Download Sulfate- and Sulfur- Reducing Bacteria

Chapter 15 (2)
Bacteria:
The Proteobacteria
15.12 Vibrio, Alivibrio, and Photobacterium
 The Vibrio Group
 Cells are motile, straight or curved rods
 Facultative aerobes
 Possess a fermentative metabolism
 Best known genera are Vibrio, Alivibrio, and
Photobacterium
 Most inhabit aquatic environments
 The Vibrio Group (cont’d)
 Some are pathogenic
 Some are capable of light production (bioluminescence)
 Catalyzed by luciferase, an O2-dependent enzyme
 Regulation is mediated by population density (quorum
sensing)
* NADH + H+ + FMN → NAD+ + FMNH2
FMNH2 + O2 + RCHO → FMN + RCOOH + H2O + light
NAD+ + RCOOH → NADH + H+ + RCHO
Bioluminescent Bacteria
Blue light
Aliivibrio fischeri MJ-1
Green light
Aliivibrio fischeri Y-1
Photobacterium phophoreum
Bioluminescent Bacteria as Light Organ Symbionts
Bioluminescent bacteria
15.13 Rickettsias
 Rickettsias
 Small, coccoid or rod-shaped cells
 Most are obligate intracellular parasites
 Causative agent of several human diseases
Rickettsias Growing Within Host Cells
Rickettsia rickettsii in tunica vaginalis cells of the vole.
Rickettsias Growing Within Host Cells
vacuole
EM of cells of Rickettsiella popilliae within a blood cells of a
beetle.
Characteristics of Rickettsias
 Wolbachia
 Genus of rod-shaped Alphaproteobacteria
 Intracellular parasites of arthropod insects
 Affect the reproductive fitness of hosts
- parthenogenesis
- killing of males
- feminization (the conversion of male insects into
females)
 Wolbachia pipientis
 Small genome: 1.5 Mbp
 Does not cause disease in either vertebrates or its
invertebrates host
 Cause disease only in insects
 Passed from infected females to her offspring
through the egg infection
- colonize the insect egg (e.g. wasp)
Wolbachia
 Wolbachia induced parthenogenesis
 Occurs in a number of species of wasps
 Male normally arise from unfertilized eggs and
female arise from fertilized eggs
 Walbachia in unfertilized eggs triggers a doubling of
the chromosome number
- yields only females
 Wolbachia induced killing of males
 In lady beetles and butterflies
 Walbachia infection results in the death of male
offspring
 Wolbachia induced feminization
 In certain species of woodlice (= pillbugs)
 Walbachia causes male to develop as females due
to the damage in the male hormone-producing
glands
 Wolbachia is essential for survival
 In the nematode worms causing the diseases
elephantiasis and river blindness
 Antibiotics kill the worms, apparantly by killing their
Walbachia symbionts
IV. Morphologically Unusual Proteobacteria
 15.14 Spirilla
 15.15 Sheathed Proteobacteria: Sphaerotilus and
Leptothrix
 15.16 Budding and Prosthecate/Stalked Bacteria
15.14 Spirilla
 Spirilla
 Group of motile, spiral-shaped Proteobacteria
 Key taxonomic features include
 Cell shape and size
 Number of polar flagella
 Metabolism
 Physiology
 Ecology
Spirilla : Spirillum volutans
Spirillum volutans
Spirilla: An intestinal spirillum
Spirilla: Cells of Ancyclobacter aquaticus
Ancyclobacter aquaticus
Characteristics of the Genera of Spiral-Shaped Bacteria
 Spirilla
 A few are magnetotactic, demonstrating directed
movement in a magnetic field
A Magnetotactic Spirillium, M. magnetotacticum
Magnetosome
(particles of Fe3O4)
 Spirilla
 Bdevellovibrio
 Prey on other bacteria
 Obligate aerobes
 Members of Deltaproteobacteria
 Widespread in soil and water, including marine
environments
Very thick flagellum
Attachment and Penetration of a Prey Cell by Bdellevibrio
