The Prokaryotes: Domains Bacteria and Archaea Part 2 Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

The Nonproteobacteria Gram-Negative Bacteria Not closely related to the gram-negative proteobacteria Several physiological and morphologically distinctive photosynthesizing bacteria Phyla Cyanobacteria, Chlorobi (green sulfur bacteria) & Choloroflexi (green nonsulfur bacteria)

The Nonproteobacteria Gram-Negative Bacteria

Photosynthetic Bacteria

Photosynthetic Bacteria Phyla Cyanobacteria, Chlorobi, Chloroflexi, photosynthetic purple sulfur bacteria (-proteobacteria), and purple nonsulfur bacteria (-proteobacteria) Photoautotrophs and chemoheterotrophs Photosynthetic purple and green sulfur bacteria are generally anaerobic and usually found in deep sediments of lakes and ponds

Cyanobacteria Oxygenic (oxygen-producing) photosynthetic bacteria Produce O2 from H2O using light energy Characteristic blue-green (cyan) pigmentation Gliding motility or gas vacuoles Fix nitrogen (into ammonium) from atmosphere in specialized cells called heterocysts Morphologically varied (Unicellular to colonial form)

Cyanobacteria Figure 11.12a-c

Purple and Green Photosynthetic Bacteria Anoxygenic photosynthesis (does not produce O2) carry out photosynthesis to make carbohydrates Possess chlorophyll 2H2S + CO2 light (CH2O) + H2O + 2S0 2H2O + CO2 (CH2O) + H2O + O2 Oxygenic Anoxygenic (purple sulfur and green sulfur bacteria)

Phylum Chlamydiae Do not contain peptidoglycan in cell walls Chlamydia: intracellular parasite; a unique developmental cycle (elementary body is the infective agent); gram-negative coccoid Transmitted via interpersonal contact or by airborne respiratory routes C. trachomatis Trachoma, STD, urethritis C. pneumoniae Mild form of pneumoniae C. psittaci Causes psittacosis (ornithosis)

In Bergey's Manual, Volume 5 Figure 11.22a

In Bergey's Manual, Volume 5 Figure 11.22b

Phylum Spirochaetes Coiled morphology; outer sheath; axial filaments (endoflagella) for motility many are found in oral cavity Borrelia Relapsing fever and Lyme disease Leptospira leptospirosis Treponema syphilis (T. pallidum) Figure 11.23

Phylum Bacteroidetes Anaerobic Bacteria Bacteroides: nonmotile; in mouth (gingival crevice) and large intestine; also recovered frequently from deep tissue infections Cytophaga: degrade cellulose and chitin in soil; gliding motility

Phylum Fusobacteria Often pleomorphic, may be spindle-shaped Fusobacterium: found in mouth (gingival crevice); may be involved in dental diseases Figure 11.24

Gram-Positive Bacteria Two groups: high G + C ratios (above 50%) e.g. Phylum Actinobacteria (mycobacteria, corynebacteria,and actinomycetes) low G + C ratios (below 50%) e.g. Phylum Firmicutes (common soil bacteria, lactic acid producing bacteria, and several human pathogens)

Phylum Firmicutes Low G + C Gram-positive

Order Clostridiales Clostridium Epulopiscium Form endospores Obligate anaerobes C. botulinum Botulism C. tetani Tetanus C. perfringens Gas gangrene Food diarrhea C. difficile Severe diarrhea Epulopiscium Giant prokaryote; symbiotic in the gut of surgeonfish Figure 11.14 & 15

Order Bacillales Important genera of gram-positive rods and cocci Bacillus Rod-shaped bacteria that form endospores Common in soils B. anthracis: Anthrax B. thuringiensis: Microbial insect pathogen B. cereus: Occasional food poisoning Figure 11.16b

Order Bacillales Staphylococcus Cocci in clusters S. aureus: facultative anaerobes; can tolerate high osmotic pressure and low moisture; produce many toxins (e.g. enterotoxin); toxic shock syndrome, food poisoning Figure 1.17

