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PubMed2004

[Application of high-efficient cellulose utilization microorganisms in co-composting of vegetable wastes and flower stalk].

An inoculation composing 17 species of cellulose utilization microorganisms was used in co-composting of vegetable wastes and flower stalk, and the efficiency of the inoculation on lignocellulose degradation was studied. The experiments result show that at the beginning of the first stage of composting, inoculating cellulose utilization microorganism in the substrates with 0.5% (V/V) can improve the biomass of the microorganisms into the substrates greatly and make them dominant ones. When the temperature was controlled as 55 degrees C, the biomass of cellulose utilization microorganisms can keep between [symbol: see text] 3.84 x 10(9)-1.80 x 10(10) CFU/g. At the beginning of the second stage, inoculating with 1% (V/V) can improve the temperature during this period effectively. Monitoring of the content of lignocelluloses in the substrate shows that the inoculation of cellulose utilization microorganism can accelerate the degradation of cellulose. The degradation efficiency of cellulose under inoculation condition is 23.64% higher than those without inoculation. This shows that inoculating with cellulose utilization microorganisms in each stage of the composting can greatly decompose the lignocellulose in the substrates, accelerate the co-composting process and improve the quality of composting production.

Bacteria↗
PubMed2006

[Approaches for increasing the culturability of microorganisms].

Only a tiny amount of microorganisms on the earth can be cultured so far, which seriously obstructs the investigation into principles of microbial activities and exploiting microbial resources. To improve the culturing methods and to develop novel culturing techniques is therefore very important to increase the culturabilty of microorganisms and to isolate more uncultured microorganisms, which is of crucial importance to research principles of microbial life, to understand the interaction between microbial cells for correctly designing, applying and manipulating environmental microbial processes. This review systematically summarized the causes for microorganisms' unculturability and recent work on the approaches to increase the culturability of microorganisms. To mimic natural environment (physically, chemically and biologically) and to introduce microbial interactions into culture medium as many as possible is suggested to be of key importance to increase culturability of microorganisms.

Biomimetics↗
PubMed2006

[Remediation of polycyclic aromatic hydrocarbons in non-fluid medium with immobilized microorganism technique].

The remediation of polycyclic aromatic hydrocarbons (PAHs) in non-fluid medium is a difficult and urgent task for environmental scientists. Due to the particularities of non-fluid medium, conventional techniques cannot work effectively, while bioremediation techniques using free microorganism also have many limitations that restricted the use of microorganism in removing PAHs from non-fluid medium. Immobilized microorganism (IM) technique is a proven approach in increasing the stability of microorganism under unfavorable conditions, which can not only provide a special microenvironment to protect dominant microorganisms from the malignant competition of aboriginal microorganism, but also improve the tolerance against toxic compounds in environment. Biodegradation using immobilized cells has been widely investigated for numerous toxic compounds in fluid medium such as in wastewater, or in half-fluid medium such as in slurry. In this paper, based on analyzing the characteristics of IM technique and its feasibility, the problem and development of future research were presented, and the new technique using IM to remediate PAHs in non-fluid medium was put forward.

Bacteria↗
PubMed1989

[A method for studying the effect of the geomagnetic field on the vital activities of microorganisms in the enteric family].

The proposed method makes it possible to find out the direct influence of the geomagnetic field (GMF) on microorganisms of the family Enterobacteriaceae (the genera Escherichia, Shigella, Salmonella). Different disturbances in the state of GMF, both in amplitude and frequency range, were modeled under laboratory conditions. Microbial cells were cultivated in sterile artesian-well water or physiological saline with no organic substrate added. Experiments were performed at room temperature for 5 and more days. In these experiments the standard dose of microbial suspension was inoculated daily into Endo medium. The differences in the reproductive capacity and survival time of microorganisms in the test and control vials were compared with the indices of geomagnetic disturbances. If the experiments were started 2-4 days before the appearance of geomagnetic disturbances, the suppression of the reproductive capacity of microorganisms occurred, then followed its stimulation; this phenomenon particularly affected Escherichia coli and Shigella sonnei. In case of the quiet state of GMF the suppression of reproductive capacity is commonly observed. If the beginning of the experiment coincides with the appearance of a magnetic storm, a sharp decrease in the reproductive capacity of microorganisms and the death of the population within 1-5 days usually occurred. The survival rate of microorganisms depended on the state of GMF disturbances. The survival time of cell generations during disturbances of GMF was considerably longer. Under the conditions of a superimposed magnetic field the reproductive capacity of microorganisms outstrips, as a rule, that developing under the conditions of the compensation of the field. Studies on the biological activity of infralow frequency showed that the multidirectional reproductivity effect was observed due to constant changes in the geomagnetic background.

