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Actinomycetes
University of Udine, Mycology Department
ISSN: 0732-0574
Vol. 2, Num. 2, 1991
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Actinomycetes, 1991, Vol.2, Part 2. pp. 43-47
Minimum description of new taxa of Actinomycetes
ALMA DIETZ
Microtax, 2929 Memory Lane, Kalamazoo, MI 49007 USA
Code Number: AC91009
Size of Files:
Text: 19.1K
Graphics: No associated graphics files.
Abstract.
Criteria for minimum description of taxa of actinomycetes is
given with this paper. It can be concluded that specialists
and senior taxonomists have responsibilities to their
profession. Experience acquired from years of exposure to the
developing field of actinomycete systematics should be
consolidated in a useful manual. It is time for actinomycete
taxonomists to unite. Let us unify our objectives to 1)
provide standards for minimum description of taxa and 2) to
provide useful keys to these taxa.
The topic which I have been asked to address at this gathering
of individuals interested in actinomycetes is one in which I
have long had a keen interest and one which is a challenge to
me to address and to you to consider.
When the famous International Streptomyces Project (ISP)(1)
was initiated the major concern was minimum descriptions of
species of the Genus Streptomyces.
Those present who have been responsible for characterizing
actinomycetes for more than 15 years and those who are
confronted with the practical problem of identifying
actinomycetes are facing a dual dilemma. New genera are
being proposed in increasing numbers; new species in the new
genera are being proposed at a similar rate. Actinomycete
taxonomists now find themselves in a state of chaos that is
more troublesome than that of the pre-ISP day. What is a
satisfactory description of a new taxon of actinomycetes? What
is a satisfactory description of a new species in a taxon?
Objectives
In considering my topic I decided that I had three objectives
1) Define the Problem(s), 2) Propose Guideline, 3) Recommend
Future Strength(s).
Discussion
This segment of my presentation will deal with the Objectives
set forth above. As a prelude to Defining the Problem(s) short
definitions are given for 'Description' and 'Taxon'.
'Description' is defined as 'a statement of the
characteristics of a specimen or taxon'.
'Taxon' is defined as 'a taxonomic group of any rank differing
in physical and chemical properties from another group '.
1. Define the problem(s).
Individuals working with actinomycetes have needs of which
they will be unaware until they find themselves in a pressure
situation. As I have stated many times, I know of no courses
that will prepare a systematics candidate for dealing with the
unique group of microorganisms known as the
Actinomycetales. Therefore, I consider the following
information essential background material for the study of the
taxa in this group.
A. Reliable, reproducible methods for growth and
characterization:
This has been a consuming interest of mine since I became
acquainted with these organisms in a Soils Microbiology course
at the University of Michigan in 1947. The instructor was Dr.
Kenneth L. Jones. I owe him a debt of gratitude for introduc-
ing me to the actinomycetes and their properties which make
them a systematic enigma. I am also indebted to The Upjohn
Company for making it possible for me to develop very
reproducible in-house methods for characterizing members of
the Actinomycetales. My peers have developed methods
that work for them. An excellent example is the "ACTINOBASE:
An image Database for the identification of Actinomycetes"(2).
Many taxonomists saw this for the first time when it was
demonstrated by Dr. Akio Seino of RIKEN at ISBA'88 in
Tokyo.
B. In-house culture collection:
The strength of the work cited in A. is based on having an
excellent in-house culture collection of actinomycetes. This
makes possible careful comparison of described and recently
isolated strains of interest. There are no practical keys for
identification available at this time except those presented
in the 8th Edition of Bergey's Manual(3).
C. Literature searching:
An In-House Collection cited above is the result of searching
culture catalogs, and doing intensive literature searching of
for ex.: Current Contents-Life Sciences(4), and two Derwent
publications - RINGDOC Drug Information (Thematic M-
Microbiology(5)) and Alerting Abstracts Bulletin B
Pharmaceuticals(6). Perusing Patent Abstracts is essential if
one desires to keep up with new names and culture deposit
numbers in the patent literature. One must also be familiar
with journals such as Actinomycetes(7) and
Actinomycetologica(8) which may not be covered by abstracting
services. Scientific Society Programs are also an excellent
source of new names before they appear in publications.
