Wood degrading fungi

Full text

MALAYSIAN FUNGAL
DIVERSITY
Edited
by
E.B.
Gareth
Jones
National Center
for Genetic
Engineering
and
Biotechnology,
BIOTEC,
Central
Research Unit
1
13
Phaholyothin
Road,
Khlong
1, Khlong
Luang,
Pathum
Thani 12120,
Thailand
Mycology
Luang
Kevin D. Hyde
Research Group, School of Science,
Mae Fa
University, Chiang
Rai 57100,
Thailand
Vikineswary
S ab aratnam
Institute
of Biological
Sciences
Faculty of Science
University
of Malaya,
50603
Kuala Lumpur, Malaysia
,i-
&
.*i,
,%4in
&
Published
by
Mushroom Research
Centre, University
of Malaya
and
Ministry of Natural Resources
and Environment Malaysig_
*ffiffiff'r
Jih**s-

e
n
Maldysian
Fungal Diversity
10
Wood
degrading
fungi'
Salmiah
Ujangr,
Andrew H.H. Wongz and E.B. Gareth Jones3
,Mycology
Laboratory,
Forest Research Institute Malaysia
(FRIM), Selangor, Malaysia
2Wood
Biodeterioration
and Protection Laboratory,
Faculty
of Resource and Technology,
Universiti Malaysia Sarawak, 94300 Kota Samarahan,
Sarawak, Malaysia; e-mail:
awong.unimas@gmail.com
TBIOTEC Central Research Unit, National Centre for Genetic Engineering and
Biotechnology,
NASDA, 113 Phaholyothin Road,
Khlong 1,
Khlong Luang,
Pathum Thani
12120
Thailand; e-mail:
bhgareth@yahoo.com
This
chapter
gives
an account of wood biodegradation,
particular
decay studies in Malaysia
which has focused on evaluating
the wood decay potential of selected basidiomycetes
(brown
and white rot fungi), ascomycetes
and anamorphic fungi (sap
stain fungi and soft
rot species)
and in relation to wood protection. Studies, of lignin degrading enzymes
produced
by selected basidiomycetes are at an early stage
of research
in Malaysia and
further studies
are warranted. Tests to determine the durability of bamboo to wood decay
fungi have
been
undertaken
and
results
indicate that it falls between
that of birch and
pine,
largely
attributed
to the lignin content of each timber.
Key words: biotechnological
application,
durability of bamboo,
lignin degrading enzymes,
wood
durability,
wood decay: white, brown,
sap
stain
and soft rot attack
General
introduction
Wood is one of the most useful naturally occurring building materials
but as an organic, heterogeneous
and biodegradable material it is also a
potential
source
of food for wood destroying
organisms such
as fungi (Rayner
and
Boddy,
1988;
Eaton
and Hale,1993). Fungi have the capability
to break
down
the complex polymers
which make up the wood structure. Some
timber
species
have evolved to produce
compounds
that can protect the wood, but
decay
resistance
may vary among tree
species, individual trees, and
within an
individual
tree (Wong et al., 1984; Eaton and Hale,lgg3). Every Malaysian
wood
species
differs in its natural
durability level (Ling, 1996 Wong et al.,
Salmiah,
U., Wong,
A.H.H. and Jones,
E.B.G.
(200'l).Wood degrading
fungi. ln: Malaysian Fungal
Diversity
(eds E.B.G.
Jones,
K.D. Hyde and S. Vikineswary).
Mushroom
Research Centre,
University of Malaya and
tvtlllStry
of Natural
Resources and Environment, Malaysia: 163-183. r63
t.
I
_...1
-ia
t

