Abstract: The epidemiological surveillance of drug-resistant strains of the fish pathogenic bacteria Vibrio anguillarum and Pasteurella piscicida carrying transferable R plasmids in fish farms is described. The DNA structure of R plasmids, and the drug-resistant determinants of R plasmids from the fish pathogens Aeromonas hydrophila,aeromonas salmonicida, Edwardsiella tarda, V. anguillarum, and P. piscicida are discussed.

Abstract: The isolation of mycobacteria from municipal and hospital water supplies prompted an investigation of the susceptibility of environmental and clinical isolates of mycobacteria other than Mycobacterium tuberculosis and Mycobacterium bovis to free chlorine. Experiments revealed that free chlorine concentrations of 1.0 mg l-1 eliminated 100,000 c.f.u. of the mycobacterial strains tested within 8 hours of exposure, whereas a concentration of 0.15 mg l-1 had virtually no bacteriocidal effect. Free chlorine residual levels of 0.1 mg l-1 or less, depending on the water temperature, within Boston, suggest that current disinfection procedures may not be adequate for effective control of potentially pathogenic mycobacteria in public water supply systems serving a population with increased risk factors.

Abstract: Pertussis toxin, an ADP-ribosylating toxin, interacts with vertebrate cells of many types and inhibits the ability of these cells to respond to certain hormones and neurotransmitters, resulting in a multitude of biological effects The structure and mechanism of action of this toxin are described

Abstract: One of the main causes of the world-wide eutrophication of rivers and lakes is the extensive use of phosphate in both detergents and agricultural fertilizers. Partial or total substitution of phosphates in household detergents by other compounds exhibiting chelating properties has been introduced in several countries to ameliorate such problems. Various microbiological aspects of the biodegradation of the complexing agents most frequently used such as aminopolycarboxylates, phosphonates, hydroxycarboxylates and polymeric polycarboxylates, as well as tripolyphosphates, are reviewed.

Abstract: Candida albicans, the major fungal pathogen of humans, is a diploid with no known sexual cycle. Recent genetic studies in C. albicans include the physical characterization of the genome, the development of systems for parasexual genetics, the cloning of Candida genes, and the development of methods for integrative and ARS-mediated transformation as well as gene disruption.

Abstract: Revue des principaux microorganismes de la microflore humaine. Discussion sur le role benefique de la microflore banale pour les vertebres: resistance vis-a-vis des microorganismes pathogenes, apports nutritionnel, reduction du taux de cholesterol, role dans les phenomenes immunologiques, detoxification, role de la microflore des produits laitiers fermentes chez les sujets ne tolerant pas le lactose

Abstract: The nematode-nematophagous fungus system offers excellent models for studies of interaction mechanisms between two groups of organism. Sufficient laboratory and field data are now available from studies at the physiological, biochemical, molecular and/or ecological levels to present a unified view of these diverse fungi, their survival strategies and their potential as regulators of nematode populations.

Abstract: Salmonella species can cause diseases ranging in severity from acute gastroenteritis to typhoid fever. These bacteria are considered as intracellular pathogens and produce several products which are required for entry and survival in the intracellular environment, in addition to factors necessary for existence in the gastrointestinal tract and the outside environment. The virulence factors used by these bacteria to cause these diseases are complex, and only recently have we begun to characterize these factors and determine the contribution they make to Salmonella virulence.

Abstract: The complement of glucan-hydrolysing enzymes produced by yeast species is considered to be relevant to morphogenesis, since this polysaccharide is the major structural component of the yeast cell wall. beta-glucanase systems of different species consist of both 1,3-beta- and 1,6-beta-hydrolases, which exert their action by either an exo- or an endo-splitting mechanism. The diversity of beta-glucanase systems, even among related species, is striking. The enzymes are produced for export, and the active forms of some of them seem to be generated upon secretion. Genetic approaches and the cloning of the glucanase genes are being used to clarify the biological role of the different enzymes. These also offer a possibility for genetic analysis of the functions related to cell wall dynamics with potential applications in biotechnology.

Abstract: Current knowledge on yeast microbodies is summarized. Emphasis is placed on their proliferation and metabolic function in relation to environmental conditions and the mechanisms involved in their biogenesis.

Abstract: Plants reacting hypersensitively to virus infection accumulate proteins that exert their activity in the cytoplasm, the cell wall or the intercellular space of the leaf. The function of a number of these proteins is described and the expression and structure of genes encoding the extracellular proteins is discussed.

Abstract: Outbreaks of food-borne listeriosis in recent years have caused governmental regulatory and health agencies and the food industry to focus on the problem of food contamination by Listeria monocytogenes. A review is presented of the association of L. monocytogenes with human illness and its occurrence in foods and the environment.

Abstract: A review and listing of antibacterial, antiviral and antiparasite factors in human breast milk is presented. Also reviewed are the microbial contaminants such as cytomegalovirus and rubella virus, which have recently been shown to infect infants via breast milk, without adverse effects. The retroviruses, human immunodeficiency virus and human T-lymphotropic virus type 1 have been detected in human milk, with the latter virus probably being transmitted through the milk. These virus contaminants can be destroyed by pasteurization of the human milk.

