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  2.  BACTERIA are microscopic, unicellular, prokaryotic organisms.  They lack memberane bound nucleus and memberane bound organelles.
  3.  Bacteria are classified into two major groups- 1)ARCHAEBACTERIA(Primitive) 2)EUBACTERIA(True bacteria)
  4. ARCHAEBACTERIA  Oldest living organism  Classified as bacteria  As they look bacteria  They have features that are quite different, however, from both bacteria and eukaryotic organisms.  Carl Woese – 3 domain system.  Woese proposed archaebacteria archae.
  5.  Archae are similar to eukaryotic organisms in that  they lack a part of the cell wall called the peptidoglycan.  Similarity in the way by which they make new copies of their genetic material  archae are similar to bacteria in that  their genetic material is not confined within a membrane, but instead is spread throughout the cell.  Thus, archae represent a blend of bacteria and eukaryotes “missing link”, although generally they are more like eukaryotes than bacteria.
  6.  Obligate anaerobes.  Cell is with thick cytoplasm and rigid cell wall.  Cell wall made up of Pseudomurein,  a combination of N-acetyltalosaminuronic acid and N- acetylglucosamine.  It gives immunity to lysozyme.  Found in extreme environmental conditions.  extremophiles  Reproduction by binary fission. You can refer:  
  7.  Includes 2 distinct groups: ➢ Methanogens ➢ Extremophiles: • Halophiles • Thermophiles • Acidophiles • Alkaliphiles
  9. METHANOGENS  Group of archaebacteria that produce methane as a byproduct in anoxic conditions (methanogenesis)  Found in wetlands, marshy areas, digestive tract of animals etc.  Coccoid or rod shaped.  Cell wall devoid of peptidoglycan.
  10.  Strictly obligate anaerobes.  Use anaerobic respiration for ATP synthesis.  Sensitive to oxygen, cannot tolerate oxygen stress for prolonged time.  Thrive in environments in which all electron acceptors other than CO2 have been depleted.
  11. Methanococcus Methanopyrus Methanobacterium bryantii
  12.  Examples for Methanogens: ❑Methanobacterium bryantii ❑Methanococcus spp. ❑Methanobrevibacter spp. ❑Methanocorpusculum spp. ❑Methanospirillum hungatei ❑Methanothermobacter thermoflexus ❑Methanothrix sochngenii
  14. EXTREMOPHILES  Organism that thrives under ‘extreme’ environmental conditions under high pressure and high temperature.  Habitats include volcanoes, hydrothermal vents, hot springs, high saline lakes, acidic and sulphur containing regions  Unique enzyme EXTREMOZYMES are present.
  15.  Various types of extremophiles: 1)THERMOPHILES 2)HALOPHILES 3)ACIDOPHILES 4)ALKALIPHILES
  17. THERMOPHILES  Group of extremophilic organisms that thrives at relatively high temperatures, between 41C and 122C  Found in geothermal heated regions of earth-hot springs, deep sea hydrothermal vents, decaying plant matter (peat bogs, compost)  Contain enzymes that can function at high temperature.  Heat stable polymerase for PCR(taq polymerase enzyme) obtained from Thermus aquaticus.
  18.  Gram negative and anaerobic.  Obligate and Facultative thermophiles.  Obligate thermophiles(extreme thermophiles) require high temperature for growth(above 80)  Facultative(moderate thermophiles) can thrive high temperature and also low temperature(below 50)  Optimum growth temperature 50 or more,upto 70 or more.  Required reduced sulphur compounds for growth.  Can grow lithotrophically with H2 as energy source.
  19. Bright colors produced by thermophiles in the hot springs ofYellow Stone National Park, USA
  20.  Examples for thermophiles: ❑Sulfobus sulfataricus ❑Sulfobus acidocaldarius ❑Thermoproteus spp ❑Pyrobaculum spp ❑Pyrodictum spp ❑Thermococcus spp ❑Archeoglobus spp ❑Acidianus spp
  22. HALOPHILES(Halobacteria)  Group of extremophiles that thrive in high salt concentrations.  Found anywhere with a concentration of salt five times greater than that of the ocean.  (Great Salt Lake in Utah,  Owens Lake in California,  Dead Sea,evaporation ponds,etc)  Slight,moderate and extreme halophiles.  Slight halophiles: salt concentration between 0.3-0.8M  Moderate halophiles: 0.8-3.4M  Extreme halophiles: 3.4-5.1M
  23.  Gram negative and aerobic or anaerobic  Cell walls with complex heteropolysaccharide, gives stability even at low salt concentration.  Photoreceptor pigment BACTERIORHODOPSIN is responsible for their photoproduction of energy.  Some species give off a red color because of the carotenoid compounds in bacteriorhodopsin.  This gives pinkish color to the water bodies often called as Pink Salt Lakes.