Malaysian Fungal
Diversih
2005). Some species, like cengal (Neobalanocqrpus
heimii), belian
(Eusideroxylon
zwageri) or balau (Shorea
maxwelliana), have a high natural
durability
with enables
outdoor applications in such
habitats as,ship
decking
and marine strucfures
(Wong, 1982).
Fungal infection requires: adequate
moisture, ambient temperafure,
oxygen and a food source.
Generally sapwood
has more nutrients,
such
as
carbohydrates available,
making it more susceptible
to fungal decay
than
heartwood
(Cartwright
and Findlay,
1958,
Eaton and
Hale, 1993).
Dry wood
does not rot and wood must contain at least 20o/o
moisture before it will
support
wood decay
fungi. At low temperatures,
fungal growth is reduced
or
may cease altogether.
Fungi
require adequate supply of oxygen
for growth
and
respiration. The normal
practice
in Malaysian sawmills
is to submerge
logs
in
log ponds or water spraying for log storage;
with the purpose
of reducing
oxygen availability.
Currently timber and wood products are a valuable commodity for
Malaysia accounting for 23.4billion
RM in exports
(Forestry
Dept.,
2005).
Types of wood decay
There are three broad groups
of fungi which can cause
timber decay:
basidiomycetes (cauge white and brown rot decay), ascomycetes and
anamorphic fungi (soft rot decay), while another group causes severe
discolouration of wood, but normally
do not cause
decay, the sap stain
and
mould
fungl.
'
White rot (Basidiomycetes)
White rot fungi degrade all the major wood components
(cellulose,
hemicelluloses,
and lignin) and derives its name from the white residue
left
after degradation
of the wood
(Wong
and Wilkes 1988). The enzymes
in white
rot fungi are closely associated
with hyphal tips
resulting in less weight
loss
in
the early stage of decay.
Wood becomes
progressively
fragile with greater
weight loss when fungal mycelium
is well distributed
throughout the wood
structure at the later stage. White rot fungi are more prevalent
in Malaysia
than brown rot fung (Salmiah, 1997).
Trametes
feei is a white rot fungus
which commonly attacks
structural
timbers in Malaysia
when the rotted
wood
feels moist,
soft, spongy and appears
white
(Salmiah,
1997).
t64

Malaysian Fungal
Diversity
Brown rot (BusidiomYcetes)
Few brown rot fungi can be found in Malaysia. Brown rot fungi are
most common on softwoods where it degrades
both the cellulose and
hemicelluloses
but leaves lignin intact
as a brown residue
(Rayner
and
Boddy,
1988,
Wong
and Wilkes 1988).
At an advanced
stage of decay, damage to the
wood results in a brown crumbly mass, with numerous cross-breaks,
perpendicular
to the grain.
A good example of a Malaysian
brown rot fungus
in logs
is Gloeophyllum
striatum
(Salmiah,
1997).
Soft
rot (Ascomycetes
and anamorphic fangi)
Soft rot fungi degrade only the cellulose and hemicelluloses and
typically
occur
in wood with high moisture
content,
such as water cooling
towers
(Savory,
1954; Leightley
and Eaton, 1977). This type of wood rot is
characterized
by diamond
shaped cavities within the secondary
layer (S2) of
the cell wall, and caused
by the erosion
of wood in close
proximity to the
mycelium
(Hale
and
Eaton, 1985).
Two types occufi 'type I' with cavities in
the 52 and 'type 2' where
erosion
groves
arise adjacent to the cell wall lumen
(Nilsson,
1973).
Sap
stain
fungi
Sap staip fungi can be a particular problem in hardwoods
with low
natural
durabilify, such
as rubber wood. In tropical locations the anamorphic
fungus Botrydiptodio theobromae is a particular problem causing
unacceptable
heavy
blue staining of commercial
timbers. Various
aspects
of
the
effect of sap stain fungi on rubberwood
(Hevea
brasiliensrs) have been
undertaken:
variation in infection rates
(Wong and Sabri, 2000);
nitrogen
and
sugar
content
of rubber wood (Ashari et al., 1999)
and decay of fibre cell
walls
(Wong
and Singh,
1998).
It is generally
regarded that sap stain fungi do
not cause
damage
to timber cell-walls, however, transmission
electron
microscopy
provided
evidence that B. theobromae hyphae formed lumen cell
wall
erosion
(type-2
soft
rot) in rubberwood
(Wong
and
Singh,
1998).
t65

Malaysian Fungal
Diversitv
Wood decay
studies
in Malaysia
One of the primary goals of Malaysian
wood mycology'
research
hag
been
to evaluate
the natural
decay resistance of selected
local timbers
to key
wood decay
fungi. Results
of this programme
are
summarized
in the followini
sections.
Figs 1-4. Wood decay fungi commonly found in Malaysia.
1. Schizophyllum
commune.2. Pycnoporus
sqnguineus.3. Microporus
ffinis. 4.
Lentinus
sajor'
ca.iu.
Basidiomycete
studies
Salmiah (1997) undertook
a study of wood decay basidiomycetes
in
Malaysia
and the taxonomical results
are discussed
in chapter
4. Thirty-stx
basidiomycetes were evaluated for their ability to cause
decay of three
common timbers: two North American
species, southern
yellow pine
(Pinus
sp.), sweetgum
(Liquidambar styraci/lua) and nartive rubberwood
(Hevea
brasiliensis), and
the
results are
listed
in Table l. Of the timbers
tested,
mot
fungi
caused
low weight
loss of rubberwood and southern
yellow
pine
(85
and
77.5oA, respectively) ihan
sweet
gum
(30%) (Table
2). Fungi
caused
ahigher
166

