MICROORGANISMS IN TERRESTRIAL ECOSYSTEM

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MICROORGANISMS IN TERRESTRIAL ECOSYSTEM

Microbial Loop

differ because plant or insect released degradative enzyme do not rapidly diffuse away

differ from in photic zome of open ocean

Subsurface Biosphere

deep

chemolithoautotrophs survive only on H2, CO2, H2O

deep hot

majority are Firmicute species

zones

methanogenic

coal, kerogen and oil and gas

shallow

Soil as microbial habitat

SOM

Production

small fraction becomes SOM

resistant material(lignin) degrade

complex carbo degrade

easily degraded comp, soluble carbohydrate n proteins

release of CO2, biomass production

Importance

level change depends on environmental change

hold water

maintain soil structure

retains nutrients

Categories

Organic

at least 20% organic C

Mineral

<20% organic C

composition

Bedrock

Unweathered rock

Parent Material

Weathered rock Inorganic material

Subsoil

Fine particles Minerals

topsoil

Humus Minerals Soil microbes Plant roots

pore space

optimum enviroment for microbial growth

critical movement of water & gas

soil particles

very complex, variety of habitat

Lithosphere

influence by:

redistribution of materials by water movement

decomposition of plants

weathering rocks

different organic and inorganic components

rocks and soil

Physicochemical that affect microbial population

Soil atmosphere

influnce by soil particle size

well-drained soil

pH

influence by

prev cropping history

climate

time of the year

microbial metabolic activity

molds (pH acidic)

bacteria ( pH 6-8)

Temperature

depends on

depth

latitude and altitude

composition of soil microflora

Water

depend on

drainage

particle size

rainfall

aerobic(outside) anaerobic (inside)

Thin water films

O2 higher & easy replenish

Surfaces

clay

contain minerals; kaolinite

smooth

hard for adhere

Soil Metagenomics

no can be very high

reflects genomic diversity in soil sample

community genome size

Soil Population

Virus

one virus of note infects fungus

to control fungal pathogen

causes chestnut blight

wide range of virus

many viruses infect plants

eg:TMV

Protozoa

food source

regulating bacteria populations

mineralizing nutrients

feeding

on bacteria other protozoa soluble OM fungi

predators of soil bacteria

Fungi

Mycorrhizae

Agrobacterium tumefaciens

T DNA

two components signal transduction

infected through wound

genes for plant infection

causes crown gall disease

Arbuscular

provide ammonium to host

trnasfer phosphorus to roots

provide host w/ protection

found associating w/ crop n tropical plant

associations

ectomycorrhizae

form by ascomycete & basidomycete

remain extracellular, form sheath (hyphae)

endomycorrhizae

enter root hairs

mutualistic fungus-plant

colonize plany roots

Rhizosphere & Rhizoplane

Roles of microbes

associative nitrogen fixation

promotion of plant growth

synthesis & degradation of OM

creating microbial loop

labile source of nutrients

surface of root

Subtopic

vol of soil around root influenced by materials released from root

Phyllosphere Microorganisms

phyllosphere

SSU rRNA analysis

aerial surfaces of plant

microbe plant i'reactions

inhabit below ground plant tissue

live in aboveground

endophytes

colonize internal plant tissue

epiphytes

live on surface of plants

microorganismassociates w/ vascular plant

molecular signalling-two way comm

pathogenic and harms the host

mutualistic

commensalistic r/ship with palnt

functions

pathogens/parasites

mutualists

Bacteria

functional groups

Lithotrophs or chemoautotrophs

Pathogens

Mutualists

decomposers

convert N2 to N

cyanobac(soil bare)

role

cycling and transformation of C,N,P,Fe,S of soil

location

surface of soilparticle, water & nutrient

aerobic(70%) anaerobic(14%) filamentous(13%)

Microorganisms in soil

bacteria archea fungi protozoa