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At least 451 records · Page 25Linked to original sources
PubMed2004

On-line load monitoring of wastewaters with a respirographic microbial sensor.

This paper demonstrates the functionality, laboratory testing and field application of a microbial sensor that is capable of monitoring the organic pollution extent of wastewaters both off-line in a laboratory and on-line in a wastewater treatment plant. The biosensor was first developed in the laboratory using synthetic wastewater and then applied to monitor the effluent of the unit. The basic working principle of the biosensor is based on the on-line measurement of CO2 concentration in the off gas produced during carbon compound degradation by microbial respiration activities. CO2 concentration under operation conditions (constant oxygen flow rate, residence time and pH) is closely related to the extent of organic pollution (biochemical oxygen demand, chemical oxygen demand). CO2 monitoring is carried out by an infrared spectrometer, whereas current organic pollution is determined off-line according to the conventional 5-day lasting BOD analysis. Off gas analysis of CO2 concentration strongly correlates with off-line biochemical oxygen demand measurements allowing continuous on-line monitoring of the organic load within a wastewater treatment plant. Thus, real time process control and operation become feasible.

Bacteria, Aerobic↗
PubMed2000

Crystallization and preliminary crystallographic study of b0220, an 'ORFan' protein of unknown function from Escherichia coli.

Newly sequenced microbial genomes continue to reveal up to 50% functionally uncharacterized 'anonymous' genes. A significant fraction of these anonymous ORFs does not exhibit any sequence similarity to any protein in the databases and constitutes a set of unique sequences, denoted 'ORFans'. The structure determination of ORFan proteins is both of evolutionary and functional interest. Here, the first crystallization of an Escherichia coli ORFan gene product, the 157 amino-acid b0220 protein, is reported. The crystals belong to the trigonal space group P3 or P3(1), with unit-cell parameters a = b = 47.2, c = 88.4 A. There are two molecules in the asymetric unit. Frozen crystals diffract to 1.6 A resolution using synchrotron radiation. Phasing was performed using multiwavelength anomalous dispersion (MAD) on the selenomethionine-substituted b0220 protein.

Bacterial Proteins↗
PubMed2003

Seasonal changes in the rhizosphere microbial communities associated with field-grown genetically modified canola (Brassica napus).

The introduction of transgenic plants into agricultural ecosystems has raised the question of the ecological impact of these plants on nontarget organisms, such as soil bacteria. Although differences in both the genetic structure and the metabolic function of the microbial communities associated with some transgenic plant lines have been established, it remains to be seen whether these differences have an ecological impact on the soil microbial communities. We conducted a 2-year, multiple-site field study in which rhizosphere samples associated with a transgenic canola variety and a conventional canola variety were sampled at six times throughout the growing season. The objectives of this study were to identify differences between the rhizosphere microbial community associated with the transgenic plants and the rhizosphere microbial community associated with the conventional canola plants and to determine whether the differences were permanent or depended on the presence of the plant. Community-level physiological profiles, fatty acid methyl ester profiles, and terminal amplified ribosomal DNA restriction analysis profiles of rhizosphere microbial communities were compared to the profiles of the microbial community associated with an unplanted, fallow field plot. Principal-component analysis showed that there was variation in the microbial community associated with both canola variety and growth season. Importantly, while differences between the microbial communities associated with the transgenic plant variety were observed at several times throughout the growing season, all analyses indicated that when the microbial communities were assessed after winter, there were no differences between microbial communities from field plots that contained harvested transgenic canola plants and microbial communities from field plots that did not contain plants during the field season. Hence, the changes in the microbial community structure associated with genetically modified plants were temporary and did not persist into the next field season.

Bacteria↗
PubMed1988

Immunogenetic aspects of host immune response.

