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.

Trametes versicolor 1 was shown to grow on phenol as its sole carbon and energy source. The culture growth and degradation ability dependence on culture medium pH value was observed. The optimal pH value of a liquid Czapek salt medium was 6.5. The investigated strain utilized completely 0.5 g/l phenol in 6 days. The dynamics of the phenol degradation process was investigated. The process was characterized by specific growth rate micromax 0.33 h(-1), metabolic coefficient k=4.4, yield coefficient Yx/s=0.23 and rate of degradation Q=0.506 h(-1). The intracellular activities of phenol hydroxylase (0.333 U/mg protein) and cis,cis-muconate lactonizing enzyme (0.41 U/mg protein) were demonstrated for the first time in this fungus. In an attempt to estimate the occurrence of gene sequences in T. versicolor 1 related to phenol degradation pathway a dot blot analysis with total DNA isolated from this strain was performed. Two synthetic oligonucleotides were used as hybridizing probes. One of the probes was homologous to the 5'end of phyA gene coding for phenol hydroxylase in Trichosporon cutaneum ATCC 46490. The other probe was created on the basis of cis,cis-muconate lactonizing enzyme coding gene in T. cutaneum ATCC 58094. The results of these investigations showed that T. versicolor 1 may carry genes similar to those of Trichosporon cutaneum capable to degrade phenol.

The ability of the white rot fungus Trametes versicolor strain 1 to degrade and utilize methylated phenols (cresols) was established for the first time in a medium not containing any other carbon components. The data obtained demonstrated the better potential of the strain to assimilate p-cresol instead of o- or m- cresol. The 0.5 g/l p-cresol provided was degraded in full after 96 h. The effect of a dual substrate mixture (0.3 g/l phenol + 0.2 g/l p-cresol) on the growth behavior and degradation capacity of the investigated strain was examined. The cell-free supernatants were analyzed by HPLC. It was established that the presence of p-cresol had not prevented complete phenol degradation but had a significant delaying effect on the phenol degradation dynamics. Phenol hydroxylase, catechol 1.2-dioxygenase and cis,cis-muconate cyclase activities were obtained in conditions of single and mixed substrates cultivation. The influence of different phenolic substrates on phenol hydroxylase activity in Trametes versicolor 1 was established. The mathematical models describing the dynamics of single substrates' utilization as well as the mutual influence of phenol and p-cresol in the mixture were developed on the bases of Haldane kinetics. The estimated interaction coefficients (I(ph/cr) = 4.72, I(cr/ph) = 7.46) demonstrated the significant inhibition of p-cresol on phenol biodegradation and comparatively low level of influence of phenol presence on the p-cresol degradation. Molecular 18S RNA gene taxonomy of the investigated strain was performed.

The industry is a major source of pollution for water ecosystems. Industrial production of textile, cellulose and various chemicals is connected with synthetic dyes usage. The discharged effluents could have a hazardous influence on the environment. The biological treatment for synthetic dyes removal is a very perspective, environmentally protective and low cost approach for solution of such problems. One of the often used and very important in dyeing of cellulosic fabrics and textile industry dyes is an anthraquinone-base chlorotriazine dye, known as Reactive Blue 4.Decolorization of Reactive Blue 4 by Trametes versicolor strain 1 was investigated. The experiments were carried out with different concentrations of dye (50mg/l and 125mg/l) and glucose (1, 2 and 3%) in a medium. The enzyme activity of laccase (EC 1.10.3.2) was measured during the process of decolorization. It was shown that there is a direct correlation between the observed enzyme activity and the investigated process effectiveness. It was established that the best conditions for laccase production and decolorization of 125mg/l Reactive Blue 4 dye are in medium containing 3% glucose. In these conditions 90% Reactive Blue 4 was decolorized in 384 hours.

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Aims: This study aims to define criteria for the main physical and chemical characteristics of the environmental niches populated with electrochemically active microorganisms, capable to perform anaerobic respiration and potentially used in Bio-electrochemical systems such as Microbial Fuel Cells.   Study Design: In this study, specific parameters of the environment in water bodies (such as lakes, streams etc.) and their bottom layers are analyzed. The main parameters of interest include the concentration of dissolved oxygen in the water column, the organic matter content in the sediments and the presence of alternative electron acceptors (such as iron and manganese ions) to support anaerobic respiration. Sediment microorganisms are characterized for their electrochemical and biodegradation activity. Place and Duration of Study: The tested sediment and water samples were collected from "Poda" Protected Site located on the outfall of Lake “Uzungeren”, south of City of Burgas, Bulgaria. Methodology: The samples were analyzed employing TGA, ICP and microbiological methods focusing on chemical, physical and biological conditions available for anaerobic respiration in this ecological niche. Results: The results show very low concentrations of dissolved oxygen (from 1.4 to 2.2 mg/dm3 in the various locations). The conductivity and the pH values ​​measured were relatively high and the mean values obtained are 5230 μS/cm and 8.2 respectively. The sediment samples demonstrated very high organic matter content (22.5% of the dry mass) and relatively high levels of iron and manganese. Microbial fuel cell powered by mixed bacterial culture isolated from the tested sediment samples demonstrated stable performance reaching power density of 3.5 W/m2 and the COD removal rate of 42 mgO2/dm3 per day. Conclusion: The result confirms the initial hypothesis that electrochemically active microorganisms are available in environments with high concentration of organic matter, iron and manganese in combination with low availability of dissolved oxygen. Mixed culture of anaerobic bacteria isolated from the tested sediment sample was successfully implemented to power Microbial Fuel Cell.

Taxonomic identification of three newly isolated Antarctic fungal strains by their 18S rDNA sequences revealed their affiliation with Aspergillus fumigatus. Phenol (0.5 g/l) as the sole carbon source was completely degraded by all strains within less than two weeks. Intracellular activities of three key enzymes involved in the phenol catabolism were determined. Activities of phenol hydroxylase (EC 1.14.13.7), hydroquinone hydroxylase (EC 1.14.13.x), and catechol 1,2-dioxygenase (EC 1.13.11.1) varied significantly between strains. The rates of phenol degradation in the three strains correlated best with the activity of catechol 1,2-dioxygenase. Six pairs of oligonucleotide primers were designed on the basis of the Aspergillus fumigatus Af293 genome sequence (NCBI Acc. No. XM_743491.1) and used to amplify phenol hydroxylase-related gene sequences. DNA sequences of about 1200 bp were amplified from all three strains and found to have a high degree of sequence identity with the corresponding gene of Aspergillus fumigatus Af293.