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The “Phytoplankton” Microcystis Spirulina Gleocapsa Cyanobacteria = architects of the earth’s atmosphere Nostoc Anabaena Scytonema 1 Timeline of Planet Earth Billion Years Before Present 4.5 4.0 3.5 Earth formed O2 3.0 2.5 2.0 1.5 1.0 0.5 0 Precambrian Time: The Time of Prokaryotes Archaean Era: Era of Archaea Proterozoic Era: Era of Cyanobacteria Time of the Eukaryotes Cyanobacteria were first “algae”! Cyanobacteria: Understanding the Past Stromatolites – Shark Bay, W. Australia 2 Cyanobacterial Evolution - extensive fossil record, oldest record from Archean rocks of western Australia - have not diversified morphologically Bitter springs chert, Australia, dating 850 million years ago, forms are colonial and filamentous - may leave chemical fossils behind - retained in stromatolites, structures formed in shallow water by trapping microfilms Cyanobacteria Terminology - Division Cyanophyta - Cyanobacteria ‘formerly known as’ BlueGreen Algae - Why bacteria 3 en P lan t s Red A lg a e G re B ro w e hea Arc nA lg a e Diat oms Fun gi ria acte nob Cya Cyanobacteria Characteristics - size range from 0.5-1µm up to 40µm in diameter - cellwall - pigments – chl a, phycobiliproteins (some with multilayer - photosynthetic membrane system phycoerythrin, phycocyanin, allophycocyanin - storage – glycogen - cell walls – amino acids, sugars 4 Characteristics - Microscopic organisms - Found in marine sediments and pelagic zone, freshwater lakes, soils, - Live in extreme environments – chemically and temperature - First organisms to have 2 photosystems and to produce organic material and give off O2 as a bi-product -fix/convert atmospheric nitrogen into usable forms = nitrogen fixation Nitrogen Fixation in Cyanobacteria - nitrogenase converts N2 into NH4+ = higher energy required 12-15 ATP per fixed N - occurs in specialized cells only, not in typical vegetative cells - O2 inactivates nitrogenase 5 General Cyanobaterial Morphology 1. Vegetative cells cells that will divide cell wall of peptidoglycan thylacoid membranes 2. Heterocyte nitrogen fixing cell enlarged, lacking granules, photosynthetic lammellae re-orient into triple cell wall, may not revert 3. Akinete Dormant cell Internal Anatomy of the Vegetative Cells light harvesting antennae amino acid polymer, nitrogen/ carbon storage inner/outer membrane, peptidoglycan, protein fibrils 6 Cyanobacterial Akinete (hypnospore) cell wall cell membrane cyanophycean starch lipid droplet polyphosphate granule vacuole thylakoid cyanophycin nucleoid Cyanobacterial Forms * * colonial branched filament uniserate filament * * * colonial filamentous unicellular colonial multiserial filament 7 Cyanobacterial Forms Unicell – with mucilaginous envelope Colonies – Filaments – uniserate in a single row OR - multiserate – not TRUE branching when trichomes are > 1 in rows mucilaginous sheath trichome Function – protects cells from drying and involved in gliding. Sheath is often colored: Red = acidic Blue = basic Yellow/Brown = high salt Reproduction binary fission, hormogonia formation, akinete formation, fragmentation, endospore, exospore 8 Binary Fission Gloeocapsa sp. (light micrograph), a type cyanobacteria. They reproduce solely by fission, a form of asexual division in which two identical algae are produced. Sexual reproduction is unknown! Habit – success due to ability tolerate a wide range of conditions Marine – littoral and pelagic Fresh Water Hot Springs Terrestrial – soil flora 9 Cyanobacterial Blooms Microcystis bloom in Matilda Bay, Swan-Canning Estuary, Western Australia. Cyanotoxins in Cyanobacteria Neurotoxins (Anabaena, Oscillatoria) Hepatotoxins (Anabaena, Oscillatoria, Nostoc) 10 Examples of Cyanobacteria Spirulina (Arthospira) - protein Lyngbya - oceanic, may form large benthic and surface mats Hyella stella - lives in marine limestone, corals 11
