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PubMed1993

[Determination of the microporosity and the microbe permeability of sterilized packs. Comparison of the bubble pressure method, testing of microbe permeability according to DIN 58953 part 6 and the particle count test].

Three different methods (the germ impermeability test according to the guidelines of DIN 58953 part 6, paragraph 2.15 (3), bubble-point method according to CEN EN AA 002 Annex C (1), and particle-penetration test (2)) were tested for their suitability to prove the microporosity and germ impermeability of sterilization packs. The results of the bubble-point method and the particle-penetration test differed from each other to a certain extent. The results of the germ impermeability test according to DIN do not agree with those of the other methods. The DIN method has the advantage of giving practice orientated conditions. Therefore we recommend for the germ impermeability test of sterilization packs the method according to the guidelines of the DIN.

Permeability↗
PubMed2026

KG-Microbe: Building modular and scalable knowledge graphs for microbiome and microbial sciences.

BACKGROUND: The integration of many disparate forms of data is essential for understanding the microbial world and its interaction with the environment and human health. Doing so is particularly challenging in the context of microbe-host and microbe-microbe interactions that contribute to health or environmental outcomes. There are thousands of relevant microbial species, and millions of interactions among those microbes and with their environment or host. Integrated information (e.g., about host and microbial physiology, genetics, and metabolism) facilitates deeper understanding of complex mechanisms and helps interpret correlative results. RESULTS: The KG-Microbe construction framework is a novel approach to harmonizing bacterial and archaeal data in the form of a findable, accessible, interoperable, reusable and AI-ready knowledge graph (KG). Starting from a core KG with organismal traits, environments, and growth preferences and the integration of established ontologies, the framework generates a hierarchy of related KGs targeting specific use cases, including the human microbiome in the context of disease, or environmental microbiomes. The framework supports customizable taxa subsets representing communities or clades of interest. Evaluations of the KG-Microbe KGs through a series of competency questions demonstrate the accuracy and effectiveness of the data harmonization, and the utility of the resulting KGs in studies of inflammatory bowel disease and Parkinson's disease. Finally, the predictive and environmental capabilities of the KGs are demonstrated by predicting growth preferences using graph features. CONCLUSIONS: The KG-Microbe framework unifies microbial contexts in a single resource to support integrative analyses across biomedical, host, and environmental domains. KG-Microbe is a flexible, modular enabling technology for humans and machine learning methods to uncover candidate mechanistic explanations of microbial associations.

Microbiota↗
PubMed2004

[Biodegradation of aromatic hydrocarbons and dynamics of microbe growth in soils contaminated with mineral oil].

Some bacteria and fungi selected from brown soil contaminated with petroleum were taken as test microbes. Degradation of mineral oil, by different combinations of microbes and the correlation between the degradation rate and microbial growth were studied. The bacteria and fungi were inoculated to a liquid substrate spiked with 1000 milligrams diesel-oil per liter. The temperature of rocking-bed was controlled at 25 to 30 centigrade and the experiment continued for 100 days. From 0 to 60 hours it was sampled continuously to monitor the dynamic of microbial growth, and sampled termly from 5 to 100 days to study the growth of microbes and the dynamic of degradation rate. At the same time, the suspension of 0 to 20 centimeters of topsoil of the meadow umber was taken as soil microbial control, and the culture without microbes as blank control. Results showed that degradation effect of the introduced microbes were superior to that of the indigenous microbes in short term (about 20 days), while the advantage of indigenous microbes got stronger and stronger, and the predominance maintained until the experiment was stopped. At the end of the experiment the degradation rate in the treatment of indigenous microbes reached 79.24%, which was above the results of other 3 treatments, and the difference was significant.

Bacteria↗
PubMed2000

Beneficial microbes: health or hazard?

Normal microbial flora support the health of the host by diverse mechanisms. When antibiotics, stress, disease or medications disrupt normal microflora, the ability to ward off infection by pathogens is compromised. The use of beneficial microbes (also known as biotherapeutic agents, probiotics, synbiotics) has been shown to be an effective therapeutic agent for some diseases. Various types of diarrhoea (antibiotic-associated diarrhoea, Clostridium difficile disease, traveller's diarrhoea) are most responsive to these beneficial microbes. Serious risks associated with these microbes are largely theoretical at this point, but the risks need to be studied as the use of these beneficial microbes increases in popularity. Beneficial microbes are living organisms used as therapeutic agents to restore the health of the host in times when normal microflora have been disturbed. The efficacy to prevent or treat diarrhoea has been documented in multiple large, placebo-controlled, blinded clinical trials with only a few of these beneficial microbes. Risks of these beneficial microbes are limited, but potential risks have not been extensively studied in large numbers of patients.

Diarrhea↗
PubMed2005

Differences in codon bias cannot explain differences in translational power among microbes.