Bacteriological Techniques↗
PubMed1989

[Effects of salivary ultrafiltrates on the production of phenol from tyrosine by oral microorganisms].

The metabolism of oral microorganisms is known to correlate with oral diseases. Protein degradation by oral microorganisms is usually followed by the production of phenol from tyrosine. The purpose of this study is to clarify the effect of salivary ultrafiltrates [MW: less than 10,000, 1,000-10,000 (intermediate fraction), less than 1,000, less than 500] on the production or the decomposition of phenol by oral microorganisms. Salivary sediment and salivary ultrafiltrate, the molecular weight of which is less than 10,000 unless otherwise stated, were incubated at 37 degrees C for 24 hours with tyrosine or phenol at a final concentration of 2.5 mg/100 ml. After incubation, the phenol produced (or remained) was extracted with ether and determined spectrophotometrically. Phenol production by oral microorganisms was not seen in the non-dialyzable fraction of saliva even when tyrosine was added. It was confirmed that the presence of the salivary ultrafiltrates was essential for the production of phenol by oral microorganisms. Phenol production in the salivary ultrafiltrate was further increased with the addition of tyrosine or non-dialyzable fraction of saliva. Phenol disappeared within 48 or 72 hours after the salivary sediment was incubated with phenol. The decomposition of phenol was inhibited with the salivary ultrafiltrate. Phenol production was enhanced with the addition of Good's buffer. Optimum pH of phenol production by oral microorganisms in the ultrafiltrate of saliva was within the range from 6.5 to 7.0 in the presence of Good's buffer (MOPS). Phenol production decreased with the reduction of the molecular weight of the salivary ultrafiltrates. The phenol production was increased when the intermediate fraction was added to the ultrafiltrate (MW: less than 1,000). The increase of the phenol production was considered to be due to the peptides in the intermediate fraction.

Bacteria↗
PubMedDate not supplied

[Nitrate-reducing microorganisms in milk products and human milk].

The quantitative determination of nitrate-reducing microorganisms in food is important because of their role in the formation of N-nitroso compounds and methemoglobin. The total counts of microorganisms and the counts of nitrate-reducing microorganisms were assayed in various milk products and in human milk by the method of the most probable numbers using nitrate broth medium. The mean value and standard deviation of the nitrate-reducing microorganisms were the following: in pasteurized milk 3.4 +/- 1.1 log/ml (in spring and summer 4.2 +/- 1.1, and in winter 2.8 +/- 0.6 log/ml), in kefir "Tallinn' 2.9 +/- 1.1 log/ml, in fat kefir 2.9 +/- +/- 0.7 log/ml, in sour milk 3.9 +/- 0.5 log/ml, in fresh milk 4.6 +/- 0.6 log/ml and in human milk 2.7 +/- +/- 1.1 log/ml. The amount of nitrate-reducing microorganisms in pasteurized milk of the spring-summer period and in fresh milk was significantly higher than in human milk. The mean count of nitrate-reducing microorganisms in human milk is regarded as a maximum permitted count of these organisms in milk for bottle-fed sucklings. For them and for atrophic gastritis patients pasteurized or fresh milk should be boiled.

Animals↗
PubMedDate not supplied

[Electron microscopy study of the microorganism topography on plant roots].

The topography of microorganisms in the root cap zone and in the absorption zone was studied with 7-day-old wheat seedlings. No microorganisms were detected in the root cap zone. Individual microorganisms as well as their accumulations were registered in the absorption zone. The topography of microorganisms in this zone was characterized. Different morphological forms were present among microorganisms. Types of interaction between these microorganisms and the cells of root epidermis are discussed.

Microscopy, Electron↗
PubMed1984

[Degradation and utilization of 2,4-dioxohexahydro-1,3,5-triazine (DHT) by soil microorganisms].

The biodegradation and utilization of the antiphytoviral substance 2,4-dioxohexahydro-1,3,5-triazine (DHT) by soil microorganisms was investigated. Mixed cultures of microorganisms deriving from different soils diminish in nutrient broth the content of DHT with increasing duration of culture. Microorganisms from an Egyptian garden soil fully degrade 10(-3) mol/1 DHT in a culture without additional aeration within 28 days. Also in deficient media the mixed microorganisms reduce the amount of DHT, reaching in nitrogen free nutrient solution even a degradation rate up to 12 mg DHT per liter and day. Pure cultures of Rhizobium leguminosarum, Proteus vulgaris, Saccharomyces cerevisiae and especially Agrobacterium radiobacter diminish the content of DHT in nitrogen free media, too. No such effect was detectable in cultures of four other species of soil bacteria. The DHT degradation by the microorganisms is connected with significant cell multiplication, e.g. A. radiobacter in shaking cultures with DHT as sole source of nitrogen shows a typical growth cycle with a lag-phase of 24 hours. The short persistence time of DHT in soils is concluded to be mainly due to biodegradation by microorganisms.

