Download presentation
Presentation is loading. Please wait.
1
Chapter 20 The Archaea
2
Archaea highly diverse with respect to morphology, physiology, reproduction and ecology best known for growth in anaerobic, hypersaline and high-temperature habitats also found in marine arctic temperature and tropical waters
3
Archaeal Cell Walls lack muramic acid walls found in group are diverse
pseudomurein (peptidoglycan-like polymer) found in some methanogenic species complex polysaccharides, proteins or glycoproteins found in some other species
4
Archaeal Membrane Lipids
differ from Bacteria and Eucarya in having branched chain hydrocarbons attached to glycerol by ether linkages sulfolipids and glycolipids are also found in archaeal membranes
5
Archaeal Lipids and Membranes
Bacteria/Eucaryotes fatty acids attached to glycerol by ester linkages Archaea branched chain hydrocarbons attached to glycerol by ether linkages some have diglycerol tetraethers
6
Archaeal Genetics and Molecular Biology
exhibit some similarities to Bacteria or Eucarya ~30% of genes shared exclusive between archeons and eucaryotes code for proteins involved in transcription, translation or DNA metabolism many genes shared only with bacteria are involved in metabolic pathways there is evidence for lateral (horizontal) gene transfer between archeons and bacteria
7
More about Archaeal Genetics and Molecular Biology
DNA replication and transcription have both bacterial and eucaryotic features archael mRNA appears to be similar to that of bacteria rather than eucaryotic mRNA
8
Like bacteria circular chromosome
Like eucarya – histone proteins
9
Genus Sulfolobus irregularly lobed, spherical shaped thermoacidophiles
cell walls contain lipoproteins and carbohydrates thermoacidophiles 70-80°C pH 2-3 metabolism lithotrophic on sulfur using oxygen (usually) organotrophic on sugars and amino acids
10
Fig. 20.7a Sulfolobus
11
Habitats of methanogens
anaerobic environments rich in organic matter e.g., animal rumens e.g., anaerobic sludge digesters e.g., within anaerobic protozoa Swamps and marshes
12
Ecological and practical importance of methanogens
important in wastewater treatment can produce significant amounts of methane can be used as clean burning fuel and energy source is greenhouse gas and may contribute to global warming can oxidize iron (mathanogen) contributes significantly to corrosion of iron pipes
13
Examples of Halobacteria
Figure 20.12
14
e.g., Halobacterium salinarium (H. halobium)
has unique type of photosynthesis not chlorophyll based uses modified cell membrane (purple membrane) contains bacteriorhodopsin absorption of light by bacteriorhodopsin drives proton transport, creating PMF for ATP synthesis
15
Bacteria: The Deinococci and Nonproteobacteria Gram Negatives
Chapter 21 Bacteria: The Deinococci and Nonproteobacteria Gram Negatives
16
Cyanobacteria largest, most diverse group of photosynthetic bacteria
many are obligate photolithoautotrophs; some can grow slowly in dark as chemoheterotrophs
17
Photosynthesis in cyanobacteria
resembles that of eucaryotes oxygenic photosynthesis
18
Photosynthesis in cyanobacteria
use phycobiliproteins as accessory pigments phycobilisomes, which line thylakoid membranes, contain phycocyanin and phycoerythrin use Calvin cycle to fix CO2
19
Cyanobacterial Thylakoids and Phycobilisomes
Figure 21.6
20
typical gram- negative contains cell phyco- wall bilin pigments site
of photo- synthesis nitrogen storage Polymer Arginine, Aspartic acid Schematic drawing of a vegetative cyanobacterial cell. The insert shows an enlarged view of the envelope with its outer membrane and peptidoglycan. Figure 21.7 (a)
21
Thin section of Synechocystis during division
Thin section of Synechocystis during division. Thylakoid membranes house photosynthetic pigments and ETC components. Phycobilisomes line the thylakoid membranes and contain phycobilin pigments, especially phycocyanin. Carboxysomes contain ribulose 1,5-bisphosphate carboxylase, which is an important enzyme of the Calvin Cycle. Figure 21.7b
