北京大学：《微生物》（英文版） Archaeal Membranes and Cell Wall

微生物学”考试时間地 点 时间:2000年1月9日上午8:00-10:00 地点:四教4206 |

“微生物学”考试时间地 点 时间：2000年1月9日上午8:00-10:00 地点：四教4206

Halobacterium Detailed phylogenetic tree of the archaea based on 16s ribosomal RNA sequence Euryarchaeota Comparisons Archaeoglobus Halophilic Methanococcus Methanobacterium Crenarchaeota Sulfolobus Thermococcus Methanosarcina Methanothermus Pyrodictium Thermoproteus Thermoplasma Methanopyn Desulfurococcus Korarchaeota

Detailed phylogenetic tree of the Archaea based on 16S ribosomal RNA sequence Comparisons

Archaeal membranes and cell wall Archaea lack fatty acids, instead have hydrocarbon moieties bonded to glycerol by ether (instead of ester) linkages Glycerol diethers and diglycerol tetraethers are the major classes of lipids present in Archaea Archaea do not contain muramic acid and D-amino acids. as in Bacteria A pseudopeptidoglycan is found in some archaea, it consists of two amino sugars: N-acetylglucosamine and N acetyltalosaminuronic acid, with only L-amino acids lin kages Some contain a thick wall consists only polysaccharide Some contain cell walls made of glycoprotein Some lack carbohydrate in their cell walls and have walls consisting of only protein

Archaeal Membranes and Cell Wall Archaea lack fatty acids, instead have hydrocarbon moieties bonded to glycerol by ether (instead of ester) linkages Glycerol diethers and diglycerol tetraethers are the major classes of lipids present in Archaea Archaea do not contain muramic acid and D-amino acids, as in Bacteria A pseudopeptidoglycan is found in some archaea, it consists of two amino sugars: N-acetylglucosamine and N￾acetyltalosaminuronic acid, with only L-amino acids linkages Some contain a thick wall consists only polysaccharide Some contain cell walls made of glycoprotein Some lack carbohydrate in their cell walls and have walls consisting of only protein

Chapter 20 Prokaryotic Diversity: Archaea Extremely Halophilic Archaea Methane-Producing Archaea: Methanogenes Hyperthermophilic archaea Thermoplasma: A Cell-Wall-Less archaean Limits of Microbial Existence: Temperature Archaea earliest life forms?

Chapter 20 Prokaryotic Diversity: Archaea Extremely Halophilic Archaea Methane-Producing Archaea: Methanogenes Hyperthermophilic Archaea Thermoplasma: A Cell-Wall-Less Archaean Limits of Microbial Existence: Temperature Archaea: Earliest Life Forms?

Extremely Halophilic Archaea in habitants of highly saline environments such as solar salt evaporation ponds and natural salt lakes Hypersaline habitats: seawater she red-r ple Great Salt Lake in Utah q erlCpnberins adEt bacteri 企!下

Extremely Halophilic Archaea: inhabitants of highly saline environments such as solar salt evaporation ponds and natural salt lakes Hypersaline habitats: Great Salt Lake in Utah Seawater evaporating ponds: the red-purple Color is due to bacterioruberins and bacterio￾rhodopsin of halobacterium

Environments for extremely halophile Solar salt evaporation ponds Natural salt lakes Artificial saline habitats(surfaces of heavily salted food such as certain fish and meats) Require at least 1.5 M(9%) Nacl for growth Most species require 2-4 M(12-23%)NaCl for growth Some can grow at pH of 10-12 No harmful to human and animals

Environments for extremely halophile Solar salt evaporation ponds Natural salt lakes Artificial saline habitats (surfaces of heavily salted food such as certain fish and meats) Require at least 1.5 M (9%) NaCl for growth Most species require 2-4 M (12-23%) NaCl for growth Some can grow at pH of 10-12 No harmful to human and animals

Physiology of Extremely Halophilic Archaea All are chemoorganotrophs Most are obligate aerobes All require large amount of sodium for growth All stain gram negatively, binary fission growth Most are nonmotile Halobacterium and Halococcus contain large plasmids Peptidoglycan replaced by glycoportein in the cell wall Cellular components exposed to the external environment require high Nat for stability Cellular internal components require high K-t for stability Nat stabilize the cell walls

Physiology of Extremely Halophilic Archaea All are chemoorganotrophs Most are obligate aerobes All require large amount of sodium for growth All stain gram negatively, binary fission growth Most are nonmotile Halobacterium and Halococcus contain large plasmids Peptidoglycan replaced by glycoportein in the cell wall Cellular components exposed to the external environment require high Na+ for stability Cellular internal components require high K+ for stability Na+ stabilize the cell walls

Bacteriorhodopsin and Light-mediated ATP Synthesis H Bacteriorhodopsin x Out H H H ATPase H ADP+P

Bacteriorhodopsin and Light-mediated ATP Synthesis Bacteriorhodopsin

Methane-Producing Archaea: Methanogens Methane formation occurs under strictly anoxic conditions CO2-type substrates(CO2, HCoO and co) can be used as carbon sources Methyl substrates(CH3OH, CH3NH2*, (CH3)#, (CH3)3NH#, CH3SH, ( CH3)2S) are methanogenic carbon sources。 Acetotrophic substrates such as acetate can also be used to produce methane Three classes of methanogenic substrates are known and all release free energy suitable for ATP synthesis

Methane-Producing Archaea: Methanogens Methane formation occurs under strictly anoxic conditions. CO2-type substrates (CO2, HCOO- and CO) can be used as carbon sources. Methyl substrates (CH3OH, CH3NH2 + , (CH3)2NH+ , (CH3)3NH+ , CH3SH, (CH3)2S) are methanogenic carbon sources. Acetotrophic substrates such as acetate can also be used to produce methane. Three classes of methanogenic substrates are known and all release free energy suitable for ATP synthesis

Diversity and physiology of methanogenic Archaea 16S ribosomal RNA sequence analyses classify methanogen into seven major groups All methanogens use NH4* as a nitrogen source A few species can fix molecular nitrogen Nickel is a trace metal required by all methanogens, it is a component of coenzyme Factor430 Iron and Cobalt are also important for methanogens Pictures on the left: morphological diversity of methanogens

Diversity and Physiology of Methanogenic Archaea 16S ribosomal RNA sequence analyses classify methanogen into seven major groups All methanogens use NH4 + as a nitrogen source A few species can fix molecular nitrogen Nickel is a trace metal required by all methanogens, it is a component of coenzyme Factor430 Iron and Cobalt are also important for methanogens. Pictures on the left: morphological diversity of methanogens