Fungi can degrade chlorinated aromatic pollutants like chlorophenols (CPs) and chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs) through various pathways. Many fungi are capable of cometabolizing CPs and converting them to intermediates like chlorocatechols which are then further oxidized. White-rot fungi possess lignin-degrading enzymes that allow them to mineralize complex pollutants like chlorinated dioxins and degrade wood. These oxidative enzymes can also degrade chlorinated organic pollutants. While dioxins are highly toxic, certain fungi are able to break them down.

2. • It is a beneficial activity of fungi in carrying out
biodegradation using chemical substances as carbon and
energy source for metabolism, thereby breaking down
larger molecules to smaller ones.

3. • (Cl-PAHs) are a group of compounds
comprising polycyclic aromatic hydrocarbons with two or
more aromatic rings and one or more chlorine atoms
attached to the ring system.
• Cl-PAHs can be divided into two groups:
• chloro-substituted PAHs, which have one or more
hydrogen atoms substituted by a chlorine atom.
• chloro-added Cl-PAHs, which have two or more chlorine
atoms added to the molecule.

4. • They are products of incomplete combustion of organic
materials.
• They have many congeners, and the occurrences and
toxicities of the congeners differ.
• Cl-PAHs are hydrophobic compounds and their
persistence within ecosystems is due to their low water
solubility.

5. • Many fungi and yeasts are capable of cometabolizing
chlorophenols.
• A wide variety of fungi from different taxanomic groups
(Ascomycetes, Basidiomycetes, Zygomycetes,
Deuteromycetes) were shown to have the capacity to
remove PCP in an extensive screening program

7. • Phenol degrading strains of the fungus, Penicillium and a
phenol-degrading yeast, Candida maltosa oxidized
monochlorinated phenols
• 4-Chlorophenol was converted to 4-chlorocatechol,
• 3- chloropehnol was converted to chlorohydroquinone

8. • The chlorocatechol intermediates were oxidized further,
4- chlorocatechol was oxidized and dehalogenated to 4-
carboxymethylenebut-2-ene-4-olide; whereas, 3-
chlorocatechol was oxidized to 2-chloromuconic acid

9. • Candida albicans PDY-07, a strain isolated from
activated sludge, was able to grow on 4-CP as a sole
source of carbon and energy.
• The soil fungus, Trichoderma harzianum, converted PCP
to pentachloroanisole.

10. • A soil fungus, Mortierella sp. was shown to biotransform
2,4-DCP via two pathways.
• One pathway involved hydroxylation and methylation
yielding 2,4-dichloroguaiacol
• the other pathway resulted in the replacement of the 4-
chloro-group with a hydroxyl group and subsequent
dechlorination of the 2-chloro group to yield
hydroquinone.

11. • Wood-degrading fungi are well established as excellent
degraders of chlorophenols.
• These fungi are divided into two categories:
• brown-rot fungi, which degrade wood polysaccharides
but lack lignin-degrading enzymes
• white-rot fungi, which posses both lignin- and
polysaccharide-degrading enzymes and thus are able to
completely degrade wood.

12. • The brown-rot fungi, Gloeophyllum striatum and
Gloeophyllum trabeum, degraded 2,4- dichlorophenol
and pentachlorophenol up to 54% and 27% respectively
• The chlorinated benzoquinones are subject to reduction
by quinone reductase activity of fungal cells forming
chlorinated hydroquinones such as TeCHQ in the case of
PCP degradation.

13. • The degradation of chlorinated hydroquinones in white-
rot fungi proceeds via two general pathways.
• In one pathway, cycles of hydroquinone oxidation by
extracellular ligninolytic enzymes and subsequent
quinone reduction by cells result in the hydroxylation and
dechlorination of the chlorinated phenols leading to the
formation of tri- and tetrahydroxybenzenes

14. • In the other pathway, TeCHQ is progressively reductively
dechlorinated by the combined activity of glutathione-S-
transferase and glutathione conjugate reductase in a fashion
similar to the bacteria, e.g. Sphingomonas. Reductive
dechlorination eventually leads to formation of the non-
chlorinated 1,4-hydroquinone
• which is subsequently oxidized to yield 1,2,4-
trihydroxybenzene

15. • The chemical name for dioxin is 2,3,7,8-
tetrachlorodibenzo para dioxin TCDD .
• The name "dioxins" is often used for the family of
structurally and chemically related polychlorinated
dibenzo para dioxins (PCDDs) and polychlorinated
dibenzofurans (PCDFs). Certain dioxin-like
polychlorinated biphenyls (PCBs) with similar toxic
properties are also included under the term "dioxins".

17. • the degradation of chlorinated dioxins by fungi is limited
to wood-, or litter-degrading white rot fungi.
• The white-rot fungi constitute the most important group
of organisms responsible for the degradation of nature’s
most complex polymer, lignin.
• Lignin is formed from the random polymerization of
phenyl propanoid units.

18. • White-rot fungi use extracellular oxidative enzymes to
initiate the attack of lignin.
• These oxidative enzymes, lignin peroxidase (LiP) and
manganese peroxidase (MnP), are also capable of
oxidizing a variety of xenobiotic pollutants including
chlorinated dioxins

19. • Some 419 types of dioxin-related compounds have been
identified but only about 30 of these are considered to
have significant toxicity, with TCDD being the most
toxic. PCDD/Fs (polychlorinated dibenzo-p-dioxins)are
Persistent Organic Pollutants (POPs), generated by
incomplete combustion of carbonaceous and chlorinate
d compounds.

20. • They have to be monitored at emission, from stationary
sources like waste incinerator, because of their toxicity.
• They are for instance products such as: inorganic
impurities arisen during industrial combustion processes
within foundries, used-oil combustion, bleaching of wood
pulp, domestic heating and road traffic.