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Actinomycetes
University of Udine, Mycology Department
ISSN: 0732-0574
Vol. 2, Num. 2, 1991
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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