Reading these publications will only be useful if the reader
is skilled in the field of nomenclature of diverse groups of
microorganisms and of the Animal and Plant kingdoms in
general.
D. Files:
The serious taxonomist will compile cross-reference files of
names, numbers, and significant properties and products of
described cultures. This will lead to [l] a familiarity with
the List of Approved Names recognized by publication in the
International Journal of Systematic Bacteriology (IJSB)
according to the Rules of Nomenclature(9) and [2] to a list of
"unapproved names" compiled from the readers literature
searches. Here is the problem. The unapproved names list and
the cross reference files can provide significant information
to the industrial taxonomist concerned with not reusing a
name. This person will have searched all references for
comparison descriptions to determine newness of his
material.
E. Description of taxon:
Although a name is validated by publication in the IJSB there
is no mechanism for determining the novelty of the described
entity. It may well be identical to one previously validated.
Determination of this depends on the serendipity of a reader
who may obtain and compare the cultures. How is the newcomer
to the field to know this? Certainly not by using Vol. 4 of
Bergey's Manual of Systematic Bacteriology(10) in which names
and descriptions have been rendered unrecognizable. This is
exemplified by the description of Streptomyces hawaiiensis.
The color pattern and spore surface type no longer match
the very valid/SP description of the culture(11).
The issue of concern in this presentation was addressed by Dr.
Thomas G. Pridham in a 1970 paper, "Nomenclature of Bacteria
with Special Reference to the Order Actinomycetales"(12).
The paper is recommended as required reading for those
concerned with the problem that I am trying to address. The
following quotes are ones that we should not forget: "...the
principal reason for naming a microorganism ...(is) to
facilitate communication" and "Applied microbiology and the
research team present many new problems to the nomenclature of
microorganisms, particularly the Actinomycetales and
other taxa of industrial-economic interest."
F. Industrial interest (Applied Microbiology):
Industrial interest has led to the discovery and description
of many actinomycetes. Industrial taxonomists are frequently
part-time taxonomists. Since the ISP ended a commitment to
cooperative studies has not existed. Therefore, it is fitting
that an effort be made at this session to address the issue
that is the subject of this presentation, "Minimum Description
of New Taxon of Actinomycetes. Our host actinomycete
taxonomists have long expressed an interest in what is
required for a good published description of an actinomycete
taxon. With this in mind, I move on to my second objective.
2. Proposed guidelines.
Discussion of the proliferation of new genera of actinomycetes
has served as a subject of interest to me for several
years(13,14). How is an actinomycete taxon recognized? What
process is used to determine novelty or similarity? What
resources are available?
In spite of all the interest in actinomycetes, there has been
no collaborative effort to establish guidelines for the de-
scription of taxon of actinomycetes other than the
streptomycetes. Our colleagues in Japan seem to be the only
ones concerned with this problem. The foremost journals
concerned with descriptions of actinomycetes are the
Journal of Antibiotics and Actinomycetologica. Editors of
both journals recognize that definitive guidelines can lead to
improved papers for publication. This year the Journal of
Antibiotics(15) has introduced minimal guidelines for the de-
scription of actinomycetes. The criteria are based on two
articles by Dr. Lechevalier(16,17) and the ISP Procedures of
Shirling and Gottlieb(1). It is my firm belief that these are
the criteria to which we should adhere.
Genus and Species Determination. With this presentation I am
suggesting tests that should give reproducible results in any
laboratory. The recorded observations should enable the
scientist to prepare a description that can be understood and
reproduced in any comparable laboratory. Results can not
be expected to be reproducible if the work is done by
different inexperienced technicians. The scientist should be
experienced in adherence to standardized procedures. controls
should be run at all times.
When I first came to the study of actinomycetes many of the
media used for cultivation and characterization were those
used for studies of unicellular bacteria. The media were
unreliable and supported minimal growth.
