in ACA microcapsules were found to be superior to the free suspended ones in terms of improving the tolerance to the environmental loadings. The optimal conditions to prepare microcapsules for achieving higher phenol degradation rate were investigated by changing the concentrations of sodium alginate, calcium chloride, and chitosan. Furthermore, the efficiency of phenol degradation was optimized by adjusting various processing parameters, such as the number of microcapsules, pH value, temperature, and the initial concentration of phenol. This microorganism has the potential for the efficient treatment of organic pollutants in wastewater.     

Isolation and characterization of phenol-degrading yeasts from an oil refinery wastewater in Brazil

This study investigated the aerobic degradation of phenol by yeast strains isolated from an oil refinery wastewater from the Northeast of Brazil. The samples displayed low fungal diversity, as only yeast colonies were detected on Sabouraud dextrose agar containing chloramphenicol 0.05% (w/v). Among the isolates, three yeast strains were selected to be evaluated for their potential for degrading high phenol concentrations. These species were identified through morphological and biochemical characteristics as Candida tropicalis, C. rugosa, and Pichia membranaefaciens. Although the strains were able to degrade the phenol concentration present in the wastewater, which was 7 mg l⁻¹, only C. tropicalis was capable of growing at high concentrations of phenol such as 500 mg l⁻¹ and 1,000 mg l⁻¹ in a mineral medium containing this pollutant as the only carbon source. C. rugosa and P. membranaefaciens were inhibited in the presence of 500 mg l⁻¹ of phenol. However, a longer incubation time was needed for C. tropicalis strain to degrade 1,000 mg l⁻¹ of phenol compared to the time required to degrade 500 mg l⁻¹. Moreover, the strain released a significant amount of polysaccharide biosurfactant in the medium probably to minimize the toxic effect of the high phenol concentration. When challenged with 1,500 and 2,000 mg l⁻¹ of phenol, C. tropicalis was unable to grow at the tested conditions. The results indicate that this strain of C. tropicalis can be considered both a good phenol-degrader and biosurfactant-producer. Application of this strain might be useful in bioremediation activities or treatment of phenol-polluted wastewater.     

Enhancement of phenol degradation by free and immobilized mixed culture of Providencia stuartii PL4 and Pseudomonas aeruginosa PDM isolated from activated sludge

Biodegradation of phenol has been investigated using a bacterial consortium consisting of two bacterial isolates; one of them used for the first time in phenol biodegradation. This consortium was isolated from activated sludge and identified as Providencia stuartii PL4 and Pseudomonas aeruginosa PDM (accession numbers KY848366 and MF445102, respectively). The degradation of phenol by this consortium was optimal at pH 7 with using 1500?mg?l^?1 ammonium chloride as a nitrogen source. Interestingly, after optimizing the biodegradation conditions, this consortium was able to degrade phenol completely up to 1500?mg?l^?1 within 58?h. The immobilization of this consortium on various supporting materials indicated that polyvinyl alcohol (PVA)-alginate beads and polyurethane foam (PUF) were more suitable for biodegradation process. The freely suspended cells could degrade only 6% (150?mg?l^?1) of 2500?mg?l^?1 phenol, whereas, the immobilized PVA-alginate beads and the immobilized PUF degraded this concentration completely within 120?h of incubation with degradation rates (q) 0.4839 and 0.5368 (1/h) respectively. Thus, the immobilized consortium of P. stuartii PL4 and P. aeruginosa PDM can be considered very promising in the treatment of effluents containing phenol.     

Destruction of chlorinated derivatives of phenol: ortho-chlorophenol, para-chlorophenol, and 2,4-dichlorophenoxyacetic acid by bacteria communities in anaerobic sludge

The bacterial community of anaerobic sludge could degrade ortho-chlorophenol, para-chlorophenol, and 2,4-dichlorophenoxyacetic acid at concentrations as high as 100 mg/l. The time needed for the degradation of a given chlorinated phenol derivative increased 1.5- to 2-fold upon a twofold increase in its concentration (from 50 to 100 mg/l). The duration of the adaptation period depended on the compound studied and on its concentration. The degradation of 2,4-dichlorophenoxyacetic acid proceeded via 2,4-dichlorophenol and p-chlorophenol as intermediates; the degradation of o-chlorophenol occurred with the formation of phenol. The dynamics of p-chlorophenol degradation and chloride ion accumulation were studied.     

Biodegradation of phenol and <Emphasis Type="Italic">m</Emphasis>-cresol by <Emphasis Type="Italic">Candida albicans</Emphasis> PDY-07 under anaerobic condition

Strain Candida albicans PDY-07 was used to study the anaerobic biodegradation of phenol and m-cresol as single and dual substrates in batch cultures. The strain had a higher potential to degrade phenol than m-cresol. The cell growth kinetics of batch cultures with various initial m-cresol concentrations was investigated, and the Haldane kinetic model adequately described the dynamic behavior of cell growth on m-cresol. When cells grew on the mixture of phenol and m-cresol, substrate interactions were observed. Phenol inhibited the utilization of m-cresol; on the other hand, m-cresol also inhibited the degradation of phenol. However, the presence of low-concentration phenol enhanced m-cresol biodegradation; 100 mg/l m-cresol could be completely degraded within a shorter period of time than m-cresol alone in the presence of 150–300 mg/l phenol. The maximum m-cresol biodegradation rate was obtained at the existence of 200 mg/l phenol. Phenol was preferably utilized by the strain as a carbon and energy source. In addition, a sum kinetics model was used to describe the cell growth behavior in binary mixture of phenol and m-cresol, and the interaction parameters were determined. The model adequately predicted the growth kinetics and the interaction between the substrates.     