Antiviral Agents↗
PubMed1996

[Comparison between two types of air microorganism sampling].

The airflow striking sampling was compared with flat utensils sedimentation sampling for collection of air microorganisms. The result showed that air microorganism count with the former method is more efficient than the latter method (P < 0.05). The flat utensils sedimentation sampling only collected larger particles of microorganism so the air microorganism count was not accurate. However, it is still a suitable method in hygiene without other choices. The airflow striking sampling collected more middle and tiny particles for air microorganism than the sedimentation sampling and can accurately show microorganism content in air, so it is an optimal sampling method.

Air Microbiology↗
PubMed1996

[Dust and microorganism count at delivery, sorting and composting of home refuse and home refuse-like industrial waste].

The exposure of employees to airborne dust and microorganisms was assessed in a waste processing plant established to recover reusable materials from unsorted domestic and industrial waste. Exposure criteria considered relevant were the quantity of the individual size-selected particle fractions, the morphological properties of the particles, their heavy metal content, and the degree of their contamination with various microorganisms and mold. In addition, separate microbiological analyses to determine potential pathogen concentrations in the air were made. The highest concentrations of total and fine dust were measured in the waste delivery area. A close correlation between the frequency of deliveries and the level of dust exposure was observed. In this area, fine dust concentrations exceeded the threshold limit value of 6 mg/m3 repeatedly for shorter periods. The average fine dust concentration during an entire work-shift, however, was considerably lower than this value. Particles with an aerodynamic diameter of 2 to 7 microns predominated both in the waste delivery and the processing areas. Fibrous dust particles were present in smaller numbers than spherical particles and consisted mainly of organic materials. Natural and artificial inorganic fibers were found only occasionally. The concentrations of lead, cadmium, nickel and mercury were considerably lower than the corresponding MAK and TRK values, and were--with the exception of lead--in the range of the respective metal concentrations in the atmosphere of urban areas. Microscopical examinations of used protective masks (protection category P2) revealed that dust particles were deposited even on the inner side of the masks. Most of the particles on this side were very small and carried nickel or titanium. Microorganism concentrations measured in air from the highly dust-exposed areas of the plant showed values up to 6.9 x 10(5) cfu/m3, with a mold content of 6.6 x 10(4) cfu/m3. Approximately 90% of the microorganisms were deposited on particles of the fine dust fraction (particle size < 7 microns), and more than 50% contaminated particles with an aerodynamic diameter of 2 to 4.7 microns. In the compost facility, mold concentrations of up to 8.4 x 10(5) cfu/m3 were measured. In contrast, the level of microbial contamination in the filtered air from the compost facility did not exceed the concentration measured in air outside the plant. The data which were obtained during the winter months are probably at the lower end of the average exposure range over the entire year. In regard to exposure assessment, it should be mentioned that particles with a size of 4 to 7 microns are not really "inert" particles, since they are preferential carriers for heavy metals and microorganisms. More studies in the future should be performed to establish, whether the level of exposure to microorganisms can be estimated indirectly by the determination of dust exposure.

Air Microbiology↗
PubMed1997

[Action of physical agents on microorganisms].

Among numerous physical agents exerting their deleterious effect on microorganisms only a few have been applied to sterilisation or disinfection used for medical purposes. Temperature is the most important agent, which from one side in a very wide range enables supporting of metabolic processes of psycho-, mezo- and thermophilic microorganisms, but beyond these limits causes their death. High temperature induces at first damage of cytoplasmic membrane and then denaturation of RNA leading to death. On the other hand, a low temperature slowly decreasing below 0 degree C induces crystallisation of water in cells and destruction of cytoplasmic structures. Ultraviolet radiation causes mutations resulting in stopping of DNA replication in all forms of the microorganisms. The same way of the lethal activity is exerted by ionising radiation. Its kinetic energy induces mutations affecting not single bases but also whole operons making gene expression impossible. Gaseous plasma is a new physical agent applied recently to sterilisation. High frequency energy initiates generation of the plasma from hydrogen peroxide vapours in a high vacuum and creates reactive species particles from the vapours that collide and kill microorganisms. On the other hand, application of ultrasound radiation to killing of microorganisms needs for further studies because of a high variability depending upon used frequency and energy. It is not known, for example, if destruction of microorganisms by ultrasounds is related to a phenomenon of cavitation or thermal energy. Nevertheless, even a range of frequency and energy used in commercial microwave ovens kills vegetative cells of coliform rods in about 15 minutes.

