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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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