  24. Dunaliellia salina Chromohalobacter salexigens
  25. Halococcus
  26.  Examples for Halophiles: ❑Halococcus ❑Haloferax ❑Chromohalobacter salexigens ❑Halogeometricum ❑Dunaliella salina(halophile alga) ❑Wallemia ichthyophaga(halophile fungus)
  28. ACIDOPHILES(Acidophilic bacteria)  Group of extremophiles that can survive under high acidic environments (pH 2.0 or below)  Found in sulfur hot springs, volcanic sites, debris in coal mines, stomachs of human, etc.  Have efficient mechanism to pump protons out of the intracellular space in order to keep the cytoplasm at or near neutral pH  The release of protective coatings on the outside of its cell protect them from damage in acidic medium.
  29. Acidic mud pond
  30.  Some acidophiles helps in controlling the Acid Mine Drainage (AMD).  AMD is the outflow of acidic water from metal mines or coal mines. Acid Mine Drainage
  31.  Acidophiles helps to catalyse the acidic liquids and other pollutants in the AMD and thus economically important.  Acidophiles in AMD are ➢Leptospirillum ferooxidans ➢Acidithiobacillus thiooxidans ➢Sulfobacillus themosulfidooxidans
  32.  Rocks with abundant sulfide minerals causes Acid Rock Drainage.(ARD)  It is natural as a part of weathering. But becomes abnormal when earth is disturbed.(construction works,mining)
  33. Acid stained rocks
  34. Acid Rock Drainage
  35.  Other acidophiles are ➢Acidianus ➢Halarchaeum acidiphilum ➢Metallosphaera sedula ➢Thiobacillus spp ➢Dunaliella acidophila etc.
  37. ALKALIPHILES  Group of extremophiles capable of survival in alkaline environments(pH 8.5-11),growing optimally around pH 10.  - obligate alkaliphiles, facultative alkaliphiles and haloalkaliphiles.  Obligate alkaliphiles require high pH.  Facultative alkaliphiles survive both in high and normal pH.  Haloalkaliphiles require high salt content.
  38.  Cystolic acidification.  Cell walls contain acidic polymers composed of galacturonic acid,gluconic acid,glutamic acid,aspartic acid,phosphoric acid etc.  This forms an acidic matrix that helps the plasma membarane from alkaline conditions by preventing the entry of OH- and allowing the uptake of Na+ and H+ ions.
  39.  Alkaliphilic enzymes such as proteases,starch degrading enzymes,lipases,pectinases etc are obtained;economically important.  Examples for alkaliphiles: ❑Halorhodospira halochloris ❑Natronomonas pharaonis ❑Thiohalospira alkaliphila ❑Microcystis spp
  40. EUBACTERIA  True bacteria.  Composed of bacteria of a large group typically having simple cells with rigid cell wall and often with flagella for movement.  Include Gram positive and Gram negative bacteria.  Present everywhere.(soil ,water, on organisms etc)
  41. MAJOR GROUPS OF EUBACTERIA  Rickettsias  Spirochates  Chlamydias  Mycoplasmas  Actinomycetes  Myxobacteria
  43. Rickettsia  Are non-motile, Gram-negative, non- sporeforming, highly pleomorphic bacteria that can present as cocci (0.1 μm in diameter), rods (1–4 μm long) or thread-like (10 μm long).  Obligate intracellular parasites  Rickettsiae comprise a group of microorganisms that phylogenetically occupy a position between bacteria and viruses.  The genus Rickettsia is included in the bacterial tribe Rickettsiae, family Rickettsiaceae, and order Rickettsiales. Named after HowardTaylor Ricketts, who first recognised the unique nature of this bacteria causing the Rocky Mountain Spotted fever.
