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PubMed1977

Transport and hydrolysis of peptides by microorganisms.

The structural specificities of the dipeptide and oligopeptide permeases of E. coli are briefly reviewed and related to the requirements found for other microorganisms. New, quick, sensitive methods for studying peptide transport are described, based on the following: (i) peptide-dependent incorporation of free radioactive amino acid into newly synthesized protein by a double amino acid auxotroph, (ii) colorimetric assay of peptide-dependent enzyme synthesis by an amino acid auxotroph, (iii) dansyl fingerprint technique. These approaches provide information on peptide binding affinity to a permease and rates of peptide uptake and amino acid efflux. Among current and future research areas considered are: the influence of the pKb of the N-terminal amino group on transport, generality of peptide transport in microorganisms, energy coupling and regulation, involvement of binding proteins, and the 'smugglin' concept. Peptide hydrolysis, and nutritional ultilization of peptides, by microorganisms are briefly discussed.

Bacteria↗
PubMedDate not supplied

Heavy metals and adsorbents effects on activated sludge microorganisms.

The sorption of Cu(II) and Cd(II) from synthetic solution by powdered activated carbon (PAC), biomass, rice husk (RH) and activated rice husk (ARH) were investigate under batch conditions. After activated by concentrated nitric acid for 15 hours at 60-65 degrees C, the adsorption capacity for RH was increased. The adsorbents arranged in the increasing order of adsorption capacities to the Langmuir Q degree parameter were biomass > PAC > ARH > RH. The addition of adsorbents in base mix solution had increased the specific oxygen uptake rate (SOUR) activated sludge microorganisms with and without the presence of metals. The increased of SOUR were due to the ability of PAC and RH in reducing the inhibitory effect of metals on microorganisms and provide a reaction site between activated sludge microorganisms and substrates.

Adsorption↗
PubMed1990

Practical aspects of sampling for organic dusts and microorganisms.

Air sampling for organic dusts and microorganisms was carried out in silos when moldy silage was discarded through the discharge chute. Concentrations of respirable dust and airborne viable microorganisms exceeded 20 mg/m3 and 1 x 10(9)/m3, respectively, when dry silage was removed from silos. Much lower concentrations of dust and microorganisms were present when wet silage was discarded. Impinger and filter cassette samplers were equally effective in collecting the hardy spores present in silage dusts.

Air Microbiology↗
PubMed1990

Flow cytometric identification of microorganisms by dual staining with FITC and PI.

The identification of microorganisms by flow cytometry was evaluated by using a double staining technique with propidium iodide and fluorescein isothiocyanate and a two dimensional analysis. A diverse group of 19 different species and strains of microorganisms was tested to determine if they could be differentiated by flow cytometry. The organisms tested displayed characteristic and distinct two dimensional fluorescent patterns which allowed ready grouping and differentiation into subsets of organisms. The slopes and correlation coefficients of the histograms and the ratio of red to green signals expressed these differences quantitatively and allowed organisms to be placed into one of three groups based on these values. In some instances, as with Streptococcus pneumoniae and pyogenes and Staphylococcus aureus and epidermidis, it was possible to distinguish between species of bacteria from the same genus. The use of dual dye labeling and flow cytometry provided a rapid method of identifying selected microorganisms and may be broadly applicable for the detection and identification of many bacteria and fungi.

Bacterial Proteins↗
PubMed2006

Fountain Flow cytometry, a new technique for the rapid detection and enumeration of microorganisms in aqueous samples.

BACKGROUND: Pathogenic microorganisms are known to cause widespread waterborne disease worldwide. There is an urgent need to develop a technique for the real-time detection of pathogens in environmental samples at low concentrations, <10 microorganisms/ml, in large sample volumes, > or =100 ml. METHODS: A novel method, Fountain Flowtrade mark cytometry, for the rapid and sensitive detection of individual microorganisms in aqueous samples is presented. Each sample is first incubated with a fluorescent label and then passed as a stream in front of a laser, which excites the label. The fluorescence is detected with a CCD imager as the sample flows toward the imager along its optical axis. The feasibility of Fountain Flow cytometry (FFC) is demonstrated by the detection of Escherichia coli labeled with ChemChrome CV6 and SYBR Gold in buffer and natural river water. RESULTS: Detections of labeled E. coli were made in aqueous suspensions with an efficiency of 96% +/- 14% down to a concentration approximately 200 bacteria/ml. CONCLUSIONS: The feasibility of FFC is demonstrated by the detection of E. coli in buffer and natural river water. FFC should apply to the detection of a wide range of pathogenic microorganisms including amoebae.

