Bacteria are the most ancient life forms - signs from ~3,500 m.y.a. BBaaccteterriiaa can tolerate great physical extremes from ocean deeps to the stratosphere to inside rocks & earth's crust

essentials = only H20 + energy + matter vast metabolic diversity, mostly unique; - many sources of energy & matter 04 : 05 1 04 : 05 2

mostly extremely tiny - 0.1 - 10 x 10-6 m. bacterial metabolic activities exchange all major reactive gases with atmosphere : but extremely numerous: all major reactive gases 10 1 spoon garden soil - 10 cells N2, N2O, O2, CO2, CO, H2, 2 9 1 cm gum scrape - 10 cells CH4, NH3, H2S and many others total weight of all earth's bacteria also central in cycling C, P, S = 1/ all earth's mammals 10 several of these re-cyclings are restricted

cover all surfaces, interior & exterior; to bacteria - notably N2 mainly benign or beneficial photosynthetic bacteria began the change ope04n : 0 5genetic exchange; sex ≠ reproduction3 in 0character4 : 05 of earth's atmosphere ~3 b.y.a.4

most are morphologically simple - single cells some generate temporary multicellular structures

some form colonies

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Prokaryote vs. Eukaryote structure Prokaryotes vs. Eukaryotes 1-10 x 10-6m 10 - 100 x 10-6m

nucleoid, genophore nucleus, chromosomes

no organelles mitochondria, Golgi, E.R.

simple flagellum tubulin cilia

highly diverse uniform metabolism metabolism mostly aerobic 04 : 05 7 04 : 05 8

~2 x 109 year bacterial dominance stromatolites structures from bacterial mats plus Pr mineral particles Ar oldest oldest Ar eukaryotes stromatolites Ha oldest 3.9 Phanerozoic fossil rocks 4.5 b.y.a. 04 : 05 9 04 : 05 living 10

16S rRNA shows two major groups traditionally, bacteria have been classified BACTERIA & ARCHAEA according to shape, chemistry & metabolism (= Eubacteria & Archaebacteria) now recognised that this is poor indication Methanogenic bacteria Halophilic Thermophilic Archaea tend to bacteria Archaea of true historical-genealogical relationships bacteria

purple live in extreme mitochondrion Plants bacteria Fungi chloroplast gram- Archaea such similarities are mostly convergent positive environments Cyano- bacteria Animals bacteria many protoctist lineages hot, acidic, true relationships becoming revealed by spirochaetes small-subunit ribosomal RNA B acteria Eukarya salty, anoxic (16S rRNA) sequences 04 : 05 11 04 : 05 12

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many Archaea live in environments Halophils typical of very early earth:

Methanogenic bacteria Halophilic extremely hot (up to ~300°C), acidic Thermophilic bacteria bacteria

purple mitochondrion Plants bacteria Fungi gram- Archaea and osmotically challenging conditions chloroplast positive Cyano- bacteria Animals bacteria many protoctist lineages spirochaetes hot springs; super-hot deep-sea vents B acteria Eukarya

hypersaline seashores - 3-5 Molar NaCl

anoxic muds and soils, sewage, guts 04 : 05 13 04 : 05 Thermacidophils14

in early earth environment, physical Methanogenic bacteria

Methanogenic (O intolerant) bacteria 2 Halophilic processes (lightning, heat, UV) generated Thermophilic bacteria bacteria reduce C with H -> CH purple mitochondrion Plants 2 4 stew of organic molecules, rich in energy bacteria Fungi chloroplast gram- Archaea positive Cyano- bacteria Animals C from CO , formate, bacteria 2 many protoctist lineages methanol & acetate anaerobic fermentation thought spirochaetes methanol & acetate B acteria Eukarya probably the earliest global metabolism H from H2, formate, methanol & acetate as life grew, organic supplies dwindled... [CO2] + 4H2 -> CH4 + 2H2O strong selection for autotrophic capability: prevent accumulation of C in sediments energy and C from inorganic sources by releasing it back to atmosphere 2O + CH -> CO + 2H O this is exactly what methanogens can do 2 4 2 2 04 : 05 15 04 : 05thus prevent accumulation of O2 in air 16

eventually, use of sunlight energy evolved PHOTO-AUTOTROPHY we think of photosynthesis as generating O NEXT CLASS 2

but first forms, probably still O2-intolerant, Other forms of autotrophic activity: used H2, H2S etc. as reducing agents for CO2 changing the world’s atmosphere 2H2X + CO2 -> CH2O + 2X + H2O use of water + sunlight a stunning technique massive consequences for earth's