Order Lactobacillales Generally aerotolerant anaerobes, lack an electron-transport chain Lactobacillus produce lactic acid (industrial and commercial application); found in vagina, intestinal tract, and oral cavity Enterococcus facultative anaerobes; found in GI tract, vagina, and oral cavity; leading cause of nosocomial infection

Order Lactobacillales E. faecalis & E. faecium: infect surgical wounds & urinary tract Listeria: facultative anaerobes L. monocytogenes: contaminate food (dairy products); can grow in refrigeration temperature Streptococcus Usually cocci in chains; human pathogens Have hemolytic activity (alpha hemolysis, beta hemolysis, and no hemolysis)

Order Lactobacillales S. pyogenes: scarlet fever, pharyngitis, impetigo, and rheumatic fever S. mutans: dental carries S. pneumoniae: most common cause of pneumonia Figure 11.18

Order Mycoplasmatales Wall-less and highly pleomorphic Very small (0.1 - 0.25 µm) Degenerative evolution M. pneumoniae: common form of mild pneumonia Spiroplasma: plant pathogens and common parasites of plant-feeding insects Figure 11.19a, b

Actinobacteria High G + C Gram-positive; highly pleomorphic; tend to be filamentous; very common inhabitants in soil

Phylum Actinobacteria Mycobacterium Aerobic, acid-fast (contains mycolic acids which forms waxy, water resistant layer in cell wall); slow grower (may take weeks for visible colonies to appear) Found in soil and water; occasional pathogens Human pathogens M. tuberculosis Tuberculosis M. leprae Leprosy

Phylum Actinobacteria Nocardia Aerobic; filamentous morphology Reproduction by forming rudimentary filaments which fragment into short rods Cell wall resemble mycobacteria; often acid-fast N. asteroides Mycetoma and occasionally cause a chronic, difficult-to-treat pulmonary infection

Phylum Actinobacteria Corynebacterium Tend to be pleomorphic; morphology varies with the age of the cells C. diphtheriae Diphtheria Propionibacterium Form propionic acid; fermentation of Swiss cheese P. acnes Common on human skin, cause acne Frankia Form nitrogen-fixing nodule in alder tree roots

Phylum Actinobacteria Gardenella Gram-variable; highly pleomorphic Cause of one of the most common forms of vaginitis Actinomyces Facultative anaerobe; filamentous morphology Found in the mouth and throat of humans and animals A. israelii actinomycosis

Phylum Actinobacteria Streptomyces One of the most commonly isolated bacteria from soil; responsible for the musty odor of soil Strict aerobes; filamentous bacteria Produce most of our commercial antibiotics Figure 11.20b

Microbial Diversity Bacteria size range Thiomargarita (750 µm) to nanobacteria (0.02 µm) in rocks Figure 11.26

Microbial Diversity PCR indicates up to 10,000 bacteria/gm of soil. Many bacteria have not been identified or characterized because they: Haven't been able to culture (need to develop special media/nutrients and cultivation condition) Are part of complex food chains requiring the products of other bacteria Need to be cultured to understand their metabolism and ecological role

Chapter Review Prokaryotic organisms are classified into 2 domains: Archaea & Bacteria based on rRNA sequences Each domain is further subdivided into phylum, class, order, family, genus, and species Domain Bacteria Relatively few species cause disease in humans, animals, plants or any other organisms Essential part of life on Earth

Domain Bacteria Phylum: Proteobacteria (gram-negative bacteria) 1) Alpha- (α-) proteobacteria Includes most of the proteobacteria that are capable of growth at very low levels of nutrients; nitrogen –fixing bacteria & several plant & human pathogens Some bacteria with unusual morphology such as prosthecae Prosthecae: a stalk or bud protruding from a prokaryotic cell

Domain Bacteria 2) Beta- (-) proteobacteria Often use nutrient substances that diffuse away from areas of anaerobic decomposition of organic matter Considerable overlap between the α- & -proteobacteria, especially among the nitrifying bacteria; some human pathogens in this group Spirillum helical shaped bacteria, but use flagella for motility (not axial filament)