Experiments conducted in many laboratories resulted in the use
of quality organic and inorganic media formulations. Growth
was heavy and definitive for color and microscopic
observations. Media selected for the ISP were the result of a
compromise. Growth is usually heavy; pigment production is
rarely definitive. Many taxonomists supplement these media
with ones found useful in their laboratories(16). Microscopic
properties are usually easy to determine.
Both light microscopy and electron microscopy must be used.
The invaluable diagnostic properties of spore chain
development and spore surface type are best observed with the
scanning electron microscope.
Chemotaxonomy and biotechnology now play important roles in
the preparation of descriptions of actinomycetes.
Chemotaxonomy has led to the designation of the many new
genera. One of the tools of biotechnology, Polyacrylamide Gel
Electrophoresis (PAGE), is valuable for species confirmation
or differentiation(14).
It is possible that we may find chemotaxonomy to be just
another test condition to be run. Investigators are now
analysing sporulation structures and vegetative structures and
detecting different isomers of DAP on the same culture. Both
LL and meso forms have been reported for some cultures.
This may have been the result of using shake-flash growth.
Fermentation microbiologists are well aware of the formation
of aerial growth on the sides of shake flasks. A technician
using shake flask growth for chemotaxonomic studies might not
note the mixture. However, determinations done on the
different structures can yield valid results.
Appended to this manuscript are pages containing the
SPECIFIC GUIDELINES proposed. It is my recommendation
that we build on the resources available through the
ACTINOBASE. This computer program should lend itself to
modification as improved methodologies appear. As a computer
program, it could be made available to the serious taxonomist.
It is possible that annual fees could be assessed for
subscription to the service or that it could be offered
on-line for a fee.
Resources
The RESOURCE MATERIAL that I consider useful is listed
after the specific guidelines. The material was selected
because reproducibility of results is stressed.
Reproducibility is essential to individuals in the applied
fields (agriculture, industry, medicine) which depend on
accurate determinations of identity. I consider this
comparable to a service I perform for the West Michigan Poison
Control Center when someone ingests an unidentified
mushroom.
Resources may be put in two categories:
Present: References giving procedures that are
reproducible.
Proposed: Reference material that I hope will be produced
by an international collaborative effort.
Philosophy
It is not my intent to ignore the interesting work done in the
interest of the advancement of knowledge of the actinomycetes
by the British group promoting Numerical Taxonomy or by the
German group promoting phylogeny. The concerns which I
perceive needed to be expressed here are practical. We have
the discoverer of a new entity who needs to prepare an
acceptable description of that entity.
We also have individuals interested in reexamining all the
material that has been described and applying arbitrary
weights to the material for evaluation. In other words, living
material with its variables is treated like inanimate
material. Statistical methods can greatly distort the
character of the material being analysed if the biological
variation in taxonomic characteristics are overlooked.
This leads to the need to COMPROMISE- It is hoped that
collaboration and discussion of significant characteristics
can lead to the development of a rational analysis of
described actinomycetes. It is important for the numerical
taxonomist to know of which strain of for example,
Streptomyces viridochromogenes, he speaks. Many are
misnamed. This is also true of the novobiocin-producing
strains. Such misnaming cannot be avoided if the cultures are
discovered at the same time in different laboratories and
interest in them leads to published descriptions. Many
individuals believe that the streptomycetes are overspeciated.
From my practical experience, I disagree. Many, like the S.
viridochromogenes strains, are misnamed and should be
given new species names. Others like the novobiocin-producers
should be reduced to synonymy. A computer search based on a
program such as that used for ACTINOBASE could help
resolve the problem.
THE RIGHT AND THE NEED TO KNOWN as much as possible
about actinomycetes described in various publications is
critical to the applied microbiologist. This person has a set
of ethics to abide by in performing his task of describing a
new taxon. It is time to cite the resources that will enable
him to perform with competence.
