TYPES OF MICROORGANISMS
TYPES OF MICROORGANISMS
I. INTRODUCTION ACELLULAR ORGANISMS: VIRUSES
1.DNA containing viruses
(e.g. warts, cold sores)
2. RNA containing viruses
(e.g. polio, common cold)
CELLULAR ORGANISMS
1. Kingdom : Procaryotae
Bacteria
Blue-Green algae (Cyanobacteria)
2. Kingdom: Protista
Algae
Fungi
Protozoa
3. Kingdom: Plantae
4. Kingdom: Animalae
II. CELL STRUCTURE A. PROCARYOTES
- Bacteria (Eubacteria, Archaeobacteria)- Blue-Green Algae (Cyanobacteria)- Size: 0.2-2.0 mm in diameter- Cell Division: Binary fission
- simple division of a cell into 2 parts
Glycocalyx:1. Slime Layer
- not highly organized- not firmly attached to cell wall- Function: Enables the bacteria to glide or slide
along solid surfaces.
2. Capsule- highly organized and firmly attached to cell
wall- Function: for attachment and anti-phagocytosis
Cell Wall
- Primary function: Protection- Main Component: Peptidoglycan (murein)
- Gram (+): thick layer of peptidoglycan (+) teichoic acid
- Gram (-): thinner layer of peptidoglycan (+) outer membrane
- Archaeobacteria: (-) peptidoglycan- Mycoplasma: no cell wall
APPENDAGES FLAGELLA
- Threadlike protein appendages with a whip like motion that enable the bacteria to move (motility).
- Arrangements:
a. Monotrichous– single polar flagellum
b. Amphitrichous– one flagellum at each end
c. Lopotrichous– 2 or more flagella at one or both poles of the cell
d. Peritrichous– flagella distributed over the entire cell
E. coli
AXIAL FILAMENTS- found in Spirochetes- bundles of fibrils that arise at the ends of a cell and spiral around the cell.
PILI OR FIMBRIAE- shorter, straighter and thinner than flagella- used as attachment- pili usually longer than fimbriae- functions:
- enables bacteria to adhere or attach to surfaces - enables transfer of genetic material from one cell to another (sex pilus)
PLASMA MEMBRANE-consists of proteins and phospholipids- controls substances that enter or leave the cell (selective permeability)- destroyed by alcohols and polymyxins
CYTOPLASM- consists of water, enzymes, oxygen, waste products, essential nutrients, proteins, carbohydrates and lipids.
CHROMOSOME (BACTERIAL NUCLEOID)
-not surrounded by a nuclear membrane
- does not have a definite shape
- fewer proteins
- serves as the control center of the bacterial cell
-capable of duplicating itself, guiding cell division and directing cellular activities
PLASMID
- small circular, double stranded DNA
- extra chromosomal genetic elements
- carry genes for antibiotic resistance, tolerance to toxic metals, production of toxins and enzymes
RIBOSOMES
- site of protein synthesis
- 70s ribosomes
- smaller and less dense than eucaryotic ribosomes
ENDOSPORES
- resting structures formed by some bacteria for survival during adverse environmental conditions.
- sporulation process of endospore formation
- germination return of an endospore to its vegetative state
INCLUSIONS- reserved deposits- metachromatic granules (volutin)
Reserved for inorganic phosphate- polysaccharide granules
glycogen and starch stores- sulfur granules reserved for sulfur- lipid inclusions lipid-storage material- carboxysomes source of carbon during
photosynthesis- gas vacoules gas vesicles for bouyancy- magnetosomes iron oxide
EUCARYOTES Protista- Algae, Fungi and Protozoa Plantae Animalae
-cell size: 10-100 micrometer in diameter
-cell division: Mitosis and Meiosis
Cell wall
- provide rigidity, shape and protection
- simpler in structure
- algae – cellulose
fungi– chitin
protozoa—no typical cell wall
- no peptidoglycan layer
Appendages1. Flagella
-organelles of locomotion- long, thin structures
2. Cilia- organelles of locomotion- shorter (hairlike), thinner and more numerous than flagella- coordinated rhythmic movement
Plasma membrane1. similar in function and basic structure with prokaryotes2. structure
-basic: proteins and phospholipids
-others:
- carbohydrates
- serve as receptor sites
- cell to cell recognition
- attachment sites for bacteria
- sterols (complex lipids)
- resist lysis from increased osmotic pressure
3. Function: selective permeability
- other functions: phagocytosis--- “cell eating”
pinocytosis---”cell drinking”
CELL WALL
Cytoplasm
- cellular material outside the nucleus and enclosed by
the cell membrane.