22
More About Cyanobacteria
range in diameter from ~1 to 10 mm may be unicellular, colonial or form filaments called trichomes (a row of cells in close contact with each other) pigmentation most appear blue-green due to presence of phycocyanin presence of phycoerythrin in many ocean isolates gives them red or brown coloration
23
Chromatic Adaptation many use gas vacuoles to optimally position themselves in optimal illumination in water column considered a form of phototaxis
24
Heterocysts specialized cells used for nitrogen fixation
produced when organism is nitrogen deprived differentiate from individual cells in filament involves reorganization of photosynthetic membranes thick heterocyst wall prevents O2 diffusion into heterocyst which would inactivate nitrogenase, enzyme responsible for nitrogen fixation
25
Fig.21.8b
26
Ecology of cyanobacteria
tolerant of environmental extremes thermophilic species can grow at temperatures up to 75°C often are primary colonizers can cause blooms in nutrient-rich ponds and lakes some produce toxins often form symbiotic relationships e.g., are phototrophic partner in most lichens e.g., symbionts with protozoa and fungi e.g., nitrogen-fixing species form associations with plants
27
Figure 21.11
28
Chlamydia gram-negative obligate intracellular parasites
although known for ability to cause disease, many grow within hosts such as protists, vertebrate and invertebrate cells without adverse effects. genus Chlamydia is best studied
29
Genus Chlamydia nonmotile, coccoid, gram-negative bacteria
cell walls lack muramic acid and peptidoglycan have very small genomes obligate intracellular parasites with unique developmental cycle involving formation of elementary body (EB) and reticulate body (RB) or initial body found mostly in mammals and birds some recently isolated from spiders, clams, and freshwater invertebrates
30
Figure 21.13b
31
Chlamydial metabolism
appear to be energy parasites, obtaining ATP from host do have genes for substrate-level phosphorylation, electron transport, and oxidative phosphorylation reticulate bodies have biosynthetic capabilities when supplied precursors from host; can synthesize some amino acids elementary bodies seem to be dormant forms
32
Important pathogens C. trachomatis C. psittaci
infects humans and mice causes trachoma (blindness), nongonococcal urethritis, and other diseases in humans C. psittaci Associated with birds - parrots infects humans and many other animals causes psittacosis in humans C. pneumoniae common cause of human pneumonia
33
Spirochetes gram-negative bacteria with distinctive structure and motility slender, long with flexible helical shape creeping (crawling) motility due to a structure called an axial filament chemoheterotrophs ecologically diverse
34
Figure 21.14
35
axial filament = complex of axial fibrils (periplasmic flagella)
Figure (a1) and (a2)
36
Symbiotic Associations between Spirochetes and Other Organisms
broad range of organisms found in a variety of locations, for example hindguts of termites digestive tracts of mollusks and mammals oral cavities of animals Treponema pallidum – syphilis STD Ulcer, rash, latent stage, Tertiary stage
37
Bacteroides gram-negative rods of various shapes
do not form endospores motile or nonmotile anaerobic chemoheterotrophs fermentative often found in oral cavity and intestinal tract of humans and other animals and the rumen of ruminants often benefit host by degrading complex carbohydrates, providing extra nutrition to host can constitute up to 30% of bacteria from human feces
38
genus Cytophaga slender rods, often with pointed ends
aerobic metabolism degrade complex polysaccharides e.g., cellulose, chitin, pectin, keratin, agar significant component of bacterial population in sewage treatment plants most are free-living; some are pathogenic in vertebrate hosts e.g., Cytophaga columnaris – pathogen of fish
39
Bacteria: The Proteobacteria
