lecture 5 - Lecture 5 October 16, 2009 1:23 PM Today:...

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Today: Fungal interaction Fungi are fundamental decomposers 1. 1 to 2 km of hyphaeper cm3 up to 1000 species Decomposes wood: involving how fungi feed themselves Fungi: most important decomposers of plants material a) Bacteria: 6 -10 million/cm2, or 3,500 kg/ acre b) Earthworms c) Mostly about food acquisition - (sex: spore dispersal stinkhorns) Fungi feeding on themselves are most important Ca. 90% of all plant materia l is broken down by fundamental decomposers - Saprophytes Parasites Symbionts Three ways how fungi feed themselves - Glucose (picture shown) Fructose Monosaccharides Sucrose (picture) Lactose Dissacharides compose 2 sugar molecues Starch Cellulose Hemicellulose Laminarin They are typical for algae Polysaccharides contain long chain of monosaccharides Lignin Chitin keratin Complex polymers have branched side chains. They are very hard to decompose and require specific enzymes. Few organisms actually produce these enzymes. Easiest sugars require least energy to break down Easy-to-digest carbs --> hard-to-digest carbs Easy carbs but need to be the first on the scene simple sugars << complex polymers Decomposition occurs very fast and need mechanisms to move around quickly Very ephemeral food source Plants and animals Feed on living organisms Food source Parasites a) Stable and long-term food source Difficult carbs, need special enzymes Less of a rat-race Saprophytes b) Fungi f ight over carbohydrates - Lecture 5 October 16, 2009 1:23 PM BIO251 Page 1
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More stabile,long-term food source Feed on dead organisms Food source Easy carbs , but not for free (by providing plants the access to several nutrients) Defined by life cycle of the host Long-term food source Get food from living organisms without harming these Return the service Food source Symbionts c) Due to different succession numerous species involved to decompose e.g. log or leaf Once their food sources run out, move to mid-succession --> late succession early fungi take simple sugars late fungi ‘clean up’ hard stuff There are not clear distinction (some species can be all) Fungal succession (colonizing food sources) Fungal succession: parasite 2. Fungus feeds on simple carbs and leaves chitineous exoskleton behind Once fungus finishes feeding, it leaves fly It colonizes fly and feeds on internal juice that is easy to decompose compared to chitin exoskeleton (long polymer) Parasite on house flies: Entomophthoramuscae (house fly killer) - Feeds on mobile nematodes by lassos structure growing on the worm --> nematods get constricted --> free nematodes but fungus grow on it enhancement of nutrient budget Catching microfauna (proteins!) Arthrobotrysforms constrictablelassos Used as bio-control
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This note was uploaded on 06/21/2011 for the course BIO BIO251 taught by Professor Busch during the Fall '11 term at University of Toronto.

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lecture 5 - Lecture 5 October 16, 2009 1:23 PM Today:...

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