Pure Culture Method Research Articles

Importance of overwintered early blight-infected potato vines in Maine

Much has been published on laboratory techniques for induction of sporulation of the potato early blight fungus, Alternaria solani (Ell. and Mart.) Jones and Grout. Douglas and Pavek (2, 3) briefly discuss this work in a report outlining a pure culture method they use to prepare inoculum for field resistance tests. Barclay, et al (1) and Venette and Harrison (9) have used a filter paper method described by Lukens (7) for the purpose. Conversely, early workers such as Folsom and Bonde (4) and Gratz and Bonde (5) favored use of infected vines as their inoculum source. The purpose of the report is to reaffirm the importance of overwintered diseased vines for both natural and artificial dissemination of early blight. Commercial Farms--Maine growers following short rotations and especially those who practice continuous cropping were found to have an increasing problem with early blight. Examination of their fields yielded dead vines carrying spores of the causal fungus. Tests showed that these spores were viable and that they readily produced infection on potato. Spore-trapping--Simple weather vane-type spore traps were used to approximate the time when primary inoculum first appeared (6). As expected, the most frequent trapping of spores occurred in a field having a high incidence of early blight the previous year. Spores were found around the first week in July each year that trapping was conducted. Fungicide Tests--In recent years tests have been conducted in Maine to determine the efficacy of fungicides and application schedules for control of early blight (8). During the course of this work it was found that dried, diseased vines, were an excellent source of primary inoculum. Each year at the conclusion of a field experiment but prior to application of a chemical defoliant, infected vines are collected and dried in the greenhouse. The dried vines are stored in an open shed through the winter. When needed the following year, they are pulverized through a coarse sieve. Inoculum thus prepared is sprinkled on potato foliage in the evening during a period of light rain or when dew is present. This procedure results in heavy and uniform infection provided that the material is distributed evenly.

Comparative Nutrition of Two Species of Blastocladia

American Journal of BotanyVolume 44, Issue 3 p. 218-224 Article COMPARATIVE NUTRITION OF TWO SPECIES OF BLASTOCLADIA Jean M. Crasemann, Jean M. Crasemann Department of Botany, University of California, Berkeley, CaliforniaThe contributions of Dr. Ralph Emerson and Dr. Leonard Machlis to the present study are numerous and include everything from patient instruction on pure-culture methods and discussions on physiological research to advice on the preparation of the manuscript. I am deeply grateful to them for the help which they gave so generously and enthusiastically.Search for more papers by this author Jean M. Crasemann, Jean M. Crasemann Department of Botany, University of California, Berkeley, CaliforniaThe contributions of Dr. Ralph Emerson and Dr. Leonard Machlis to the present study are numerous and include everything from patient instruction on pure-culture methods and discussions on physiological research to advice on the preparation of the manuscript. I am deeply grateful to them for the help which they gave so generously and enthusiastically.Search for more papers by this author First published: 01 March 1957 https://doi.org/10.1002/j.1537-2197.1957.tb08233.xCitations: 7 AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume44, Issue3March 1957Pages 218-224 RelatedInformation

ATTEMPTS TO APPROACH TO THE CLARIFICATION OF CHEMICAL COMPOSITION OF MYCOBACTERIUM LEPRAEMURIUM

In the previous report (1), an isolation method of Myc. lepraemurium from subcutaneous tissue of rat infected with rat leprosy bacilli by means of chloroform fractionation, the infectivity of the isolated bacilli, and some other properties, i. e. nitrogen, phosphorus, and amino acid contents in the concentrated bacilli were described. The purpose of this present paper is to report further efforts toward the clarification of other properties of the bacilli which are obtained by the same method as the previous report (1). Furthermore, if any different properties will exist between Myc. lepraemurium and other acid-fast bacilli which can cultivate in vitro, they will suggest some idea of attempt to the pure culture method of Myc. lepraemurium.