- composed of semi-fluid, gelatinous, nutrient matrix
(cytosol)
- contains insoluble storage granules and cytoplasmic
organelles
MEMBRANE BOUND ORGANELLES1. NUCLEUS
- unifies, controls and integrates the functions of the entire cell
- surrounded by a nuclear membrane
- NUCLEOLUS condensed regions of chromosomes where ribosomal
RNA is synthesized
- usually spherical or oval
2. ENDOPLASMIC RETICULUM
- Extensive network of flattened membranous sacs or tubules (cisterns)
- Continuous with the nuclear envelope- Transports nutrients to the nucleus and also provides
structural support for the cell.- Rough ER
-Ribosomes attached to outer surface- Function: protein synthesis
- Smooth ER- no ribosomes attached
- Function: lipid synthesis
3. RIBOSOME - 80s- Produced in nucleolus ----free and
membrane bound
4. GOLGI COMPLEX
- flattened membranous vesicles
- synthesis of secretory products for storage within the cell or export outside the cell (exocytosis or secretion)
5. MITOCHONDRIA
- “power plant” of the cell
- ATP formation by cellular respiration
6. LYSOSOMES
- formed from GOLGI complex
- store powerful digestive enzymes
7. CHLOROPLAST
- found in algae and green plants
- contains chlorophyll and the enzymes required for photosynthesis
8. MICROTUBULES
- long, hollow tubes
- consists of tubulin
- provides support and shape
- assists in transporting substances through the cell
PROCARYOTES EUCARYOTES
Organisms Bacteria Algae, Fungi, Protozoa
Animals, Plants
Size of cell 0.2-2.0 micrometer 10-100 micrometer
Cell Division/Rep. Binary Fission Mitosis/Meiosis
Cell Wall Usually present and chemical complex
+/- (when present chem. Simple)
Glycocalyx Present Absent
Plasma Membrane
CHO
Sterols
absent
absent
Present-serve as receptor
Present—serve as receptor
Nucleus No nuclear membrane or nucleoli
True nucleus with nuclear membrane and nucleoli
Ribosomes Smaller size (70s) Larger size (80s)
Membrane-enclosed
organelles
Absent present
Cytoskeletons Absent Present
Flagella Simple structure Complex structure
PROCARYOTES
Bacteria: Archaeobacteria & Eubacteria Basis for Classification:
1. Cell Morphology
a. Spherical or round (cocci)
b. rod-shaped (bacilli)
c. curved and spiral-shaped (spirilium)
d. Pleiomorphic
2. Cell arrangement
a. in pairs: diplo-
b. in chains: strep-
c. in clusters: staph-
3. Staining characteristics
- gram (+) vs Gram (-)
- AFB (Acid-Fast bacilli)
4. Motility
5. Colony morphology
6. Atmospheric Requirements
- aerobes vs anaerobes
7. Nutritional requirements
8. Biochemical and metabolic activities
9. Pathogenecity
10. Amino acid sequencing
11. Genetic composition
Classification1. Archaeobacteria (Ex. Halobacterium)
- contain cell walls but no peptidoglycan- closely related to eucaryotes- “extremophiles”
2. Eubacteria (“True” bacteria)A. Gliding Bacteria (Photosynthetic bacteria)
-flexible cells, motility conferred by gliding
- non-pathogenic bacteria (for humans)- ex. Cyanobacteria
B. Spirochetes- flexible cells, motility conferred by
