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PubMed1987

Analytical and functional assessment of lymphoid cells within murine lung.

In this study we sought to characterize the tissue leukocytes in murine lung which (when derived from peripheral lymphoid organs) have been associated with host defense against tumors and certain microbial agents. Numerical and functional properties of lung lymphoid populations obtained by collagenase digestion were evaluated in inbred mice. Flow cytometric analysis of monoclonal and polyclonal antibody labelled preparations revealed that lung cells so derived were 47% T-lymphocytes (helper-suppressor ratio 4.25), 23% B-cells (surface immunoglobulin+) and 26% asialo GM1 (natural killer) cells. Lung T-cells responded well to mitogen stimulation after partial depletion of adherent macrophages, but the magnitude of this response was less than that of autologous spleen cells. Natural killer cell (NK) activity against chromium labelled tumor target cells was also manifested by lung cells and was similar to that of peripheral spleen cells. This lung NK activity could be boosted in vitro by incubation with interferon and in vivo by treatment with poly I:C. Together, these data indicate that normal murine lung contains a large number of functional T-cell and NK cell mononuclear populations. The characterization of the cell populations presented here should facilitate future studies of their role(s) in host defense against infection and neoplasia.

Animals↗
PubMed2005

Effects of community versus single strain inoculants on the biocontrol of Salmonella and microbial community dynamics in alfalfa sprouts.

Potential biological control inoculants, Pseudomonas fluorescens 2-79 and microbial communities derived from market sprouts or laboratory-grown alfalfa sprouts, were introduced into alfalfa seeds with and without a Salmonella inoculum. We examined their ability to inhibit the growth of this foodborne pathogen and assess the relative effects of the inoculants on the alfalfa microbial community structure and function. Alfalfa seeds contaminated with a Salmonella cocktail were soaked for 2 h in bacterial suspensions from each inoculant tested. Inoculated alfalfa seeds were grown for 7 days and sampled during days 1, 3, and 7. At each sampling, alfalfa sprouts were sonicated for 7 min to recover microflora from the surface, and the resulting suspensions were diluted and plated on selective and nonselective media. Total bacterial counts were obtained using acridine orange staining, and the percentage culturability was calculated. Phenotypic potential of sprout-associated microbial communities inoculated with biocontrol treatments was assessed using community-level physiological profiles based on patterns of use of 95 separate carbon sources in Biolog plates. Community-level physiological profiles were also determined using oxygen-sensitive fluorophore in BD microtiter plates to examine functional patterns in these communities. No significant differences in total and mesophilic aerobe microbial cell density or microbial richness resulting from the introduction of inoculants on alfalfa seeds with and without Salmonella were observed. P. fluorescens 2-79 exhibited the greatest reduction in the growth of Salmonella early during alfalfa growth (4.22 log at day 1), while the market sprout inoculum had the reverse effect, resulting in a maximum log reduction (5.48) of Salmonella on day 7. Community-level physiological profiles analyses revealed that market sprout communities peaked higher and faster compared with the other inoculants tested. These results suggest that different modes of actions of single versus microbial consortia biocontrol treatments may be involved.

Colony Count, Microbial↗
PubMed2026

A genomic catalog of Earth's bacterial and archaeal symbionts.

Microbial symbiosis drives the functional and phylogenomic diversification of life on Earth yet remains underexplored because of culturing challenges. This study used machine learning (ML) to predict symbiotic lifestyles in more than a hundred thousand microbial genomes from diverse environmental metagenome samples and reference genomes. Predictions were performed using symclatron, an ML framework developed to identify genomic signatures of symbionts. Predictions were deposited in a catalog we established called Symbiont Genomes (SymGs). The results indicate that 15-23% of uncultivated microorganisms likely engage in symbiotic relationships with other organisms, categorized as host-associated or obligate intracellular lifestyles, and are present in half of all known bacterial and archaeal phyla. We also identify genomic signatures of symbiotic lifestyles, including the loss of certain metabolic functions and the differential presence of metabolic modules that may enable host-dependent living. The symclatron software and the SymGs catalog represent valuable resources for studying symbioses, potentially facilitating future mechanistic investigations and engineering of host-microorganism associations.

Journal Article↗
PubMed2002

Understanding the diversity in catabolic potential of microorganisms for the development of bioremediation strategies.