Malaysian Fungal
Diversity
Table 1. Percentage weight loss of sweetgum
(SG), southern
yellow pine (SYP) and
rubberwood
(RW)
exposed to attack
by selected wood
decay fungi
over a ten
week
period
(Fungi
are
listed
alphabetically).
Fungus SYP Std.
weight dev.
loss
SG Std.de RW Std
weight v. weight dev.
loss loss
Antrodia
sp.
(FRIM 93-67)
Coriolopsis
asPera
Earliella scabrosa
Flavodon
flavus
Ganoderma
applanatum
Ganoderma
austale
Gtoeophyllum
striatum
Gyrodont
ium vers ic
o lor
Lentinus
polychrous
Lentinus
squarrosulus
Lentinus
sajor-coju
Lentinus strigosus
Lenzites
acuta
Lenzites
elegans
Microporellus
inus itatus
Microporus
ffinis
Microporus
xanthopus
Nigroporus
vinostts
Phellinus
sp.
(FRIM 93-47)
Phellinus
setulosus
Phellinus
sublinteus
Phellinus
umbinellus
Pleurotus
djamor (A)
Polypotus
grammocephalus
Pycnoporus
sanguineus
Rigidoporus
microp
o
rus
Schizophylhtm
commune
Stereum
ostrea
Tinc
t
op
o r
e
I
lus ep im
il t inus
Trametes
carneo-nigra
Trametes
villosa
Trametes
feei
Trametes-
men//ziesii
Tramefus
modesta
Trametes
poccts
Trametes
socotrana
60.7
2r.2
9.r
19.1
23
25.4
33.1
0.6
25.8
15.6
17.9
0.6
21.6
2.1
5.6
17.6
41
62.3
19.9
^1
z.J
15
8.8
8.8
12.3
26.4
19.2
0
3.9
20.6
15.6
24.3
1.7
4.5
24.9
0
24.6
0.6
t.2
4.2
t.7
1.5
3.3
1.3
0.2
3
3.2
0.4
0.4
0.3
2.3
t.2
1.9
6.7
0.9
13
0.2
0.7
0.5
1.3
4
64.8
s6.2
38.8
25.7
32.8
62.9
32.6
0.2
48.5
50.2
68.9
8.7
30. l
27
9.1
54.9
63.9
63.6
34
8.9
38.3
18.7
t4.2
54.6
33.2
40.5
0.3
28.9
34.1
J
L.3
58. l
3.4
36.3
4t.2
0.3
18
1.6
2.5
0.8
J.J
2.3
3.9
2.6
0.3
2.3
4.4
7.7
5.3
8.3
1l.l
1.6
1.1
3.9
0.9
2.2
0.7
t.+
0.2
l.l
8.3
1.4
4.6
0.1
1.3
2.9
2.9
12.3
0.7
a
J
0.7
0.3
2.3
53.8
17.6
6.9
l6
9.5
16.7
25.4
7.9
14.3
25.4
18.6
8.2
22.3
7.8
4.1
19.2
14.2
39
4.1
5.9
27.6
r0.4
8.7
24.1
13
9.5
10.4
5.9
3.5
7.8
7.6
r 3.8
rt.2
18.8
10.1
15.3
3.6
2.1
2
1.8
6.1
2
1.6
1.3
3.5
8.4
4.8
5.1
6.9
5.3
I
6
t.7
a
J
0.7
0.7
1.2
5.3
2.7
12.7
5.7
2.7
0.6
3.8
0.5
3.6
2
2.3
8.1
10
t.4
5.4
0.7
0.7
0
1.3
2.5
2.8
1.9
0.3
r.7
0.6
0
1.1
ht67