endoflagella- ex. Treponema, Borrelia, Leptospira
C. Rigid Bacteria- rigid cells immotile or motility conferred by flagella1. Mycelia (Actinomycetes)
- branching filamentous growth which have external asexual spores (conidia)- similar to fungi-ex. Mycobacterium, Actinomycetes,
Nocardia, Streptomyces2. Simple Unicellular a. Obligate intracellular Parasite
-depend on the host for energy rich compound and co-enzymes
- ex. Rickettsiae (rickettsia, Coxiella) Chlamydiae (Chlamydia)
b. Free living Form
- majority of pathogenic bacteria
- General rule:
All Cocci are gram (+) except:
-- Neisseria, Branhamella, Veilonella
All Bacilli are gram (-) except:
--- Corynebacterium, Erysipelothrix,
Mycobacterium, Clostridia, Listeria
D. Lack Cell Wall (mycoplasma)
- pleiomorphic
GRAM POSITIVE
COCCI RODS
STAPH STREPNON SPORE SPORE FORMER
- Corynebacterium - Erysipelothrix - Listeria
Obligate Obligate Aerobes Anaerobes
(Bacillus) (Clostridia)
GRAM NEGATIVE
COCCI RODS Neisseria
Non Enteric Enteric
Spiral Straight Facultative Obligate Anaerobes Anaerobes
Spirilium Pastuerella Escherichia
Bacteriodes Brucella Salmonella
Fusobacterium Yersinia Shigella
Franciscella Klebsiella Obligate Aerobe
Hemophilus Proteus Pseudomonas Bordetella Vibrio
Legionella
EUCARYOTES- ALGAE, FUNGI, PROTOZOA
EUCARYOTES PROTISTA--- ALGAE, FUNGI, PROTOZOA
A. ALGAE- tiny, unicellular, microscopic microbes ( diatoms,dinoflagellates, desmids)- large, multicellular, plant like seaweeds (kelp)- energy production: photosynthesis (have chlorophyll)- cell wall: cellulose - basis for classification: PIGMENTS (green, brown or
red algae)- Phycotoxins substances poisonous to humans,
fish and other animals shellfish poisoning (RED TIDE/ paralytic shellfish poisonimg)
B. FUNGI
- main source of food: decaying matter
- have no chlorophyll
- cell wall: chitin
- cell membrane: ergosterol
- forms: unicellular (yeasts), filaments (hyphae),
mass (mycelia)
- reproduce by budding, hyphae extension, formation of spores
- -
Classification Of True Fungi
Basis: mode of reproduction and type of mycelia, spore and gamete produced
1. Oomycetes– aseptate hyphae ex. Potato blight mold
2. Zygomycetes– usually aseptate hyphae
ex. Bread mold (rhizopus)3. Basidiomycetes (mushrooms)- septate hyphae4. Ascomycetes– septate hyphae
ex. Antibiotic-producing fungi
5. Deuteromycetes (Fungi Imperfect)
- septate hyphae-most human
pathogenic molds and yeastsa. Superficial and
cutaneous mycosesdermatophytes: tinea, candida
b. Subcutaneous and systemic mycosesCoccidioidomycoses, Blastomycoses, Histoplasmosis, Cryptococcus
Clockwise from top left: Amanita muscaria, a basidiomycete; Sarcoscypha coccinea, an ascomycete; black bread mold, a zygomycete; a chytrid; a Penicillium conidiophore.
C. PROTOZOA- usually single-celled animal- no chlorophyll-ingest whole algae, yeasts, bacteria and other small protozoas- Classification – based on method of locomotion
Class Movement Examples1. Ciliophora cilia Balntidium coli
Paramecium2. Sarcodina pseudopodia Entamoeba sp.