04 : 05 17 04 : 05 atmosphere and its life...... 18

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100 oxygenic photosynthesis developed ~2.5 b.y.a. (end-Archaean) 50 % O2 accumulated, raising level from today's 0.01% of atmosphere then to 20% today O2 (~10% at ~0.5 b.y.a. - first vertebrates) 10 5 first O2 photosynthesizers were probably just like today's Cyanobacteria LOG dominated 2.5 - 0.6 b.y.a. - stromatolites 2 SCALES

global primary production 3 1.0 0.4 0.1 04 : 05 19 04 : 05 billions of years ago 20

Cyanobacteria OXYGEN AS A PROBLEM

highly reactive; oxidises organics to CO2 - - O2 , OH , H2O2 seriously disruptive

O2 -> O3, which screens UV; this further reduces production of organics O2 production was a serious problem for O2-intolerant forms selection for new metabolic styles

Methanogenic bacteria Halophilic and ways of dealing with free O Thermophilic bacteria 2 bacteria they had to retreat purple mitochondrion Plants bacteria Fungi catalases, peroxidases to convert free radicals chloroplast gram- Archaea positive to O -free places or Cyano- bacteria Animals 2 bacteria many protoctist USE O to oxidise organics - respiration lineages evolve tolerance 2 spirochaetes 04 : 05 21 04 : 05 22 B acteria Eukarya fermenting - 1:18 - respiring

one way of dealing w/free radicals involves luciferin; light emitted with reaction this is bioluminescence most biotic light production involves symbiosis with bioluminescent bacteria

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Bacterial Metabolic Diversity thus bacteria perform a bewildering huge diversity, even within "species” diverse array of metabolic activities can switch according to conditions found can switch according to conditions found most are different from those in addition to eukaryote processes: of eukaryotes aerobic respiration and O2 photosynthesis and ethanol & lactate fermentation for most bacterial metabolic by-products, (organoheterotrophy & photoautotrophy) there are other bacteria who can use them chem. energy org. carbon light energy inorg. carbon (CO2) as substrates for their own activities non-O2 photoautotrophy - H2S, H2 entirely self-contained bacterial communities lithoautotrophy - methanogenesis, N2-fixation lithoheterotrophy - metal oxidizers can be independent of eukaryotes 04 : 05 25 04 : 05 26

Nitrogen Cycle we shall sample bacterial activities Rhizobium nodules through looking at how they contribute to the cycling of life's essential elements Nitrogen-fixers can be free or symbiotic, aerobic or anaerobic, lithotrophic, organotrophic or phototrophic crucial in cycling of N2, S and metals many fermenting major contributions to C, P cycling major contributions to C, P cycling and respiring decomposer bacteria substantial impact on O2 balance Nitrifying bacteria

04 : 05 27 04 : 05 28 bacteria are unique in fixing N2 gas

Cyanobacteria Sulphur Cycle heavy metal cycling organic sulphur Iron-Oxidizing (lithoautotroph) bacteria many bacteria (and fungi) assimilation decomposition 2- SO4 H2S

photosynthetic oxidation several groups oxidize Fe2+ to Fe3+ S usually under acidic conditions 04 : 05 purple and green S-bacteria29 04 : 05 30

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Cyanobacteria Carbon Cycle CO2 Bacterial Ecology 2 respiration Terrestrial generally live in H O films on soil particles photosynthesis 2 densest and most diverse communities live near surface - most organic debris decomposition major contributions to cycling of C, N & O methanogens live on all biological surfaces; CO2 guts etc. occasionally pathogenic 04 : 05 31 04 : 05 32

Aquatic Marine Aquatic Freshwater bacteria generally poorly represented except at shores and in great deeps Most primary production is done by aphotic hydrothermal vents bacteria and algae vents produce 270-380°C bacteria dominate in anoxic, extreme parts water w/highconcentrations of 2+ much primary production is respired by H2S, H2, CO, Mn the bacteria, consuming O2 lithotrophic bacteria excess organics -> O2 depletion provide base of special communities, dynamics of both C and O closely linked through bacterial activities 04 : 05 independent of sun33 04 : 05 34

cyanobacteria PLANTS Treponema - syphilis chloroplasts spirochaete Neisseria - gonorrhea, ANIMALS meningitis cilia fermenting archae- Borellia - Lyme disease bacterium FUNGI mitochondria Vibrio - cholera 04 : 05 35 04 : 05 respiring bacterium 36

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This SET view now broadly accepted but long-resisted; symbiosis now : recognised as being very common in life NEXT CLASS: Other symbioses Other symbioses The Protoctista - the simplest lichens Eukaryote organisms corals vent-worm bacteria root nodules mycorrhizae 04 : 05 37 04 : 05 38

thanks to the authors of the following sites http://www.bact.wisc.edu/bact303/bact303mainpage http://www.bact.wisc.edu/bact303/MajorGroupsOfProkaryotes http://lifesci.ucsb.edu/~biolum/organism/photo.html

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