Showing papers on "Bacteria published in 1993"
TL;DR: The biochemical and genetic characteristics of these antimicrobial proteins are reviewed and common elements are discussed between the different classes of bacteriocins produced by these Gram-positive bacteria.
Abstract: Lactic acid bacteria produce a variety of bacteriocins that have recently come under detailed investigation. The biochemical and genetic characteristics of these antimicrobial proteins are reviewed and common elements are discussed between the different classes of bacteriocins produced by these Gram-positive bacteria.
2,013 citations
Book•
01 Jan 1993
TL;DR: This chapter discusses the development of approaches to bacterial systematics in theory and practice as well as the practical application of these approaches in the field of bacteriology.
Abstract: Foreword Introduction 1. Classification and nomenclature 2. Culture media: constituents and sterilization 3. Principles of isolation 4. Bacterial characters and characterization 5. Theory and practice of bacterial identification 6. Characters of Gram-positive bacteria 7. Characters of Gram-negative bacteria 8. Taxonomy in theory and practice 9. Bacterial identification by cards 10. Bacterial identification by computer 11. Quality control in microbiology 12. Reconciliation of approaches to bacterial systematics Glossary References Index.
1,361 citations
01 Jan 1993
TL;DR: The present taxonomy relies partly on true phylogenetic relationships, largely based on morphology, mode of glucose fermentation, growth at different temperatures, configuration of the lactic acid produced, ability to grow at high salt concentrations, and acid or alkaline tolerance.
Abstract: Lactic acid bacteria (LAB) constitute a group of gram-positive bacteria united by a constellation of morphological, metabolic, and physiological characteristics The general description of the bacteria included in the group is gram-positive, nonsporing, nonrespiring cocci or rods, which produce lactic acid as the major end product during the fermentation of carbohydrates The LAB term is intimately associated with bacteria involved in food and feed fermentation, including related bacteria normally associated with the (healthy) mucosal surfaces of humans and animals The boundaries of the group have been subject to some controversy, but historically the genera Lactobacillus, Leuconostoc, Pediococcus, and Streptococcus form the core of the group Taxonomic revisions of these genera and the description of new genera mean that LAB could, in their broad physiological definition, comprise around 20 genera However, from a practical, food-technology point of view, the following genera are considered the principal LAB: Aerococcus, Carnobacterium, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Oenococcus, Pediococcus, Streptococcus, Tetragenococcus, Vagococcus, and Weissella The genus Bifidobacterium, often considered in the same context as the genuine lactic acid bacteria and sharing some of their typical features, is phylogenetically unrelated and has a unique mode of sugar fermentation The classification of lactic acid bacteria into different genera is largely based on morphology, mode of glucose fermentation, growth at different temperatures, configuration of the lactic acid produced, ability to grow at high salt concentrations, and acid or alkaline tolerance Chemotaxonomic markers such as fatty acid composition and constituents of the cell wall are also used in classification In addition, the present taxonomy relies partly on true phylogenetic relationships,
995 citations
TL;DR: In this article, the mass-transfer kinetics of the immobilized bacteria and the electrode surface were investigated and a computer-controlled carbohydrate feed system enabled the cell to generate a constant output with improved efficiency compared to the performance obtained with single large additions of fuel.
Abstract: Microbial fuel cells containingProteus vulgaris and oxidation-reduction (“redox”) mediators were investigated. The bacteria were chemically immobilized onto the surface of graphite felt electrodes, which supported production of continuous electric current and could be reused after storage A computer-controlled carbohydrate feed system enabled the cell to generate a constant output with improved efficiency compared to the performance obtained with single large additions of fuel. The response to additions of substrate when immobilized bacteria were used was faster than that achieved with freely suspended organisms. This is attributed to the advantageous mass-transfer kinetics resulting from the proximity of the immobilized bacteria and the electrode surface.
590 citations
TL;DR: The following review will discuss the successful application of several of the metabolic products produced by lactic acid bacteria in food systems.
