Classification of Classification of microorganisms and microorganisms and

functional anatomy of functional anatomy of prokatyoticprokatyotic

and eukaroytic cellsand eukaroytic cells

CLASSIFICATION OF CLASSIFICATION OF ORGANISMSORGANISMS• 1735 - Linnaeus-Established first classification 1735 - Linnaeus-Established first classification

system for classifying living things. system for classifying living things.

• Established the binomial*" system of Established the binomial*" system of nomenclature for_-naming organisms. nomenclature for_-naming organisms.

• This means that each living organism is given This means that each living organism is given a * genus and species name. a * genus and species name.

• This is called the scientific name and MUST This is called the scientific name and MUST always be written with the genus name first always be written with the genus name first and the species name second. and the species name second.

• The genus name must be The genus name must be capitalized and the species name capitalized and the species name written in lower case letters. written in lower case letters.

• The entire scientific name must The entire scientific name must be either italicized or underlined. be either italicized or underlined.

Linaeus's classification Linaeus's classification system was composed of 2 system was composed of 2 KingdomsKingdoms• . A plant kingdom and an animal . A plant kingdom and an animal

kingdom. kingdom.

• Microorganisms were considered Microorganisms were considered so unimportant that they were so unimportant that they were grouped under a heading of grouped under a heading of Vermes in a catagory Chaos.Vermes in a catagory Chaos.

1969.Robert Whittaker-devised 1969.Robert Whittaker-devised a five-kingdom classification a five-kingdom classification system based on the 'cellular system based on the 'cellular organization and nutritional organization and nutritional patterns of organismspatterns of organisms..

• In 1969, R. H. Whittaker developed In 1969, R. H. Whittaker developed a 5 kingdom system which a 5 kingdom system which included:included:

1.1.PlantsPlants

2.2.AnimalsAnimals

3.3.ProtistProtist

4.4.FungiFungi

5.5.Monera/ Prokaryotes Monera/ Prokaryotes

ALL CELLS ARE CLASSIFIED AS ALL CELLS ARE CLASSIFIED AS EITHER PROKARYOTES OR EITHER PROKARYOTES OR

EUKARYOTESEUKARYOTES • PROKARYOTES PROKARYOTES - pro means primitive- pro means primitive• DNA contains no protein .lack nucleusDNA contains no protein .lack nucleus• no organellesno organelles• single chromosome composed of DNA in loop.single chromosome composed of DNA in loop.• chlorophyll, if present, is in cytoplasm.chlorophyll, if present, is in cytoplasm.• ribosomes are smaller and free in the ribosomes are smaller and free in the

cytoplasm.cytoplasm.• cell usually surrounded by a cell wall.cell usually surrounded by a cell wall.• Reproduce by fission: no evidence of mitosis Reproduce by fission: no evidence of mitosis • EXAMPLES - bacteria, rickettsiae, chlamydiae, EXAMPLES - bacteria, rickettsiae, chlamydiae,

mycoplasms, cyanobacteria mycoplasms, cyanobacteria

EUKARYOTEEUKARYOTESS - eu means - eu means truetrue • have nucleushave nucleus• have organelles (ex. mitochondria, have organelles (ex. mitochondria,

lysosomes, Golgi apparatus,lysosomes, Golgi apparatus,endoplasmic reticulum.endoplasmic reticulum.

• have multiple chromosomes in nucleus have multiple chromosomes in nucleus with protein around chromosomewith protein around chromosome

• ribosomes bound to membrane or free in ribosomes bound to membrane or free in cytoplasm. Larger.cytoplasm. Larger.

• chlorophyll, if present, is in organelle.chlorophyll, if present, is in organelle.• cell wall absent or less complex chemistrycell wall absent or less complex chemistry• reproduce by mitosisreproduce by mitosis• EXAMPLE - fungi, protozoa, plants, animalsEXAMPLE - fungi, protozoa, plants, animals

Cellular Components:Cellular Components:

• PlastidsPlastids- - contains pigmentcontains pigment

NUCLEUSNUCLEUS

• double membrane double membrane boundboundcontains chromatin contains chromatin disappears during disappears during mitosis or meiosis mitosis or meiosis when the when the chromosomes chromosomes divide and is divide and is reformed after reformed after cytoplasmic cytoplasmic organelleorganelle