Molecular ecological approaches have detected diverse microorganisms that occur in response to pollution and bioremediation; however, most of these organisms have not been isolated, and their physiological traits are poorly understood. One important objective in current bioremediation studies would therefore be an assessment of the physiology and functions of the diverse microbial population at a polluted site. Among the parameters relating to the diversity of the microbial catabolic potential, e.g., substrate specificity, inducer specificity, number of catabolic routes and kinetics of catabolic enzymes, our studies have focused on the kinetic diversity of phenol-degrading bacteria. In one example, a kinetic analysis allowed functionally important phenol-degrading bacteria to be identified in activated sludge; this information could be used to improve the performance of phenol-degrading activated sludge. In an analysis of phenol-degrading bacteria present in trichloroethylene (TCE)-contaminated aquifer soil, the kinetic data could be linked to group-specific monitoring of their phenol-hydroxylase genes. The results have suggested that one group of phenol-degrading bacteria can effectively contribute to TCE bioremediation, while other groups work poorly. Based on this information, we have succeeded in developing a high-performance TCE-degrading bioreactor. We suggest that a careful analysis of the diversity of microbial catabolic potential, particularly of the kinetic traits, may facilitate the development of new bioremediation strategies.

Biodegradation, Environmental↗
PubMed1979

Neutrophil function and host resistance.

The part played by the phagocytic cells against invading pathogens has been known since the work of Metchnikoff nearly a century ago. This review deals primarily with the role of the neutrophilic polymorphonuclear leukocyte in host defense against microbial infections. The overall function of these cells in protection from infection is dependent on a number of steps. First, an adequate number of functionally mature neutrophils have to be produced and released into the circulation by the bone marrow. Cells must circulate normally and be capable of adhering to capillary and venule walls overlying inflammatory sites. The next step involves the exit of phagocytes from the blood stream through the capillary wall and emigration into the tissues to establish contact with the invading pathogens. This process is accomplished by the locomotive characteristics of these cells and chemotaxis. Most organisms must then be phagocytized to be killed. Two discrete phases are involved in phagocytosis; the "recognition" and attachment phase followed by the ingestion phase. After phagocytosis a series of coordinated morphologic and biochemical events are set into motion which leads to eventual death and lysis of the ingested microbes. A variety of antimicrobial mechanisms are involved in this final step and indicate that these cells have an appreciable reserve capacity if one mechanism is impaired. Recent evidence which clarifies mechanisms involved in all these stages is discussed.

Animals↗
PubMed2002

Role of probiotics in the treatment of intestinal infections and inflammation.

Despite the relative success of analogous approaches in soil, aquatic, and animal environments, the enhancement of human health through probiotic consumption has not been generally endorsed in modern medicine. Laboratory-based studies are elucidating the mechanisms that mediate the properties attributed to beneficial lactic acid bacteria and Saccharomyces species in vivo. This research is now providing fundamental evidence to support observations of adhesion of probiotic species to intestinal tissue, antimicrobial activities, and immunomodulation. Probiotics appear to have a promising future in the treatment of certain disorders. Rigorously performed, controlled, double-blinded trials will overcome doubts relating to efficacy in vivo and open avenues along which probiotic-based therapies will rapidly progress. As a result of our emerging understanding of microbial activities and gene expression in situ, novel strategies will combine complementary probiotic functionalities in the form of microbial consortia or genetically enhanced organisms. As scientific knowledge and biotechnologic proficiency advance at an accelerating pace, the requirement for informed legislation and for mechanisms of effectively delivering these therapies to the sites of their intended function may limit the applications of probiotics.

Journal Article↗
PubMed1987

Selenium and immune responses.

Selenium (Se) affects all components of the immune system, i.e., the development and expression of nonspecific, humoral, and cell-mediated responses. In general, a deficiency in Se appears to result in immunosuppression, whereas supplementation with low doses of Se appears to result in augmentation and/or restoration of immunologic functions. A deficiency of Se has been shown to inhibit resistance to microbial and viral infections, neutrophil function, antibody production, proliferation of T and B lymphocytes in response to mitogens, and cytodestruction by T lymphocytes and NK cells. Supplementation with Se has been shown to stimulate the function of neutrophils, production of antibodies, proliferation of T and B lymphocytes in response to mitogens, production of lymphokines, NK cell-mediated cytodestruction, delayed-type hypersensitivity reactions and allograft rejection, and the ability of a host to reject transplanted malignant tumors. The mechanism(s) whereby Se affects the immune system is speculative. The effects of Se on the function of glutathione peroxidase and on the cellular levels of reduced glutathione and H2Se, as well as the ability of Se to interact with cell membranes, probably represent only a few of many regulatory mechanisms. The manipulation of cellular levels of Se may be significant for the maintenance of general health and for the control of immunodeficiency disorders and the chemoprevention of cancer.

