Biodegradation of phenolic compounds is a promising alternative to physical and chemical methods used to remove these toxic pollutants from the environment. The ability of various microorganisms to metabolize phenol and its derivatives (alkylphenols, nitrophenols and halogenated derivatives) has therefore been intensively studied. Knowledge of the enzymes catalyzing the individual reactions, the genes encoding these enzymes and the regulatory mechanisms involved in the expression of the respective genes in bacteria serves as a basis for the development of more efficient degraders of phenols via genetic engineering methods. Engineered bacteria which efficiently degrade phenolic compounds were constructed in laboratories using various approaches such as cloning the catabolic genes in multicopy plasmids, the introduction of heterologous genes or broadening the substrate range of key enzymes by mutagenesis. Efforts to apply the engineered strains in in situ bioremediation are problematic, since engineered strains often do not compete successfully with indigenous microorganisms. New efficient degraders of phenolic compounds may be obtained by complex approaches at the organism level, such as genome shuffling or adaptive evolution. The application of these engineered bacteria for bioremediation will require even more complex analysis of both the biological characteristics of the degraders and the physico-chemical conditions at the polluted sites.

• Keywords
• Adaptive evolution, Genome shuffling, In situ bioremediation, Phenol biodegradation, Phenolic compounds, Synthetic biology,
• MeSH
• Bacteria enzymology   genetics   metabolism   MeSH
• Genes, Bacterial genetics   MeSH
• Bacterial Proteins genetics   MeSH
• Biodegradation, Environmental * MeSH
• DNA Shuffling MeSH
• Phenols chemistry   metabolism   MeSH
• Genetic Engineering methods   MeSH
• Nitrophenols metabolism   MeSH
• Gene Expression Regulation, Bacterial genetics   MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Bacterial Proteins MeSH
• Phenols MeSH
• Nitrophenols MeSH

Secondary plant metabolites (SPMEs) play an important role in plant survival in the environment and serve to establish ecological relationships between plants and other organisms. Communication between plants and microorganisms via SPMEs contained in root exudates or derived from litter decomposition is an example of this phenomenon. In this review, the general aspects of rhizodeposition together with the significance of terpenes and phenolic compounds are discussed in detail. We focus specifically on the effect of SPMEs on microbial community structure and metabolic activity in environments contaminated by polychlorinated biphenyls (PCBs) and polyaromatic hydrocarbons (PAHs). Furthermore, a section is devoted to a complex effect of plants and/or their metabolites contained in litter on bioremediation of contaminated sites. New insights are introduced from a study evaluating the effects of SPMEs derived during decomposition of grapefruit peel, lemon peel, and pears on bacterial communities and their ability to degrade PCBs in a long-term contaminated soil. The presented review supports the "secondary compound hypothesis" and demonstrates the potential of SPMEs for increasing the effectiveness of bioremediation processes.

• Keywords
• bioremediation, carbon flow, community structure, secondary plant metabolites (SPMEs),
• MeSH
• Bacteria classification   isolation & purification   metabolism   MeSH
• Biodegradation, Environmental * MeSH
• Soil Pollutants chemistry   toxicity   MeSH
• Polychlorinated Biphenyls toxicity   MeSH
• Soil Microbiology * MeSH
• Plants metabolism   microbiology   MeSH
• Secondary Metabolism MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Soil Pollutants MeSH
• Polychlorinated Biphenyls MeSH