CLASSIFICATION

PROKARYOTES

Prokaryotic cells have no nucleus, no membrane bound organelles, and

undergo binary fission. An example is a bacterium.

EUKARYOTES

Eukaryotic cells have a nucleus, their organelles may or may not have a membrane, and they reproduce asexually or sexually. Examples

include protozoans, molds, plants, and animals.

WHITTAKER’S CLASSIFICATION

TAXONOMY System for organizing,

classifying, naming living things

Kingdom - 5 Phylum or Division Class Order Family Genus Species

NAMING MICOORGANISMS

Binomial (scientific) nomenclature Gives each microbe 2 names

Genus - noun, always capitalized species - adjective, lowercase

Both italicized or underlined Staphylococcus aureus (S. aureus) Bacillus subtilis (B. subtilis) Escherichia coli (E. coli)

METHODS IN BACTERIAL IDENTIFICATION

1. Microscopic morphology2. Biochemical characteristics3. Gram stain + or -4. pH requirement– most live within pH 5-8

a. Acidphiles – pH below 5.5b. Neutrophiles – pH 5-8c. Alkalophiles – pH above 8.5

METHODS IN BACTERIAL IDENTIFICATION5. Temperature requirement

a. Psychrophiles – 0-15o

Cb. Psychrotrophs- 20-30o C,

but grow well at lower temperatures

c. Mesophiles - 25-45o C, pathogens and soil bacteria

d. Thermophiles - 45-70o C, hot springs and compost

e. Hyperthermophiles – 70o C and above.

METHODS IN BACTERIAL IDENTIFICATION6. Oxygen requirement

a. Obligate Aerobes – must have oxygen to produce energy.b. Obligate Anaerobes – cannot multiple if any oxygen is present, they are often killed if oxygen is present.c. Facultative anaerobes - grow with or without oxygen. Use both aerobic and anaerobic respiration.d. Microaerophiles – require small amount of oxygen for aerobic respiration.e. Aerotolerant anaerobes – can grow in oxygen’s presence, but they do not use it to transform energy.

OXYGEN REQUIREMENT

METHODS IN BACTERIAL IDENTIFICATION7. Sources of Essential Nutrients

a. Photoautotroph – are photosynthetic. They are eventually consumed by other organisms including humans.b. Chemoautotroph – have unusual nutritional adaptations that requires neither sunlight or organic nutrients. Usually live harsh environments like sulfur hot springs. This group use inorganic compounds for energy and derive their carbon from carbon dioxide. c. Photoheterotrophs – use the energy of sunlight and derive their carbon from organic compounds.d. Chemoheterotrophs – derive both carbon and energy from organic compounds. This group is the most common group associated with humans and other animals.

1. Saprobe – free living organisms that feed primarily on organic debris from dead organisms.

2. Parasite - live in or on the body of a host, which they usually harm to some degree.

FUNGI

FUNGI The study of fungi is known as MYCOLOGY Describes a taxonomic classification of

organisms. One of 5 Kingdoms of life. No longer includes slime molds and water

molds All fungi are heterotrophic Fungi require organic compounds for

energy and as a carbon source Most are aerobic or facultative anaerobe Large number of fungi cause disease in

plants Only a few cause disease in humans

Classification of fungi Can be both micro and macroscopic Cell wall consists of chitin No flagellated cells Four groups of true fungi

Zygomycetes Basidiomycetes Ascomycetes Deuteromycetes

fungi imperfecta Classification in groups based on sexual reproduction

Except in Deuteromycetes where sexual reproduction is not seen

FUNGI

Classification of fungi Zygomycetes

Include common bread mold Rhizopus Ascomycetes Includes Microsporum and Penicillium

Basidiomycetes Include common mushroom and puffballs

Deuteromycetes Includes yeasts and molds, some saprobes, and some

plant and animal parasites

FUNGI

FUNGI ZYGOMYCETES

The ZygomycetesZygomycetes are saprophytic molds: are saprophytic molds: Rhizopus and and Mucor

They have nonseptated (coenocytic) hyphaeThey have nonseptated (coenocytic) hyphae They reproduce asexually using They reproduce asexually using

sporangiosporessporangiospores They reproduce sexually using zygospores They reproduce sexually using zygospores They can be an opportunistic pathogen They can be an opportunistic pathogen

producing systemic mycosisproducing systemic mycosis

FUNGI ZYGOMYCETES

Note that the septa are no segmented

This is known as nonseptate hyphae or coenocytic hyphae

FUNGI ZYGOMYCETESNote the sporangia, sporangiospores, and nonseptate hyphae

Fig. 5.20

Formation of zygospores in Rhizopus

FUNGI ASCOMYCETES

The Ascomycetes include molds and yeasts: Penicillium and Aspergillus.