Milaysian Fungal Diversih
weight
loss in sweetgum
(27.So/o)than
in the other
two timbers
(2.5,
5%).
Five
wood inhabiting
fungi caused
weight
losses greater than
600/o
on sweetgum
(Atrodia Sp., Ganorderma australe, Lentinus sajour caju, Microporus
xanthopus, and Nigroporus vinosus), two species on southern
yellow pine
(Atrodia sp., N. vinosus)
but none caused this magnitude of weight loss
on
rubberwood
(Table 1).
The most activelaggressive fungus tested
was
Antrodia
sp., with weight
losses >50o in the
three tested timbers
(53.8-64.8%).
Timbers
can be
graded
into four classes
based on
the weight
loss
caused
resistance
class: highly resistant
(0-10%), resistant
(ll-25%), moderatelv
resistant
(26-50%)
and slightly
resistant
(5I% or above).
Southern yellow pine
Most fungi tested
(77.5%)
caused low weight loss
on this timber
while
5% did not cause
any weight loss of the test blocks.
Nigroporus vinoszs
and
Antrodia sp.
(FRIM 93-67)
yielded
the highest
weight losses
(62.3 and
60.7%,
respectively)
on this timber and it can be graded
as only slightly resistant
against fungal attack. Schizophyllum commune, Lentinus strigosus,
Gyrodontium
versicolor and
Trametes
sp.
(FRIM 93-71)
caused little decay
of
this timber
(< 1%).
Sweetgum
Testblocks of this timber were decayed
to a greater
extent than
for the
other
two species with most
fungi causing
weight losses
of 25-50%. Eleven
fungi (27.5%),
including three
Lentinus
species and two Microponzs species,
caused weight losses greater
than 50Yo
(Table 1). Sweetgum was the least
durable
timber against
Lentinus
sajou caju, which caused almost 70o/oweight
loss. Weight losses
greater
than 6A0/o were noted for Ganoderma
australe,
Microporus xanthopus,
Nigroporus vinoszs and Antrodia sp. (FRIM 93-67),
while Gyrodontium versicolor, Schizophyllum commune and Trametes
sp.
(FRIM 93-71) caused little wood
decay
(<l%).
Rubberwood
Test
blocks were remarkably
resistant
to attack, with 85% of the fungi
causing
weight losses
below
25 % (Table
2).
Antrodia sp.
(FRIM 93-67)
was
the most destructive isolate causing 53.8% weight loss, while Nigropons
vinosus,
Lentinus sajor-caju,
Phellinus sublinteus
and Gloeophyllum
sftiatum
produced
weight losses
between
25.4-39.0%. Rubberwood
was considered
168

Malaysian
Fungal
Diversity
very durable
(< 5% weight loss) against Microporellus invisitatus,
Phellinus
sp. (FRIM 93-47) and Tinctoporellus epimiltinus. Over 44% of the fungi
caused
weight
losses below
l0 %. r
Figs
5-7.
Test
blocks exposed
to the basidiomycete
Pleurotus
djamor.5. Pine.
6.
Sweetgum.
7. Rubberwood.
The ability of some
wood inhabiting fungi to cause
significant
weight
losses
is well documented
(Davidson
et al., 1942; Duncan
and Lombard,
1983;
Cowling, 196I; Tanesaka
et al., 1993; Wilcox, 1993)
and
is confirmed
in the
present
sfudy.
A number of factors and limitations
govern
the decay of
wood: temperature, ability to withstand desiccation,
high moisture content,
proportion of tannins and phenolic compounds and lignin content. For
example: the inhibitory effect of tannins and polyphenols on enzymes
(Goldstein
and Swain, 1965), and on the decay of wood (Hart and Hillis,
1972),
are wqll documented.
Highley (1982),
Rayner
and
Boddy (1988),
and
Eaton
and
Hale
(1993)
noted that
softwoods
are more resistant
to degradation
by white rot fungi than hardwoods,
due to the different lignin types they
contain
(Nilsson
et al., 1989). White rot fungi have
little ability to degrade
sringylpropane,
the lignin polymer present in softwoods, but can cause
considerable
degradation
to the guaiacylpropane
units
in hardwoods.
Wood in temperate regions is more susceptible
to fungal attack
whereas,
the primary agents
for timber destruction
in the tropics are termites
besides
decay
fungi (Findlay,
1985; Kirton and Wong,2001). For example,
Microporers
species which are white rot fungi, showed strong ligninolytic
activity
(Salmiah, 1997).
However there is evidence
that brown rot fungi do
degrade
lignin
to a limited extent
(Kirk, 1975; Haider and
Trojanowski,
1980;
Wong
and
Wilkes 1988).
Kirk and
Shimada
(1985)
observed
"white rot wood
decay
fungi are
probably
the
major lignin degraders".
Rubberwood
is regarded
as
a non-durable
timber (Anon, 1982; Hong and Wong, 1994), and even with
the presence
of phenols this timber is quite susceptible
to fungal attack.
Schizophyllum
commLtne, Gyrodontium versicolor and Trametes
feei and T.
pocqs
(FzuM 93-71) did not cause significant decay of pine and swee,*i#

