When the domains of individual microorganisms overlap, it is likely that interactions will occur (Boddy and Wimpenny 1992) The outcome of these interactions is evaluated on the basis of the effect they have on population size (Odum 1953) regardless of whether the interactions are detrimental, neutral or beneficial The types of interaction found in mixed populations of microorganisms are classified on the basis of these effects as direct or indirect interactions (Bull and Slater 1982) Indirect interaction refers to competition, commensalism, mutualism, amensalism or antagonism and neutralism (Linton and Drozd 1982), and direct interaction to predation and parasitism (Frederickson 1977; Bull and Slater 1982) However, fermented foods and beverages develop their nutritional and organoleptic qualities as a result of the metabolic activity of a succession of different microorganisms and it is unlikely that the interactions will separate into these discrete groups since more than one type of interaction occurs simultaneously (Verachtert et al 1990) Present understanding of the positive, negative or neutral role of interactions between yeasts, bacteria and fungi has its origins the first time fermentation was employed The fermentation of many products includes interaction both within and between different microbial groups (eg yeast–yeast, yeast–bacteria, yeast–moulds), the physiological activity of which brings about desirable changes which decisively determine the character of a product and stabilise the population in a specific ecological niche (Wood and Hodge 1985; Leroi and Pidoux 1993; Geisen et al 1992; Rossi 1978; Challinor and Rose 1954) However, interaction does not necessarily only imply the positive or negative attributes within fermentation but it also involves the antagonistic activity of yeasts against other microorganisms by means of the production of microcins (Baquero and Moreno 1984; Golubev and Boekhout 1992), secretion of antibacterial and antifungal compounds, co-fermentation, and their role as in biological control Chapter 4

Yeast Ecological Interactions. Yeast'Yeast, Yeast'Bacteria, Yeast'Fungi Interactions and Yeasts as Biocontrol Agents

The parenteral administration of nonspecific agents for the stimulation of host resistance to bacterial infections has been investigated for many decades. The main efforts have been directed toward the enhancement of leukocytosis and phagocytosis, the induction of local inflammation, and the stimulation of an increase in production of natural or acquired antibodies or in the bactericidal power of serum. A wide variety of these nonspecific substances have been used clinically with varying success. These have been reviewed by Petersen' and by Perla and Marmorston,2 and they include such diverse preparations as animal and plant proteins, protein split products, enzymes, bacterial extracts and vaccines, tissue and leukocytic extracts, and colloidal metals. In 1923 Gay and Morrison3 demonstrated that the introduction of a mild irritant such as meat-infusion broth into the pleural cavity protected rabbits against a lethal dose of Streptococcus pyogenes injected 24 hours later. The accumulation of clasmatocytes in the thoracic cavity apparently accounted for this increased resistance. In the same year Opie* reported that a peritonitis induced with aleuronat, a plant protein, protected animals against intraperitoneal infection with streptococci introduced 2 days later. These results were associated with an increase in macrophages in the peritoneal exudate. Menkin5 has shown that potent chemical irritants such as aleuronat also stimulate the rapid formation of a fibrinous network, favoring development of a lymphatic blockade that contributes to the host defenses. In a more recent monograph, Menkin6 has summarized his studies of chemical constituents in exudates that influence accumulation of phagocytes in inflamed areas and that increase capillary permeability. According to Nakahara,? mice were rendered refractory to intraperitoneal infection with Diplococcus pneumoniae and other pathogens if they received an injection of olive oil in the same site 2 days earlier. The oil produced an exudate containing about 75 per cent macrophages. More recently, Nungester and Arne9 successfully controlled pneumococcal infections in mice with quaternary ammonium compounds that were devoid of bacteriostatic activity but were capable of stimulating phagocytosis in witro. Konowalchuk and his associatesg reported that intravenous administration of a preparation of colloidal sulfur 2 to 7 days before an intraperitoneal challenge with D. pneumoniae gave a high degree of protection but was without effect if the preparation was given simultaneously with the bacteria. Since this preparation was inhibitory to D. pneumoniae and other organisms in vitro, the protection was ascribed to a delayed antimicrobial action in vivo. The use of hog gastric mucin as an adjuvant for enhancing experimental infections, particularly in the abdominal cavity, is well known (Nungester, Wolf, and Jourdonais,*o and Miller\"). The literature on this subject has been reviewed by Olitzki.12 When mucin is injected 24 to 48