The central role of histocompatibility leukocyte antigens (HLA) class II molecules in antigen presentation has received great attention in recent years, yet class I molecules have been defined as primarily functioning as a restriction element for cytotoxic T cell killing of virus-infected cells. Extensive clinical evidence, however, indicates that the HLA class I genes are strongly associated with nonseptic complications of enteric and genitourinary bacterial infections. Ninety percent of patients with Reiter's syndrome and reactive arthritis are positive for HLA-B27, yet the mechanism of disease susceptibility conferred by this gene remains obscure. Hypotheses concerning this interaction include (i) class I antigens functioning as receptors for microbial antigens; (ii) class I antigens expressing determinants that cross-react with microbial antigens; and (iii) class I genes controlling immunoregulatory functions that dictate qualitative differences in immune response to pathogenic organisms. These hypotheses await formal testing and hold great promise for understanding immunogenetic control of immune responses in general.

Genes, MHC Class I↗
PubMed2025

Microbial metagenomes from Lake Soyang, the largest freshwater reservoir in South Korea.

Lake ecosystems play a fundamental role in the global biogeochemical cycling of essential elements such as carbon, nitrogen, and phosphorus. Microorganisms within these ecosystems mediate key processes that regulate these cycles. Metagenomic analyses provide valuable insights into the taxonomic and functional diversity of microbial communities in various environments, including freshwater habitats. Here, we present a comprehensive metagenomic dataset derived from Lake Soyang, the largest freshwater reservoir in South Korea. A total of 28 metagenomes were generated from water samples collected across two distinct sampling periods: the first set (n = 8) was obtained between April 2014 and January 2015 from two depths (1 m and 50 m) in four different seasons, while the second set (n = 20) was collected between January 2019 and November 2019 from five depths (1, 10, 20, 40, and 90 m) over four seasons. Metagenomic sequencing yielded 9.3-21.8 Gbp per sample. This dataset provides a valuable resource for future studies exploring the ecophysiological characteristics of microbial communities in pelagic freshwater environments.

Republic of Korea↗
PubMed1986

Expression of recombinant DNA functional products in Escherichia coli anucleate minicells.

This review covers the use of anucleate minicells of Escherichia coli for expressing the recombinant DNA encoded proteins. We briefly discuss the methods being used for preparation of anucleate minicells, incorporation of cloned DNA and assessment of gene expression. While the largest use has been that of microbially derived cloned functional DNA, examples of eukaryotic gene product synthesis have also been reviewed. This technology may represent some interesting commercial opportunities.

Journal Article↗
PubMed2004

Effects of cross-substrate interaction on biotrickling filtration for the control of VOC emissions.

The effects of cross-substrate interaction to the performance of a gas-phase biotrickling filter for treating a mixture of volatile organic compounds (VOCs), including three structural heterologous in acetone, toluene, and trichloroethylene, were investigated. The biotrickling filter was inoculated with microbial consortium containing at least seven bacterial species utilizing either acetone or toluene, or both, as their carbon sources. In the performance study, the column operating under variable conditions typifying the waste gas emission from the microelectronics fabrication processes achieved a total hydrocarbon (THC) removal efficiency in excess of 85% and a mineralization capacity over 50% for THC mass loading as high as 36.2 g-CH4 m-3h-1. The cross-substrate effects were examined by correlating the relative changes in the mass removal of each substrate with the biodegradative capability of the microbial consortium. The degradation of trichloroethylene was primarily due to co-metabolism by the toluene-oxidizing enzymes, but the results also indicated that trichloroethylene partially induced its own degradation. Concentration increases in acetone appeared to cause a diauxie effect that suppressed degradation of toluene and trichloroethylene, and shifted the microbial population toward the selective acetone-degraders. No irrecoverable toxicity or inhibitory effects were observed throughout the experiments. These results suggest that the relative VOC concentration in the waste gas mixture is a factor as important as the biodegradative function of the microbial consortium, and thus should be carefully evaluated to satisfy the treatment objectives.

Acetone↗
PubMed1993

Within and between sample comparisons of Gompertz parameters for Salmonella enteritidis and aerobic plate counts in chicken stored in air and modified atmosphere.

