The Bacteria Phylogenetic tree of the major lineages of Bacteria based on 16S ribosomal RNA Sequence comparisons

The Purple Bacteria, also called Proteobacteria is the largest and most physiological diverse of all bacteria

Bacteria §Purple and Green (Anoxygenic Phototrophic Bacteria)Purple and Green (Anoxygenic Phototrophic Bacteria) §CyanobacteriaCyanobacteria §ProchlorophytesProchlorophytes §Chemolithotrophs: Nitrifying BacteriaChemolithotrophs: Nitrifying Bacteria §Chemolithotrophs: Sulfur- and Iron-Oxidizing BacteriaChemolithotrophs: Sulfur- and Iron-Oxidizing Bacteria §Chemolithotrophs: Hydrogen-Oxidizing BacteriaChemolithotrophs: Hydrogen-Oxidizing Bacteria §Methanotrophs and MethylotrophsMethanotrophs and Methylotrophs §Sulfate and Sulfur-Reducing BacteriaSulfate and Sulfur-Reducing Bacteria §Homoacetogenic BacteriaHomoacetogenic Bacteria §Budding and Appendaged (Prosthecate) BacteriaBudding and Appendaged (Prosthecate) Bacteria §SpirillaSpirilla §SpirochetesSpirochetes §Gliding BacteriaGliding Bacteria §Sheathed BacteriaSheathed Bacteria

Bacteria §PseudomonadsPseudomonads §Free-Living Aerobic Nitrogen-Fixing BacteriaFree-Living Aerobic Nitrogen-Fixing Bacteria §Acetic Acid BacteriaAcetic Acid Bacteria §Zymomonas and ChromobacteriumZymomonas and Chromobacterium §Vibrio and Related GeneraVibrio and Related Genera §Facultatively Aerobic Gram-Negative RodsFacultatively Aerobic Gram-Negative Rods §Neisseria and other Gram-Negative CocciNeisseria and other Gram-Negative Cocci §RickettsiasRickettsias §ClamydiasClamydias §Gram-Positive Bacteria: CocciGram-Positive Bacteria: Cocci §Lactic Acid BacteriaLactic Acid Bacteria §Endospore-Forming Gram-Positive Rods and CocciEndospore-Forming Gram-Positive Rods and Cocci §MycoplasmasMycoplasmas §High GC Gram-Positive Bacteria: “Actinomycetes”High GC Gram-Positive Bacteria: “Actinomycetes” §Coryneform BacteriaCoryneform Bacteria §Propionic Acid BacteriaPropionic Acid Bacteria §MycobacteriaMycobacteria §Filamentoud ActinomycetesFilamentoud Actinomycetes

Sulfate- and Sulfur-Reducing Bacteria Representative Sulfate-reducing and sulfur-reducing bacteria Most are Delta Purple Bacteria Desulfovibrio desulfuricans Desulfonema limicola Desulfobacter postgatei Desulfobulbus propionicus Desulfosarcina variabilis Desulfuromonas acetoxidans Sulfur-reducing bacteria

Sulfate-Reducing Bacteria §Strict anaerobes, §Divided into two broad physiological subgroups: l Genera in Group I (Desulfovibrio, Desulfomonas, Desulfotomaculum, Desulfobulbus) utilize lactate, pyruvate, ethanol, or certain fatty acids as carbon and energy sources, reducing sulfate to hydrogen sulfide l Genera in Group II (Desulfococcus, Desulfosarcina, Desulfonema, Desulfonema) specialize in the oxidation of fatty acids, particularly acetate, reducing sulfate to sulfide §Growth and reduction of sulfate by Desulfotomaculum in certain canned foods leads to a type of spoilage called sulfide stinker, §Habitants of anoxic aquatic and terrestrial environments

Sulfur-Reducing Bacteria §Able to reduce elemental sulfur to sulfide §Unable to reduce sulfate to sulfide §Obligate anaerobes §Utilize only sulfur as an electron acceptor §Also referred to as dissimilatory sulfur- reducing bacteria §Members of the genus Desulfuromonas can grow anaerobically by coupling the oxidation of substrates such as acetate to ethanol to the reduction of elemental sulfur to hydrogen sulfide

