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“STUDYING THE LIGNIN DEGRADING OF SOME
BASIDIOMYCETES AND THEIR APPLICATIONS”
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Speciality
:
Biochemistry
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Code :
1.05.12
- PhD
student :
Nguyễn
Thị Thanh Kiều
- Scientific
advisor :
Ass.
Prof. Dr Phạm Thành Hổ
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Instructor :
University of Natural Sciences – Viet Nam National University - HCM City
ABSTRACT
The
study of the lignin and cellulose degrading activities of the
Basidiomycestes strains in Vietnam and the foreign Phanerochaete
chrysosporium (Taiwan):Under the process
of hybridizing spores from these strains, there appear some hybrid
strains of Schizophyllum commune, Lentinula edodes with possibly better
lignin degrading activities and lower cellulose degrading activities
than the original strains. The three strains of Phanerochaete
chrysosporium , signed as PC.36200, PC36201, PC.36319 all meet these
demands, especially at heat shock temperatures of 500C and 600C.
Culturing
Phanerochaete chrysosporium on some kinds of wood in paper industry such
as Callistemon citrinus, Acacia mangium, Eucalyptus globules, Bambusa
variabilis could also discern the lignin degrading activity of this
fungus on these substrates.
The
lignin degrading enzyme could be extracted by culturing Phanerochaete
chrysosporium signed as PC.36201 on Callistemon citrinus sawdust and
nitrogen limited liquid medium. As a result, the enzyme activity from
liquid medium is better than from sawdust.
Under the
PCR method, two PCR products can be collected with the size of 375bp of
gene coding manganese peroxidase mnp1 from PC.36201 and LEC strains.
Comparing to the sequence of fragment from Phanerochaete chrysosporium
which is referred from GenBank, the sequence of these fragments show
82.2% and 96.5% identity at lever of nucleotide sequence.
RESULTS OF THE DISSERTATION
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The lignin degrading activities have
been systematically researched on Basidiomycetes in Vietnam, so that
the hybrid method under high heat shock should be suggested to
select the best lignin degrading strains. The initial achievement
can be applied in the paper industry for both economic benefits and
pollution prevention.
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The strains of Phanerochaete
chrysosporium have been studied appropriate to Vietnam environmental
conditions and applicable in lignin degrading for enzyme extract.
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PCR method has been proved efficient
to detect the presence of mnp1, a gene which rules lignin
degradation in the Vietnam edible LEC (a hybrid Lentinula edodes),
as a scientific study of lignin degradation.
SOME
INITIAL PRACTICAL APPLICATIONS AND FURTHER STUDY
Being
cultured from 30 to 40 days on Callistemon citrinus, Acacia mangium,
Eucalyptus globules, PC.36201 strain degrades a lot of lignin but only a
few of cellulose during. The reducing of lignin contents is 26-29% and
reducing of cellulose contents is 12-16%. Particularly, PC.36201 strain
on Bambusa variabilis from Vinh Hue paper factory creates excellent
impacts. After 45 days, the reducing of lignin content is 43% and
reducing of cellulose content is 8%. It is advisable to vary the
pre-material-treating process when applying this research into
production. No longer has wood been logged than it has been cultured by
fungi. The materials, thus, have been softer as a considerable lignin
content has been reduced, which facilitates the transportation to
factories. Accordingly, factories should be well-prepared for these
variations to produce biopulp.
Anyway,
the following should be further studied:
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Collecting more fungi and improving them by hybrid method in order
to collect the strains that adapt to environment of Vietnam. The
local Phanerochaete chrysosporium have to be specially studied.
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Continuing to study molecular biological about the main genes which
rule lignin degradation such as lignin peroxidase, manganese
peroxidase, laccase.
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Cloning the collecting genes to form the lignin degrading genes
library for application.
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