NUCLEOLUSNUCLEOLUS

• Aka “Aka “little nucleuslittle nucleus” ”

• Found in the Found in the nucleusnucleus

• Contains RNA and Contains RNA and proteins for proteins for ribosome synthesisribosome synthesis

CYTOPLASMCYTOPLASM

• gelatin-likegelatin-like inside cell membrane inside cell membrane

• constantly constantly flowsflows

• It contains the variousIt contains the various

organelles of the cellorganelles of the cell

ENDOPLASMIC ENDOPLASMIC RETICULUMRETICULUM

• extensive convoluted extensive convoluted membrane continuous membrane continuous with the outer nuclear with the outer nuclear membrane and membrane and enclosing a continuous enclosing a continuous internal space involved internal space involved in the synthesis and in the synthesis and transport of membrane transport of membrane proteins and lipids and proteins and lipids and of proteins destined for of proteins destined for secretion from the cellsecretion from the cell

ENDOPLASMIC ENDOPLASMIC RETICULUMRETICULUM

• A series of A series of folded folded membranesmembranes that that move move materials materials (proteins) (proteins) around in a cell like a around in a cell like a conveyor beltconveyor belt

• Smooth ERSmooth ER – – ribosomes ribosomes not attached not attached to ER, to ER, functions in lipid functions in lipid synthesissynthesis

• Rough ERRough ER – – ribosomes ribosomes attachedattached to ER, to ER, functions in producing functions in producing proteinsproteins

RIBOSOMESRIBOSOMES

• Make Make proteinsproteins

• Float freelyFloat freely or or attached to the attached to the endoplasmic endoplasmic reticulum (ER)reticulum (ER)

• Ribosomes are made Ribosomes are made in the in the nucleolus nucleolus and and are small particles are small particles of RNAof RNA

MITOCHONDRIAMITOCHONDRIA

• Organelles that Organelles that release release energyenergy from from foodfood (power (power house of cell) house of cell)

• This energy is This energy is released by AKA released by AKA the the powerhousepowerhouse b/c they release b/c they release energyenergy (ATP)(ATP) from from foodfood

Folds of mitochodria are Folds of mitochodria are called:called:

GOLGI BODIESGOLGI BODIES (GAWL jee) (GAWL jee)

• Stacked Stacked flattenedflattened membranesmembranes

• SortSort and and packagepackage proteins proteins

LYSOSOMESLYSOSOMES (LI suh sohmz) (LI suh sohmz)

• The word "lysosome" is Latin for The word "lysosome" is Latin for "kill body." "kill body."

• The purpose of the lysosome is to The purpose of the lysosome is to digest things. They might be used digest things. They might be used to digest to digest foodfood or break down the or break down the cell when it dies.cell when it dies.

• Break down Break down foodfood molecules, molecules, cell cell wasteswastes & & worn outworn out cell parts cell parts

VACUOLESVACUOLES

•Temporary Temporary storage storage spaces spaces

•Store Store foodfood, , waterwater, , wastewaste

• may contain air, may contain air, water, cell sap, water, cell sap, partially digested partially digested food etc...food etc...

CentriolesCentrioles

• Short cylinder near nuclear Short cylinder near nuclear envelopeenvelope

• There generally are 2 at right There generally are 2 at right angles to each otherangles to each other

• They control cell divisionThey control cell division

Peroxisome-Peroxisome-

• small organelle bounded by a small organelle bounded by a single membrane and containingsingle membrane and containing

• catalase and peroxidasescatalase and peroxidases

• important in detoxification important in detoxification reactionsreactions

Cell WallCell Wall

• located beneath the capsule and located beneath the capsule and external to the cytoplasmic external to the cytoplasmic membrane. All bacteria except for membrane. All bacteria except for mycoplasms have cell walls.mycoplasms have cell walls.

• Functions:Functions:• A.A. Maintain shape of bacteriaMaintain shape of bacteria• B.B. Prevent cell from rupturing - Prevent cell from rupturing -

internal pressure 20 times externalinternal pressure 20 times externalpressure.pressure.

• C.C. Point of anchorage for flagellaPoint of anchorage for flagella

• The cell wall is composed of The cell wall is composed of peptidoglycan which is present peptidoglycan which is present either alone or in combination either alone or in combination with other substances. with other substances.