Animals↗
PubMed2006

Improved 2-DE of microorganisms after acidic extraction.

2-DE separations of protein extracts sometimes have problems with poor resolution and streaking. This problem is particularly apparent with microorganisms, most notably those with a large cell wall. Here we describe a novel, rapid protocol for the extraction of microorganisms in acidic conditions, leading to increased resolution and 2-D gel quality. The efficiency of the protocol is demonstrated with extracts of bacteria, Escherichia coli and Bacillus subtilis; fungus, Trichoderma harzianum and yeast, Saccharomyces cerevisiae. We also demonstrate using a membrane centrifugal filtration, that large acidic molecules in excess of 100 kDa, probably including cell wall material, are responsible for the separation difficulties. A range of acidic extraction conditions were investigated, and it was found that optimal extraction is achieved using an extraction solution acidified to pH 3 by 80 mM citric acid. These findings have significant implications for the proteomic study of many medically, agriculturally and environmentally significant microorganisms, as the cell walls of these organisms are often considerably more complex than many commonly studied laboratory strains.

Acids↗
PubMed1988

Microorganisms associated with mouldiness of dried yam chips and their prevention.

The broad objective of this study was to isolate and identify the microorganisms causing mouldiness of stored yam chips and to look for ways of preventing the problem. Microorganisms isolated included Aspergillus flavus, A. glaucus, A. nidulans, A. niger, A. ochraceous, A. tamarii, A. candidus, Penicillium oxalicum, Trichoderma longibrachyatum, Rhizopus nigricans, Cylindrocarpon radicicola, Neurospora crassa, Botryodiplodia theobromae, Bacillus subtilis, Bacillus cereus, Erwinia carotovora and Serratia marcescens. Some of these microorganisms are transient invaders. Of the calcium-based chemicals used to prevent mouldiness, only CaCO3 and Ca(OH)2 proved effective and also prevented infestation of the chips by storage pests throughout the period of study. Whereas the product of the untreated yam chips was preferred in terms of colour, the product of CaCO3- and Ca(OH)2-treated yam chips were preferred in terms of taste and texture. As for physiological reaction after eating the products of the treated chips, Ca(OH)2- treated chips seemed to be more preferred by the members of the tasting panel.

Calcium Chloride↗
PubMed1993

111Indium labeling of microorganisms to facilitate the investigation of bacterial adhesion.

The ability of bacteria to adhere to polymeric interfaces has attracted considerable attention in recent years. Metabolic labeling of microorganisms with 35S-methionine or other beta-emitters is commonly utilized for quantification of bacterial adhesion to biopolymers. Since the use of these isotopes is cumbersome, the possibility of labeling the microorganisms with 111Indium, a strong gamma-emitter, was explored. This report demonstrates that bacteria can be easily labeled with 111Indium. Staphylococcus aureus, Staphylococcus epidermiids, and Pseudomonas aeruginosa were labeled with either 111Indium-oxine or 35S-methionine; and labeling efficiency, retention of incorporated labels, and growth kinetics of labeled bacteria were compared under identical experimental conditions. Bacteria labeled with 111In-oxine incorporated approximately 90% of radioactivity within 10 min, whereas 35S-methionine incorporation required many hours of incubation. Both the incorporated isotopes were gradually released by rapidly growing bacteria into the suspension medium. Of the total incorporated labels, approximately 20% 111In and 15% 35S were released in the surrounding medium every 24 h. No release of incorporated labels occurred when cells were fixed with 2.5% buffered glutaraldehyde. Growth kinetics and scanning or transmission electron microscopic analysis showed no detectable differences among control (nonlabeled), 111In-, or 35S-labeled bacteria. Labeling of bacteria with 111In-oxine does not interfere with bacterial adherence. These observations suggest that 111In incorporation provides a simple and rapid method of labeling of microorganisms. Compared to currently available techniques, the use of 111In-labeled bacteria will facilitate the quantitation of adherent bacteria to interfaces.