Malaysian
Fungal
Diversitu
compared
to rubberw:ood.
llsloporus vinosus
and,
Antrodia sp.(FRIM 93-67),
on
the
other
hand,
caused
high
weight
losses
on
all wood
species.
Tabte
2. Percentage
of the
fungi
tested
in the
present
study
..*ing decay
of
the test
blocks.
Wood species No weight
loss Low weight
Ioss Medium
weight
loss High weight
loss
Southern yellow
pine
Sweetgum
Rubberwood
0.1
- 25o/o 26 - 500 > 50010
77.5
5
0
030
85
12.5
42.5
12.5
5
27.5
2.5
Wood inhabiting fungi which caused
healy weight losses
included
Nigroporus vinosus, and Antrodia Sp., while Leniinus squaryosulus,
Microporus xanthopus and Ganoderma australe caused high losses
in
sweetgum.
Based
on the
results,
these
five fungi could
be identified
as
suitable
test
fungi
to be used
in wood
decay
assessment
studies
and
above
ground
testing
methodologies)
in Malaysia.(laboratory,
field
stake
They
fulfill the
criteria
such 8s, availability of the fungus locally, rapid
aggressive
ability to decay
wood. growth in culture and
An unusual superficial wood decay pattern (refened to as ..hyphal
tunneling"),
ascribed
to an unidentified
fungus,
was detected
microscopically
on naturally.
durable
belian (Eusideroxylon
zwagen) hearfwood
in wateriogged
peat
soil (wong et al., 1996,
Singh
and
wong, 1996;
wong and
Singh tssl1.
This was initially thought
to be soft rot attack (Wong and Singh plSy. fne
decay
pattern
did not resemble
typical white rot wood fibre wai degradation,
although both the secondary
walls and the lignified middle lamella were
degraded.
This unusual
decay
was also
reported
on CCA treated
pinus rodiata
wood
in wet
acidic
soils
(Xiao
et
al.,1997).
Soft rot decay
In Malaysia
various
aspects
of timber decay
by soft rot fungi have
been
undertaken:
visualization
and detection
of soft rot attack:
observation of soft
rot attack
in durable
timbers
and preservation
of Malaysian
hardwoods
against
decay
by soft rot fungi.
170

'w
Malaysian
Fungal Diversity
Visualization
and detection
of soft rot attuck
Wong (1989, 1993b) examined soft rot decay of three,Malaysian
hardwoods
at the light and scanning electron microscope
level: kempas,
red
balau
(moderately
durable)
and
jelutong (non-durable).
Soft rot occurred
in all
three
timbers
regardless
of their natural
durabilify.
By Transmission
electron
microscopy,
soft rot Type 2 decay of the fibre lumen was detected in
rubberwood
attacked by the sap stain fungus Botryodiplodia theobromae
(Wong and
Sing,
1998).
Ohsemation
of soft rot sttack of Malaysiun timbers
Timbers evaluated
include: kempas (Koompassia
malaccensis,
Wong,
1988;
Schmitt
et al., 1996;
Singh et a1.,2004); cengal
(Neobalanocarpus
heimii,
Singh et al., 2003; Kim et a|.,2006); belian (Eusideroxylon
zwageri,
Wong et al., 1996a; Wong and Singh, 1995). They range
in their natural
durability
from moderate
(kempas)
to extremely durable
(belian)
and give 20
to 30
years
service
(Wong
et
al.,1996a).
Studies in Malaysia have evaluated their decay resistance
to white
(Pycnoporus
sanguineus, Coriolous versicolor) and brown (Porta Sp.,
Gloeophyllum
trabeum)
rot fungi, but focusing on soft rot fungi (Chaetomium
globosum).
Studies
on natural
durability of hardwood to tropical fungi have
been
summarized
by Wong et al. (2005)
and
included
evaluation
of the role of
heartwood
extractives
on bioefficacy, their micro-distribution and
the effect of
lignin.
Percentage
mass loss due to decay
by four basidiomycetes
varied: with
cengal
the
most resistant
(0.5,3.2,1.2,0.7o glg),and
kempas
(11.9,
19.5,4.6,
6.7%
g/g) after 12 weeks exposure
to the fungi. In comparison,
less
durable
Malaysian hardwoods performed poorly when exposed to Chaetomium
globosum,
with mass loss of 20.7 fielutong),23.6 (kayu arang) to 38%
(rubber-wood).
Plantation grown rubberwood (Hevea brasilliensis) is a highly valued
hardwood
for variety of end uses,
but is highly subject
to biodeterioration by
fungi and insects (Hong and Won
g, 1994). Fungi with known or suspected
soft
rotting
abilities
of decay-susceptible wood and cellulosic substrates
have
been
detected
using a combination
of mass loss data and correlative light
microscopy
(Tables
3, 4).
- Usually
soft rot fungi are
relatively slower wood degrading
compared to
basidiomycetes.
Nevertheless
prolonged
soil-burial (similar to in-ground)
exposure
of non-durable woods
(Wong, 2006a) to soft rot organisms show
dramatic destruction of the wood secondary wall matrix, resulting in
t7l

