Bacterial Degradation and Bioremediation of Chlorinated Herbicides and Biphenyls

Abstract

Chlorinated herbicides (e.g. s-triazines) and polychlorobiphenyls (PCBs) are persistent organic pollutants (POPs) that are widely distributed in the environment. s-Triazine herbicides are used in agriculture and forestry in diverse regions of the world. PCBs were produced worldwide for industrial applications, and an important amount of these compounds have been released into the environment. PCBs and s-triazines are toxic compounds that could act as endocrine disrupters and cause cancer. Therefore, environmental pollution with s-triazines and PCBs is of increasing concern. Bioremediation is an attractive technology for the decontamination of polluted sites. Microorganisms play a main role in the removal of POPs from the environment. Diverse bacteria able to degrade s-triazines and PCBs have been characterized. Bacterial degradation of s-triazine herbicides involves hydrolytic reactions catalyzed by amidohydrolases encoded by the atz genes. Anaerobic and aerobic bacteria are capable of biotransforming PCBs. Higher chlorinated PCBs are subjected to reductive dehalogenation by anaerobic microorganisms. Lower chlorinated biphenyls are oxidized by aerobic bacteria. Genome analyses of PCB-degrading bacteria have increased the knowledge of their metabolic capabilities and their adaptation to stressful conditions. For the removal of s-triazines and PCBs from the environment, efficient bioremediation processes have to be established. In this report, bacterial degradation of s-triazines and PCBs is described and novel strategies to improve bioremediation of these POPs are discussed.

Biodegradation of Polychlorinated Biphenyls (PCBs), Aroclor 1260, in Wastewater by Isolate MD2 (Pseudomonas aeruginosa) from Wastewater from Notwane Sewage Treatment Plant in Gaborone, Botswana

“…The HPLC results confirmed that these results were reliable as the screening for the compound following extraction of the same aliquot product of the experiment did not show the presence of the compound. The degradation of PCBs by Pseudomonas strains from Notwane Sewage Treatment Plant has not been reported before and thus these results suggest that strains from Gaborone wastewater have the ability to degrade recalcitrant compounds as reported from other studies in different areas [7,25,27].…”

“…The shifts are an indication of the presence of initial ring oxidation metabolites and ring fission metabolites [25,27] PCBs first get degraded into chlorobenzoates [27] that have been found to have λ max ranging from 244-270nm in the C-band when dissolved in water [28], a range that was observed in the results obtained after 24 hours of incubation of treated wastewater with bacterial isolate MD2 used in this study and PCBs aroclor 1260 (Figure 1) which proves that the bacteria was able to breakdown the compound. The product chlorobenzoate is biodegraded into benzoate and eventually pyruvate and acetyladehyde which are essential in the tricarboxylic cycle (TCA) [25,27].…”

“…The product chlorobenzoate is biodegraded into benzoate and eventually pyruvate and acetyladehyde which are essential in the tricarboxylic cycle (TCA) [25,27].…”

Nanopharmaceuticals and Bioremediation

“…Transgenic algae and microorganisms mutated with bioluminescence genes could be using in biomonitoring of organic and inorganic pollution 133,134 . Expression of the catabolic genes of PCB-degrading microorganisms is a key factor for biodegradation of PCBs 135 . Transgenic plants expressing the bacterial xenobiotic degradation genes combine the advantages of both the systems.…”

Novel hydrocarbonoclastic metal-tolerant Acinetobacter and Pseudomonas strains from Aconcagua river oil-polluted soil

“…Bioremediation is an attractive technology for removal of POPs from the environment (Atlas and Philp, 2005;Morgante et al, 2010;Seeger et al, 2010;Ponce et al, 2011). Degradation of alkanes by Alcanivorax borkhumensis SK2, Pseudomonas putida GPo1 and Acinetobacter baylyi ADP1 has been characterized (Ratajczak et al 1998;van Beilen et al, 2001).…”