bdelloplast
Developmental Cycle of Bdellevibrio bacteriovorus
15.15 Sheathed Proteobacteria: Sphaerotilus & Leptothrix
 Sheathed bacteria
 Filamentous Betaproteobacteria
 Unique life cycle in which flagellated swarmer cells
form within a long tube or sheath
 Under unfavorable conditions, swarmer cells move out
to explore new environments
 Sheath: a complex of protein and polysaccharides
 Common in freshwater habitats rich in organic matter
 Sphaerotilus
 Nutritionally versatile
 Able to use simple organic compounds
 Obligate aerobes
 Cells within the sheath divide by binary fission
 Eventually swarmer cells are liberated from sheaths
Sphaerotilus natans
Sphaerotilus natans
Sphaerotilus natans
Swarmer cells with polar flagellar tuft
 Sphaerotilus and Leptothrix are able to precipitate
iron oxides on their sheath
 Leptothrix also can oxidize Mn2+ to Mn4+
■
the protein responsible for the oxidation process
resides in the sheath
Leptothrix and Iron Precipitation
Protuberance of the cell
envelope contacting the sheath
15.16 Budding and Prosthecate/Stalked Bacteria
 Budding and Prosthecate/Stalked Bacteria
 Large and heterogeneous group
 Primarily Alphaproteobacteria
 Form various kinds of cytoplasmic extrusions bounded
by a cell wall (collectively called prosthecae)
Features of Stalked, Appendaged and Budding Bacteria
Prosthecate Bacteria
Asticcacaulis biprosthecum
Ancalomicrobium adetum
Stella sp.
Cell Division
 Budding Bacteria
 Divide as a result of unequal cell growth
 Two well-studied genera
 Hyphomicrobium (chemoorganotrophic)
 Rhodomicrobium (phototrophic)
Stages in the Hyphomicrobium Cell Cycle
Morphology of Hyphomicrobium
 Prosthecate and Stalked Bacteria
 Appendaged bacteria that attach to particulate matter,
plant material, and other microbes in aquatic
environments
 Appendages increase surface-to-volume ratio of the
cells
Stalked Bacteria
A Caulobcater rosettes
 Caulobacter
 Chemoorganotroph
 Produces a cytoplasm-filled stalk
 Often seen on surfaces in aquatic environments with
stalks of several cells attached to form rosettes
 Holdfast structure present on the end of the stalk used
for attachment
 Model system for cell division and development
Growth of Caulobacter
 Gallionella
 Chemolithotrophic iron-oxidizing bacteria
 Possess twisted stalk-like structure composed of ferric
hydroxide
 Common in waters draining bogs, iron springs, and
other environments rich in Fe2+
Neutrophilic Ferrous Iron Oxidizer, Gallionella ferruginea
V. Delta- and Epsilonproteobacteria
 15.17 Gliding Myxobacteria
 15.18 Sulfate- and Sulfur-Reducing Proteobacteria
 15.19 The Epsilonproteobacteria
15.17 Gliding Myxobacteria
 Gliding
 A form of motility exhibited by some bacteria
 Gliding Bacteria
 Are typically either long rods or filaments
 Lack flagella, but can move when in contact with
surfaces
Classification of the Fruiting Myxobacteria
 Myxobacteria
 Group of gliding bacteria that form multicellular
structures (fruiting bodies) and show complex
developmental life cycles
 Deltaproteobacteria
 Chemoorganotrophic soil bacteria
 Lifestyle includes consumption of dead organic matter
or other bacterial cells
 Most are obligate aerobes
- exception: a facultative aerobe Anaeromyxobacter
that can grow by anaerobic respiration
 Fruiting myxobacteria exhibit complex behavioral
patterns and life cycles
 Vegetative cells are simple, nonflagellated rods that
glide across surfaces and obtain their nutrients
primarily by lysing other bacteria and utilizing released