Homoacetogenic Bacteria §Obligate anaerobes §Gram-positive §CO 2 as a terminal electron acceptor §Acetate as the sole product of anaerobic respiration §Acetyl-CoA pathway convert CO 2 to acetate §Typical species: Acetobacterium woodii and Clostridium aceticum

Homoacetogenic Bacteria Mechanism of autotrophy in homoacetogenic, sulfate-reducing and methanogenic bacteria Reactions of the Acetyl-CoA Pathway

Budding and Appendaged (Prosthecate) Bacteria Asticcacaulis biprosthecum Ancalomicrobium adetum Ancalochloris perfilievii Stella

Budding and Appendaged (Prosthecate) Bacteria §Contain various kinds of cytoplasmic extrusions: l Stalk l Hyphae l Appendages §These kinds of extrusions, which are smaller in diameter than mature cell, contain cytoplasma, and are bounded by the cell wall, are called prosthecae (singular prostheca) §Unequal cell growth, such as polar growth §Majority is purple bacteria except Planctomyces and Pirella which are unusual as their cell walls consist mainly of protein §Most are aquatic, many live attach to surfaces using prosthecae §A stalk is usually a prostheca except in Planctomyces

Budding and Appendaged (Prosthecate) Bacteria Contrast between cell division in conventional bacteria and in budding and stalked bacteria

Budding and Appendaged (Prosthecate) Bacteria A Caulobacter rosette. The five cells are attached by their stalks (prosthecae)

Budding and Appendaged (Prosthecate) Bacteria Stages in the Hyphomicrobium cell cycle

Budding and Appendaged (Prosthecate) Bacteria Physiology and Ecology §Hyphomicrobium is a methylotrophic bacteria, widespread in freshwater, marine and terrestrial habitates. Photomicrographs of cells of Hyphomicrobium

Spirilla Spirillum volutans Spirosoma linguale Intestinal spirillum Purple bacteria Gram-negative The genus Spirillum includes only S. volutans Spirillum volutans is a large bacteria, micro- aerobic Azospirillum lipoferum is a nitrogen-fixing organism. It can form a loose symbiotic relationship with tropical grasses and grain crops Aquaspirillum magnetotacticum has magnetotaxis ability

Spirilla §Aquaspirillum magnetotacticum contains particles of Fe 3 O 4 (magnetite) called magnetosomes arranged in a chain Auqasirillum magnetotacticum

Spirilla: Bdellovibrio Bdellovibrio bacteriovorus

Spirilla: Bdellovibrio §Preying on other bacteria §Attack and develop intraperiplasmically §A wide variety of gram-negative bacteria can be attacked by a single Bdellovibrio species §Gram-positive cells are not attacked §Obligate aerobe, purple bacteria (delta group)

Spirilla: Bdellovibrio bacteriovorus Developmental Cycle

Spirochetes §Typically slender, flexuous, helical in shape, often rather long §Axial fibrils or axial filaments are attached to the cell poles and wrapped around the coiled protoplasmic cylinder. §Both the axial fibrils and the protoplasmic cylinder are surrounded by a three-layered membrane called the outer sheath or outer cell envelope Spirochaeta stenostrepta Spirochaeta plicatilis Treponema pallidum causes syphilis diseases

Spirochetes §Arrangement of the protoplasmic cylinder, axial fibrils, and external sheath §The manner in which the rotation of the rigid axial fibril can generate rotation. Spirochaeta zuelzerae

Spirochetes: Classification §Six genera (based on habitat, pathogenicity, and morphological, physiological characteristics): l Spirochaeta l Cristispira l Treponema (Host in human, causes sexual disease syphilis) l Leptospira (L. Interrogans causes nephritis and jaundice) l Leptonema l Borrelia (B. recurrentis causes relapsing fever) Cristispira

Spirochetes §Morphology of Treponema saccharophilum Treponema saccharophilum

Gliding Bacteria §No flagella but can move when in contact with surfaces §Gram-negative, purple bacteria, some are Bacteroides-Flavobacterium §Myxobacteria can form multicellular structures called fruiting bodies Beggiatoa Thioploca Filamentou sulfur-oxidizing bacteria in a small stream Sulfur-oxidizing bacteria

Gliding Bacteria: Leucothrix §Chemoorganotrophic, requires both H2S and an organic compounds for growth §Form gonidia under unfavorable conditions §May aggregate to form rosette when gonidia have high concentration Leucothrix mucor

