Chapter outline: Biodegradation of Organochlorine Pesticides (Nagata and Tsuda)

Outline of Manual of Environmental Microbiology, 4th ed., book chapter

Proposed title:  Biodegradation of organochlorine pesticides         Chapter no.: _________

Author(s):      Yuji Nagata (PhD), Yoshiyuki Ohtsubo (PhD) and Masataka Tsuda (PhD)

                        Department of Environmental Life Sciences
                        Graduate School of Life Sciences
                        Tohoku University
                        Sendai, 980-8577
                        Phone:  +81-22-217-5682
                     Fax: +81-22-217-5704  
                        E-mail: aynaga@ige.tohoku.ac.jp

Notes:

·        Biodegradation of dioxin-like compounds including PCB, dioxin, and dibenzofuran should be described in other chapter.

Proposed topics

1) Overview of organochlorine pesticides as agrochemicals: Organochlorine pesticides were widely used as agrochemicals in the past, and many of them have caused serious environmental problems and appointed in persistent organic pollutants (POPs).

2) Fate of organochlorine pesticides in the environment: degradation and contamination

3) Bacteria degrading organochlorine pesticides: pathways and genes for the degradation

a. 2,4-dichlorophenoxyacetic acid (2,4-D)

b. 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)

c. pentachlorophenol (PCP)

d. g-hexachlorocyclohexane (g-HCH or lindane) and its isomers

e. 1,1,1-trichloro-2,2-bis(p-chloro-phenyl)ethane (DDT)

f. aldrin, dieldrin, endrin, heptachlor, and chlordane.

g. Others: mirex, toxaphene, hexachlorobenzene (HCB), chlordecone, and pentachlorobenzene

4) Dehalogenases as key enzymes for the degradation of organochlorine pesticides: variation, reaction mechanisms, and protein engineering of dehalogenases

5) Factors except catalytic enzymes that are necessary for the assimilation of organochlorine pesticides in bacteria: transporters, mechanisms for the detoxification of toxic intermediates, etc.

6) Genomes and mobile genetic elements of bacteria degrading xenobiotic organochlorine pesticides: appearance and evolution of bacteria degrading xenobiotics, such as g-HCH and PCP, in sphingomonads

7) Bioremediation of organochlorine pesticides: present state, possibility, and perspectives

Chapter Highlights

The following concepts will be conveyed in this chapter:

1. Many bacterial strains have been isolated that degrade organochlorine pesticides including man-made ones.

2. Various pathways and genes for the degradation of organochlorine pesticides are known, but there still remain compounds whose biodegradation pathways are unknown.

3. Appearance and evolution of bacteria degrading man-made organochlorine pesticides can be discussed on the basis of genomic information.

4. Perspectives of bioremediation of organochlorine pesticides will be discussed.