Bacterial systematics has undergone several changes
and is continuously in a state of flux as our knowledge of microorganisms is
far from complete and new information is being added every day.
In 1923 David Hendricks
Bergey, professor of bacteriology at the University of Pennsylvania, and four
colleagues published a classification of bacteria that could be used for the
identification of bacterial species.
The first eight
editions were published under the name ‘Bergey’s
Manual of Determinative Bacteriology’. In the 9th edition, it was renamed
as ‘Bergey’s Manual of Systematic
Bacteriology’ and was published in four volumes in 1984, 1986, 1989 and 1991.
It is highly regarded
by bacteriologists as this manual is continuously updated with successive
editions and helps in bacterial taxonomy and research.
The manual classifies
bacteria on the basis of their functional and structural attributes and
arranges the organisms into familial orders. In recent years, empirical
evidence has also been considered in this classification.
Note: Since 2015, the
manual has been replaced with Bergey’s
Manual of Systematic of Archaea and Bacteria and is available online.
Organization
The 1980 edition of the
manual took into consideration the relationship between organisms along with an
expanded scope in bacterial taxonomy. The set of four volumes contains:
Volume
I:
It talks about all Gram-negative bacteria and considers them important for
medicinal and industrial purposes.
Volume
II:
It includes all the information about Gram-positive bacteria.
Volume
III:
It includes information about the remaining Gram-negative bacteria and about
Archaea as well.
Volume
IV:
It talks about filamentous actinomycetes and similar types of bacteria.
The second edition has
been published in five volumes, the details of which are given below:
Volume
I:
It was published in 2001 and talks about the archaea and the branching
phototrophic bacteria.
Volume
II:
It was published in 2005 and gives details about the proteobacteria.
Volume
III:
It was published in 2009 and gives details about the firmicutes.
Volume
IV:
It was published in 2011. It mentions the Spirochaetes, Bacteroidetes,
Tenericutes (Mollicutes), Chlamydiae, Acidobacteria, Verrucomicrobia,
Fusobacteria, Dictyoglomi, Fibrobacteres, Gemmatimonadetes, Lentisphaerae, and
Planctomycetes.
Volume
V:
It was published in 2012 and talks about the actinobacteria.
The
First Edition
In the first edition,
Bergey classified the kingdom Prokaryotae in four divisions:
Gracilicutes:
they have a gram-negative cell wall.
Firmicutes:
they have a gram-positive cell wall.
Tenericutes:
they do not have a cell wall.
Mendosicutes:
they lack peptidoglycan in their cell wall and are similar to Archaea.
This classification was
entirely based upon gram staining, presence of endospore, general shape,
motility, morphology and mode of energy production. While the first edition of
Bergey’s manual is entirely phenetic, the second edition was based on phylogenetic
characters such as its DNA, RNA and protein.
In the current 9th
edition, the manual is designed for identification of bacteria that is very
different from the previous editions. In this edition, the bacteria are divided
into 35 groups in the four major divisions.
The first division
includes groups 1 to 16 (example: spirochete, sulphur-reducing bacteria,
chlamydia and rickettsia), the second division includes groups 17 to 29
(example: gram-positive cocci, endospore forming, gram-positive cocci and rods,
gram-positive, non-sporing rods), the third division includes group 30 such as
Mycoplasma and the the last division includes groups 31 to 35 (example:
methanogens, halophiles and archaebacteria).
Reference
Bergey's
Classification of Bacteria (byjus.com)
Bergey's
Manual of Systematic Bacteriology and Determinative Bacteriology
(microbenotes.com)
Bergey's Manual of Systematics of Archaea and Bacteria | Major Reference Works (wiley.com)