ATTEMPTS TO APPROACH TO THE CLARIFICATION OF CHEMICAL COMPOSITION OF MYCOBACTERIUM LEPRAEMURIUM

Because of undiscovery of pure culture method of Myc. lepraemurium in vitro, the bacterial cells have not been separated purely from infected tissue. Any study on the chemical composition of the bacilli, therefore, has not been reported. However, the pure isolation of the bacterial cells from infected tissue and the studies on chemical composition of the bacilli should be attempted in order to approach toward determination of their properties and discovery of the pure culture method of the bacilli. Hanks (1) and Gray (2) reported the isolation of the bacilli from infected rat testicles employing Hogeboom, Schneider, and Palade's method (3) for isolation of mitochondoria, for the studies on the metabolism of murine leprosy bacllli. Toda and Lew (4), and Dharmendra and Mukherjee (5) reported also the isolation of pure bacterial cells by means of toluol or chloroform fractionation for preparing the antigen of Mitsuda reaction (6). The purpose of this present paper is to report the efforts toward the isolation method of Myc. lepraemurium from infected tissue by several fractionations employing organic solvents, and the clarification of some properties of the bacilli which are obtained by the method mentioned above, and to determine whether chemical differences exist between Myc, lepraemurium and other acid-fast bacilli which can cultivate in vitro or not.

The Biphasic or Soil-Water Culture Method for Growing Algae and Flagellata

Progress in microbiology, as a result of the adoption of pure-culture methods, has been so striking that in the opinion of some biologists a culture not free of bacteria is not a real culture at all. The statement that bacteria-containing cultures of various kinds may be of use, and the enumeration of successive stages in the attempt to obtain pure cultures (Pringsheim, 1926, p. 287), has, for this reason, led to misunderstandings. To-day, after many more years of research in this field, I can emphasize that uni-algal cultures containing a certain amQunt of bacteria are in more than one respect a suitable basis for investigationi. They are often not merely a preliminary to the production of pure cultures but, if based on ecological considerations, they may also be the best approach to the biology of a form. The matter in question is therefore of more than technical importance. Without cultures originating from single cells, progress along diverse lines would be arrested, and the elucidation of many problems of algal physiology, taxonomy and ecology would take place far more slowly than would be possible with the help of the method described in these pages. One often meets with a few algal cells or filaments which are of special interest but cannot be identified for one or more of the following reasons: scanty representation, absence of reproductive stages, quick movement, the necessity of performing microchemical tests, of applying stains or utilizing special optical equipment. Such obstacles to detailed investigation may be encountered every time they are observed. It may be argued that forms which are only represented by a few individuals are unimportant, but such scarcity may be misleading. The individuals may be concentrated round a particular spot, e.g. a decaying worm, within the habitat. If a certain quantity of water and mud is gathered, the forms inhabiting ecologically different micro-habitats become mingled with one another. In fact biological investigations have often hitherto been restricted to species occurring in relatively dense communities, a condition which may never be realized in nature in the case of various species. This was so with the Astasiaceae, most species of which remained unrecognized until single-celled putrefaction cultures were prepared (Pringsheim,

Guignardia Rhodorae, the Perfect Stage of Phyllosticta Maxima on Rhododendron

SUMMARYIn this study an ascigerous stage, originally described as Sphaerella (Laestadia) Rhodorae Cooke, is connected by means of pure culture methods with its pycnidial stage P. maxima Ellis & Ev. and its spermagonial stage P. Saccardoi Thüm. The characteristics of the perithecial stage are considered to be those of the genus Guignardia and the name G. Rhodorae (Cooke) comb. nov. is proposed. Synonyms are listed.P. maxima is considered a distinct species and not synonymous with P. Rhododendri West, as reported by Ellis and Everhart. It is also considered distinct from the fungus determined by Tengwall as P. maxima and reported by him as the imperfect stage of Venturia Rhododendri Teng.