• The peptidoglycan is composed The peptidoglycan is composed of a carbohydrate backbone of a carbohydrate backbone linked together by peptides.linked together by peptides.

• Gram positive cell walls are Gram positive cell walls are composed of a thick layer of composed of a thick layer of peptidoglycan approximately 25 peptidoglycan approximately 25 nm in thickness. nm in thickness.

• Teiochoic acid is also present in Teiochoic acid is also present in the peptidoglycan layer. the peptidoglycan layer.

• The peptidoglycan makes up The peptidoglycan makes up about 50% about 50% of of the dry weight.the dry weight.

• Gram negative cell walls are composed Gram negative cell walls are composed of a thin layer of peptidoglycan of a thin layer of peptidoglycan approximately 3 nm in thickness. approximately 3 nm in thickness.

• There is no teiochoic acid in the There is no teiochoic acid in the peptidoglycan layer but there are peptidoglycan layer but there are layers of lipopolysaccharide, layers of lipopolysaccharide, phospholipids, and lipoproteins phospholipids, and lipoproteins outside the peptidoglycan layer. outside the peptidoglycan layer.

• The peptidoglycan layer makes up The peptidoglycan layer makes up about 10% of the dry weight.about 10% of the dry weight.

• Penicillin Penicillin - antibiotic that functions in - antibiotic that functions in preventing the formation of cell walls. preventing the formation of cell walls.

• Works best on Gram + bacteria.Works best on Gram + bacteria.

• LysozymeLysozyme - an enzyme found in body - an enzyme found in body secretions that breaks down cell walls. secretions that breaks down cell walls. Protoplast - a Gram + bacterium that has Protoplast - a Gram + bacterium that has had the cell wall removed. had the cell wall removed.

• Made by treating cell with Lysozyme.Made by treating cell with Lysozyme.• Spheroplast - a Gram - bacterium that has Spheroplast - a Gram - bacterium that has

had the peptidoglycan layer of the cell wall had the peptidoglycan layer of the cell wall removed. removed.

• Still has the cell membrane with the lipid Still has the cell membrane with the lipid layers of the cell wall on the outside. layers of the cell wall on the outside.

• Both protoplast and spheroplast will be Both protoplast and spheroplast will be spherical regardless of their original shape.spherical regardless of their original shape.

CELL MEMBRANECELL MEMBRANE • approximately 7.5 nm thick and approximately 7.5 nm thick and

composed of a phospholipid bilayer composed of a phospholipid bilayer with proteins dispersed throughout. with proteins dispersed throughout.

• The phospholipid bilayer is composed The phospholipid bilayer is composed of phosphates and glycerol on the of phosphates and glycerol on the outside with tails of fatty acids on the outside with tails of fatty acids on the inside. inside.

• The polar heads are on the 2 outside The polar heads are on the 2 outside surfaces and the non-polar tails are on surfaces and the non-polar tails are on the inside. the inside.

• The arrangement of The arrangement of phospholipids and proteins is phospholipids and proteins is referred to as the referred to as the fluid mosaic fluid mosaic modelmodel due to the continuous due to the continuous change in the arrangement of change in the arrangement of the molecules. the molecules.

• Ethyl alcohol Ethyl alcohol and poly myxin and poly myxin destroys the membrane.destroys the membrane.

Functions:Functions:

1.1. selective barrier - membrane is selective barrier - membrane is selectively permeableselectively permeable

2.2. serves as anchor for attachment of serves as anchor for attachment of DNADNA

3.3. site of enzymes that function in cell site of enzymes that function in cell wall synthesis (permeases)wall synthesis (permeases)

4.4. site of enzymes that function in site of enzymes that function in energy productionenergy production

5.5. secretes exoenzymes that break secretes exoenzymes that break down large moleculesdown large molecules

MAJOR GROUPS OF MAJOR GROUPS OF MICROORGANISMSMICROORGANISMS

1.1. BACTERIA BACTERIA – – • unicellular, prokaryotic organisms that unicellular, prokaryotic organisms that

are among the most abundant on are among the most abundant on earth. earth.

• May be aerobic (requires oxygen) May be aerobic (requires oxygen) anaerobic (Needs no oxygen), or anaerobic (Needs no oxygen), or facultative (indifferent to oxygen, can facultative (indifferent to oxygen, can survive either way). survive either way).

