Download - 1.Fungi as Saprophytes
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Fungi As
Saprophyt
es
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Successions Of Fungi On Deadmaterials
• Saprophytic fungi grows on dead organic
matters such as fallen leaves, dung pellet,
human hair and even dead animals and
insects.
• These fungi have enzymes that digest
cellulose and lignin found in the organic
matter.
lignin - organic substance which act as binders for thecellulose bers in wood and certain plants
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• Succession of species occurs withgroups that breakdown easily digested
small molecules and the last callinvolves species that can breakdownthe resistant cellulosic wall
impregnated with lignin.• period of ! to " years may be
needed for complete decomposition.
•
Succession may occur in the order# $ygomycotina scomycotina
# Deuteromycotina %asidiomycotina
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• %ut still&&& There are some points thatmust be taken into account
# Original substrates are not completely
e'hausted in se(uence.
# Simpler microbes may be unavailable to
microbes in the early stage. )) these molecules are chemicallycomple'
with more resistant one )) or they are physically coated withmore
resistant one *enzyme can+t gain access
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# Small animal ingest part of the original
material, particularly if it is enriched with
thefungal hyphae and they deposit it in their
faeces.
)) animals comminute the material,making
it more readily accessible to microbes.
# Fungus e'hausts the substrates available to
it )) its cells die
)) support secondary colonists
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• Fungus may synthesis some
e'tremely resistant polymers like
melanins that persist long after theoriginal substratum has disappeared.
• Succession of microbes are
fre(uently associated withprogressive changes in thecomposition of the substratum or
with progressive changes in theenvironmental conditions.
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Successionassociated with
Nutritional FactorsDecomposition Of -eaves and
Stems Of erbaceous /lants
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0. 1eak parasites or saprophytes
# 2g. 3ladosporium herbarum, lternaria
tenuis, ureobasidium pullulans,
2picoccum purpurascens
# utilize simple soluble nutrients that
leachout of the leaves or that are present in
aphid honeydew * restricted abilities to
degrade structural polymers likecellulose
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# commonly occur on plant surface
)) ability to withstand drying of the
hyphal
tips.
)) pigmented hyphae which are
resistant to 45 radiation.
# they compete poorly with other fungi
)) have limited phase of activity afterthe
leaf dies.
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!. /rimary saprophytic sugar fungi
# 6rst part of the secondary succession
# 7sugar fungus+ denotes that they readily
utilize simple organic materials but have
restricted abilities to use cellulose.
# 2g. 8embers of zygomycotina like 8ucorand 9hizopus.
)) occur on dung, heating composts,
autoclaved materials etc.
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)) high growth rates and short life cycles
)) able to produce se'ual and ase'ual
spores within a few days of starting togrow.
# /ythium mamillatum *oomycete shows
behavior of a primary sugar fungus.
)) colonize virgin, sugar rich substrata
)) but can+t invade the same materials
if they have been precolonized by others.
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:. 3ellulolytic fungi
# decompose by utilizing cellulose and
hemicellulose
# 2g. 3haeotomium, Fusarium,Stachybotrys,
and Trichoderma
". -ignin# degrading fungi
# slow growing members of%asidiomycotina
such as 8ycena galopus
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# utilize cellulose chemically comple'edwith
lignin.
# cannot use lignin as sole carbonsource
)) degrades lignin in the presence ofcellulose.
# often grow on materials after other
fungihave utilized some of the substrates.
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;. ssociated fungi
# occur together with cellulolytic fungi and
lignin#degrading fungi # members of oomycetes or zygomycoyina
* several deuteromycotina also found
# some may parasitize the hyphae of the
other fungi
# secondary sugar saprophytism< grow in
close association of other fungi, sharing
proportion of the enzymic breakdownproducts.
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Succession ofFungi On Dung
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• $ygomycotina scomycotina
%asidiomycotina
• 8any of them may be presented when dungis deposited, do not di=er in rates of spore
germination and mycelial growth.
# succession of fruitbodies and notnecessarily
of vegetative growth.
• rgument because< %asidiomycotina
re(uires
considerable nutrient reserves to develop
fruiting bodies * longer period of vegetative
growth
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• Thus, succession should be
combination of successive phases of
vegetative growth and
sporulation.
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