Animals↗
PubMed2003

[Micro-ecology in animal stomach and digestive tracts--theory and practice].

The origin, development and practical use of animal micro-ecology community in the gastrointestinal tract of domestic animals were reviewed, and the microbial species, features, and their function mechanism were introduced. Meanwhile, the relationship of micro-ecological theory, microbial additives and their practical use in animal feeding were emphatically discussed.

Animal Nutritional Physiological Phenomena↗
PubMed2001

Functional patterns and temperature response of cellulose-fermenting microbial cultures containing different methanogenic communities.

The effect of microbial composition on the methanogenic degradation of cellulose was studied using two lines of anaerobic cellulose-fermenting methanogenic microbial cultures at two different temperatures: that at 15 degrees C being dominated by Methanosaeta and that at 30 degrees C by Methanosarcina. In both cultures, CH4 production and acetate consumption were completely inhibited by either 2-bromoethanesulfonate or chloroform, whereas H2 consumption was only inhibited by chloroform, suggesting that homoacetogens utilized H2 concomitantly with methanogens. Hydrogen was the intermediate that was consumed first, while acetate continued to accumulate. At 15 degrees C, acetoclastic methanogenesis smoothly followed H2-dependent CH4 production. Fluorescence in situ hybridization showed that populations of Methanosaeta steadily increased with time from 5 to 25% of total cell counts. At 30 degrees C, two phases of CH4 production were obtained, with acetate consumed after the abrupt increase of Methanosarcina from 0 to 45% of total cell counts. Whereas populations of Methanosaeta were able to adapt after transfer from 15 to 30 degrees C, those of Methanosarcina were not, irrespective of during which phase the cultures were transferred from 30 degrees C to 15 degrees C. Our results thus show that the community structure of methanogens indeed affects the function of a cellulose-fermenting community with respect to temperature response.

Archaea↗
PubMed2001

Structure of microbial communities in activated sludge: potential implications for assessing the biodegradability of chemicals.

Various methods used to assess the biodegradability of chemicals often employ activated sludge as an inoculum since chemicals that ultimately enter the environment are often discharged through wastewater. Differences in the structure and function of activated sludge microbial communities that may complicate interpretation of biodegradation tests could arise from differences in wastewater composition, wastewater treatment plant (WWTP) operation, or manipulations done after collection of the activated sludge. In this study, various methods were used to characterize the structure of microbial communities found in freshly collected activated sludge from WWTPs in Japan, Europe, and the United States, as well as sludge that had been continuously fed either sewage or a glucose-peptone mixture for several weeks after collection. Comparisons of biomass levels, whole-community substrate utilization (determined using Biolog GN and GP plates), and phospholipid fatty acid (PLFA) profiles indicated there were both geographical and temporal differences among freshly collected activated sludge samples. Moreover, marked shifts in the structure of activated sludge microbial communities occurred upon continuous cultivation in the laboratory for 5 weeks using a glucose-peptone feed. These shifts were evident from whole-community substrate utilization and PLFA profiles as well as differences in the profiles of 16S rDNA genes from numerically dominant populations obtained by denaturing gradient gel electrophoresis and terminal restriction fragment analyses. Further studies are needed to better define the variability within and between activated sludge from wastewater treatment plants and laboratory reactors and to assess the impact of such differences on the outcome of biodegradability tests.

Bacteria↗
PubMed2026

Symbiotic interactions and climate change implications of the octocoral microbiome.

Octocorals are vital components of tropical, temperate, and cold-water benthic marine ecosystems. Their associated microbiomes, comprising microeukaryotes, prokaryotes, and viruses, are increasingly recognised as central to host health, nutrient cycling, and chemical defence. Metagenomics and amplicon sequencing have uncovered taxonomic and functional complexity within these microbial communities, revealing patterns of host specificity and health status, along with seasonality and geographic structuring. However, anthropogenic stressors, particularly those associated with global climate change, exert intense pressure on coral-dominated ecosystems, leading to complex and poorly understood local and regional patterns of octocoral expansion and mortality. Microbial interactions may be a main driver of these contrasting outcomes by mediating the ecological resilience of octocorals to environmental stress. We synthesise the current state of research on the diversity, organisation, and function of the octocoral microbiome, and identify critical knowledge gaps on octocoral holobionts relative to scleractinian corals. Our meta-analysis of 79 publicly available bacterial genomes from octocorals reveals group-specific specialisation in denitrification and nitrate assimilation, along with widespread capacities for essential amino acid, cofactor, and vitamin production, suggesting important contributions to nutrient cycling in the holobiont. While sampling efforts between cultured and uncultured lineages are even, our genomic survey reveals strong sampling bias toward the Atlantic Ocean, temperate gorgonians, and healthy host states, whereas bacterial genomes representing the pathobiome, tropical and/or deep-sea regions, and other octocoral taxa remain underrepresented. Accordingly, we propose future research directions to advance understanding of octocoral microbiome ecology and its role in the resilience of tropical, temperate and cold-water coral reefs.

