Forchhammer

Naturally Fe II occures -> Fe III is indicator that something must have been oxidized

Biofilm produces sediment rock

-> Resoinsible: Cyanobacteria: grow in shallow water as biofilms, deeper layers die off & are converted into some kind of stone, biofilms keep growing on top

• atmosphere was anaerobic before cyanobacteria

• First oxygen caused first organism made environtmental crisis: oxygen was toxic for most organism

  • oxygen reacts with some electron carriers -> O2-

    -> Attacks DNA or enzymes

    -> had to develop oxygen defense mechanisms

-> Chance: aerobic respiration -> respiratory chains

Beginning of life must be earlier

• autolytic reactions

• A: self sustaining abiotic chemical reactions such as polymerization of CO2 & H2 could have formed the basis of cellular metabolism, the reductive TCA cycle arose out of intermediates with small thermodynamic transitions to CO2

• B: the genetic code may have originated from synthesis of an amino acid complexed to a dinuclotide, this dinulceoride could later have evolved into the first two nucleotides of the codon specifiying the amino acid

• RNA can store information & catalyze reactions

-> must have been precursor of dsDNA

• earliest cells may have been composed of RNA enzymes (ribozymes)

• As the RNA cells evolved, ribozymes acquired protein subunits that eventually assumed most of their catalytic functions

• Remnants of the original RNA may persist as nucleotide cofactors such as NADH

• characteristic traits of living organisms

• Trees have been made by analysis of ine RNA molecule -> one molecule represents one organism, horizontal gene transfer not considered

= last universal common ancestor

Comparing gene sequences both within & between genomes enables us to track how organisms adapted in the past

Environments under intensive selective pressure such as antibiotic exposure in hospitals & high temperature habitats reveal repid evolution

Experimental strategies can now reveal evolution in the laboratory, enabling us to test predictive models

DNA hybridization ≥ 70%

SSU rRNA similarity ≥ 97%

Average nucleotide identity (ANI) of orthologs ≥ 95%

Co evolution of symbiotic partners

E.g. endosybiosis theory as the origin of the eukaryotic cell, mitochondria & chloroplasts

• Facultative CO2 fixation using 3-hydroxypropionate cycle carboxylation of acetyl-CoA & propionyl-CoA

• Reaction centre: photosystem II type

• Light harvesting: chlorosomes

• Green nonsulfur bacteria

resembles chloroplast

-> Photosynthesisapparat was invented

Single cell with binary devision

Single cell with baeocysts

Simple filamentous without specialized cells

Simple filamentous with heterocysts

Complex filamentous

High GC, gram+ with moderate salt tolerance

• Actinomyces: A. Israelii causes actinomycosis

• Mycobacterium: M. Tuberculosis causes tuberculosis, M. leprae cause leprosy

• Propionibacteriaceae: Propionic acid fermentation; P. Acnes causes acne, P. Freudenreichii makes swiss cheese

• Bifidobacteriales: ferment without gas, enteric biota of breast-fed infants Bifidobacterium

Los GC, gram+ rods & cocci

• Bacillales: Bacillus, Staphylococcus

• Clostridiales: Clostridium

• Lactobacillales: non spore formers, facultative anaerobes, fermenr producing lactic acid, Enterococcus, Lactococcus, Streptococcus

Alpha, beta, gamma, delta & epsilon groups

High metabolic diversity: phototrophy, chemolithotrophy, chemoorganotrophy

Heterotrophic rods or spirilla

• Caulobacter

• Rhizobium group: fix nitrogen with legumes

• Rickettsia

• Agrobacterium tumefaciens causes plant tumors

Phototrophs, lithotrophs & pathogens

• Neisseriales: N. Gonorrhoeae causes gonorrhea, N. Meningitis causes meningitis

Facultative anaerobes & lithotrophs

• Enterobacteriales: Escherichia coli, Salmonella, Yersinia

• Pseudomonadales: P. Aeruginosa

Lithotrophs & multicellular communities

• Bdellovibrionales: Bdellovibrio bacteriovorus: bacterial predator

• Myxococcales: form fruiting bodies & predators on other bacteria

Campylobactrales: Campylobacter & Helicobacter

Transcriptional machinery resembles eukaryotes

cell wall:

CO2 + 4H2 -> CH4 + 2H2O

-> 25 times more active as CO2 as greenhouse gas

From farming & from rice fields

• light driven proton pump

• Live up to 121°C

• Different types of membrane & cell wall