假单胞菌诱导筛选菌株PhA苯酚降解动力学及SDS对其影响

为提高苯酚降解速率,由假单胞菌(Pseudonomonas．sp)诱导筛选得到了一株能以苯酚为唯一碳源生长的新菌株Pha,并使其苯酚选择压力从400mg／L逐步提高到了700mg／L。且Pha菌株降解苯酚过程符合一级反应动力学方程。使用十二烷基磺酸钠(SDS)作为增溶剂来促进降解时,发现在SDS浓度为50～150mg／L时,降解苯酚的速率随SDS浓度增加而提高。SDS在低浓度时对其生长影响很小,但浓度达到300mg／L时,对其生长开始有了明显的抑制作用。结果标明PhA菌株有着较高的苯酚耐受浓度,SDS可以显著的提高苯酚的降解速率。SDS的理论最佳投放量为150mg／L。     

Aerobic biodegradation of nitrobenzene by a defined microbial consortium immobilized in polyurethane foam

An aerobic microbial consortium constructed by the combination of Rhodotorula mucilaginosa Z1, Streptomyces albidoflavus Z2 and Micrococcus luteus Z3 was immobilized in polyurethane foam and its ability to degrade nitrobenzene was investigated. Batch experimental results showed that polyurethane-foam-immobilized cells (PFIC) more efficiently degrade 200–400 mg l⁻¹ nitrobenzene than freely suspended cells (FSC). Kinetics of nitrobenzene degradation by PFIC was well described by the Andrews equation. Compared with FSC, PFIC exhibited better reusability (over 100 times) and tolerated higher shock-loadings of nitrobenzene (1,000 mg l⁻¹). Moreover, In the presence of salinity (≤5% NaCl, w/v), phenol (≤150 mg l⁻¹) and aniline (≤50 mg l⁻¹), respectively, degradation efficiency of nitrobenzene by PFIC reached over 95%. Even in the presence of both 100 mg l⁻¹ phenol and 50 mg l⁻¹ aniline, over 75% nitrobenzene was removed by PFIC in 36 h. Therefore, the immobilization of the defined consortium in polyurethane foam has application potential for removing nitrobenzene in industrial wastewater treatment system.     

Simultaneous Cr(VI) reduction and phenol degradation in pure cultures of Pseudomonas aeruginosa CCTCC AB91095

Simultaneous Cr(VI) reduction and phenol degradation were investigated in a reactor containing Pseudomonas aeruginosa CCTCC AB91095. Phenol was used as carbon source. P.aeruginosa utilized metabolites formed during phenol degradation as energy source for Cr(VI) reduction. Cr(VI) inhibited both Cr(VI) reduction and phenol degradation when Cr(VI) concentration exceeded the optimum value (20 mg/L), whereas phenol enhanced both Cr(VI) reduction and phenol degradation below the optimum initial concentration of 100 mg/L. Cr(III) was the predominant product of Cr(VI) reduction in cultures after incubation for 24 h. Both Cr(VI) reduction and phenol degradation were influenced by the amount of inocula. The concentration of Cr(VI) and phenol declined quickly from 20, 100 to 3.36, 29.51 mg/L in cultures containing of 5% (v/v) inoculum after incubation for 12 h, respectively. The whole study showed that P. aeruginosa is promising for the reduction of toxic Cr(VI) and degradation of organic pollutants simultaneously in the mineral liquid medium.     

Degradation of phenol by a defined mixed culture immobilized by adsorption on activated carbon and sintered glass

Summary A defined mixed culture of the yeast Cryptococcus elinovii H1 and the bacterium Pseudomonas putida P8 was immobilized by adsorption on activated carbon and sintered glass, respectively. Depending on its adsorption capacity for phenol the activated carbon system could completely degrade 17 g/l in batch culture, whereas the sintered glass system was able to degrade phenol up to 4 g/l. During semicontinuous degradation of phenol (1 g/l) both systems reached constant degradation times with the fourth batch that lasted 8 h when using the activated carbon system and 10 h in the sintered glass system. In the course of continuous degradation of phenol the activated carbon system reached a maximum degradation rate of 9.2 g l^–1 day^–1 compared to 6.4 g l^–1 day^–1degraded by the sintered glass system. 2-Hydroxymuconic acid semialdehyde could be identified and quantitatively determined as a metabolite of phenol degradation by P. putida P8. Increased membrane permeability under the influence of phenol was demonstrated by the examination of K⁺ efflux from P. putida P8. Offprint requests to: H.-J. Rehm     

Modelling and simulation of steady-state phenol degradation in a pulsed plate bioreactor with immobilised cells of Nocardia hydrocarbonoxydans

A novel bioreactor called pulsed plate bioreactor (PPBR) with cell immobilised glass particles in the interplate spaces was used for continuous aerobic biodegradation of phenol present in wastewater. A mathematical model consisting of mass balance equations and accounting for simultaneous external film mass transfer, internal diffusion and reaction is presented to describe the steady-state degradation of phenol by Nocardia hydrocarbonoxydans (Nch.) in this bioreactor. The growth of Nch. on phenol was found to follow Haldane substrate inhibition model. The biokinetic parameters at a temperature of 30 ± 1 °C and pH at 7.0 ± 0.1 are μ _m = 0.5397 h⁻¹, K _S = 6.445 mg/L and K _I = 855.7 mg/L. The mathematical model was able to predict the reactor performance, with a maximum error of 2% between the predicted and experimental percentage degradations of phenol. The biofilm internal diffusion rate was found to be the slowest step in biodegradation of phenol in a PPBR.