The have septate hyphae They reproduce asexually using They reproduce asexually using

conidiosporesconidiospores MicrosporumMicrosporum can cause ringworm and can cause ringworm and

athlete’s foot.athlete’s foot.

FUNGI ASCOMYCETES

Note that the hyphae are septate or divided.

FUNGI ASCOMYCETESNote the conidia at the tips of

conidiophores

FUNGI BASIDIOMYCETES

The Basidiomycetes include mushrooms and puff balls, rust, and smuts.

They have septate hyphae. They reproduce asexually using They reproduce asexually using

conidiospores.conidiospores. They reproduce sexually using They reproduce sexually using

basidiospores.basidiospores.

FUNGI BASIDIOMYCETES

FUNGI BASIDIOMYCETES

Note that the diagram shows the surface of the gill will a mass basidia, bearing spores

FUNGI

Classification of fungi Grouping of fungal forms

Yeasts Single-celled fungi Spherical, oval or cylindrical Reproduction through binary fission or budding

Molds Filamentous fungi contain hypa collection of hyphae

called mycelium Reproductive spore is single celled germinates to

develop hyphae cells divide into new form

YEAST

MOLD-FILAMENTOUS FUNGI

FUNGI Fungal habitats

Found in virtually every habitat

Mainly terrestrial Fungal spores found

throughout the earth Uncountable

numbers found in air Major cause of

asthma

Growth requirements of fungi Slightly moist

environment with high humidity

70% or higher pH range varies

Most grow well in slightly acidic environment

Most are aerobic Some yeast aerobic Some fungi facultative

anaerobes and carry out alcoholic fertilization

FUNGI Fungal diseases in humans

Cause disease in one of four ways Allergic reaction

Result from inhaling fungal spores React to fungal toxin

Many have hallucinogenic properties Certain species produces toxins implicated in cancer

Mycoses Fungi grows on or in the body Can be superficial, intermediate, systemic

Economic impact Destroy human food supply causing starvation

PROTOZOANS

PROTOZOA

Microscopic unicellular organisms

Lack photosynthetic capability

Usually motile Reproduce by asexual

fission

Classification of protozoa Not a unified group

Lumped together as unicellular organisms lacking chlorophyll

Traditionally divided into groups based on mode of locomotion

Some belong to phylum Sarcomastigophora Include two subphyla

Mastigophora Sarcodina

PROTOZOA

PROTOZOA

Classification of protozoa Mastigophora

Include flagellated protozoa Most significant include

Giardia lamblia, Leshmanii species Trichomonas vaginalis and Trypanosoma species

Sarcodina Move by means of pseudopodia Entamoeba hystolitica produces disease in humans

Fig. 5.28

Fig. 5.29

SARCODINA

Classification of protozoa Other phylum include

Ciliophora Organisms have cilia Balantidum coli only pathogenic ciliate

Apicomplexa Cause most serious protozoan disease

Plasmodium species causes malaria Microspora

Cause severe infection in immunocompromised

PROTOZOA

Fig. 5.31

PROTOZOA Protozoan habitats

Majority are free-living Found in marine, fresh water and terrestrial habitats

Essential decomposers Require large amounts of moisture Important part of food chain

Protozoa eat bacteria and serve as food for larger species

Help maintain ecological balance in soil Important in sewage disposal

Results in decrease of sewage solids

PROTOZOA

Structure of protozoa Cell wall

Lack cell wall Shape determined by material beneath plasma

membrane Cell structures

Have membrane bound nucleus and organelles Lack photosynthetic chloroplasts

Have specialized structures for movement Cilia, flagella or pseudopodia

Protozoa grouped by mode of locomotion

PROTOZOA Protozoan reproduction

Life cycles complex Often require more than one

habitat or host Polymorphic

Can exist as trophozoite or as cyst

Both sexual and sexual reproduction common

Many replicate via binary fission Many replicate by schizogony

Many fissions Nucleus divides numerous times

then cell produces numerous single-celled organisms