TIMBER DECAY*

SummaryAfter a brief historical introduction, attention is drawn to the importance of the correct sylviculturaj management of woodlands in the production of clear, disease‐free timber. Methods for the identification of the organisms which cause decay in timber are discussed, and the importance of pure culture methods is stressed. The principal contributions to the general descriptive work on timber decay in various countries are referred to, and it is pointed out how the usefulness of much of this work has been enhanced by the publication of books and monographs collating this scattered information. In a discussion of the physiology of wood‐rotting fungi the temperature relations and nutritional requirements, growth in relation to pH, and moisture content of the substratum are considered. The unsatisfactory state of present‐day knowledge of the enzymes of wood‐decaying fungi is mentioned. Recent work on the metabolic products of wood‐rotting fungi is referred to briefly. The effects of decay on the physical properties of wood are described, i.e. on the density, strength and optical properties, etc. The mechanical strength of timber, especially the toughness, may be appreciably affected in a very early stage of decay before any measurable loss in weight has occurred. The chemical changes brought about during the decomposition of wood are discussed. Rot of timber can be classified chemically into two main types: brown rots, in which only hydrolysis of cellulose and other polysaccharides occurs, and white rots, in which all the constituents of the wood, including the lignin, are attacked in varying degrees and in which oxidizing as well as hydrolysing enzymes are present. The effect of fungal attack on the microscopic structure of wood is described, and the theories put forward to explain the penetration of the cell walls by hyphae are critically examined. Methods of determining the natural resistance to decay of timber in the laboratory are referred to, and the basis of natural durability in wood is shown to lie mainly in the nature of the chemical ‘extractives’ present in the wood. Recent advances are described in the use of water‐soluble wood preservatives which become fixed in the wood by the addition of a chromate to the treating solution, and the establishment of a British Standard method of test and the use of field tests are noted. Finally, attention is drawn to the great lag in the application to practice of recent advances in the study of timber decay and its prevention.

IS HETEROAUXIN A GROWTH‐PROMOTING SUBSTANCE?

SUCH A VOLUMINOUS literature has grown around auxins that it is neither possible nor advisable to include a comprehensive survey of it within the scope of a short paper. The reader is referred to Boysen Jensen's (1936) book, which treats the subject very exhaustively. In experiments with heteroauxin (indole-3-acetic acid) the Avena-coleoptile test has been used by most workers as a standard, and the bending of the coleoptile has been freely ascribed to the hormone-like property of this substance. Yet we have no satisfactory explanation for the fact that the same substances which seem to induce growth in coleoptile, foliage leaves, hypocotyls, and stems inhibit the elongation of the roots. But roots are not the only organs to be suppressed; Le Fanu (1936) found that the axillary buds of Pisum sativurn on single-node stem cuttings were inhibited when the ends were placed in heteroauxin solution, and when whole shoots were placed in this solution the growth of the young stem was inhibited; similarly, buds of cuttings were inhibited when heteroauxin was applied below or above the bud. Solacolu and Constantinesco (1936) observed that within the limits of concentration used, heteroauxin prevented the development of the radicle and the plumule during the germination of Ricinus and Phaseolus, and that tumors were produced at the level of the collar or along the axis of the hypocotyl. Most data on the effect of auxins have been obtained within a few hours of the initiation of the experiments. What would happen if the time were extended? Since this is possible largely by pure culture methods, the work presented in this paper follows microbiological technique. About one hundred different fungi, seven different unicellular green algae, and corn seedlings were used as test plants. Fungi are particularly well suited for experiments with growth-promoting substances because many of them 'iIi not grow in a medium consisting of dihydrogen potassium phosphate, 0.5 g., magnesium sulfate, 0.5 g., ammonium nitrate, 1 g., and dextrose, 5 g. in 1000 cc. of distilled water. Consequently, one can readily observe whether or not a given substance is capable of inducing growth. Many other fungi grow readily in such a synthetic medium. The following representative fungi of the first group were tested in our work: Allomyces javanicus, Basidiobolus ranarum, Blakesleea trispora, Chaetocladium brefeldii, Conidiobolus villosus, Dasyobolus immersus, Dicranophora fulva, Pilaira moreaui, Plectospira gemmifera, Phytophthora cactorum, Pythium polymastum, Pythiomorpha gonapodioides, Phycomyces nitens, Saproleqnia diclina, and Thamnidium chaetocladioides. Of the second group of fungi the following, among many others, were used:

Effect of 4-6 Dinitro-O-Cresol on Oxidation of d'- and l'-Arabinose by Previously Starved Yeast.