Naegleria3. Mastigophora flagella Giardia, Trichomonas
Trypanosoma4. Sporozoa non-motile Plasmodium
Toxoplasma Cryptosporidium
Ciliophora: Paramecium
Sarcodina: amoeba
Mastigophora: Gardia Lamblia
Malarial sporozoa
ACELLULAR ORGANISMS: VIRUSES Specific Properties
1. Possess either DNA or RNA (never both)
2. Replication is directed by the viral nuclei acid within a host cell.
3. Do not divide by Binary fission or mitosis
4. Lack the genes and enzymes necessary for energy production.
5. Depend on the ribosomes, enzymes and nutrients of the infected (host) cells for protein production.
Lytic Cycle
1. Attachment
--viruses attach to host cell with the correct receptor.
2. Penetration
-- viral nucleic acid enters the cell
3. Biosynthesis
-- genetic info contained in viral nucleic acid directs production of viral proteins and nucleic acids.
4. Assembly or Maturation
-- viral proteins and nucleic acids are assembled into complete viral particles (virions)
5. Release– newly formed viruses/virions are released
either by lysis or budding.
-- most host cells are destroyed.
Basis for Classification
1. Type of genetic material (DNA or RNA)
2. Shape of capsid (polyhedral, helical, complex)
3. Number of capsomeres
4. Size of capsid
5.presence or absence of an envelope
6. Host that it infects
7. Type of disease produced
8. Target cell
9. Immunological properties Classification
DNA Viruses- Herpes, Hepadna, Adeno, Papova, Parvo, Pox
RNA Viruses- Toga, Corona, Retro, Picorna, Calici, Reo, Orthomyxo, Paramyxo, Rhabdo, Bunya, Arena, Filo, Flavi
HIV VIRUS
Influenza virus
Quiz time
1. Acellular organismbacteriafungivirus
2. Ability to change form or shapepathogenicpleiomorphicaerobic
3. Source of food: decaying matterbacteriafungivirus
4. Algae poisonmycotoxinphycotoxinendotoxin
5. Gram (-) cocci
staphylococcus
neisseria
mycobacterium
PHYSIOLOGY OF THE ORGANISM
PHYSIOLOGY OF MICROORGANISMI. NUTRITIONAL REQUIREMENTS Source of Energy
--Phototrophs---light
--Chemotrophs– inorganic or organic compounds Source of Carbon
-- Autotrophs---CO2
-- Litotrophs—inorganic compound except CO2
-- Heterotrophs (Organotrophs) ---Organic compounds Energy Source and Carbon Source
--Photoautotrophs---Light + CO2
---ex. Plants, algae, cyanobacteria, purple and green
sulfur bacteria
--Photoheterotrophs (Photoorganotrophs) --- Light + organic compounds—ex. Green and purple non-sulfur bacteria
--Chemoautotrophs– Chemical + CO2
ex. Nitrifying, hydrogen, iron and sulfur bacteria
--Chemolitotrophs--- Chemical + inorganic compound except CO2
-- Chemoheterotrophs– Chemical + organic compound
ex. All animals, protozoa, fungi, most bacteria
-- Photolithotrophs – Light + inorganic compound
except CO2
ex. Plants and algae: producers of food and O2 for chemoheterotrophs
II. ENVIRONMENTAL REQUIREMENTS
A. TEMPERATURE
1. Psychrophiles
-- cold loving microbes
2. Mesophiles
--moderate-temperature loving organism
-- most pathogens and indigenous flora
3. Thermophiles
-- heat loving microbes
-- ex. Thermophilic cyanobacteria found in
hot springs
-- Thermodurics: organisms that can survive or endure boiling--- ex. Endospores and viruses
GROWTH TEMPERATURES:
1. Minimum Growth temperature
- lowest temperature at which the species will grow
2. Optimum Growth temperature
- temperature at which the species grows best
3. Maximum Growth temperature- highest temperature at which growth is
possibleB. pH
-- acidity or alkalinity of a solution1. Neutrophiles
-- neutral growth medium (pH 7)-- most microorganisms