Bacteria↗
PubMed1992

Dye-mediated bactericidal effect of He-Ne laser irradiation on oral microorganisms.

Little attention has been given to the bactericidal effect of laser irradiation, particularly using low-power energy lasers. It has been demonstrated that He-Ne laser light has an inhibitory action on dental plaque. The purpose of this study was to investigate the bactericidal effect of He-Ne laser irradiation on cariogenic microorganisms. The bactericidal effect was determined by the formation of a growth-inhibitory zone or by the counting of viable bacterial colonies. Streptococcus sobrinus AHT that is a Gram-positive microorganism was sensitive to He-Ne laser light, but Escherichia coli, a Gram-negative microorganism, was resistant. The effect of several dyes necessary to instigate a bactericidal action was also examined. A growth-inhibitory zone was observed using 10 kinds of blue, purple, or green dyes, which were mainly phenylmethane dyes. The leakage of potassium from S. sobrinus AHT following laser irradiation was determined using an atomic absorption spectrophotometer. The leakage began to increase following irradiation for 2 min, and reached a plateau following irradiation for 30-60 min. Moreover, to examine some changes in the dye itself following laser irradiation in the absence of bacteria, ultraviolet-visible absorption spectra and 1H NMR spectra were recorded. In this study, it was indicated that the bactericidal effect on cariogenic bacteria by He-Ne laser irradiation was efficient only in the presence of specific dyes. It is suggested that this laser may be suitable for clinical applications in preventive dentistry.

Colony Count, Microbial↗
PubMed2003

Chromium-microorganism interactions in soils: remediation implications.

Discharge of Cr waste from many industrial applications such as leather tanning, textile production, electroplating, metallurgy, and petroleum refinery has led to large-scale contamination of land and water. Generally, Cr exists in two stable states: Cr(III) and Cr(VI). Cr(III) is not very soluble and is immobilized by precipitation as hydroxides. Cr(VI) is toxic, soluble, and easily transported to water resources. Cr(VI) undergoes rapid reduction to Cr(III), in the presence of organic sources or other reducing compounds as electron donors, to become precipitated as hydroxides. Cr(VI)-reducing microorganisms are ubiquitous in soil and water. A wide range of microorganisms, including bacteria, yeasts; and algae, with exceptional ability to reduce Cr(VI) to Cr(III) anaerobically and/or aerobically, have been isolated from Cr-contaminated and noncontaminated soils and water. Bioremediation approaches using the Cr(VI)-reducing ability of introduced (in bioreactors) or indigenous (augmented by supplements with organic amendments) microorganisms has been more successful for remediation of Cr-contaminated water than soils. Apart from enzymatic reduction, nonenzymatic reduction of Cr(VI) can also be common and widespread in the environment. For instance, biotic-abiotic coupling reactions involving the microbially formed products, H2S (the end product of sulfate reduction), Fe(II) [formed by Fe(III) reduction], and sulfite (formed during oxidation of elemental sulfur), can mediate the dissimilatory reduction of Cr(VI). Despite the dominant occurrence of enzymatic and nonenzymatic reduction of Cr(VI), natural attenuation of Cr(VI) is not taking place at a long-term contaminated site in South Australia, even 225 years after the last disposal of tannery waste. Evidence suggests that excess moisture conditions leading to saturation or flooded conditions promote the complete removal of Cr(VI) in soil samples from this contaminated site; but Cr(VI) reappears, probably because of oxidation of the Cr(III) by Mn oxides, with a subsequent shift to drying conditions in the soil. In such environments with low natural attenuation capacity resulting from reversible oxidation of Cr(III), bioeremediation of Cr(VI) can be a challenging task.