It has been shown in previous papers from, this laboratory that the respiratory rate of yeast suspended in non-nutrient phosphate buffer solutions or in glucose phosphate can be markedly increased on treatment with proper concentrations of 2–4 dinitrophenol (DNP), 4–6 dinitro-o-cresol (DOC) and some related compounds.1–5 We report herewith the results of experiments in which it is shown that the effects of such metabolic stimulants upon the respiration of yeast is profoundly affected by the type of “exogenous”6 carbohydrate fuel available.A pure culture of Saccharomyces cerevisiae and pure culture methods were used throughout. The experimental procedures were the same as described previously2,3 except that yeast was first grown 48 hours on Orla-Jensen agar medium, then taken up in 0.2M phosphate buffer, pH 6.8, and starved 24 hours under aerobic conditions in Fraser tubes7 at 25° ± 0.02°C. before the beginning of each experiment. Respiration was measured in the conventional form of Warburg apparatus at 25...

Traité d'algologie: introduction à la biologie et à la systématique des algues

THIS volume is primarily a comprehensive treatise on the structure and morphology of the Algae. It contains also useful summaries of recent work on their cytology, physiology, biology and fossil occurrence. In the absence of recent works of this character, it is a distinctly useful volume and may well become a standard work of reference. The morphological chapters are, on the whole, judiciously treated and the illustrations, often original, are good and well chosen. Where so much ground is adequately covered, it is perhaps ungracious to remark that the treatment is in parts rather uneven, notably in the chapters on algal physiology and on pure culture methods. Moreover, the Rhynic fossil algae should certainly be mentioned in any chapter dealing with that subject, as they are the earliest the structure of which is known.

Some Pure Culture Methods in the Algae

Too much confidence has frequently been placed by algologists in their ability to recognize a given species of alga among varying numbers of other species, and in the various forms which it may assume-a fact which has led to much confusion and error, especially among members of the Protococcales. While it is now definitely known that in a number of algoe a single species may present markedly dissimilar appearances, either as a result of varying environmental conditions, or because of the presence in the life history of several unlike stages, it is certain that much of the so-called polymorphism, or pleomorphism, of algae finds its explanation in inadequate methods of study. It is becoming recognized that for life history studies in the algae it is necessary to employ cultures free from other species of algae. Even in cases where this is not, on first thought, necessary, as in the large, filamentous forms, it should be observed, for the possibility of introducing spores or sporelings of closely allied species is by no means excluded in all cases. Gratifying.progress has already been made by some algologists, working especially with members of the Volvocales and Protococcales, and it seems reasonably certain that the originally chaotic condition existing in the latter will be ultimately reduced to complete order by a careful observance of the necessity of working with pure cultures, or at least cultures containing but a single species of alga. In life-history studies where physiological differences between species are to be investigated, it is especially desirable and indeed necessary to employ pure cultures. Certain species of algae, especially representatives of the Chlorophycece, have been much used in physiological investigations-chiefly those concerning themselves with various

II. On the histology of uredo dispersa , erikss., and the "mycoplasm" hypothesis

There are still so many and such important gaps in our knowledge of the biology of the Uredineæ, that no one will expect an apology for a serious attempt to fill any of them, and the less so in the particular case of the Rust-fungi of the Gramineæ and cereals, because, notwithstanding the numerous researches which have succeeded each other since De Bary’s classical investigations, the whole question of the origin and spread of epidemics of rust has been raised again owing to the remarkable discovery of the specialised parasitism exhibited by certain adapted races of these fungi, and to the still more remarkable assumptions published by Eriksson in what is known as the “Mycoplasm” hypothesis. I have from time to time brought before the notice of the Royal Society and elsewhere, the results of my own investigations into the biology of that particular form of Rust-fungus known as Puccinia dispersa , Erikss., more especially with reference to its peculiar parasitism on the grasses of the genus Bromus , and have treated successively of the questions of predisposition and immunity, of the relations between the host and the parasite, of the method of pure cultures of such a Uredine as the one in question, and of the effects of mineral starvation on its parasitism. In all these cases, however, the studies were chiefly experimental, dealing with the physiology of infection, and the publication of the results of the extensive and far more laborious microscopic investigations was reserved, a few remarks only being made here and there showing the directions in which these were leading from time to time.