In reviewing material for this presentation, I have come to
realize that university courses cannot be offered on the
subject of actinomycete systematics because those in the
teaching field would never have been exposed to the vast
resources at the disposal of the industrial microbiologist.
Acknowledgement-
I wish to thank Dr Okami and his colleagues for inviting me to
participate in this challenging session.
References
1) Shirling, E.B. & D.Gottlieb: Methods for characterization
of Streptomyces species. Int.J.Syst.
Bacteriol., 16: 313-340, 1968.
2) Ugawa, Y.; K.Sugawa, T.Kudo, H.Sugawara, Y.Tateno &
A.Seino: ACTINOBASE: An image database for identification of
actinomycetes. In Trends in Actinomycetology in Japan.
Actinomycetologica Forum 1989 (ed. Y.Koyama), pp. 17-19,
Society for Actinomycetes, Japan, 1989.
3) Pridham, T.G. & H.D.Tresner: Family VII.
Streptomycetaceae Waksman and Henrici 1943, 339. In
Bergey's Manual of Determinative Bacteriology 8th ed."
(eds. R.E. Buchanan and N.E.Gibbons), pp. 747-845, Williams
& Wilkins, Baltimore, 1974.
4) Current Contents, Life Science (ISSN 00113409). Institute
for Scientific Information (R) Inc. (ISI), Philadelphia.
5) RINGDOC Drug Information, Thematic Microbiology, Derwent
Publications Limited, London.
6) Alerting Abstracts Bulletin B Pharmaceuticals. Chemical
Patents Index, Country Order, Derwent Publications Limited,
London.
7) Actinomycetes. (Formerly published by Waksman
Institute of Microbiology at Rutgers, the State University of
New Jersey, USA) Ceta/Actinomycetes, Gorizia, Italy.
8) Actinomycetologica. The Society for Actinomycetes,
Japan, Tokyo.
9) Lapage, S.P., P.H.A.Sneath, E.F.Lessel, V.B.D.Skerman,
H.P.R.Seeliger & W.A. Clark: International Code of
Nomenclature of Bacteria. 1976 Revision, Am. Soc.
Microbiol., Washington D.C., 1975.
10) Bergey's Manual (R) of Systematic Bacteriology Vol.
4 (eds. S.T.Williams et al.), Williams & Wilkins,
1989.
11) Shirling, E.B. & D.Gottlieb: Cooperative descriptions of
type cultures of Streptomyces. 11 Species
descriptions from first study. Int. J. Syst.Bacteriol.,
18:130-131,1968.
12) Pridham, T.G.: Nomenclature of bacteria with special
reference to the Order Actinomycetales. Int. J. Syst.
Bacteriol., 21:197-206, 1971.
13) Dietz, A.: Structure and Taxonomy of Streptomyces.
In "The Bacteria, Vol. IX.
Antibiotic-Producing Streptomycetes" (eds. S.W.Queener &
L.H.Day), pp. 1-25, Academic Press Inc., New York, 1986.
14) Dietz, A.: Practical and proposed cooperative
investigational criteria for taxonomic studies of the
actinomycetes. In "Biology of Actinomycetes '88" (eds.
Y.Okami, T.Beppu & H.Ogawara), pp. 203-209, Japanese
Scientific Societies Press, Tokyo, 1988.
15) J. Antibiotics, 43: 8, 1990.
16) Dietz, A. & D.W.Thayer: Eds., Actinomycete Taxonomy, SIM
Special Publ. No. 6, Soc. Ind.Microbiol., Arlington,
Virginia, 1980.
17) Lechevalier, H.: Criteria to be used in the description of
new actinomycetes. Actinomycetes and Related
Organisms, 16: 46-48, 1981.
18) Lechevalier, H.A.: The actinomycetes. III. A practical
guide to generic identification of actinomycetes. In
"Bergey's Manual Systematic Bacteriology, Vol. 4"
(eds. S.T. Williams et al.), pp. 2344-2347, Williams &
Wilkins, 1989.
Copyright 1996 C.E.T.A., The International Centre for
Theoretical and Applied Ecology, Gorizia
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