The objective of this work was to compare between and within sample differences in aerobic plate counts (APC) and Salmonella in chicken held at abusive temperatures under air and modified atmosphere (MA). Three independent samples and three subsamples of ground raw chicken meat were inoculated with a nalidixic acid-resistant Salmonella enteritidis var. Rochester, packaged in barrier films containing air or 75% CO2, 20% N2, and 5% O2, and stored at 13 and 27 degrees C for 120 h. Samples were quantitatively enumerated for APC and S. enteritidis colony forming units (cfu/g). Gompertz function parameters for microbial growth in each sample and subsample were statistically compared in order to determine if within sample variation was different to between sample variation. At 13 degrees C, APC organisms averaged 1.27 log units lower in the MA compared to air while Salmonella counts averaged 1.44 log units higher. At 27 degrees C APC averaged 0.46 log units lower in the MA compared to air while Salmonella averaged 0.30 log units lower. The data fit the Gompertz function such that no systematic deviations from the curves were detected and the confidence bands were relatively narrow. Except for initial microbial load, there were no significant differences in variance of Gompertz parameters between the subsamples and the independent samples. This indicates that samples from different chickens with the same initial APC can be expected to be as similar in growth patterns and final counts as subsamples from the same chicken.

Air↗
PubMed2006

Phylogenetic diversity and activity of aerobic heterotrophic bacteria from a hypersaline oil-polluted microbial mat.

The diversity and function of aerobic heterotrophic bacteria (AHB) in cyanobacterial mats have been largely overlooked. We used culture-dependent and molecular techniques to explore the species diversity, degradative capacities and functional guilds of AHB in the photic layer (2mm) of an oil-polluted microbial mat from Saudi Arabia. Enrichment isolation was carried out at different salinities (5% and 12%) and temperatures (28 and 45 degrees C) and on various substrates (acetate, glycolate, Spirulina extract and crude oils). Counts of most probable number showed a numerical abundance of AHB in the range of 1.15-8.13x10(6) cellsg(-1) and suggested the presence of halotolerant and thermotolerant populations. Most of the 16S rRNA sequences of the obtained clones and isolates were phylogenetically affiliated to the groups Gammaproteobacteria, Bacteriodetes and Alphaproteobacteria. Groups like Deltaproteobacteria, Verrucomicrobia, Planctomycetes, Spirochaetes, Acidobacteria and Deinococcus-Thermus were only detected by cloning. The strains isolated on acetate and glycolate belonged to the genera Marinobacter, Halomonas, Roseobacter and Rhodobacter whereas the strains enriched on crude oil belonged to Marinobacter and Alcanivorax. Members of the Bacteriodetes group were only enriched on Spirulina extract indicating their specialization in the degradation of cyanobacterial dead cells. The substrate spectra of representative strains showed the ability of all AHB to metabolize cyanobacterial photosynthetic and fermentation products. However, the unique in situ conditions of the mat apparently favored the enrichment of versatile strains that grew on both the cyanobacterial exudates and the hydrocarbons. We conclude that AHB in cyanobacterial mats represent a diverse community that plays an important role in carbon-cycling within microbial mats.

Bacteria, Aerobic↗
PubMed2003

Effects of rhizoxin, a microbial angiogenesis inhibitor, on angiogenic endothelial cell functions.

Our previous study revealed that rhizoxin ([1S-[1R*,3R*,5S*,8R*(1R*,2S*,3E,5E,7E),10R*,11S*,13S*,14E,16S*,17S*]]-10-hydroxy-8-[2-methoxy-1,3,7-trimethyl-8-(2-methyl-4-oxazolyl)-3,5,7-octatrienyl]-11,16-dimethyl-4,7,12,18-tetraoxatetracyclo[15.3.1.03,5.011,13]heneicos-14-ene-6,19-dione) has a potent inhibitory effect on in vivo angiogenesis. However, little is known regarding the mechanism by which rhizoxin exhibits antiangiogenic activity. In this study, we examined its effects on the functions of endothelial cells associated with neovascular formation in vivo, using cultured vascular endothelial cells. Rhizoxin concentration-dependently inhibited the proliferation of bovine carotid artery endothelial cells, human umbilical vein endothelial cells and human dermal microvascular endothelial cells, the IC(50) values being 7, 5 and 0.4 nM, respectively. In addition, it reduced the extracellular plasminogen activator level in bovine vascular endothelial cells in the low nM range, and suppressed the migration of human dermal microvascular endothelial cells in the pM range. Furthermore, it blocked the tubular morphogenesis of human umbilical vein endothelial cells and human dermal microvascular endothelial cells on Matrigel in a concentration-dependent manner; the IC(50) values being 40 and 130 pM, respectively. These results suggest that rhizoxin exhibits antiangiogenic activity through the combined inhibition of some functions of endothelial cells responsible for induction of in vivo angiogenesis.