Endozoicomonadaceae↗
PubMed2001

The human genome, implications for oral health and diseases, and dental education.

We are living in an extraordinary time in human history punctuated by the convergence of major scientific and technological progress in the physical, chemical, and biological ways of knowing. Equally extraordinary are the sparkling intellectual developments at the interface between fields of study. One major example of an emerging influence on the future of oral health education is at the interface between the human genome, information technology, and biotechnology with miniaturizations (nanotechnology), suggesting new oral health professional competencies for a new century. A great deal has recently been learned from human and non-human genomics. Genome databases are being "mined" to prompt hypothesis-driven "postgenomic" or functional genomic science in microbial models such as Candida albicans related to oral candidiasis and in human genomics related to biological processes found in craniofacial, oral, and dental diseases and disorders. This growing body of knowledge is already providing the gene content of many oral microbial and human genomes and the knowledge of genetic variants or polymorphisms related to disease, disease progression, and disease response to therapeutics (pharmacogenomics). The knowledge base from human and non-human genomics, functional genomics, biotechnology, and associated information technologies is serving to revolutionize oral health promotion, risk assessment using biomarkers and disease prevention, diagnostics, treatments, and the full range of therapeutics for craniofacial, oral, and dental diseases and disorders. Education, training, and research opportunities are already transforming the curriculum and pedagogy for undergraduate science majors, predoctoral health professional programs, residency and specialty programs, and graduate programs within the health professions. In the words of Bob Dylan, "the times they are a-changing."

Biotechnology↗
PubMedDate not supplied

Stimulus-specific effects of endotoxin on superoxide production by rabbit polymorphonuclear leukocytes.

The release of superoxide (O2-) by polymorphonuclear leukocytes (PMN) is an important function that contributes to microbial death. Controversy exists as to the effect of bacterial endotoxin (lipopolysaccharide, or LPS) on the production of O2-. We have injected rabbits with 25 micrograms Escherichia coli LPS intravenously and studied PMN function 18 to 24 hours later. Relative to PMN from saline-injected controls, PMN from LPS-treated rabbits released markedly greater amounts of O2- in response to 10 ng/ml phorbol myristate acetate (PMA) as measured by nmol cytochrome C reduced in 20 minutes (40.8 +/- 7.8 for LPS-treated PMN versus 10.1 +/- 1.6 for control, p less than 0.01). LPS injection, however, significantly reduced O2- release in response to C (complement) 5a (1.4 +/- 0.6 nmole/20 minutes for LPS-treated PMN versus 5.6 +/- 1.3 nmole/20 minutes for control, p less than 0.01). O2- release in response to a third stimulus, n-formyl-methionyl-leucyl-phenylalanine (10(-7) to 10(-9) M), was not affected by LPS. O2- release in response to PMA was enhanced over a wide range of PMA concentrations (10 to 300 ng/ml). Kinetic studies over 30 minutes indicated that, after a brief initial latency in measurable response, LPS enhanced responsiveness to PMA at all time points observed. The reduced responsiveness to C5a corresponds to a previously reported down regulation of receptors for this ligand after intravenous LPS. The observations indicate that intravenous LPS can alter a critical function of PMN for at least 24 hours in a stimulus-specific manner.

Animals↗
PubMed1988

Changes in epilithic communities due to individual and combined treatments of zinc and snail grazing in stream mesocosms.