Chapter 22 Bacteria: The Proteobacteria
40
Rickettsia rod-shaped, coccoid, or pleomorphic
typical gram-negative cell walls no flagella very small Rickettsia – 0.3 to 0.5 by 0.8 to 2.0 m Obligate intracellular parasites. Grow in vertebrate erythrocytes, macrophages, and vascular endothelial cells also live in blood-sucking arthropods, which serve as vectors or primary hosts Rickettsia rickettsii – rocky mountain spotted fever Transmitted by ticks Rash on palms
41
Rickettsia metabolism
lack glycolytic pathway do not use glucose as energy source oxidize glutamate and TCA cycle intermediates (e.g., succinate) take up and use ATP and other materials from host cell
42
Important pathogen Rickettsia rickettsii – Rocky Mountain Spotted Fever
43
Genus Caulobacter in class Caulobacteraceae
may be polarly flagellated rods or may possess prostheca and holdfast(end of the stem like stucture. used to attach to solid substrata with what is known as the strongest biological adhesion molecule (superglue) prostheca lacks cytoplasmic components
44
Genus Caulobacter usually found in oligotrophic aquatic and terrestrial habitats often adhere to other microorganisms may absorb nutrients released from hosts long prosthecae – stalk (extension of the cell, but narrower) may improve nutrient uptake
45
Caulobacter Figure 22.7 (b) and (c)
Figure 22.6b: A cell dividing to produce a swarmer. Note prostheca and flagellum. Figure 22.6c: A cell with a flagellated swarmer. Figure 22.7 (b) and (c)
46
Caulobacter life cycle; timing for growth at 30° in glucoser minimal medium
Figure 22.8
47
Genus Rhizobium gram-negative, motile rods
often contain poly-b-hydroxybutyrate granules become pleomorphic under adverse conditions grow symbiotically as nitrogen-fixing bacteroids within root nodule cells of legumes Form nodules in the roots and convert nitrogen gas to ammonia Plants use ammonia to make protein
48
Figure 22.9
49
Figure 22.11
50
Nitrification ammonianitritenitrate
conversion of ammonia to nitrate by action of two genera e.g., Nitrosomonas – ammonia to nitrite e.g., Nitrobacter – nitrite to nitrate fate of nitrate easily used by plants Chemolithotrophs – get electrons from inorganic substance
51
Genus Neisseria nonmotile, gram-negative cocci
most often occur in pairs with adjacent sides flattened may have capsules and fimbriae aerobic chemoorganotrophs inhabitants of mucous membranes of mammals some human pathogens Neisseria gonorrhoeae – gonorrhea - STD Neisseria meningitidis – meningitis - aerosol
52
Genus Bordetella gram-negative coccobacilli aerobic chemoorganotrophs
some have capsules aerobic chemoorganotrophs respiratory metabolism require organic sulfur and amino acids for growth mammalian parasites that multiply in respiratory epithelial cells e.g., Bordetella pertussis nonmotile, encapsulated species causes whooping cough Cough violently gasp for air DTP pertussis - vaccine has heat killed bacteria
53
Thiobacillus well studied chemolithotroph
prominent member of colorless sulfur bacteria chemolithotrophs that oxidize sulfur compounds Gram negative rod, soil
54
Genus Thiobacillus found in soil and aquatic habitats
production of sulfuric acid can cause corrosion of concrete and metal structures may increase soil fertility by releasing sulfate
55
Figure 22.18
56
Chromatium typical purple sulfur bacteria strict anaerobes
usually photoautolithotrophs use H2S as electron donor deposit sulfur granules internally often eventually oxidize sulfur to sulfate may also use hydrogen as electron donor usually found in anaerobic, sulfide-rich zones of lakes can cause large blooms in bogs and lagoons
57
Fig a
58
purple photosynthetic sulfur bacteria growing in a bog
Figure (a)
59
Fig b
60
Pseudomonas chemoheterotrophs with respiratory metabolism
usually use oxygen as electron acceptor sometimes use nitrate as electron acceptor have functional TCA cycle
61
Practical importance of pseudomonads