Bacteria, Anaerobic↗
PubMed2000

Recovery of proteins and microorganisms from cultivation media by foam flotation.

Foaming is often present in aerated bioreactors. It is undesired, because it removes the cells and the cultivation medium from the reactor and blocks the sterile filter. However, it can be used for the recovery of proteins and microorganisms from the cultivation medium. The present review deals with the characterization of model protein foams and foams of various cultivation media. The suppression of foaming by antifoam agents and their effect on the oxygen transfer rate, microbial cell growth and product formation are discussed. The influence of process variables on the recovery of proteins by flotation without and with surfactants and mathematical models for protein flotation are presented. The effect of cultivation conditions, flotation equipment and operational parameters on foam flotation of microorganisms is reviewed. Floatable and non-floatable microorganisms are characterized by their surface envelope properties. A mathematical model for cell recovery by flotation is presented. Possible application areas of cell recovery by flotation are discussed.

Animals↗
PubMed2005

Extreme environments as a resource for microorganisms and novel biocatalysts.

The steady increase in the number of newly isolated extremophilic microorganisms and the discovery of their enzymes by academic and industrial institutions underlines the enormous potential of extremophiles for application in future biotechnological processes. Enzymes from extremophilic microorganisms offer versatile tools for sustainable developments in a variety of industrial application as they show important environmental benefits due to their biodegradability, specific stability under extreme conditions, improved use of raw materials and decreased amount of waste products. Although major advances have been made in the last decade, our knowledge of the physiology, metabolism, enzymology and genetics of this fascinating group of extremophilic microorganisms and their related enzymes is still limited. In-depth information on the molecular properties of the enzymes and their genes, however, has to be obtained to analyze the structure and function of proteins that are catalytically active around the boiling and freezing points of water and extremes of pH. New techniques, such as genomics, metanogenomics, DNA evolution and gene shuffling, will lead to the production of enzymes that are highly specific for countless industrial applications. Due to the unusual properties of enzymes from extremophiles, they are expected to optimize already existing processes or even develop new sustainable technologies.

Archaea↗
PubMed1991

The screening of selected microorganisms for use as models of mammalian drug metabolism.

Fifty fungi and two Streptomyces species were screened for their ability to metabolise the probe substrates aminopyrine, diazepam, testosterone, theophylline and warfarin. The metabolism of the 14C-labelled substrates by whole growing cells was compared with that by rat liver microsomes using TLC-autoradiography. Testosterone, warfarin and diazepam were readily metabolised by most microorganisms, and aminopyrine and theophylline were only metabolised by a few. A relationship between substrate lipophilicity and number of microorganisms able to biotransform the substrate was observed, lipophilic substrates being favoured for metabolism, analagous to mammalian cytochrome P-450. A wide variety of metabolites were produced by the screened cultures, with a significant number co-chromatographing with mammalian metabolites. Most microorganisms appeared to exhibit cytochrome P-450-type oxidative reactions such as hydroxylation and N-demethylation, similar to mammalian hepatic microsomal cytochrome P-450 systems.

Animals↗
PubMed1992

Safe biotechnology (4). Recommendations for safety levels for biotechnological operations with microorganisms that cause diseases in plants.

The Working Party on Safety in Biotechnology of the European Federation of Biotechnology has proposed a classification of microorganisms that cause diseases in plants. In this paper appropriate safety levels are proposed for these classes of microorganisms in order to ensure that research, development and industrial fermentation work with plant pathogens will limit the risk of outbreaks of diseases in crops that could result from work with such microorganisms when they are cultivated in laboratories, glasshouses and biotechnology installations.

Containment of Biohazards↗
PubMed1995

Screening and characterization of microorganisms with glutaryl-7ADCA acylase activity.

