BIOL1131 Lecture Notes - Lecture 7: Lignin, Decomposer, Saprotrophic Nutrition
7 Jun 2018
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Microbes, fungi and plants
• Microbial activity
o Iron deposits arose from activity 1.8 – 2.3 billion years ago
• Biodiversity of micro-organisms
o Been diversifying for over 3.85 billion years, compared to only 600 million
years for macro=organisms – Atlas & Bartha 1998
o Recent surveys of the smallest eukaryotic planktonic fractions at different
oceanic surface regions in deep-sea Antarctic samples revealed
astonishing protist diversity, both phototrophic and heterotrophic.
• Prokaryotes
o Before nucleus
o Bacteria, Archean bacteria
o Simplified structure, no membrane-bound organelles, no clues and no
other organelles typical of eukaryotes, no wall of microfilaments
o Move by Flagella
o Number of bacterial species .-100 million
o A spoonful of soil has at least 10,000 species of bacteria
o Number of prokaryotes on earth estimated at 5 x 10^30 cells.
o Total amount of their cellular carbon is estimated at 350-550 x 10^12 kg
of Carbon (60-100% of the estimated total carbon in plants of bacterial
origin).
o Prokaryotes contain 85-130 x 10^12 kg of N and 9-14 x 10^12 kg of P, or
about 10-fold more of these nutrients than do plants, and represent the
largest pool of these nutrients in living organisms.
▪ (W.B. Whittman, D.C. Coleman & W.J. Wiebe, Proc. Natl. Acad.
Sciences, USA 95:6578-6583 (1998)
• Algal Bloom
o Australia holds the world record for the largest algal bloom
o In November 99 we scored the largest toxic cyanobacterial (blue-green
algae) bloom in history. An estimated 1000-kilometre stretch of the
Barwon and Darling rivers in New South Wales was affected; from the air
it looked like a long ribbon of pea soup
• Eukaryotes
o All non-bacteria, viruses and related organisms
o Have a nucleus
o Complex cellular structure
o Plastids – mitochondria as well as chloroplasts in plants
• Fungi
o Heterotrophic
o Occupy the entire biosphere
o 72,000 named species but only %5 of what we suspect there to be,
estimates at 1.5 million
o Fungi – eukaryotic heterotrophs with external digestion that reproduce by
spores
o Mycelium – body of fungus
o Hyphae - filamentous, microscopic, chitinous tubes
o Closest relatives of kingdom Animalia
o Fungi have
▪ Chitin in cell walls
▪ Haploid nuclei in non-sexual (vegetative cells)
o They can digest nearly any form of organic carbon
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