Abstract: Lactic acid bacteria produce a variety of metabolic products that are capable of interfering with the growth of other microbes. These bacterial end products have been applied to food systems to prevent the growth of certain undesirable bacteria. The following review will discuss the successful application of several of the metabolic products produced by lactic acid bacteria in food systems.
490 citations
TL;DR: While direct evidence that high affinity mechanisms for iron acquisition function as bacterial virulence determinants has been provided in only a small number of cases, it is likely that many if not all such systems play a central role in the pathogenesis of infection.
Abstract: Most of the iron in a mammalian body is complexed with various proteins. Moreover, in response to infection, iron availability is reduced in both extracellular and intracellular compartments. Bacteria need iron for growth and successful bacterial pathogens have therefore evolved to compete successfully for iron in the highly iron-stressed environment of the host's tissues and body fluids. Several strategies have been identified among pathogenic bacteria, including reduction of ferric to ferrous iron, occupation of intracellular niches, utilisation of host iron compounds, and production of siderophores. While direct evidence that high affinity mechanisms for iron acquisition function as bacterial virulence determinants has been provided in only a small number of cases, it is likely that many if not all such systems play a central role in the pathogenesis of infection.
419 citations
382 citations
TL;DR: "All stood amazed, until an old woman, tottering out from among the crowd, put her hand to her brow, and peering under it in his face for a moment exclaimed, 'Sure enough! it is Rip Van Winkle-it is himself!'
Abstract: \"All stood amazed, until an old woman, tottering out from among the crowd, put her hand to her brow, and peering under it in his face for a moment exclaimed , 'Sure enough! it is Rip Van Winkle-it is himself. Welcome home again, old neighbour-Why, where have you been these twenty long years?\"' lrving, W. An analogical \"field\" construct in cellular biophysics: history and present status. \"These germs-these bacilli-are transparent bodies. Like glass. Like water. To make them visible you must stain them. Well, my dear Paddy, do what you will, some of them won't stain; they won't take cochineal, they won't take any methylene blue, they won't take gentian violet, they won't take any colouring matter. Consequently, though we know as scientific men that they exist, we cannot see them.\" Sir Ralph Bloomfield-Bonington. The Doctor's Dilemma.
321 citations
TL;DR: Observations provide further evidence that the coexistence and interaction of bacteria in drinking water biofilms may be an integral part of their growth and survival strategies.
Abstract: Free-water-phase and surface-associated microorganisms from drinking water were detected and roughly identified by hybridization with fluorescence-labeled oligonucleotide probes complementary to regions of 16S and 23S rRNA characteristic for the domains Bacteria, Archaea, and Eucarya and the beta and gamma subclasses of Proteobacteria. Samples of glass-attached biofilms and plankton were taken from a Robbins device installed in a water distribution system. More than 70% of the surface-associated cells and less than 40% of the planktonic cells visualized by 4',6-diamidino-2-phenylindole staining bound detectable amounts of rRNA-targeted probes. These findings are an indication for higher average rRNA content and consequently higher physiological activity of the attached microbial cells compared with the free-living cells. All detectable cells hybridized with the bacterial probe, whereas no Archaea and no Eucarya cells could be detected. Simultaneous hybridization with probes specific for the beta and gamma subclasses of Proteobacteria revealed that microcolonies already consisted of mixed populations in early stages with fewer than 50 cells. These observations provide further evidence that the coexistence and interaction of bacteria in drinking water biofilms may be an integral part of their growth and survival strategies.
300 citations
TL;DR: The competition between polyphosphate accumulating bacteria (PP bacteria) and another group of microorganisms (tentatively named “G bacteria”) has been observed in laboratory sequencing batch reactors exhibiting enhanced biological phosphate removal (EBPR).
TL;DR: This review will examine current knowledge and outstanding problems regarding the proteolytic system in lactococci and also the extent to which the lactococcal system provides a model for understanding proteolysis in other groups of lactic acid bacteria.