Abstract: The ruminant animal is dependent upon anaerobic microorganisms for the digestion of plant materials in the rumen. The resultant microbial cells and fermentation acids are primary nutrients for the animal. Polysaccharides, such as hemicelluloses, are only partially degraded because of the chemical complexities of plant materials and biochemical processes involved in degradation.

Abstract: Degradation of cell wall components of certain microbial species following phagocytosis by neutrophils and macrophages might involve the activation, by leucocyte cationic proteins, of the bacterial autolytic wall enzymes, leading to bacteriolysis. Lysozyme (a distinct cationic agent), which is the main muramidase present in leucocytes and in body fluids, might function not only as an enzyme but also as a potent activator of autolysis. Sulphated polyelectrolytes, proteolytic enzymes and oxygen radicals, which are released in inflammatory sites, might inactivate the autolytic wall enzymes, leading to the accumulation of peptidoglycan-polysaccharide complexes within macrophages. Activated macrophages are instrumental in initiating chronic inflammatory reactions. Undegraded microbial cell wall components also function as immunomodulators and as enhancers of non-specific resistance to infections and to malignancy.

Abstract: Epoxides are intermediates in the metabolism of many alkenes and aromatic compounds in higher organisms and in microorganisms. In microbial formation of epoxides, and further metabolism or excretion of these reactive compounds, many different enzymes are involved. Bacteria and fungi sometimes form optically active epoxides or are able to degrade epoxides enantioselectively, allowing the biotechnological production of these chiral building blocks in organic synthesis.

Abstract: DNA probes are useful for both identification and enumeration of specific bacteria and functional groups of bacteria in environmental samples. Because probes can detect genes, chromosomes, and plasmids, they also promise to be major sources of information about the relatedness of bacteria and groups of bacteria in the environment.

Abstract: Intracellular multiplication of Rickettsia tsutsugamushi, a causative agent of scrub typhus, was examined by electron microscopy of specimens prepared at various time intervals after infection of in vitro cultured cells. The sequential morphological growth cycle of the microorganism is presented diagrammatically.

Abstract: Microorganisms that are capable of growth at reduced water activities all rely on a common strategy for survival, i.e. the intracellular accumulation of a solute or solutes to balance the external water activity (aw), thus preventing the mass movement of water out of the cell. Understanding the physiological mechanisms that enable solutes to be accumulated and retained against strong concentration gradients, and the genetic controls on these processes may, in future, lead to the genetic manipulation of crop plants to increase their drought resistance.

Abstract: The genus Clostridium contains some of the most toxic bacteria known to man (e.g., Clostridium tetani, Clostridium botulinum) as well as solvent-producing organisms of biotechnological interest (e.g., Clostridium acetobutylicum). Developments within the areas of plasmid vector construction and plasmid delivery methodology now provide the opportunity for applying recombinant DNA technology to this important group of bacteria.

Abstract: Microcosms are used regularly in the study of the toxicity of environmental chemicals and their biodegradation. The use of these systems to study genetic interactions and adaptation mechanisms in soil and aquatic microorganisms is discussed, and their application to studies on the fate of genetically engineered organisms and their genes in the natural environment is outlined.

Abstract: Agrobacterium tumefaciens is a soil inhabitant that infects many dicotyledonous plants, causing crown gall disease. The success of Agrobacterium radiobacter K84 to control this disease in agroecosystems throughout the world has been impressive. This review describes the attributes of K84, its mechanism of control, its failures, and other alternative biocontrol agents.

Abstract: The discovery of teichoic acids in the cell walls of a number of actinomycetes suggests that these polymers are widespread in the order Actinomycetales. Structural variations in the teichoic acids are described and their possible physiological functions are discussed.

Abstract: Fungal zoospores respond to external stimuli in at least four phases of their activity: swimming, encystment, adhesion of the cyst and orientation of the germ tube. Specificity and recognition in these events are described and related to the ecology of zoosporic fungi.

Abstract: Recent concepts on the role of non-specific (normal) and specific (immune) defence mechanisms against fungal infection are discussed on the basis of the evidence obtained from experimental animals. Commonly occurring systemic mycoses, i.e. candidosis (candidiasis), cryptococcosis and histoplasmosis, are discussed.

Abstract: Specialized structures (periseptal annuli) appear at future cell division sites long before the division septum is formed. Studies of their biogenesis and localization are providing unexpected insights into the earlier stages of localization and differentiation of the division site.

Abstract: Biological N2 fixation is performed most effectively by prokaryotic diazotrophs when in mutualistic symbioses with higher plants. The most intensively studied N2-fixing symbioses involve leguminous plants and rhizobia. However, Frankia actinomycetes have attracted attention recently because they form root nodules on a broad range of non-legumes and because such nodules fix N2 as effectively as rhizobial nodules. Since the Frankia symbiosis results from an actinomycetic invasion of plant roots, it has been termed the 'actinorhizal symbiosis'.

Abstract: Mycobacterial antigens which play a major role in humoral and cell-mediated immune recognition are related to proteins which are induced in response to stress stimuli. The potential involvement of stress-induced proteins in infectious disease and in autoimmune responses is discussed.