Gliding Bacteria: Fruiting Myxobacteria Myxococcus fulvus Mellitangium erectum Myxococcus stipitatus Chondromyces crocatus Stigmatella aurantiaca Exhibit the most complex behavioral patterns and life cycles of all known prokaryotes

Gliding Bacteria: Fruiting Myxobacterium Gliding myxobacterium Stigmatella aurantiaca Have rather large chromosome size Rely on lysis of other bacteria for nutritions Myxospores are more resistant to drying, sonic vibration, UV and heat. Usually colored by carotenoid pigments

Gliding Bacteria

§Myxobacteria have distinct growth morphology Myxococcus xanthus on agar Myxococcus fulvus slime tracks on agar Fruiting body of stigmatella aurantiaca

Gliding Bacteria Fruiting body formation in Chondromyces crocatus Early stage Stalk formation Three stages in head formation Mature fruiting bodies

Sheathed Bacteria §Filamentous organisms with a unique life cycle involving formation of flagellated swarmer cells within a long tube or sheath §Under unfavorable conditions, the swarmer cells move out and become dispersed to new environments, leaving behind the empty sheath Sphaerotilus natans Active growth stage Swarmer cells leaving the sheath Swarmer cell

Pseudomonads §Purple bacteria (Proteobacteria), gram-negative §Polar flagella, aerobic, grow at neutral pH mesophilically §Chemoorganotrophic, never show a fermentative metabolism §P. aeruginosa is opportunistic pathogen, some are plant pathogens Pseudomonas have broad substrate utilization, some produce polyhydroxy- butyrate and some synthesize medium- chain-length polyhydroxyalkanoates, have been studied in our lab

The Entner-Doudoroff pathway, the major means of glucose catabolism in pseudomonads

Free-Living Aerobic Nitrogen-Fixing Bacteria §Large, gram-negative, obligately aerobic rods, capable of fixing N 2 nonsymbiotically §Azotobacter has the highest respiratory rate of any living organism (purple bacteria) §Azotobacter cells are very large, almost the size of yeasts, produce cysts Vegatative cells of Azotobacter vinelandii Cysts Azotobacter cysts have low endogenous respiration and are resistant to desiccation, mechanical disintegration, and UV as well as ionizing radiation however, they are not especially heat-resistant

Free-Living Aerobic Nitrogen-Fixing Bacteria §Major genera: Azotobacter, Azomonas, Azospirillum and Beijerinckia, Derxia Colonies of Beijerinckia species growing on a carbohydrate-containing medium Derxia gummosa encased in slime

Free-Living Aerobic Nitrogen-Fixing Bacteria §Acid-tolerant, free-living N 2 -fixing Bacteria Acid-tolerant, free-living N 2 -fixing bacteria Beijerinckia indica Derxia gummosa PHB

Acetic Acid Bacteria §Purple bacteria, gram-negative, aerobic, motile rods, tolerance to low pH §Carry out incomplete oxidation of alcohols, leading to the accumulation of organic acids as end products §With ethanol as a substrate, acetic acid is produced Acetobacter aceti on calcium carbonate agar containing ethanol as energy source. The clearing around the colonies due to the dissolution of calcium carbonate by the acetic acid produced by the bacteria Classified as Gluconobacter Can carry out incomplete oxidation of higher alcohol and sugars: Glucose Gluconic acid Galactose Galactonic acid Arabinose Arabonic acid Sorbitol Sorbose Ascobic acid

Zymomonas and Chromobacterium §Facultatively aerobic gram-negative rods, beta purple bacteria §Chromobacterium violaceum produces a purple pigment violacein, a water-insoluble pigment that has antibiotic properties and is produced only from tryptophan §Zymomonas carries out fermentation of sugar to ethanol, used in beverage industry. A large colony of Chromobacterium violaceum growing among other colonies on an agar plate Pigment violacein produced by various species of the genus Chromobacterium

Vibrio and Related Genera Gram-negative, facultatively aerobic rods and curved rods that possess a fermentative metabolism Most are aquatic. The Group contains Vibrio, Aeromonas, Photobacterium Some can emit light (luciferase luciferase), these are associated with fish. and Plesiomonas