considerably
increased wood strength
losses, similar to the effects
of
Maiaysian
Fungal
O
".*,"ffi
s-.,
usmg
to
be
basidiomycetes. Therefore stringent control of biodeterioration,
preservative
treatment or immediate
seasoning,
is applied
if the most is
made of this hardwood
(Hong
and
Wong,1994).
Table 3. Examples of reported
percentage
mass losses
of Malaysian
and
other
tropical species due
to soft
rot decay.
Wood species
(and
other plant material) Laboratory
decay test
duration
Mass loss
(% ete) Test
fungus* Reference
weeks
Diospyros spp.
(sapwood)
Dyera cos tulala (sapwood)
Blumeodendron
tokbrai
(sapwood)
Sapium spp. (sapwood)
Hevea brasiliensis
(sapwood)
Als tonia spp. (sapwood)
Koompass ia ma laccens is
(heartwood)
Ko o
mp as
s
ia mal tccens is
(sapwood)
Eusideroxylon zwageri
Elaeis guineensis
Pinus caribaea
Wong
(2006a)
Wong
(2006a)
Hong
(1976)
Wong
(2006a)
Wong
(2006a)
Wong
(2006a)
Wong
(1988)
Wong
(2006a)
Wong
(2000)
Wong
(2000)
Wong
(1993a)
Florence
(1991)
Encinas
and Daniel
(1996)
Wong
(2006a)
Wong
(2006a)
Wong
(1988)
Wong
(1988)
Wong
(2006a)
l2
28
524
A^l
A''
20
42
23.6
-37.2
20.7
- 42.4
7
t2.4
- 31.7
19
- 52.5
26.5
- 40.6
15.4
s8.9
z)
12.2
l0
t2
18
3.5
t.6
0.5
10.9
0
30-42
CG,
US
CG,
US
BT
CG, US
CG,
US
CG, US
CG
CG
CG, US
PF
BT
BT
BT
CG,
US
CG
CG
CG
CG
CG
BT
42
Aa
AL
6
t2
t2
l2
6
l6
'24
42
t2
6
6
Wong and Wan
Asma
(1994)
Encinas and
Daniel
(1995)
*CG : Chaetomium
globosum, US : unsterile soil, BT : Botryodiplodia theobromae,
PF : Phialophora
fastigiata
Preservation
of Malaysian
hardwoods against
decay by soft
rot fungi
Soft rot fungi are a particular problem in the groundline decay
of
copper-chrome-arsenic
(CCA) treated heartwood,
such as utility poles
(Wong
et al., 1992; Wong and Pearce, 1997); CCA-treated
stakes
(Ling and Wong,
2005) and copper-chrome-boron
(CCB) treated heartwood stakes
(Wong and
Ling, 2007). Consequently, extensive studies have been undertaken
in
Malaysia in the evaluation of the effectiveness
of such treatment
(Wong et
al.,
1992); microanalysis of CCA macro-distribution
in hardwoods
(Wong
et
ol',
1996b; Wong et al., I999c); variable preservative retentions
(Wong ano
172

Maiaysian
Fungal Diversity
Pearce,
1997;
Ling and Wong,2005;
Wong and Ling, 2007),
and
tolerance
of
Phialophora
fastigiata and
other wood decay fungi to high CCA preservative
1997;
LingandWong,2005;
ffeatment
(Wong, 1996,2000),
and
bioassay
of both
heartwood
and
sapwood
extractives
(Wong,
1993a;'
Wong and
Pearce,2007)
Table 4. Examples
of ascomycete
and
anamorphic
fungi reported with wood-
and
cellulosic-degrading
ability, from Malaysian laboratory
studies
(Source:
Wong,
1993a,1997;
Wong
and Pearce,1997;
Wong
and Singh, 1998)
Fungus Wood/cellulosic Mass loss Soft rot
Itype**
u
Substrate
Acremonium
strictum
Botryodiplodia throbromae
Chaetomium
globosum
C
lados
po r iu
m c
ladospo
r io ides
Fusarium
oxysporum
Paecilomyces variotii
Penicillium citrinum
P. crysogenum
P. miczynski
P. raistrickii
Pes t a lot
iops
is vers
ico lo r
Phialophora
fas
tigiata
P. richardsiae
Trichoderma
spp.
Rubberwood
Rubberwood
Filter paper
Rubberwood
Rubberwood
Rubberwood
Filter paper
Rubberwood
., Rubberwood
Rubberwood
Rubberwood
Rubberwood
Filter paper
Filter paper
Rubberwood
Rubberwood
Rubberwood
Rubberwood
8.6
?
7.6
ll
3.6
6.2
6.2
8.5
4.5-**-
5.8
2.4
1
55
12.8
4.9
3.6
6.1
2.8
+
1*1
+
+
+
(+)
l
(+)
(+)
(+)
(+)
(+)
f
+
(+)
*masslossofdeiay-susceptiblerubberwood(HeveaD'os,7;,,'ng
and
Pearce,
1997)
or on cellulose filter paper
after
8 weeks
at25"C
(wong lggi.).
**soft
rot type
on rubberwood:
I = cavity forming,
II : lumen
wall erosion, ( ) = observed
occasionally.
Oil palm (Elaeis
guineenis)
trunks
offer a potential
alternative
source
of
hardwood
to the depleting
naturally-grown
Malaysian
hardwoods.
However,
treatmentof palm trunkswith selected
ucarment
oI oll palm trunks wlth selected
monomer system,
(e.g. methyl
methacrylate)
indicated
that they would not withstand
attack
by tropical
wood
decay
fungi (wong and wan Asma, r9g4), but probably woulo u" quite
oil
decay-resistant
as
(Wong
et
al.,1990;
ammonia-plasticized
densified trunks (via compression)
Wong and
Koh, l99l ).
Sap
stain fungi
Sap
stain
fungi can be a particular
problem
in hardwoods
with low
::Tol durability,
such
as
rubber wood
(Florence,lggl; Hong
and
wong,
1994;
wong and
woods, 1997,
wong et
al., 1999a).
This has
attracted
much
lnterest
in temporary
protection
of non-durable
species
(mainly
of sapwood)