Angiogenesis Inhibitors↗
PubMed1999

Structure-function relationships of bacterial endotoxins. Contribution to microbial sepsis.

A substantial body of knowledge has emerged over the past several decades concerning the primary and tertiary, and quaternary structure of endotoxic LPS and their contribution to the pathogenesis of gram-negative sepsis; however, important questions remain. Among them are the precise three-dimensional configuration of the LPS macromolecule and the contribution of the quaternary structure to the ability of these potent microbial factors to interact with host humoral and cellular inflammatory mediator systems. Also remaining to be sufficiently addressed is the relative contribution of endotoxin interactions with the host to the overall manifestation of disease and conditions under which such contributions serve as the pivotal event in determining outcome. The answers to these questions can be expected to provide valuable insights into potential novel therapeutic intervention strategies and approaches that will ultimately reduce both morbidity and mortality in infection from gram-negative microbes.

Animals↗
PubMed2001

Synthesis of a broad array of highly functionalized, enantiomerically pure cyclohexanecarboxylic acid derivatives by microbial dihydroxylation of benzoic acid and subsequent oxidative and rearrangement reactions.

[reaction: see text]. We have found that the 1,2-dihydroxylation of benzoic acid with Alcaligenes eutrophus strain B9, first reported in 1971 by Reiner and Hegeman, is readily adapted for the preparation of tens to hundreds of grams of (1S,2R)-1,2-dihydroxycyclohexa-3,5-diene-1-carboxylic acid of >95% ee. This unique substrate undergoes many specific oxidative and rearrangement processes. Among these are transformations of unanticipated chemical novelty and many products that have not been previously described.

Benzoic Acid↗
PubMed2002

Supplemental fructooligosaccharides and mannanoligosaccharides influence immune function, ileal and total tract nutrient digestibilities, microbial populations and concentrations of protein catabolites in the large bowel of dogs.

The goal of this study was to examine whether supplemental fructooligosaccharides (FOS) and (or) mannanoligosaccharides (MOS) influenced indices of gut health of dogs. Adult female dogs (n = 4) surgically fitted with ileal cannulas were fed a dry, extruded, kibble diet twice daily. At each feeding, the following treatments were administered: 1) Control (no FOS or MOS); 2) 1 g FOS; 3) 1 g MOS; or 4) 1 g FOS + 1 g MOS. Fecal, ileal and blood samples were collected during the last 4 d of each 14-d period to measure protein catabolite concentrations, microbial populations, immune characteristics and nutrient digestibilities. Treatment means were compared using preplanned orthogonal contrasts. Dogs supplemented with MOS had lower (P = 0.05) fecal total aerobes and tended to have greater (P = 0.13) Lactobacillus populations. Ileal immunoglobulin (Ig) A concentrations were greater (P = 0.05) in dogs supplemented with FOS + MOS vs. control. Lymphocytes (% of total white blood cells) were greater (P < 0.05) in dogs supplemented with MOS. Serum IgA concentrations also tended (P = 0.13) to be greater in dogs supplemented with MOS. Dogs supplemented with FOS and FOS + MOS had lower (P < 0.05) fecal total indole and phenol concentrations. Dogs supplemented with MOS tended to have lower ileal DM (P = 0.149) and OM (P = 0.146) digestibilities vs. control. Results of this study suggest that dietary supplementation of FOS and MOS may have beneficial effects on colonic health and immune status of dogs.

Animals↗
PubMed1998

Rifampin increases cytokine-induced expression of the CD1b molecule in human peripheral blood monocytes.