nutrients
 Under appropriate conditions, vegetative cells aggregate,
construct fruiting bodies, and undergo differentiation into
myxospores
Myxococcus xanthus
A vegetative cell
Myxococcus xanthus
Myxospore with multilayered outer wall
Stigmatella aurantiaca
Stigmatella aurantiaca
Fruiting Bodies of Myxococcus fulvus
Fruiting Body of Myxococcus stipitatus
Fruiting Body of Chondromyces crocatus
 The life cycle of fruiting myxobacterium is complex
(e.g.) glycerol
Life cycle of Myxococcus xanthus
Swarming in Myxococcus
Fruiting Body Formation in Chondromyces crocatus
15.18 Sulfate- and Sulfur-Reducing Proteobacteria
 Dissimilative sulfate- and sulfur-reducing bacteria
 Over 40 genera of Deltaproteobacteria
 Use SO42- and So as electron acceptors and organic
compounds or H2 as electron donors
 H2S is an end product
 Most obligate anaerobes
 Widespread in aquatic and terrestrial environments
Characteristics of Sulfate- and Sulfur-Reducing Bacteria
 Physiology of sulfate-reducing bacteria
 Group I
 Oxidize lactate, pyruvate, or ethanol to acetate and
excrete fatty acid as an end product
 Group II
 Oxidize fatty acids, lactate, succinate, and benzoate to
CO2
Sulfate- and Sulfur- Reducing Bacteria: Desulfovibrio desulfuricans
Sulfate- and Sulfur-Reducing Bacteria: Desulfonema limicola
Sulfate-and Sulfur-Reducing Bacteria: Desulfobulbus propionicus
Sulfate- and Sulfur-Reducing Bacteria: Desulfobacter postgatei
Sulfate- and Sulfur-Reducing Bacteria: Desulfosarcina variabilis
Sulfate- and Sulfur-Reducing Bacteria: Desulfuromonas acetoxidans
Enrichment Culture of Sulfate-Reducing Bacteria
Sterile medium
Positive enrichment
showing black FeS
Colonies of sulfatereducing bacteria
15.19 The Epsilonproteobacteria
 Epsilonproteobacteria
 Abundant in oxic–anoxic interfaces in sulfur-rich
environments
 e.g., hydrothermal vents
 Many are autotrophs
 Using H2, formate, sulfide, or thiosulphate as electron
donor (nitrite, oxygen, or elemental sulfur as electron
acceptor)
 Pathogenic and non-pathogenic representatives
 Campylobacter and Helicobacter
 All Gram-negative, microaerophilic, motile spirilla
 Most are pathogenic to humans or other animals
 e.g., Campylobacter sp.
- acute enteritis leading to usually bloody diarrhea
 e.g., Helicobacter pylori
- chronic and acute gastritis, leading to peptic ulcers
(Barry Marshall and Robin Warren: 2005 Nobel Prize in
Physiology and Medicine)
Helicobacter pylori
 Arcrobacter
 Unusually wide diversity of habitats
 Some are pathogenic to humans and other animals,
infecting the reproductive and intestinal tract of
humans and other animals
 Cause reproductive failures in animals, diarrhea-like
diseases in a wide range of animals, and gastroenteritis
and appendicitis in humans
 Infection route: fecal-to-water-to-oral (?)
 Sulfurospirillum and Thiovulvum
 Sulfurospirillum
 Non-pathogenic, free-living microaerophiles
 Freshwater and marine habitats
 Use elemental sulfur, selenate, or arsenate as an electron acceptor
 Thiovulvum
 Microaerophilic
 Freshwater and marine habitats in which sulfide-rich muds interface
with oxygen-containing waters
 Forms large internal sulfur granules
 No pure culture is available yet
 Secretes a slime stalk
 Wolinella
 Wolinella succinogenes
 Anaerobic, isolated from the bovine rumen
 Anaerobic respiration using fumarate or nitrate as
electron acceptors with hydrogen or formate as electron
donors
 Contains genes for nitrogen fixation
Characteristics of Key Genera of Epsilonproteobacteria