Microbial Degradation Of Environmental Pollutants Of Heterocyclic Compounds With Lone Electron Pair

Sulfur, nitrogen, and oxygen heterocycles (SNO-heterocycles) with lone electron pair are polycyclic aromatic compounds containing one or more S-, N-, and/or O-atoms in five or six membered rings. SNO-heterocycles and their degradation products have been detected to be toxic and mutagenic. Additionally, sulfur and nitrogen oxides released from fossil fuel combustion contribute to acid rain and air pollution. At the present time, petroleum refining is mainly based on the use of physicochemical processes such as distillation and chemical catalysis that operate under severe conditions, i.e. high temperatures and pressures. Such processes are energetically costly and highly contaminating. "Biorefining", in contrast, operates at ambient temperature and pressure and is endowed with a high selectivity, resulting in decreased energetic costs, low emissions and no generation of undesirable by-products, so it is thought to be an interesting complement for the development of new petroleum refining processes. S-heterocycles, dibenzothiophene (DBT) and N-heterocycles, carbazole (CA) are the main heterocyclic structures in petroleum. Therefore, DBT and CA are widely used as model compounds for the study of the biodegradation of polycyclic aromatic sulfur- and nitrogen-containing hydrocarbons, respectively. Additionally, O-heterocyclic compound, dibenzofuran (DBF) was a model compound to study the biodegradation of the 'dioxin-like' compounds and its chlorinated derivatives, which are of great environmental concern.This work focused on a mesophilic strain isolated in our laboratory previously. The strain XP was capable of degrading DBT at 30°C. Strain XP was previously identified as a Rhodococcus species and further identification was performed in Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH (DSMZ). Strain XP was an aerobic, gram-positive bacterium. The cells were shown to be short branched hyphae, which disintegrated to rod and coccus-like elements. Colonies were shiny dissolving, cream to pink. The mycolic acid pattern was...