2. Acidophiles--prefer a pH of 2-5--microbes that can live in the stomach
3. Alkaliphiles (Basophiles)--prefer pH greater 8.5-- found in intestine
C. OXYGEN REQUIREMENTS
-Based on relationship to O2
1. Aerobes---use molecular O2 for life and reproduction
a. Obligate aerobes
- require an atmosphere that contains O2 similar to room air (20-21% O2), Ex. Mycobacteria
b. Microaerophiles
- require O2 lower than room air (=5% O2)
- ex. Neisseria, Campylobacter
2. Anaerobes
- do not require O2 for life and reproduction
- vary based on sensitivity to O2
a. Obligate anaerobe
- unable to grow in O2, ex. Clostridium
b. Facultative anaerobe
- capable of surviving in the presence or absence of O2 (0% to 20-21% O2)
- ex. Enterobacteria, streptococci, staphylococci
c. Aerotolerant anaerobe
- does not require O2
- grows better in the absence of oxygen but can
survive in atmosphere containing O2
- ex. Lactobacilli- Based on relationship to CO2
- Capnophiles– grow better in the presence of increased concentrations of CO2
- Anaerobes– Bacteroides, Fusobacterium
- Aerobes– Neisseria,Campylobacter, Hemophilus
B. BACTERIAL GROWTH CURVE- Obtained from growing the organism in pure culture
(in vitro)
- growth of cells over time
1. LAG Phase
- period of little or no cell division
-bacteria absorbs nutrients, synthesize enzymes and
prepare for reproduction
- period of intense metabolic activity involving DNA and enzyme synthesis
2. LOG Phase-exponential growth phase or logarithmic growth phase- cells begin to divide and enter a period of growth or
logarithmic increase- cellular reproduction is most active- growth rate is at its greatest- microorganisms sensitive to adverse conditions
ex. Penicillin3. STATIONARY Phase
- period of equilibrium- during this phase that the culture is at its greatest
population density- # of cells produced= # of deaths
4. DEATH phase
- Logarithmic decline phase
- # of deaths greater than the # of cells formed
- toxic waste products increase and nutrient supply
decrease
III. MICROBIAL GROWTH- An increase in the number of organisms
Culture Media
Requirements:
1. Contain the right nutrients
2. Must be initially sterile
3. Incubated at proper temperature
Forms:
1. Liquid (broth)- infusion media
2. Agar– addition of a solidifying agent poured into tubes or Petri dishes
Blood agar
Types:
1. Synthetic Media
- chemically defined medium
- exact chemical composition is known
- used for growth of chemoautotrophs and
photoautotrophs and microbiological assays.
2. Complex Media
- natural medium
- contains digested extracts from animals, meats, fish, yeast and plants
-used for growth of most heterotrophic bacteria and
fungi
3. Enriched Media
- broth or solid medium containing a rich supply of special nutrients that promote the growth of fastidious organisms (ex. Complex nutritional requirements)
- add nutrients to the basic medium (nutrient agar)
- ex. Blood Agar---nutrient agar + 5% sheep RBC
Chocolate agar--- nutrient agar + powdered
Hemoglobin
- increase numbers of desired microbes to detectable levels
4. Selective media
- suppress the growth of unwanted bacteria and encourage the growth of desired microbes
- ex. Bismuth sulfite agar--- Salmonella typhi
Mac Conkey’s agar– Gram- negative bacteria
Thayer-Martin agar --- Neisseria
Sabouraud dextrose agar--- fungi
5. Differential media
- permits the differentiation of organisms that grow in the medium
- ex. Mac Conkey’s Agar --- gram negative organisms
lactose fermenters----pink colonies
Non-lactose fermenters-- colorless
Salmonella culture
MacConkey’s agar
End of Lecture