metabolically versatile degrade wide variety of organic molecules mineralization microbial breakdown of organic materials to inorganic substrates important experimental subjects some are major animal and plant pathogens some cause spoilage of refrigerated food can grow at 4°C Pseudomonas aeruginosa – opportunist Wound and burn infections
62
Vibrio cholerae causes cholera genome has been sequenced
has two circular chromosomes copies of some genes present on both chromosomes Contaminated water Cholera toxin – stimulates the cell to release Water and electrolytes – profuse and watery diarrhea- rice water stools
63
Vibrio cholerae G-, bent rod, single flagellum Intestine, toxin
Cells lining the intestine Stimulate them to release water and electrolytes Profuse and watery diarrhea Rice water stools – mucus, epithelia cells, bacteria
65
Escherichia coli probably best studied bacterium
inhabitant of intestinal tracts of many animals used as indicator organisms for testing water for fecal contamination some strains are pathogenic gastroenteritis urinary tract infections E. coli O157:H7 – dysentery – contaminated undercooked hamburgers
66
Important pathogenic enteric bacteria
Salmonella – typhoid fever and gastroenteritis Shigella – bacillary dysentery Klebsiella – pneumonia Yersinia - plague
67
Salmonella typhi G- rod, typhoid fever Found in humans
Carriers – gall bladder Fluoroquinilones, chloramphenicol Contaminated food or water
68
Salmonella enteritidis
Salmonellosis Poultry and cattle Undercooked, contaminated food Fever, abdominal pain, diarrhea Fluid and electrolyte therapy Cooking the meat thoroughly
69
Shigella dysenteriae G- rod, shigellosis Humans Contaminated food
Produces toxin Damage to the intestinal wall Fluoroquinilones
70
Yersinia pestis G- rod, plague Fleas from rats
Southwestern – squirrels, chipmunks Direct contact Proliferate in the blood stream
71
Y. pestis Buboes – swelling of lymph nodes. Bubonic plague
Mortality – 50 to 75% Streptomycin and tetracycline – prophylaxis Pneumonic plague – aerosol Mortality rate 100%
73
Bdellovibrio pathogenic to other bacteria
Negatively stained; shows sheathed polar flagellum. Figure 22.23
74
Figure (a)
75
Myxococcus gram-negative, rod-shaped gliding bacteria
aerobic chemoorganotrophs with respiratory metabolism most are micropredators or scavengers that lyse bacteria and yeasts by secretion of digestive enzymes most use amino acids as major source of C, N, and energy
76
Myxobacteria distinctive life cycle which resembles that of cellular slime molds in presence of food form a swarm and migrate on solid surfaces form a fruiting body when nutrients are exhausted involves at least 5 extracellular signaling molecules which allow cells to communicate with each other
77
Myxobacterial life cycle
Myxobacterial life cycle. The outermost sequence depicts the chemical induction of myxospore formation followed by germination. Regular fruiting body production and myxospore germination are also shown. Figure 22.36
78
Fruiting Bodies formation requires gliding motility and involves at least 5 extracellular signaling molecules which allow cells to communicate with each other range in height from 50 to 500 mm colored by carotenoid pigments vary in complexity some cells develop into dormant myxospores
79
Myxospores frequently enclosed in walled structures called sporangioles (sporangia) dormant and desiccation-resistant may survive up to 10 years
80
Figure 22.37
81
Bacteria: The Low G + C Gram Positives
Chapter 23 Bacteria: The Low G + C Gram Positives
82
Endospores have a complex structure containing a coat, cortex, and inner spore membrane surrounding the protoplast dipicolinic acid is present heat resistant dormant and viable for long periods of time
83
Figure 23.6
84
Important species of Clostridium
C. botulinum – food spoilage (especially canned foods); botulism C. tetani – tetanus C. perfringens – gas gangrene
85
Figure 23.7
86
Clostridium Gram + Obligate anaerobe Endospores Soil
3 pathogenic species
87
Clostridium tetani - tetanus