Abstract: The inability of lactic acid bacteria to synthesize many of the amino acids required for protein synthesis necessitates the active functioning of a proteolytic system in those environments where protein constitutes the main nitrogen source. Biochemical and genetic analysis of the pathway by which exogenous proteins supply essential amino acids for growth has been one of the most actively investigated aspects of the metabolism of lactic acid bacteria especially in those species which are of importance in the dairy industry, such as the lactococci. Much information has now been accumulated on individual components of the proteolytic pathway in lactococci, namely, the cell envelope proteinase(s), a range of peptidases and the amino acid and peptide transport systems of the cell membrane. Possible models of the proteolytic system in lactococci can be proposed but there are still many unresolved questions concerning the operation of the pathway in vivo. This review will examine current knowledge and outstanding problems regarding the proteolytic system in lactococci and also the extent to which the lactococcal system provides a model for understanding proteolysis in other groups of lactic acid bacteria.
TL;DR: The means by which lactic acid bacteria defend against low intracellular pH are presented, and particular attention is devoted to the proton-translocating ATPase, an enzyme that is largely responsible for pH homeostasis in fermentative lactic Acid bacteria.
TL;DR: The presence and chain length of mycolic acids of bacteria of the genera Corynebacteria, Rhodococcus, Gordona, Mycobacterium, and Arthrobacter and of coryneform bacteria containing a type B peptidoglycan were related to the cell surface hydrophobicity of the bacteria, which in turn was related to adhesion of the cells to defined surfaces such as Teflon and glass.
Abstract: The presence and chain length of mycolic acids of bacteria of the genera Corynebacterium, Rhodococcus, Gordona, Mycobacterium, and Arthrobacter and of coryneform bacteria containing a type B peptidoglycan were related to the cell surface hydrophobicity of the bacteria, which in turn was related to adhesion of the cells to defined surfaces such as Teflon and glass. The origin of the overall negative charge of these bacteria is discussed.
TL;DR: Phylogenetic analyses of small subunit ribosomal RNA sequences showed that all known magnetotactic bacteria of the iron oxide type are associated with the a subgroup of the Proteobacteria in the domain Bacteria, and suggest that magnetotaxis based on iron oxides and iron sulfides evolved independently.
Abstract: Magnetosomes are intracellular, iron-rich, membrane-enclosed magnetic particles that allow magnetotactic bacteria to orient in the earth's geomagnetic field as they swim. The magnetosomes of most magnetotactic bacteria contain iron oxide particles, but some magnetotactic species contain iron sulfide particles instead. Phylogenetic analyses of small subunit ribosomal RNA sequences showed that all known magnetotactic bacteria of the iron oxide type are associated with the a subgroup of the Proteobacteria in the domain Bacteria. In contrast, uncultured magnetotactic bacteria of the iron sulfide type are specifically related to the dissimilatory sulfate-reducing bacteria within the delta subdivision of the Proteobacteria. These findings indicate a polyphyletic origin for magnetotactic bacteria and suggest that magnetotaxis based on iron oxides and iron sulfides evolved independently.
TL;DR: This work not only includes the biochemistry of the enzymes and the bioenergetics of the processes, but also the genetics of the genes encoding the energy transducing proteins.
Abstract: In the discovery of some general principles of energy transduction, lactic acid bacteria have played an important role. In this review, the energy transducing processes of lactic acid bacteria are discussed with the emphasis on the major developments of the past 5 years. This work not only includes the biochemistry of the enzymes and the bioenergetics of the processes, but also the genetics of the genes encoding the energy transducing proteins. The progress in the area of carbohydrate transport and metabolism is presented first. Sugar translocation involving ATP-driven transport, ion-linked cotransport, heterologous exchange and group translocation are discussed. The coupling of precursor uptake to product product excretion and the linkage of antiport mechanisms to the deiminase pathways of lactic acid bacteria is dealt with in the second section. The third topic relates to metabolic energy conservation by chemiosmotic processes. There is increasing evidence that precursor/product exchange in combination with precursor decarboxylation allows bacteria to generate additional metabolic energy. In the final section transport of nutrients and ions as well as mechanisms to excrete undesirable (toxic) compounds from the cells are discussed.