  44. RICKETTSIAS  Earlier, this group was positioned between viruses and eubacteria.  Because of the presence of true cell walls similar to other Gram negative bacteria, it is now grouped under eubacteria.  Cell walls are with peptidoglycan.  Susceptible to Tetracycline antibiotics.  Causes several human diseases transmitted by arthropod vectors such as fleas, mites, lice, ticks etc.  Some of them are fatal too.  For eg: Typhus fever caused by Rickettsia prowazekii, transmited by lice to man.
  45. Rickettsia prowazekii
  46.  Important rickettsial diseases. ➢ Rocky Mountain Spotted fever-Rickettsia rickettsi(by ticks) ➢ Endemic typhus or Murine Typhus-R.mooseri ➢ Rickettsial pox orVesicular rickettsiosis-R.akari(by blood sucking mites) ➢ Scrub typhus-R.tsutsugamushi ➢ Q-fever(influenza like disease infecting respiratory tract)-Coxiella burnetti ➢ Trench fever among soldiers during World war1-Rochalimaea quintana
  48. Spirochetes  are long, slender and helically coiled motile bacteria  only a fraction of a micron in diameter but 5 to 250 microns long.  look like miniature springs or telephone cords.  Presence of axial filaments  they enable the bacterium to move by rotating in place.  run along the outside of the protoplasm, but inside an outer sheath Treponema - the only genus to lack the outer sheath.
  49.  Gram-negative.  Chemotrophic in nutrition.  there are only six genera and includes  aerobic and anaerobic species  free-living and parasitic forms  syphilis and Lyme disease are caused by these bacteria  other species are important symbionts in the stomachs of cows and other ruminants.  Some species of Treponema live in the rumen of a cow's stomach, where they break down cellulose and other difficult to digest plant polysaccharides for their host.
  50.  Spirochetal diseases are characterized by-  entry through skin or mucus membranes.  Dissemination via blood, tissue and body fluids, especially to cardiovascular, neurologic and skin tissues.  They lack surface proteins on their outer membrane.  This helps them in immune evasion.  Neurotropic spirochetes enter the central nervous system (CNS) early in the course of disease.
  51.  Some of the pathogenic species are significant health threat to humans.  Major diseases caused by spirochetes include: ➢ Leptospirosis-Leptospira. Transmission from animals to humans.
  52. ➢ Lyme disease-Borrelia burgdorferi,B.garinii,B.afzelii etc. ➢ Relapsing fever-Borrelia recurrents ➢ Syphilis-Treponema pallidum ➢ Intestinal spirochetosis-Brachyspira pilosicoli
  54. CHLAMYDIAS  Include a group of pathogenic bacteria that are obligate intracellular parasites.  Cell is more or les spherical with a diameter of 0.25- 0.30m.  First recognised in 1930 as the causative agent of a type of Pneumonia called Psittacosis.  Gram negative.  Cannot synthesis its own ATP, and cannot be grown at artificial medium.
  55.  Exists in 2 stages:  Infectious particles called Elementary bodies and  intra cytoplasmic reproductive forms called Reticulate bodies.  They alternate with each other.  Once inside the cell, the elementary body reacts with glycogen and germinates to reticulate form.  Capable of binary fission.  Chlamydia infections-sexually transmitted diseases in humans, blindness etc.  Diseases do not cause symptoms.
  56.  Major diseases include: ➢Chlamydia infection-Chlamydia trachomatis • most common sexually transmitted disease both in men and women. • “silent epidemic” ➢Trachoma or Chlamydia conjucivitis-Chlamydia trachomatis. • Serious eye infection. • Inflammation of eye, irritation and thick discharge. ➢Pneumonia- Chlamydia pneumoniae • Infection in respiratoy tract. ➢Psittacosis(Parrot fever)-C. psittaci • Carried by parrots.
  58. Mycoplasma  do not have a cell wall  like a tiny jellyfish with a pliable membrane can take on many different shapes  make them difficult to identify, even under a high powered electron microscope.  very hard to culture in the laboratory  They can be parasitic or saprotrophic  Several species are pathogenic in humans, including M. pneumoniae  But they are unaffected by many common antibiotics
  59. MYCOPLASMA  Smallest self replicating prokaryotes capable of generating their own energy.  Smallest bacterial cells which can survive without oxygen.  Lack cell wall. ❖Pleomorphic. ❖Unaffected by antibiotics. ❖Plasiticity of cell allows to pass through bacterial filters.  Smallest cell have 0.3m diameter.  Also called as PPLO.