A screening of microorganisms producing glutaryl-7ADCA acylase, an enzyme able to hydrolyse glutaric acid selectively from glutaryl-3-deacetoxy-7-aminocephalosporanic acid (glutaryl-7ADCA), has been carried out in soil samples. Five microorganisms expressing acylase activity were isolated and classified as Bacillus cereus, Achromobacter xylosooxidans, Bacillus sp., Pseudomonas sp. and Pseudomonas paucimobilis. The screening was carried out by preparing enrichment cultures containing glutaryl-7-ADCA or cephalosporin C as the selective carbon source. Four model compounds (adipoyl-, glutamyl- and glutaryl-p-nitroanilide and glutarylcoumarin), mimicking the glutaryl-7ADCA beta-lactam moiety, were synthesized as substrates suitable for the rapid screening of the microorganisms (2500) isolated from the enrichment cultures. A total of 300 strains were active on the model substrates and only 5 displayed acylase activity on glutaryl-7ADCA. The fermentation parameters, such as pH and inducer concentration, for the optimal acylase expression and acylase specificity towards the model substrates were different for each strain.

Amidohydrolases↗
PubMed1983

Morphology of experimental actinomycotic abscess in mice with Dermatophilus-like microorganisms from porcine tonsil.

Experimental infection in mice with Dermatophilus (D.) congolensis-like microorganisms was carried out, intraperitoneally and subcutaneously. This strain had been isolated from porcine tonsil and reported to be different in some morphological and biological points from D. congolensis. Macroscopic examination revealed multiple abscesses in the peritoneal cavities, or subcutaneous abscesses after the intraperitoneal or subcutaneous injection respectively. Histopathologic examination revealed the characteristic arrangement of the neutrophils surrounding the bacterial colony and peripheral macrophages in the abscess lesions. The lesions contained many microorganisms which showed wide range of the characteristic morphologic variation such as: mycelial elements, coccoid elements and large coccoid elements with transverse or longitudinal septa. Chlamydospore-like elements were sometimes found in the microcolonies in early lesions. The morphology of the lesions and the microorganisms was compared with those of other bacteria including D. congolensis.

Abscess↗
PubMed1988

Phototoxicity of skin microorganisms tested with a new model.

A new standardized method for testing phototoxicity of chemicals against microorganisms is described. The inoculum size of the microorganism, application of test chemicals, prediffusion time, incubation time and incubation period are defined. Staphylococcus aureus, S. epidermidis, Candida albicans, and Pityrosporum orbiculare were studied. Both 8-methoxypsoralen and trimethylpsoralen were phototoxic against all microorganisms tested, while tetracycline and doxycycline were not phototoxic. C. albicans may be chosen for phototoxicity testing because it has been used earlier, it is easy to maintain in culture, it grows easily when tested, and its pathogenicity is low. The phototoxicity of S. aureus, S. epidermidis, Pseudomonas aeruginosa, Propionibacterium acnes, C. albicans, and P. orbiculare against each other were also investigated. Only P. orbiculare was inhibitory. It inhibited the growth of S. aureus, S. epidermidis, and Ps. aeruginosa - both in the dark and after irradiation. The growth inhibition was markedly enhanced after UVA irradiation, indicating phototoxicity. The phototoxic effect of P. orbiculare may play a role in the ecology of the human skin flora.

Bacteria↗
PubMed1981

[Definition of the term "work with pathogenic microorganism" a problem of quality control in the food industry (author's transl)].

According to the Federal Communicable Disease Act a permission is required for work with pathogenic microorganisms. Current interpretations of these legal requirements, however, pose considerable problems. For example it is quite open whether the determination of total counts or sterility tests are to be considered as work with pathogenic organisms or not. In a recent article a prominent representative of the federal health authority has discussed some of the aspects of this topic Unfortunately no progress in defining the term "work with pathogenic microorganisms" has been achieved. Therefore it seemed necessary to come back to that issue. The discussion presented here shows that the wording of the Federal Communicable Disease Act implies a rather restrictive interpretation of these provisions. Total counts, sterility tests, microbial flora analysis and salmonella tests in food quality control should not be considered as work with pathogenic microorganisms at all. Because of the great importance of these legal provisions health authorities definitely should avoid vague interpretation. Instead, if necessary, proper amendment of the legislation should be considered.

Bacteria↗