• Multiply by binary fission (single Multiply by binary fission (single chromosome duplicates and 2 chromosome duplicates and 2 chromosomes move to different areas chromosomes move to different areas and membranes grow inward).and membranes grow inward).

Bacteria have 3 basic Bacteria have 3 basic shapesshapes – –

a)a) coccus-coccus-roundroundb)b)bacillusbacillus -rod -rodc)c) spiral-curvedspiral-curved shape called spirillum shape called spirillum• Some form endospores-cell Some form endospores-cell

shrinks, rounds up within old shrinks, rounds up within old membrane and forms new thicker membrane and forms new thicker walls. walls.

• Average size is one micrometer.Average size is one micrometer.• BACTERIOLOGBACTERIOLOGY-study of bacteriaY-study of bacteria

Types of BacteriaTypes of Bacteria

• RickettsiaeRickettsiae• -small bacteria, among the tiniest microorganisms, -small bacteria, among the tiniest microorganisms,

usually transmitted by arthropods. Grow and multiply usually transmitted by arthropods. Grow and multiply only within living cells. .5 urn. in size. Ex. Rocky only within living cells. .5 urn. in size. Ex. Rocky Mountain Spotted Fever 1 micrometer = 1 thousandth Mountain Spotted Fever 1 micrometer = 1 thousandth of a millimeterof a millimeter

• ChlamydiaeChlamydiae• -subgroup of Rickettsiae, among smallest -subgroup of Rickettsiae, among smallest

Rickettsiae, .25 urn. Grow and multiply only in living Rickettsiae, .25 urn. Grow and multiply only in living cells. Ex. disease of eye, lung, and urogenital tract.cells. Ex. disease of eye, lung, and urogenital tract.

• MycoplasmsMycoplasms• smaller than Chlamydiae, .1 urn. Pleomorphic, has no smaller than Chlamydiae, .1 urn. Pleomorphic, has no

cell wall, can grow on artificial media if certain cell wall, can grow on artificial media if certain steroids are added. Ex. walking pneumonia.steroids are added. Ex. walking pneumonia.

Types of BacteriaTypes of Bacteria

• CyanobacteriaCyanobacteria

• Known as blue-green algae. Nore Known as blue-green algae. Nore closely related to bacteria because of closely related to bacteria because of structural and biochemical properties. structural and biochemical properties.

• Not true bacteria. Possesses light-Not true bacteria. Possesses light-trapping pigments, many are blue but trapping pigments, many are blue but some are black, red, yellow, or green. some are black, red, yellow, or green. Inhabit both fresh and salt water. Ex Inhabit both fresh and salt water. Ex makes swimming pools green.makes swimming pools green.

2.2. ProtozoansProtozoans::

• Single celled eukaryotes that are Single celled eukaryotes that are usually microscopic. usually microscopic.

• Can cause parasitic diseases such as Can cause parasitic diseases such as malaria. malaria.

• Some are capable of photosynthesis Some are capable of photosynthesis but most are not. but most are not.

• They are classified according to their They are classified according to their locomotion ( flagella, cilia, pseudopods) locomotion ( flagella, cilia, pseudopods) Protozoa average about 100um. Protozoa average about 100um.

• ProtozoologyProtozoology is the study of protozoasis the study of protozoas

3.3. FUNGIFUNGI--

• eukaryotic, non-photosynthetic, and eukaryotic, non-photosynthetic, and contain chitin in their cell walls. contain chitin in their cell walls. Plants do not have chitin in the cell Plants do not have chitin in the cell walls. Aid bacteria in decomposition. walls. Aid bacteria in decomposition.

• Include yeast, molds, and Include yeast, molds, and mushrooms. Yeast are 8 urn and mushrooms. Yeast are 8 urn and molds are 40 - 100 urn. molds are 40 - 100 urn.

• MycologyMycology is the study of fungi. is the study of fungi.

4. ALGAE4. ALGAE--

• eukaryotic, photosynthetic plants eukaryotic, photosynthetic plants that range in size from a single cell to that range in size from a single cell to giant kelp 30 m. in length. giant kelp 30 m. in length.

• One genus produces neurotoxins One genus produces neurotoxins causing shellfish poisoning. causing shellfish poisoning.

• Microbiologist are interested in the Microbiologist are interested in the algae classified in the kingdom algae classified in the kingdom Protista. Protista.