TL;DR: Identifying the functional domains of salivary proteins is vital in understanding the mechanisms of action and this information can be exploited in the development of therapeutic agents.
Abstract: Saliva plays an important role in the maintenance of oral health by exhibiting multiple host defense functions. These include homeostatic processes, lubrication, antimicrobial activity, and the control of demineralization/remineralization of teeth. Biochemical studies of saliva and salivary secretions established that specific salivary proteins are responsible for these defense functions. Because some of these salivary proteins have been characterized extensively, including their primary structures, it has become feasible to explore their structure/function relationships. Acidic proline-rich proteins (PRPs), for example, exhibit high affinity to hydroxyapatite, inhibit crystal growth of calcium phosphate salts from solutions supersaturated with respect to hydroxyapatite, bind calcium ions, and interact with several oral bacteria on adsorption to hydroxyapatite. Statherins, histatins, and cystatins also exhibit affinities to mineral surfaces, inhibit calcium phosphate precipitation, and play a role in maintaining the integrity of teeth. Furthermore, histatins exhibit both antibacterial and antifungal activities. Approaches to identifying the functional domains of these salivary proteins include functional assays of enzymatically digested proteins and peptides, synthetic peptides and peptide analogues, and chemically modified proteins as well as biophysical studies of native proteins or peptides. Such studies have demonstrated that the fungicidal activities of histatins reside in the middle portion of the polypeptide chain, whereas the hydroxyapatite binding domains of PRPs and statherin reside in the phosphorylated amino-terminal regions. Identification of functional domains is vital in understanding the mechanisms of action and this information can be exploited in the development of therapeutic agents.
TL;DR: The toxicity of homologous series of organic solvents has been investigated for gram‐positive bacteria, Arthrobacter sp.
Abstract: The toxicity of homologous series of organic solvents has been investigated for the gram-positive bacteria, Arthrobacter sp. and Nocardia sp., and the gram-negative bacteria, Acinetobacter sp. and Pseudomonas sp. The hydrophobicity of the solvent, expressed by its logP(octanol), proves to be a good measure for the toxicity of solvents in a two-phase system. The transition from toxic to nontoxic solvents occurs between logP(octanol) 3 and 5 and depends on the homologous series. No correlation has been found between the hydrophobicity of the substituent on the alkyl backbone of the solvent and the location of the transition point in toxicity. The logP(octanol), above which all solvents are nontoxic, is used to express the solvent tolerance of the bacteria. In general, the solvent tolerance of gram-negative bacteria is found to be slightly higher than that of gram-positive bacteria, but this does not hold for all homologous series of organic solvents investigated.Because the toxicity effects of organic solvents in a two-phase system can be ascribed to molecular as well as phase toxicity effects, molecular toxicity effects were investigated separately in a one-phase system with subsaturating amounts of organic solvent. The solvent concentration in the aqueous phase, at which 50% of the metabolic activity of the bacteria is lost, is used to express solvent toxicity. This concentration is found to be similar for the gram-positive Arthrobacter and the gram-negative Acinetobacter. Assuming the critical membrane concentration theory (G. J. Osborne et al. Enzyme Microb. Technol. 1990, 12: 281-291) to be valid, it can be concluded that differences in solvent tolerance between these two bacteria, cannot be ascribed to differences in response to molecular toxicity. Prediction of the toxicity of any solvent, using the critical membrane theory, appears to be possible in the case of alkanols or alkyl acetates. However, prediction of the toxicity of ethers appears to be impossible.
TL;DR: Eiectroneutral solute uniport, electrogenic solute/cation antiport, and secondary transport mechanisms .
