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