Effects of 0.5 mg/liter zinc (Zn) and snail grazing (400 snails/m2) on density of dominant algal and protozoan taxa, epilithic glucose respiration, and ash-free dry weight (AFDW) were examined using established (12-day colonization) periphyton communities in flow-through stream mesocosms with four treatments (Zn, snails, Zn and snails, control) for 30 days. Grazing and Zn similarly reduced the abundance of 5 of 10 dominant algal taxa and AFDW during the first 10 days of treatment. Abundance of these taxa and AFDW in grazed (ambient Zn) treatments approached control levels after 10 days as the effect due to snails decreased. Decreasing temperatures may have reduced snail activity. Snails, Zn, and the combination of these treatments contributed to higher rates of glucose respiration per unit AFDW. Protozoan species abundance was reduced to less than half by Zn but was unaffected by snails. Although Zn and snails individually altered structural and functional aspects of this microbial community, the effects when both treatments were combined could not always be inferred from the individual effects. Testing individual and combined variables that affect periphyton with a corresponding assessment of population dynamics, biomass, and community functional attributes will enhance understanding of the overall effects of pollutants on periphyton communities.

Animals↗
PubMed2005

Sediment resuspension effects on the benthic microbial loop in experimental microcosms.

Sediment resuspension induced by anthropogenic disturbance is becoming a major threat of marine coastal ecosystems worldwide. The effects of sediment resuspension on the pelagic domain and on macro- and meiobenthos are well documented in the literature, whereas the effects on the benthic microbial components are nearly neglected. We have investigated the effects of sediment resuspension at two different disturbance levels on benthic bacterial abundance, biomass, and activities and on heterotrophic nanobenthos abundance in experimental microcosms. The results of our experiments pointed out that, independently from the amount of involved energy, sediment resuspension determined a general decrease of all benthic microbial components. The main effects consisted of a decreased abundance of the metabolically active bacterial fraction and of heterotrophic nanobenthos abundance. However, the amount of energy involved in sediment resuspension had differential effects on the structure and functioning of the benthic microbial loop, but only in the short term (i.e., within 36 h). Sediment resuspension had a stimulatory effect on activities of surviving bacterial cells, which, in turn, resulted in increased sediment organic C turnover rates. We hypothesize that such an effect, enhancing nutrient availability, might have relevant consequences on the trophic state of coastal marine ecosystem.

Aminopeptidases↗
PubMed2001

Advances in disinfection testing and modelling.

AIMS: To develop a set of kinetic equations which more ably describe the disinfection process. METHODS AND RESULTS: A group of functions, the fat equations, based on the model used for the quantification of microbial inhibition, was produced. These functions introduce a limit to the numbers of micro-organisms capable of being disinfected. These new expressions were shown to be more general forms of currently-used (e.g. log-linear) disinfection models, and accommodate the lags and/or tails of non-linear log-survivor--time plots. An advance in the experimental procedures used to obtain disinfection data, using an optical density technique, was developed concomitantly. CONCLUSION: The methods of analyses (experimental and modelling) allow the researcher to examine, more ably, five-minute disinfection (or specific time disinfection tests) as well as the more important disinfection rate analyses. SIGNIFICANCE AND IMPACT OF THE STUDY: The fat equations are an improvement over commonly-used rate models of disinfection, which are shown to be special cases of these equations. This raises the question as to whether our current understanding of the kinetic basis of disinfection requires revision.

Chloramphenicol↗
PubMed2003

Activity and population dynamics of heterotrophic and ammonia-oxidizing microorganisms in soil surrounding sludge bands spiked with linear alkylbenzene sulfonate: a field study.

Recent research has documented soil microorganisms to be rather sensitive to linear alkylbenzene sulfonates (LAS), which may enter the soil environment in considerable quantities following sewage sludge disposal. We here report field effects of LAS on selected microbial populations present in a sandy soil surrounding well-defined sludge bands spiked with high but realistic LAS levels (7.1 or 31.3 g/kg). Surprisingly, LAS had no effect on heterotrophic respiration in the sludge compartment per se but stimulated activity and metabolic quotient (microbial activity per unit of biomass) in the surrounding soil. By contrast, autotrophic ammonia oxidation was initially inhibited in the LAS-spiked sludge. This led to dramatic transient increases of NH4+ availability in the sludge and surrounding soil, subsequently stimulating soil ammonia oxidizers. As judged from a Nitrosomonas europaea bioluminescence toxicity assay, however, LAS or other sludge components never accumulated to toxic levels in the soil compartments and the LAS tolerance of the indigenous microbes further remained unchanged following LAS exposure. LAS effects on the investigated microbial populations largely occurred during the first two months and were confined to soil closer than 30 mm from LAS-spiked sludge. Our results strongly suggest that disposal of LAS-contaminated sludge does not pose a major risk to the function of the soil microbial community under field conditions.

Alkanesulfonic Acids↗