• Extremely important in food chain in Extremely important in food chain in oceans. oceans.

• PhycologyPhycology is the study of algae.' is the study of algae.'

5. 5. VIRUSESVIRUSES

• --neither prokaryote or eukaryote. neither prokaryote or eukaryote.

• Viruses are obligate intracellular Viruses are obligate intracellular parasites. parasites.

• This means that the virus depends This means that the virus depends on the host'cell for reproduction on the host'cell for reproduction and growth. and growth.

• Viruses are non-cellular, infectious Viruses are non-cellular, infectious agents composed of a nucleic acid agents composed of a nucleic acid surrounded by a protein coat. surrounded by a protein coat.

• Viruses are considered the link Viruses are considered the link between the living and the between the living and the nonliving. nonliving.

• Cause diseases such as herpes, Cause diseases such as herpes, rabies, flu, hepatitis, polio, and rabies, flu, hepatitis, polio, and chickenpox. chickenpox.

• Only observable activity is Only observable activity is reproduction. reproduction.

• Viruses are measured Viruses are measured nanometers. Smallpox largest nanometers. Smallpox largest ( 250nm) polio smallest ( 20 nm) ( 250nm) polio smallest ( 20 nm)

• VirologyVirology is the study of viruses. is the study of viruses.

Bacteria Morphology: Bacteria Morphology: the the size, shape, structure and size, shape, structure and arrangement of cells.arrangement of cells.• SIZESIZE - average one urn. - average one urn.• Because of small size have high surface area to Because of small size have high surface area to

volume ratio. This explains the high rate of volume ratio. This explains the high rate of growth and metabolism. Sphere has the growth and metabolism. Sphere has the smallest surface area to volume ratio.smallest surface area to volume ratio.

• SHAPE SHAPE - three basic shapes governed by cell - three basic shapes governed by cell wall.wall.

• coccus - spherical, may be oval, elongated, or coccus - spherical, may be oval, elongated, or indented. indented.

• bacillus-rodbacillus-rod• spiral-helically curvedspiral-helically curved• a.a. vibrios-comma shapedvibrios-comma shaped• b.b. spirilia-rigid cell wall with flagellaspirilia-rigid cell wall with flagella• c.c. spirochetes-flexible wall with no flagellaspirochetes-flexible wall with no flagella

• diplococcusdiplococcus - cells divide in one plane - cells divide in one plane and remain attached in pairs.and remain attached in pairs.

• streptococcusstreptococcus - cells divide in one - cells divide in one plane and remain attached to form plane and remain attached to form chains.chains.

• tetracoccustetracoccus - cells divide in two - cells divide in two planes and form groups of 4 cells.planes and form groups of 4 cells.

• staphylococcusstaphylococcus - cells divide in three - cells divide in three planes and produce grape like planes and produce grape like clusters of bacteria.clusters of bacteria.

• sarcinaesarcinae - cells divide in three planes - cells divide in three planes in a regular pattern pro ducing in a regular pattern pro ducing cuboidal arrangement of cells.cuboidal arrangement of cells.

• Occasionally bacterial cells may be Occasionally bacterial cells may be star shaped or square.star shaped or square.

BACTERIAL SIRUCTURES BACTERIAL SIRUCTURES Structures External to Cell WallStructures External to Cell Wall

• 1.1. Glycocalyx-general term Glycocalyx-general term used for substances that used for substances that surround the cell.surround the cell.

• Viscous, gelatinous substance Viscous, gelatinous substance composed of polysaccharide, composed of polysaccharide, polypeptide, or both.polypeptide, or both.

• A.A. Capsule-a Capsule-a glycocalyxglycocalyx that is organized that is organized and firmly attached to the cell wall. Forms and firmly attached to the cell wall. Forms in various species of bacilli and cocci, in various species of bacilli and cocci,

• BUT NOT IN SPIRAL BACTERIA.BUT NOT IN SPIRAL BACTERIA.• Functions-Functions-• provide protection against drying by provide protection against drying by

binding water moleculesbinding water molecules• blocks attachment by bacteriophagesblocks attachment by bacteriophages• may be antiphagocytic (enhibits engulfment may be antiphagocytic (enhibits engulfment

of pathogenic bacteria by white blood cells.of pathogenic bacteria by white blood cells.• promotes attachment of bacteria to promotes attachment of bacteria to

surfacessurfaces• 5.5. if capsule has electrical charge may if capsule has electrical charge may

promote stability of bacterialpromote stability of bacterialsuspension by preventing cells from settling suspension by preventing cells from settling out. out.