Domain Bacteria 3) Gamma- (-) proteobacteria Constitute the largest subgroup of proteobacteria; many are human & plant pathogens (e.g. Order Pseudomonadales, Legionellales, Vibrionales, Enterobacteriales, & Pasteurellales) 4) Delta (-) proteobacteria Include some bacteria that are predators of other bacteria and important contributors to the sulfur cycle (e.g. Bdellovibrio, Desulfovibrio, and Myxococcus) Myxococcus form fruiting bodies under low nutrients condition

Domain Bacteria Gram-negative Nonproteobacteria 5) Epsilon- (-) proteobacteria Slender gram-negative rods that are helical or vibrioid (e.g. Campylobacter & Helicobacter) Vibrioid: helical bacteria that do not have a complete turn Gram-negative Nonproteobacteria Include several photosynthetic bacteria: Phyla cyanobacteria, green sulfur bacteria, & green nonsulfur bacteria (Table 11.2)

Domain Bacteria Purple sulfur (α-proteobacteria) & purple nonsulfur (-proteobacteria) also included in this section Cyanobacteria carry out oxygenic (oxygen-producing) photosynthesis and fix nitrogen gas (in specialized cell called heterocyst) from the atmosphere into ammonium Green & purple photosynthetic bacteria carry out anoxygenic photosynthesis (generally anaerobic)

Domain Bacteria Gram-positive bacteria 2 groups based on G + C ratio 1) Firmicutes (low G + C ratio) Includes important endospore forming bacteria (e.g. Bacillus & Clostridium), medically important bacteria (e.g. Staphylococcus, Enterococcus, & Streptococcus), industrially important bacteria (e.g. Lactobacillus), and wall-less Mycoplasma

Domain Bacteria Assorted Phyla 2) Actinobacteria (high G + C ratio) Highly pleomorphic, but tend to be fimalentous Common inhabitants in soil e.g. acid-fast group (e.g. Mycobacterium & Nocardia), and antibiotic producing Streptomyces. Assorted Phyla Chlamydiae: no peptidoglycan in cell wall; intracellular parasite (human pathogen); has unique developmental cycle (elementary body = infectious)

Domain Bacteria Spirochaetes: coiled morphology; motility by axial filament; many found in human oral cavity & in environment; some human pathogens Bacterioidetes: several genera of anaerobic bacteria Fusobacteria: anaerobic bacteria, spindle-shaped (often pleomorphic); can cause dental diseases

Domain Archaea Cell wall lacks peptidoglycan; a few lack cell wall Frequent inhabitants of exceptional extreme environment (heat, cold, acidity, & pressure) 3 major groups: Extreme halophiles: survive in very high concentrations of salt; found in Great Salt Lake, solar evaporating ponds, salinas, & Dead Sea

Domain Archaea Microbial Diversity Extreme thermophiles: thrive in high temperature (above 70 oC) or sulfur rich environment; found in acidic, sulfur rich hot springs or deep ocean hydrothermal vents Methanogens: obligately anaerobic methane producing bacteria; found in human intestines and used in sewage-treatment processes Microbial Diversity Various sizes: nanobacteria (0.02 – 0.03 μm) to giant bacteria (750 μm)

Microbial Diversity Many bacteria in the environment have not been identified or characterized due to: Lack of culture method Some bacteria are part of complex food chains and can only grow in the presence other microbes that provide specific growth requirements PCR can be used to reveal the presence of bacteria that cannot be cultured in the laboratory

Chapter Review Know these terms: prosthecae, vibrioid, and oxygenic Know different groups of proteobacteria (and some examples) given in the chapter review section Know the names of different photosynthesizing bacteria and their mode of photosynthesis

Chapter Review Know characteristics of 2 groups of gram-positive bacteria and some of the examples listed in the chapter review Know characteristics of Arhaea, and its 3 major groups (characteristics and where they are found) given in the chapter review Know why many bacteria have not been classified and identified (2 main reasons) & use of PCR to detect them without culturing them