Infects deep puncture wounds Endospores become vegetative cells Neurotoxin – spastic paralysis Stiffness of the muscles Lockjaw DTP vaccine – tetanus toxoid Antitoxin – antibodies Tetanus immune globulins (TIG)
88
Clostridium botulinum - botulism
Improperly canned food Neurotoxin Flaccid paralysis Double vision, drooping eyelids Toxin is heat labile
89
Clostridium perfringens
Gas gangrene Gangrene – death of a tissue due to the loss of blood supply Ferments carbohydrates and releases gas Toxins kill cells Bullet wounds, frost bites Amputation
91
Bacillus subtilis type species
used as model organism for cellular differentiation, division and other processes various species produce antibiotics
92
Other important species of Bacillus
B. cereus – food poisoning B. anthracis – anthrax B. thuringiensis – used as insecticide
93
Bacillus anthracis - anthrax
Sheep, cattle – endospores are ingested from the soil – septicemia People at risk – work with animals Cutaneous anthrax – cuts and breaks in the skin. Inhalation anthrax – wool sorter’s disease Dangerous form of pneumonia Tetracycline
94
Figure 23.9
95
Figure 23.13
96
Pathogenic Staphylococcus
Staphylococcus epidermidis common skin resident sometimes responsible for endocarditis and for infections of patients with lowered resistance e.g., wound infections, surgical infections, and urinary tract infections
97
Antibiotic Resistant Staphylococci
resistance to methicillin Methicillin-Resistant Staphylococcus aureus (MRSA) obtained from genetic elements received from other organisms resistance to vancomycin, the “drug of last resort”
98
Staphylococcus aureus
produces the virulence factor coagulase causes blood plasma to clot produces hemolysin toxin which lyses cells major cause of food poisoning recently >1,000 school children in Texas had staphylococcal food poisoning caused by eating improperly handled chicken found on nasal membranes and skin, and in gastrointestinal and urinary tracts
99
Genus Lactobacillus widely distributed in nature on plant surfaces
in dairy products, meat, water, sewage, beer, fruits, and other materials normal flora of mouth, intestinal tract, and vagina usually not pathogenic
100
Figure 23.14
101
Figure 23.17
102
Important streptococci, enterococci, and lactococci
Streptococcus pyogenes – streptococcal sore throat, acute glomerulonephritis, and rheumatic fever Streptococcus pneumoniae – lobar pneumonia and otitis media Streptococcus mutans – dental caries Enterococcus faecalis – opportunistic pathogen (urinary tract infections and endocarditis) Lactococcus lactis – production of buttermilk and cheese
103
Bacteria: The High G + C Gram Positives
Chapter 24 Bacteria: The High G + C Gram Positives
104
Corynebacterium many are animal and human pathogens
e.g., C. diphtheriae - diphtheria
105
Genus Mycobacterium straight or slightly curved rods that sometimes branch or form filaments
106
Figure 24.10
107
Mycobacterial cell walls
contain waxes with 60 to 90 carbon mycolic acids acid-fast basic fuchsin dye cannot be removed from cell by acid alcohol treatment
108
Important species of Mycobacterium
M. bovis – tuberculosis in cattle and other ruminants M. tuberculosis – tuberculosis in humans M. leprae – leprosy
109
Impact of Nocardia most are free-living saprophytes
can degrade many molecules e.g., petroleum hydrocarbons, detergents, benzene involved in biodegradation of rubber joints in water and sewage pipes some are opportunistic pathogens causing nocardiosis usually infect lungs; can infect central nervous system
110
Streptomycetes are 1 to 20% of culturable soil microbiota
produce geosmin volatile substance that is source of moist earth odor important in mineralization process aerobically degrade many resistant substances (e.g., pectin lignin, and chitin) produce vast array of antibiotics most are nonpathogenic saprophytes
111
Streptomyces aerial hyphae that divide in single plane to form chains of 3-50 nonmotile spores
112
Figure 24.15
Similar presentations