evaluated with several
types
of anti-sapstain
preservatives
(Hong, 1983;
Hons
and Wong, 1994; Wong et al., 1995; Wong and Lum, 1996;
Wong and
Woods,
1997;
Wong
et al., 1999b Ling et a1.,2002).In
tropical
focations
the
anamorphic
fungus
Botrydiplodia theobromae
is a particular
problem
causing
unacceptable
heavy staining of commercial
timbers
(Hong,1976;
Encinas
and
Daniel, 1995). Various aspects of the effect of sap
stain fungi on rubberwood
have been undertaken:
variation in infections rates
(Wong and Sabri,
2000);
the role of nitrogen and sugar content of rubber
wood (Ashari
et a|.,2000a);
methods of evaluating sapstain severif or preservative
performance (Ashari
er
a1.,2000b; Wong et al., 1999b) and degradation of fibre cell walls (Encinas
and Daniel, 1995;
Wong and Singh,
1998). It is generally
regarded
that
sap
stain fungi do not cause damage to timber cell walls, however, transmission
electron microscopy
provided evidence that B. theobromae
hyphae
formed
lumen cell wall erosion
(Wpe-2
soft rot) in rubberwood
(Encinas
and
Daniel,
1995;
Wong
and
Singh,
1998).
Decay of bamboo
Bamboo
can be a resilient timber and
is widely used
in the construction
industry for scaffolding and other end uses, as it is quite strong and
yet cheap
(Janssen,
1980). Industrially it is also used as
pulp and for paper production
and a replacement for other low cost timbers
(Sulaiman,
1993).
Bamboo culms comprise
50% ground
tissue
parenchyma,
40 o/o
frbres
and 10% cqnducting tissue
(Liese, 1985). Some 50-80% of the bamboo
vascular
bundles
are located in the outer one
third of the culm, which gives
it
its strength
and
pliability. Bamboo
fibres are unusual
in that the cell walls are
comprised of a series of lamellations, the number dependent on age and
location within the culm. Lignin content is typical of grasses
varying from
18.2-26.9% depending on species, with sinapyl
lignin
predominating. Bamboo
density depends on species
and ranges
from 500-900
Kg/m3 and
is greatest
in
the outer
part
of the culm
(Liese,
1985). Bamboo
has a low natural durability,
with 1-3 years
service
life if in ground
contact, but 4-6
years
if used
in dryer
and
protected
areas
(Liese,
1985).
Sulaiman
(1993) and Murphy et al. (1997a,b)
under took a study
to
evaluate the susceptibility of bamboo to selected fungi: Chaetomium
globosum
(ascomycete:
soft rot), and the basidiomycetes Coriolus versicolor
(white rot) and Coniophora
puteana (brown rot) with the timbers Pinus
sylvestris and Betula
pendula
for comparison. These
timbers were selected
for
variability in their lignin content and
degree of durability.
174