  60.  Sterol containing cell membarane.  Fried egg or mulberry colonies on agar.  Mycoplasma pneumoniae causes Atypical Pneumonia(“walking pnemonia”), sore throat and inflammation of bronchi in humans.
  61.  M.hominis , M.urealyticum,M.genatalium - “Genital mycoplasmas” • Found in the genital and urinal tracts of adults. • Causes Urethritis and Vaginitis in women.  Mycoplasmosis in Cats-M.felis, M.gateae, M. feliminutum.
  63. ACTINOMYCETES  Include a group of Gram-positive, filamentous,rod and coocus, showing branching growth patterns, aerobic bacteria found abundantly in soil.  They were called as “Ray fungi” because they formed branching filaments(hyphae) and mats(mycelium).  Unlike true fungi, actinomycetes have thin hyphae(0.5- 1.5m in diameter).  Many genera forms spores, sporangia and spore cases.  Cell walls with cross-linked polymers containing short amino acids and long chains of amino sugars.
  64.  Some are harmless to animals and plants,while some are important pathogens and many others are sources of antibiotics. ▪ Streptomycin-by Streptomyces griseus. ▪ Tetracycline-by S.aureofaciens. ▪ Neomycin-by S.fradiae  Majority feed on protein or non protein organic matter.  Play an important role in soil ecology. • Produces enzymes that can degrade organic plant material, lignin, chitin etc. • Important in the formation of compost.
  65.  Pathogenic forms causes diseases in humans.  Nocardia spp. causes infection in lungs similar to tuberculosis.
  66.  Mycobacterium tuberculosis causesTuberculosis.  Corynebacterium diphtheriae causes diphtheria.  Corynebacterium pyogenes causes Mastitis,Pharyngitis and Urethritis in Sheep,cows,swines,horses etc.
  67.  Actinomycosis caused by Actinomyces israelii ❖Characterised by abscesses in mouth, lungs or gastrointestinal cavities. ❖Sensitive to Penicillin.
  69. MYXOBACTERIA  Myxobacteria are unicellular bacteria  characterized by complicated multicellular behaviors, such as  feeding, social movement, aggregation, and fruiting body formation  It make them highly unusual.  They are gliding bacteria  Gliding movement,  No flagella or cilia.  Travel in swarms.  produce fruiting bodies in starvation conditions.  They are common in animal dung and organic-rich soils  Some of them grow by utilising cellulose,  but many of them feed by secreting antibiotics to kill other bacteria and then produce enzymes to lyse the cells of their prey.
  70.  The vegetative cells of all myxobacteria are aerobic, Gram-negative, elongated rods with either rounded or tapered ends
  71.  They glide in water films across solid surfaces, secreting slime (polysaccharide) tracks in which many cells migrate to produce feathery extensions at the colony margin
  72.  At the onset of nutrient depletion the cells migrate back along the slime tracks, aggregating by chemotaxis, to form large concentrations of cells.  These aggregates then develop into fruiting bodies which are raised above the agar surface and typically develop a bright yellow, red or brown pigmentation.  As the vegetative cells migrate upwards into the fruiting body they undergo a progressive differentiation into rounded myxospores
  73. VBNC -viable but non-culturable  One particular survival strategy in bacteria is the ability to enter a state that permits endurance to unfavorable environmental conditions  VBNC cells are not culturable on routine laboratory media  Due to their reduced metabolic activity and increased peptidoglycan cross-linking, manyVBNC bacteria have higher physical and chemical resistances compared to culturable cells  VBNC cells remains challenging to microbiologists.  Until now, approximately 85 species have been shown to enter the VBNC state, including 67 pathogenic bacteria  VBNC state is similar to dormancy with the cells retaining an intact membrane, undamaged genetic material and metabolic activity.
  74. Nanobes  miniature organisms of 20 to 150 nanometres (billionths of a metre) in length  Discovered by University of Queensland researchers  are much smaller than the smallest certified terrestrial bacteria ever found on the planet.  Researchers discovered the living colonies of organisms in ancient sandstones retrieved from an oil drilling site 3- 5km below the Australian seabed.
  75.  Nanobes are thought to exist everywhere!  Nanobe structures have been found within organisms as well as rocks.  Nanobes may also exist on other planets!  some speculate that nanobes may even outnumber bacteria by an order of magnitude!