Biodegradation of xenobiotics
? Xenobiotics are chemically
synthesized compounds that
have never been existed
naturally.
? Pesticides (herbicides,
insecticides,and fungicides)
are xenobiotics that desired
to be degraded by
microorganisms
Biodegradation of
herbicide 2,4,5-T
by Burkholderia
cepacia
2,4,5-T,2,4,5-trichlorophenoxyacetic acid
Biodegradable
Polymers
? Most
synthesized
polymers are
not
biodegradable,
only microbial
polymers PHA
are truly
biodegradable
PHB/HV
Plant-Microorganism Interactions
Lichen consisting of two
organisms,a fungus and an
alga,Algae or cyanobacteria
grow phototrophically and
provide nutrient for the
fungus,which offers a firm
anchor and inorganic nutrient
for the algae.
A cross section through a lichen
Mycorrhizae,the symbiotic association
between plant roots and fungi
Effect of
mycorrhiza on
plant growth
? Left,nonmycorrhizal
? Right,mycorrhizal
? The plants are six-
month-old seedling
of Monterey Pine
growing in praire soil.
Agrobacterium and Plant Interactions,
Crown gall and Hairy Root
? Crown gall,caused by
Agrobacterium tumefaciens
which carries a Ti (Tumor
induction) plasmid that
promotes the crown gall
formation
? Hairy Root,caused by
Agrobacterium rhizogenes
which carries a Ri plasmid
that leads to hairy roots
formation
Overview of events of
crown gall disease
following infection of
A,tumefaciens
Ti plasmid of Agrobacterium
tumefaciens
Mechanism of transfer
of T-DNA to the plant
cell