Malaysian
Fungal Diversity
Young bamboo
test
blocks
(lcm x 3 cm) were decayed
more rapidly
than those
from mature culms, for all the fungi tested
(Table 5). Coriolus
versicolor
and Ch. globosum
caused
16-21% and ll-1606 weight losses
respectively
of pine and mature bamboo. Losses of 29.5% of 45.5o/o
respectively,
were caused
in birch by Coniophora
puteano and
Ch. globosum
(Table
5)
(Sulaiman,
1993)
Table 5. Weight loss of mini test blocks of four timbers after 60 days
exposure
to Chaetomium
globosum
(soft rot), Coriolous
versicolor
(white rot)
and
Coniophora
putana (brown
rot) (After Sulaiman
1993).
Substratum Ch. globosum Cor. versicolor Con.
puteana
Mature bamboo
Young bamboo
Pinus sylvestris
Betula
pendula
The wood anatomy of bamboo
differs markedly from angiosperm wood
cell walls in particular
the polylamenate
structure
with alternating
broad and
narrow lamellae (Sulaiman, 1993 Sulaiman and Murphy, l995a,b).
Microfibrills in the broad
lamellae are
orientated
at a narrow angle to the cell
axis,
while t[ose in the narrow lamellae are
orientatedhorizontally
(Sulaiman
and
Murphy, 1995a). This will affect the colonization
pattern
of soft rot fungi,
whose mycelium normally follow the orientation of the microfibrills.
Sulaiman
and Murphy (1992) demonstrated
three types of soft rot branching:
typical 'T' branch, longitudinal penetrating hyphae (broad lamellae),
tangential
orientated branching (narrow lamellae) and radially orientated
branching
when
hyphae traverse across the cell wall either
via pits or by direct
penetration.
Treated bamboo has been tried with l% and 3Yo w/v CCA wood
preservative
and was effective against all three fungal decay
types
(Sulaiman
and
Murphy, l gg3\.
Use
of fungal enzymes
in bioremediation
Lignocellulosic
agro-industrial residues/wastes are
abundant and readily
available
in Malaysia (Vikneswary et al., 1997, 2006; Chapter 19), and
include
palm oil processing
industry, sago,
starch
processing
industries,
oil
palm
fronds,
and
rubber
wood products
and their residues. Presently
these
are
t75
l1
32
6.7
45.5
16
32
2l
35.4
1l
18.8
4T
29.5

Malaysian
Fungal
Diversitu
burnt,
allowed
to decay
naturally,
fuel for the
kiln drying
of timber
and
other
products
or dumped
in land fills. The major agllulturar crops
grown
in
Malaysia
include
rubber
(39.67vo,
oil
palms
11li.serl"),
cocoa
'(6.75%)
nce
(12.68%)
and coconut
(6.34%).
Thesi sources
produce
wastes
of 11.32
million
m3
(rubberwood);
8.69
m m3 (oil palm
residues)
and,3.4l
m m, (rice
husk)
(Koh,2005).
I:::::l1l.t:.is.now ,u.sTu]:r
awareness
that
these
residues
can
be
rvo vctrl Oe
;:li::i t,j1;,:;:.T"flm*1y,:1 fo1
these
wastes
incrude
generating
Iri ::^ :l:-.Ti.iq, cellulose-ethanol
conversion
p.o..rr;-""d ;",'fi
'
ffi:
'vrru JLiIJ€
fn:y*:" ll ,1.,p1:durlion
of enzymes
and
other
fine
chemicals.
Hoi
rrvsro. I IUI
Ir,9?.:l_ln ::,:T?::g :h" there
is enough
oil palm
waste
to supporr
an
ey1zv.r r dU
:11i"^l:f3:ll.o,Y* of
energv
generation""apu"itv
in
peninsurar
Malaysia,
a
commodity
that
is currently
unutilized.
11 I _::-tTative^study,...Vikneswary
et al. (2006)
evaluated
solid
substrate
fermentation
of sago
..hampas",
o'i
, oil palm frond
parenchyma
tissue
"o*ii""' "rirg
^irrr
tungus
Prrn-nnnuard ---^---:--^- T ' r. rrv r qrr6qJ
!ryyqo'us sanguineus.
Laccase
yield was
highist on hampas
uira
opppt ut
7
'5-7
'6 U/g respectively.
This aspect
is revie*ia in greater
depth
in Chapters
19,20
and2l.
Conclusions
The rich fungal diversity documented
in this volume indicates
a great
potential for' their utilization in bioremediation,
for screening
for bioactive
compounds,
fine chemical
and
novel enzymes,
and
wood protJction
research.
However,
research
on many of these
topics
are still embrytnic and in need of
stimulation
and adequate
financial supiort. wood decay
and sap stain
fungi
occur widely and are a problem in biodeterioration,
especiallf
of wooden
structures
in houses.
Acknowledgment
We are grateful to Sulaiman
othman for data
of his studies
on the decav
of bamboo.
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:"t"*Funs "€
Research
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(IRGAVP 03-10501;,
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