In recent years, it has been shown that a nonclassical, major histocompatibility complex-independent system (i.e., CD1-restricted T-cell responses) is involved in T-cell immunity against nonpeptide antigens. The CD1 system appears to function by presenting microbial lipid antigens to specific T cells, and the antigens so far identified include several known constituents of mycobacterial cell walls. Among the four known human CD1 isoforms, the CD1b protein is the best characterized with regard to its antigen-presenting function. Expression of CD1b is upregulated on human blood monocytes upon exposure to granulocyte/macrophage-colony stimulating factor, alone or in combination with interleukin-4 (IL-4) (S. A. Porcelli, Adv. Immunol. 59:1-98, 1995). Rifampin (RFP) and its derivatives are widely used for chemoprophylaxis or chemotherapy against Mycobacterium tuberculosis. However, this agent was found to reduce the mitogen responsiveness of human B and T lymphocytes, chemotaxis, and delayed-type hypersensitivity. The present study extends the immunopharmacological profile of RFP by examining its effects on CD1b expression by human peripheral blood monocytes exposed to GM-CSF plus IL-4. The results showed that clinically attainable concentrations (i.e., 2 or 10 microg/ml for 24 h) of the agent produced a marked increase in CD1b expression on the plasma membrane, as evaluated by fluorescence-activated cell sorter analysis, whereas it had no effect on cytosolic fractions, as indicated by Western blot analysis. This was found to be the result of increased CD1b gene expression, as shown by Northern blot analysis of CD1b mRNA. These results suggest that RFP could be of potential value in augmenting the CD1b-restricted antigen recognition system, thereby enhancing protective cellular immunity to M. tuberculosis.

Antibiotics, Antitubercular↗
PubMed1991

Domains in microbial beta-1, 4-glycanases: sequence conservation, function, and enzyme families.

Several types of domain occur in beta-1, 4-glycanases. The best characterized of these are the catalytic domains and the cellulose-binding domains. The domains may be joined by linker sequences rich in proline or hydroxyamino acids or both. Some of the enzymes contain repeated sequences up to 150 amino acids in length. The enzymes can be grouped into families on the basis of sequence similarities between the catalytic domains. There are sequence similarities between the cellulose-binding domains, of which two types have been identified, and also between some domains of unknown function. The beta-1, 4-glycanases appear to have arisen by the shuffling of a relatively small number of progenitor sequences.

Amino Acid Sequence↗
PubMed1997

MHC class II positive retinal pigment epithelial (RPE) cells can function as antigen-presenting cells for microbial superantigen.

Retinal pigment epithelial (RPE) cells induced to express MHC class II (HLA-DR) by incubation with interferon gamma (IFN-gamma) were investigated for their ability to present a microbial superantigen to T lymphocytes. Superantigens bind to MHC class II antigens and appear to play a role in a number of infectious and autoimmune diseases through stimulation of large numbers of T cells. Primary cultures of human RPE cells treated with IFN-gamma for three days to induce HLA-DR expression bound staphylococcal enterotoxin E (SEE) via HLA-DR and presented SEE to T cells as measured by proliferation of purified peripheral blood T cells and IL-2 synthesis by the Jurkat T cell line. Untreated RPE cells were essentially ineffective as superantigen presenting cells. These results suggest that MHC class II expressing RPE cells could contribute to immune and inflammatory activity in the eye by presenting superantigens to T lymphocytes.

Antigen Presentation↗
PubMed2005

[Construction and function of a high-efficient complex microbial system to degrade cellulose and lindane in compost].

A complex microbial system capable of degrading cellulose and lindane with high efficiency was isolated from four compost heaps. It was selected and domesticated through two methods and by combination of different microbial communities. The results show that the complex microbial system can decompose filter paper, absorbent cotton, rice straw powder and sawdust effectively, especially has high degrading activity for the materials with higher native cellulose such as filter paper and absorbent cotton. As for both of them, the CMC saccharification activity is more than 40U and the degradation efficiency is more than 95% on the 5th day of inoculation. The complex microbial system can also keep a higher degrading capability in a wider range of pH. Filter paper and lindane can be degraded effectively by the complex microbial system during pH 7.0 - 9.0, and the degradation rates are more than 90 % and 45% respectively. Under pH 6.0 - 9.0, there is a good consistency between the degradation of Lindane and the decomposition of filter paper.

Bacteria, Aerobic↗