Bacteria↗
PubMed1963

Comparison of enterococci and coliform microorganisms in commercially produced pecan nut meats.

Pecan nut meats in the unbroken shell are sterile for enteric microorganisms. Recovery of coliform microorganisms or enterococci from finished pecan nut meats indicated contact contamination, assuming the tempering procedures to be satisfactory. Results of specific studies, designed toward developing background data on the sanitary significance of enterococci and coliform microorganisms in the production of pecan meats are reported. Unbroken pecan nuts or nut meats from various stages of shelling operations were diluted with a phosphate-buffered diluent. Serial dilutions were inoculated into Lactose Broth and Azide Dextrose Broth. The lactose fermentors were carried through indole, methyl red, Voges-Proskauer, and citrate reactions; the positive Azide Dextrose cultures were confirmed in Ethyl Violet Azide Broth and microscopically. Viable plate counts were obtained. Enterococci were found resistant to many deterrent factors affecting coliforms. Recoveries of enterococci were detected long after pollution had occurred. Little correlation was found between enterococcal recovery and observed insanitary practices in commercial shelling operations. Using the coliaerogenes group and, specifically, Escherichia coli as a sanitation index, microorganisms allowed accurate appraisal of tempering, personnel practices, and contact surface contaminating factors. It is felt this was due, in part, to the more delicate growth characteristics of E. coli. The fact that other pathogenic microorganisms, capable of causing gastrointestinal upsets, are associated with the presence of E. coli introduces a health factor which is important to regulatory agencies concerned with consumer protection.

Carya↗
PubMed2004

Growth behavior of microorganisms using UV-Vis spectroscopy: Escherichia coli.

Multiwavelength transmission spectra of microorganisms and cell suspensions consist of combined absorption and scattering phenomena resulting from the interaction of light with microorganisms or cells typically suspended in a nonabsorbing media. The distribution of intensities as a function of wavelength depends on the size, shape, and optical properties of the sample. The optical properties are functions of the chemical composition and the state of aggregation, or association, of the chromophoric groups contained in the microorganisms. This article explores the growth behavior of Escherichia coli from the perspective of multiwavelength UV-Vis spectroscopy. Experimentally, it is demonstrated that the spectral signatures of the microorganism evolve as a function of time. It is also demonstrated that the spectral changes observed during growth are consistent with data reported elsewhere. From the theoretical point of view, it is demonstrated that the spectral signatures can be adequately represented with an interpretation model based on light-scattering theory. The parameters from the interpretation model reflect changes in size and chemical composition known to take place in the microorganisms during growth.

Cell Culture Techniques↗
PubMed1987

Microorganisms associated with epithelial surfaces and stability of the indigenous gastrointestinal microflora.

Indigenous microorganisms of many genera and species associate with mucosal epithelia in the gastrointestinal tracts of animals and humans. These mechanisms may involve a high degree of specificity for host and surface habitat. They may include a capacity of the microorganisms to adhere to the membranes of substratum epithelial cells, to colonize and utilize as a source of nutrients the mucus overlying epithelial cells, and to be motile and attracted into the mucous layer by chemotaxis. The microbes must be able as well to thrive in the nutritional and environmental conditions prevailing on the epithelial surfaces. Microbial communities associated with epithelial surfaces are critical for maintaining a microflora in areas of the tract (i.e., stomach, small intestine) where the lumenal content moves at a rate exceeding the maximum rates at which indigenous microorganisms can multiply. Such communities even may be important in areas (i.e., the cecum and colon) where the content moves at rates below those at which the microbes can multiply. In such areas, microorganisms colonizing mucus on the epithelium and in the crypts of Lieberkuhn may provide a stable inoculum for the lumenal content which may be altered in composition in times of dietary change. Microorganisms associated with gastric and intestinal surfaces undoubtedly serve in a major way to stabilize the composition of the indigenous gastrointestinal microflora. At the molecular level, however, little is known about the mechanisms stabilizing the composition or the biochemical and genetic activities of the microflora. Such mechanisms are important subjects for research in the future.