The effect of various substances on resistance to experimental infections

My assigned topic, “Chemical Methods of Stimulation of the Reticuloendothelial System,’’ (RES) seems rather too inclusive, since chemical intermediaries are released by almost every type of stimulus. If one were to discuss literally the chemical methods of stimulation of the RES, one would monopolize this entire monograph, since in the final analysis most influences on the RES a t a cellular and physiological level are chemical. I shall therefore limit this paper to a discussion of the influence of some exogenously supplied chemical compounds upon the system. In so doing it is not assumed that I am dealing with uncomplicated effects, since (1) the administration of any chemical or drug by a parenteral or oral route involves a variable amount of concomitantly administered stress to the animal, and (2) the detailed mode of action of the chemical or drug on the RES in eViwo therefore involves, in addition to the effects produced by the drug itself, responses to physical trauma involved in the procedure of administration. These effects may be minimized, but they cannot be eliminated. The best that one can hope to do is to make them as uniform as possible throughout the experimental groups. The point to emphasize is that we are always dealing with the effects produced by a combination of physiological stimuli on the RES. The specific problem in studying the chemical stimulation of the RES is so to standardize the procedures and the biological material as to be able to assign any changes we observe in function to the biochemical interactions of the compounds being investigated rather than to background effects produced by the technique; such effects must be kept minimal. Hence the multiplicity of the variables and the complexity of the problem of estimating the chemical stimulation of the RES is immediately apparent to the investigator entering this field, even prior to his selection of any given test or battery of tests, for background influences will affect drastically any assay chosen. Basically, we are dealing with a system so sensitive to external stimuli of all types as to challenge the very best efforts of the investigator in devising suitable tests with suitable controls for the analysis of its normal function. Such diverse environmental influences as starvation,’ X irradiation,2S3 environmentally conditioned and autonomic nervous reflexes: and genetics6 affect the ability of the system to react to hormones, drugs, and chemicals.

The reticuloendothelial system: i. chemical methods of stimulation of the reticuloendothelial system*

Substances with antibacterial activity were recovered from the extracellular medium and from the acidified cell extract of Saccharomyces cerevisiae R107 by binding onto a cation exchanger. The fraction eluted with NaOH contained two different antibacterial factors, one with the characteristics of lysozyme, the other apparently a small protein with a similar high pI. Die Isolierung von zwei bakteriziden, kationischen Proteinen aus Saccharomyces cerevisiae , die Bakterien des Saureabbaus hemmen Substanzen mit bakterizider Wirkung wurden sowohl aus dem Kultursubstrat als auch aus angesauertem Zellextrakt von Saccharomyces cerevisiae Rl07 mit Hilfe von Kationenaustauscher isoliert. Die mit NaOH eluierte Fraktion enthielt zwei unterschiedliche bakterizide Substanzen, eine mit Lysozymeigenschaften, die andere, ein kleines Protein, mit ahnlich hohem isoelektrischen Punkt.

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The isolation from Saccharomyces cerevisiae of two antibacterial cationic proteins that inhibit malolactic bacteria

Verschiedene Stamme der Gattung Saccharomyces werden in unterschiedlichen Bereichen der Medizin zu Therapiezwecken eingesetzt, in der Dermatologie zur Behandlung von Akne, in der Gastroenterologie zur Prophylaxe und Therapie von antibiotikainduzierter Diarrho und Reisediarrho.

Untersuchungen zur In-vitro-Wechselwirkung zwischen Saccharomyces boulardii und Enterobakterien

Since 1940 when we began a study of sensitization in laboratory animals treated with pertussis vaccine we have emphasized the role of the bacterial protein in this phenomenon. Considerable information has been accumulated which indicates that vaccination with Hemnophilus pertussis, while increasing resistance against infection by the same organism will, at the same time, produce hypersensitivity to the Hen?ophilus pertussis antigen. Such sensitivity, however, is not specific for pertussis but crosses with several other species of gram negative bacteria.1 28 Furthermore, mice immunized against pertussis are much more susceptible to infection by other gram negative bacteria than are their normal litter mates. Apparently, specific immunization can produce a non-specific lowering of resistance which predisposes the host to unrelated infections\"5 and this may well be listed as another untoward effect of bacterial allergy. Because bacterial protein has been shown to play a part in hypersensitivity and, from the above observation, is implicated in the etiology of infections, the search for an appropriate protein for desensitization was undertaken. The obvious selection was protein associated with the nucleic acid of the bacterial cell from the specific Henmophilus organism. Injection of this material reinforced the resistance of sensitized animals. However, since hypersensitivity is not species specific, the possibility of another source of comparable material was apparent and it was found that a commercial preparation of yeast sodium nucleate would not only reduce the hypersensitivity of vaccinated animals to the same pertussis antigen, but would make them refractory to gram negative bacteria. This logically lead to the possibility of protection for normal animals against similar infection. Our numerous experiments prove that normal mice after injection with sodium nucleate are protected against infection by Proteus, Pasteurella, Brucella and E. coli organisms. Subsequent studies indicated that different brands of sodium nucleate were variable in potency; some were even inactive. Furthermore, the protective dosage of the active preparations ran as high as 100 mg./mouse. In search of the active principle we looked to the

Parfentjev Ia

Papers

A fraction of commercial yeast which protects against bacterial infection.