• B.B. Slime layerSlime layer - glycocalyx of looser - glycocalyx of looser consistency and less tightly bound to consistency and less tightly bound to cell wall. cell wall.

• Contains mass of tangled fibers of Contains mass of tangled fibers of polysaccharide called dextran. polysaccharide called dextran.

• Attaches bacteria to tissue. EX. Attaches bacteria to tissue. EX. Alcaligenes viscolactisAlcaligenes viscolactis - ropy milk - ropy milk

• Bacillus subtilisBacillus subtilis • ropy bread • ropy bread• Streptococcxis mutansStreptococcxis mutans - tooth decay - tooth decay

• 2.2. Flagella Flagella - Hairlike, helical - Hairlike, helical appendages composed of appendages composed of protein that protrude through protein that protrude through the cell wall and are responsible the cell wall and are responsible for swimming motility.for swimming motility.

• They are much thinner and less They are much thinner and less complex in structure than complex in structure than eukaryotic flagellaeukaryotic flagella

Location of FlagellaLocation of Flagella

• A.A. monotrichous - 1 flagellum at monotrichous - 1 flagellum at one pole of cell.one pole of cell.

• B.B. amphitrichous - 1 flagellum amphitrichous - 1 flagellum at each pole of cell.at each pole of cell.

• C.C. lophotrichous - a tuff of lophotrichous - a tuff of flagella at one pole.flagella at one pole.

• D.D. peritrichous - flagellaperitrichous - flagella

Composed of three Composed of three parts:parts:• A.A. helical filament - usually several helical filament - usually several

times as long as the cell. 20 nm.in times as long as the cell. 20 nm.in diameterdiameter

• B.B. short hookshort hook• C.C. Basal body-ring shaped bases (2 Basal body-ring shaped bases (2

in Gram negative and 1 in Gram in Gram negative and 1 in Gram positive cells) associated with cell positive cells) associated with cell wall and cell membrane.wall and cell membrane.

• Common in spiral and rod shaped Common in spiral and rod shaped bacteria but bacteria but Rare in cocciRare in cocci. .

•

Taxis: movement toward or Taxis: movement toward or away from a certain away from a certain stimulus.stimulus. • ChemotaxisChemotaxis refers to movement refers to movement

toward or away from a chemical.toward or away from a chemical.

• PhototaxisPhototaxis refers to movement refers to movement toward or away from lighttoward or away from light

• 3. Pili and fimbriae - hollow, 3. Pili and fimbriae - hollow, non helical, filamentous non helical, filamentous appendages that are thinner, appendages that are thinner, shorter, and more numerous shorter, and more numerous than flagella. than flagella.

• Do not function in motility. Do not function in motility. Composed of protein pilin.Composed of protein pilin.

• A.A. Fimbriae may be located all Fimbriae may be located all over the bacteria and function inover the bacteria and function inattachment.attachment.

• B.B. Pili - one or two per cell and Pili - one or two per cell and function in the transfer offunction in the transfer ofDNA. Called sex pili.DNA. Called sex pili.

• Fimbriae are found primarily on Fimbriae are found primarily on Gram negative bacteriaGram negative bacteria

• Endospores - a highly resistant, Endospores - a highly resistant, metabolically dormant form metabolically dormant form which under appropriate which under appropriate conditions can germinate to form conditions can germinate to form a new vegatative cell.a new vegatative cell. This is a This is a survival mechanism for the cell. survival mechanism for the cell. Spores resistance due to:Spores resistance due to:

• dehydrationdehydration• large amounts of dipicolinic acidlarge amounts of dipicolinic acid

Endospore Endospore

• Spore formation is genetically determined.Spore formation is genetically determined.• Spore formation is NOT a form of Spore formation is NOT a form of

reproduction.reproduction.• Spore formation is found primarily in Gram Spore formation is found primarily in Gram

positive organisms.positive organisms.• Spores can remain alive in boiling water for Spores can remain alive in boiling water for

hours, can survivehours, can survive• The genera The genera BacillusBacillus and and ClostridiumClostridium are the are the

best known spore formers. best known spore formers.