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Microbiology Ecology [Jan 6th + Jan 11th] Set of lecture slides on UWACE with additional notes made during lectures

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BIOL 241
Barbara Butler

ME1 Microbial ecology (chpt 23 12 ed; chpt 19 11 ed) •study of interrelationships between microorganisms and their environments ecosystem: a community of organisms and their natural environment • population • guild • microbial communities + communities of macroorganisms → energy flow and materials cycling th th (Fig 23.2, 12 ed; 19.1, 11 ed) ME2 heterotroph Energy and carbon flow in microbial metabolism (Fig 5.23a) (e.g., NH , S, H S, Fe ) 4 2 autotroph (Fig 5.23b) (Fig 5.23c) ME3 objectives in microbial ecology: (1)to explore & understand the biodiversity of microorganisms in nature, and interactions in communities (2) to measure of microbial activities in nature, and monitor effects of microbes on ecosystems activities commonly measured when studying microorganisms within an ecosystem: • primary production of organic matter (phototrophic, chemolithotrophic activity) CO +2H O 2 energy → new biomass • decomposition of organic matter (chemoorganotrophic/heterotrophic activity) dead biomass → CO + H 2 + e2ergy • biogeochemical cycling of elements C, N, P, S, Fe ME4 Microorganisms in nature • live in “common” habitats suited to higher organisms, also in “extreme” environments • extremes in temperature, pH, pressure, salinity; anoxic habitats • inanimate (soil, sediment, water, food) & animate habitats (on/in animals, plants, insects) • necessities for growth include available resources (nutrients), suitable physiochemical conditions th (Table 19.1, 11 ed) ME5 psychrophiles, thermophiles, hyperthermophiles: “extremophiles” that live in habitats of extreme temperature, incl. cold (e.g., deep sea, Antarctica, the Arctic), or hot habitats (e.g., compost piles, deep sea hydrothermal vents) (Fig 6.19 12 ed; 6.17 11 ) seawater evaporating ponds near San Francisco Bay, for harvesting “solar” salt. The red colour is due to pigments of the extreme halophile Halobacterium, an archaeal genus that inhabits the ponds. th th (Fig 17.2, 12 ed; 13.2, 11 ) ME6 niche: the functional role of an organism within an ecosystem; combined description of the physical habitat, functional role, and interactions of the microorganism occurring at a given location microenvironment: where a microorganism lives, metabolizes within its habitat • physicochemical gradients • spatial, temporal variability • O 2ontours (as %O ) w2thin a soil particle, measured by microelectrode (air is 21% O 2 • each zone in the soil particle could be considered a different microenvironment (Fig 23.3 12 ; 19.2 11 ) ME7 Nutrient levels and growth rates: • microbial life in nature often differs from microbial life in lab culture (i) entry of nutrients into an ecosystem is often intermittent • “feast-or-famine” existence • adaptations: accumulate reserves in times of plenty (e.g., inclusions of poly-β-hydroxybutyrate (PHB), polyphosphate); high growth rates when growth is possible, quiescence when growth is not possible • extended periods of exponential growth probably rare in nature • E. coli in intestinal tract: ~12 h; E. coli in lab culture: t~20 min gen gen • growth of some soil bacteria in nature is less than 1% of maximal growth rate possible under laboratory conditions (ii) distribution of resources in nature is often non-uniform • e.g., soil underlying a dead animal versus soil nearby (iii) competition for resources is likely • microbial monocultures are rare in nature Surfaces and biofilms :
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