Animals↗
PubMed1992

Molecular methods for environmental monitoring and containment of genetically engineered microorganisms.

Plans to introduce genetically engineered microorganisms into the environment has led to concerns over safety and has raised questions about how to detect and to contain such microorganisms. Specific gene sequences, such as lacZ, have been inserted into genetically engineered microorganisms to permit their phenotypic detection. Molecular methods have been developed based upon recovery of DNA from environmental samples and gene probe hybridization to specific diagnostic gene sequences for the specific detection of genetically engineered microorganisms. DNA amplification using the polymerase chain reaction has been applied to enhance detection sensitivity so that single gene targets can be detected. Detection of messenger RNA has permitted the monitoring of gene expression in the environment. The use of reporter genes, such as the lux gene for bioluminescence, likewise has permitted the observation of gene expression. Conditional lethal constructs have been developed as models for containment of genetically engineered microorganisms. Suicide vectors, based upon the hok gene have been developed as model containment systems.

Bacteria↗
PubMed1993

Evaluating the fate of genetically modified microorganisms in the environment: are they inherently less fit?

Genetically modified microorganisms hold great promise for environmental applications. Nonetheless, some may have unintended adverse effects. Of particular concern for risk assessment is the simple fact that microorganisms are self-replicating entities, so that it may be impossible to control an adverse effect simply by discontinuing further releases of the organism. It has been suggested, however, that genetically modified microorganisms will be poor competitors and therefore unable to persist in the wild due to energetic inefficiency, disruption of genomic coadaptation, or domestication. Many studies support the hypothesis that genetically modified microorganisms are less fit than their progenitors, but there are a few noteworthy counter-examples in which genetic modifications unexpectedly enhance competitive fitness. Furthermore, subsequent evolution may eliminate the maladaptive effects of some genes, increasing the likelihood that a modified organism or its engineered genes will persist. Evaluating the likelihood that a genetically modified microorganism or its engineered genes will persist is a complex ecological and evolutionary problem. Therefore, an efficient regulatory framework would require such evaluations only when there are plausible scenarios for significant adverse environmental effects.

Bacteria↗
PubMed2000

Plant-Microbe Interactions: Wetting of Ivy (Hedera helix L.) Leaf Surfaces in Relation to Colonization by Epiphytic Microorganisms.

Leaf wettability, cuticular wax composition, and microbial colonization of upper and lower leaf surfaces of ivy (Hedera helix L.) was investigated for young and old leaves sampled in June and September. Contact angles of aqueous buffered solutions measured on young leaf surfaces ranged between 76° and 86° and were not dependent on the pH value of the applied droplets. Contact angles measured on old leaf surfaces were up to 32°, significantly lower than on young leaf surfaces. Furthermore, contact angles were significantly lower using aqueous solutions of pH 9.0 compared to pH 3.0, indicating the influence of ionizable functional groups on leaf surface wetting properties. Observed changes in leaf wetting properties did not correlate with different levels of alkanoic acids in cuticular waxes. However, microscopic examination of the leaf surfaces indicated the influence of epiphytic microorganisms on wetting properties of old leaves, since their surfaces were always colonized by epiphytic microorganisms (filamentous fungi, yeasts, and bacteria), whereas surfaces of young leaves were basically clean. In order to analyze the effect of epiphytic microorganisms on leaf surface wetting, surfaces of young and clean ivy leaves were artificially colonized with Pseudomonas fluorescens. This resulted in a significant increase and a pH dependence of leaf surface wetting in the same way as it was observed on old ivy leaf surfaces. From these results it can be deduced that the native wetting properties of leaf surfaces can be significantly masked by the presence of epiphytic microorganisms. The ecological implications of altered wetting properties for microorganisms using the leaf/atmosphere interface as habitat are discussed.

Journal Article↗
PubMed2006

Simultaneous P-solubilizing and biocontrol activity of microorganisms: potentials and future trends.

Phosphate (P)-solubilizing microorganisms as a group form an important part of the microorganisms, which benefit plant growth and development. Growth promotion and increased uptake of phosphate are not the only mechanisms by which these microorganisms exert a positive effect on plants. Microbially mediated solubilization of insoluble phosphates through release of organic acids is often combined with production of other metabolites, which take part in biological control against soilborne phytopathogens. In vitro studies show the potential of P-solubilizing microorganisms for the simultaneous synthesis and release of pathogen-suppressing metabolites, mainly siderophores, phytohormones, and lytic enzymes. Further trends in this field are discussed, suggesting a number of biotechnological approaches through physiological and biochemical studies using various microorganisms.

Bacteria↗