Classification and Taxonomy

Amit Gautam

General Classification

Muller and Ehrenberg

Haeckel – all unicellular as Protista.

Cohn- integrated bacteria with blue green algea -

Schizophyta.

Migula- given more detail classification.

Linnaeus divided all living being into two

kingdoms – plant and animals - Schizomycetes

Monera a new kingdom proposed

Division ProtophytaClass SchizomycetesOrder EubacterialesceaeFamily EnterobacteriaTribes SalmonellaeGenus SalmonellaSpecies Typhi

Species concept of bacteria

The differences between the classification of the bacteria and other higher organisms.

Changes in the genetic characters.

Species concept of bacteria

The differences between the classification of the bacteria and other higher organisms.

Changes in the genetic characters.

Phylogenetic classification

The hierarchical classification Special weightage is given to the special characters. Eg- gram negative bacteria – lactose fermenting or

not.

Limitation

1. Characters may be invalid

2. May not be permanent.

3. It can be acquired or lost.

Adansonian classification

Micheal Adanson

Takes all the characters.

Called as Phenetic system.

Numerical taxonomy.

Molecular genetic classification

Depend on genetic relatedness.

Relatedness of DNA nucleotide sequence.

No method of bacterial classification is widely

accepted.

Bergey’s manual of determinative bacteriology.

Interspecies Classification

For diagnostic or epidemiological

Biotype

Serotype

Phage type

Colicin type

Nomenclature

Two names are given to the bacteria

Commom name

Eg. Typhoid or gonnococcal.

International name

Classification and nomenclature of viruses

Classification of viruses

Primary charactristics Secondary characteristics

Chemical nature of nucleic acid RNA or DNA (Single or double)

Host range

Host species, specific host tissue or cell type

Structure of virions helical icosahedral or complex

Mode of transmission

Site of replication

Nucleus and Cytoplasm

Specific surface structure

DNA viruses

1) Poxviridae Family

• Large, brick shaped, complex structure,

• Lipid containing outer coat,

• Double stranded DNA.

• Multiplication maturation in cytoplasm

DNA viruses

2) Herpesviridae family:

Medium sized

Linear double stranded DNA.

Isosahedral nucleocapsid , lipid envoloped.

Multiplication takes place in nucleus

Maturation by nuclear membrane.

DNA viruses

3) Adenoviridae family:

Medium sized

Non envoloped, Isosahedral nucleocapsid

Two types

Mastedenoviruses

Aviadenoviruses

DNA viruses

4) Papovaviridae family:

Small sized.

Non envoloped, Double stranded

Two types

Papillomavirus

Polyomavirus

DNA viruses

5) Parvoviridae family:

Small sized.

Non envoloped, Single stranded DNA

Three types

Parvovirus

Adenosatellovirus

Densovirus

DNA viruses

6) Hepadnaviridae family:

Small sized, spherical

Envoloped

Causitive organisms of hapatitis B.

DNA viruses

6) Hepadnaviridae family:

Small sized, spherical

Envoloped

Causitive organisms of hapatitis B.

RNA viruses

1) Picornaviridae family:

Small sized, isosahedral

Non Envoloped

Single stranded RNA genome

Three genera

Enterovirus

Rhinovirus

Hepatovirus

RNA viruses

2) Orthomyxoviridae family:

Medium sized, spherical or elongated

Envoloped with peplomers

Single stranded RNA genome

RNA viruses

3) Paramyxoviridae family:

Pleomorphic

Envoloped with peplomers

Unsegmented Single stranded RNA genome

Three genera-

Paramyxovirus

Morbillivirus

Pneumovirus

RNA viruses

4) Togaviridae family:

Spherical viruses

Lipoprotein Envolop

Single stranded RNA genome

Three genera-

Alpha virus

Rubivirus

Pestivirus

RNA viruses

5) Flaviviridae family:

6) Bunyaviridae family:

Spherical, envoloped.

Arthopod borne

Five genus

Largest Bunyavirus with 150 species

RNA viruses

7) Arenaviridae family:

Spherical or pleomorphic

Have sandy apperance

8) Rhabdoviridae family:

Bullet shaped virus

Envoloped with peplomers

Two genera- Vesiculoviruses and lyssaviruses

RNA viruses

9) Reoviridae family:

Isosahedral, non envoloped viruses

Double stranded RNA

Three genera

Reovirus

Orbivirus

Rotavirus

RNA viruses

10) Coronaviridae family:

Pleomorphic, envoloped viruses with peplomers.

Double stranded RNA

11) Retroviridae family

RNA tumor virus

Classification of Fungi

Division Gymnomycota

Slime molds

Organisms which ingest particulate nutrients

Lack cell wall in vegetative stage

Class Acrasiomycetes (cellular slime molds)

• Vegetative stage, free living amoebae

• Spores in mucilageneous matrix

Eg- Dictyostelium discoideum

Division Gymnomycota

Class Myxomycetes (acellular slime molds)

• Vegetative

stage, multicelllular

• Wall less plasmodium

• organized

sporangia bearing sporangiospores

Eg- Physarum polycephalum

Didimium iridis

Division Mastigomycota

Flagellated lower fungi

Aquatic fungi

Class Chytridiomycetes

• Motile cell

• Posteriorly positioned whiplash like flagellum

Eg-Allomyces macrogynus

Division MastigomycotaClass Hyphochytridiomycetes Motile cell anteriorly positioned tinsel like

flagellum

Eg-RizidomycesArbuscula

Class Plasmodiophoromycetes Obligate parasite Vegetative stage plasmodium Motile cell with two un equal

whiplash flagella

Eg- Plasmodiophora brassica

Division MastigomycotaClass Oomycetes

Motile cell with two laterally

inserted flagella

One tinsel and anteriorly directed

Flagella posteriorly and whiplash.

Eg- saprolegnia ferax

Division AmastigomycotaClass Deuteromycetes

Sexual reproduction absent

Vegetative reproduction by

ConidiosporesEg- molds, Candida albicans.

Division Amastigomycota

Terrestrial fungi

Flagella absent

Class Zygomycetes

• Sexual reproduction by gametengial fusion,

• Zygote transformed into thick wall resting

spore.

• Sporangium present.Eg- Rhizofer stolonifer

Division AmastigomycotaClass Ascomycetes

Sexual spore produce

endogeneously in ascus

Vegetative reproduction by

ConidiosporesEg- yeast, morels and truffels.

Class Basidiomycetes

Sexual spore produce exogeneously

Club like cellsEg- mushroom puffball.