TL;DR: One of the main functions of the large intestine is to salvage energy from dietary carbohydrate which has neither been digested nor absorbed in the small intestine through a process known as fermentation in which anaerobic bacteria breakdown carbohydrate to short chain fatty acids (SCFA), which in turn provide energy for the host.
TL;DR: The molecular biology of these widely dispersed elements provides clues to explain the origin of linear DNA in bacteria, including evidence for genetic exchange between prokaryotes and eukaryotes.
Abstract: Linear plasmids and chromosomes were unknown in prokaryotes until recently but have now been found in spirochaetes, Gram-positive bacteria, and Gram-negative bacteria. Two structural types of bacterial linear DNA have been characterized. Linear plasmids of the spirochaete Borrelia have a covalently closed hairpin loop at each end and linear plasmids of the Gram-positive filamentous Streptomyces have a covalently attached protein at each end. Replicons with similar structures are more frequent in eukaryotic cells than in prokaryotes. Linear genomic structures are probably more common in bacteria than previously recognized, however, and some replicons may interconvert between circular and linear isomers. The molecular biology of these widely dispersed elements provides clues to explain the origin of linear DNA in bacteria, including evidence for genetic exchange between prokaryotes and eukaryotes.
TL;DR: An obligate intracellular bacterium was isolated from the intestines of all 10 cases of porcine proliferative enteropathy from four different pig farms and appeared to be free of other microorganisms, including chlamydiae and viruses.
Abstract: An obligate intracellular bacterium was isolated from the intestines of all 10 cases of porcine proliferative enteropathy from four different pig farms. The organism grew in a rat enterocyte cell line (IEC-18) and was maintained over 20 passages. The growth of the bacteria was assessed by immunostaining of cells exposed to infection. Infection was not associated with morphological cell change, and growth was confined to cells infected at the time of each transfer of infection and the progeny of these cells. The bacterium is a microaerophilic, cell dependent, curved or rod-shaped, gram-negative bacillus that multiplies freely in the enterocyte cytoplasm. Cell cultures containing the intracellular bacteria appear to be free of other microorganisms, including chlamydiae and viruses.
TL;DR: A very uniform microflora was demonstrated in 15 samples of fermented maize dough from different larger commercial production sites, indicating a selection towards a micropopulation dominated by lactic acid bacteria.
TL;DR: The timing of lytic phage development and the relationship between host generation times and latent periods were investigated by electron microscopy of one-step growth experiments in two strains of marine Vibrio species and results were used in a correction factor developed to interpret field studies of phage-infected marine bacteria.
Abstract: The timing of lytic phage development and the relationship between host generation times and latent periods were investigated by electron microscopy of one-step growth experiments in two strains of marine Vibrio species. Results were used in a correction factor developed to interpret field studies of phage-infected marine bacteria. Both the number of mature phage per average cell section and the percentage of cells with mature phage increased exponentially by 73-86% into the latent periods. Assuming that bacterial infection and lysis take place continually in the ocean, conversion factors for relating the percentage of visibly infected bacteria to the total percentage of the bacterial community that are phage-infected were calculated as 3.70-7.14. When this range of factors was applied to previously-collected field data [Proctor LM, Fuhrman JA (1990) Nature (Lond) 343:60-62; Proctor LM, Fuhrman JA (1991) Mar Ecol Prog Ser 69:133-142] from 3 to 31% of the free-living bacteria and 3 to 26% of particulate-associated bacteria appeared to be phage-infected at any given time. Based upon a steady-state model in which half the daughter cells survive to divide again, the percent of total mortality would be twice the total percentage of phage-infected cells. From 6 to 62% and from 6 to 52% of mortality for the free-living and particulate-associated bacterial community, respectively, may be due to viruses.
TL;DR: Modifications of the microstructure were recognized with all species, the size depending on the size of organism, and polysaccharide-mediated aggregation was predominant.