BACKGROUND: Translational power is the cellular rate of protein synthesis normalized to the biomass invested in translational machinery. Published data suggest a previously unrecognized pattern: translational power is higher among rapidly growing microbes, and lower among slowly growing microbes. One factor known to affect translational power is biased use of synonymous codons. The correlation within an organism between expression level and degree of codon bias among genes of Escherichia coli and other bacteria capable of rapid growth is commonly attributed to selection for high translational power. Conversely, the absence of such a correlation in some slowly growing microbes has been interpreted as the absence of selection for translational power. Because codon bias caused by translational selection varies between rapidly growing and slowly growing microbes, we investigated whether observed differences in translational power among microbes could be explained entirely by differences in the degree of codon bias. Although the data are not available to estimate the effect of codon bias in other species, we developed an empirically-based mathematical model to compare the translation rate of E. coli to the translation rate of a hypothetical strain which differs from E. coli only by lacking codon bias. RESULTS: Our reanalysis of data from the scientific literature suggests that translational power can differ by a factor of 5 or more between E. coli and slowly growing microbial species. Using empirical codon-specific in vivo translation rates for 29 codons, and several scenarios for extrapolating from these data to estimates over all codons, we find that codon bias cannot account for more than a doubling of the translation rate in E. coli, even with unrealistic simplifying assumptions that exaggerate the effect of codon bias. With more realistic assumptions, our best estimate is that codon bias accelerates translation in E. coli by no more than 60% in comparison to microbes with very little codon bias. CONCLUSIONS: While codon bias confers a substantial benefit of faster translation and hence greater translational power, the magnitude of this effect is insufficient to explain observed differences in translational power among bacterial and archaeal species, particularly the differences between slowly growing and rapidly growing species. Hence, large differences in translational power suggest that the translational apparatus itself differs among microbes in ways that influence translational performance.

Bacterial Physiological Phenomena↗
PubMedDate not supplied

The potential of rhizosphere microbes isolated from a constructed wetland to biomethylate selenium.

The potential of rhizosphere microbes isolated from common reed [Phragmites australis (Cav.) Trin. ex Steud] plants grown in a subsurface-flow constructed wetland to biomethylate selenate or selenite was studied in liquid cultures under controlled conditions. Total mean percentages of volatilized Se from half-strength Hoagland culture solutions (low C content) supplemented with selenate or selenite and inoculated with cultured rhizosphere microbes after 15 d of incubation were 7.9 and 49.1%, respectively. There was a relative best fit (r = 0.87) between total number of rhizosphere and cultured microbes and the percentage of volatilized Se in Hoagland solution after 15 d of incubation. However, when the same microbes were cultured in tryptic soybean broth (TSB) medium (high C content), the percentages of volatilized Se from selenate and selenite were 1.3 and 1.9%, respectively. The volatilization percentages of Se from selenate or selenite in culture solutions inoculated with rhizosphere suspension instead of cultured rhizosphere microbes were very low (1.2-3.0%) in both cultivation media. In all experiments, selenite was volatilized significantly (p < 0.05) in higher amounts by cultured rhizosphere microbes after 15 d of incubation compared with selenate. Dissolved biomethylated dimethylselenide (DMSe) in water samples taken from the subsurface-flow bed was determined by purging with helium. The DMSe in water samples was indirectly detected up to 2.4 microg Se L(-1), which indicates that part of the produced DMSe was dissolved in the matrix before being released into the atmosphere. Our results show that rhizosphere microbes isolated from common reed plants have a high potential of Se biomethylation and volatilization from selenate and selenite.

Bacteria↗
PubMed1995

Host-microbe interaction in the gastrointestinal tract.

In order for an infection to occur, the target organ must come in contact with sufficient microbes, the microbe must possess specific virulence factors, these virulence factors must be expressed, and the defenses of the organ system must be overcome. This dynamic process, which is ongoing in all living entities, can be described by the following relationship: [formula: see text] The establishment of infection first occurs in a particular organ. This phenomenon is known as tissue trophism and the association of microbes with organ systems governs the practice of clinical microbiology and infectious disease. With some microbes (e.g., Giardia, Cryptosporidium) the interaction with the particular organ is so specific that infections are almost always confined to one site; with others (e.g., Salmonella, enterovirus) the microbe has the potential to become systemic. When attempting to establish health risk assessment from microbes by contact with food and drinking water, one must therefore consider that the gastrointestinal tract is a complex organ system with a variety of specific host defense mechanisms. It is only when the microbe has particular virulence factors for sites in gastrointestinal tract, and the specific host defense mechanisms in the gastrointestinal tract are breached, that infection of this organ system occurs. Therefore, the general terms "immunosuppression" or "immunocompromise" are meaningless unless the specific immune defect is known. A description of the microbial virulence factors active against the gastrointestinal tract and the defense mechanisms of this organ system are reviewed to provide a biological basis health risk assessment and future food and drinking water regulations.

Antibody Formation↗
PubMed2000

Microbes in tree swallow semen.

A frequently hypothesized but poorly studied cost of multiple mating in birds is that exposure to pathogenic sexually transmitted microbes (STM's) can lower reproductive success. Conversely, female birds may benefit from high frequencies of copulation and multiple copulation partners if they receive cloacal inoculations of beneficial STM's that can either protect them against future encounters with pathogens and/or serve as therapy against present infection. We examined the semen of 30 male tree swallows (Tachycineta bicolor) in 1998 to determine the presence and prevalence of potential pathogenic and beneficial STM's. Semen was collected directly from males after applying gentle pressure to the cloaca and we used standard microbiological techniques to identify microbes. We found that 19 of 30 samples contained one or more types of microbes. In these 19 positive samples, we isolated both pathogenic and beneficial microbes from 11, only pathogenic microbes from seven, and only beneficial microbes from one. This variation among males suggests that females would benefit from considering a particular male's potential as a donor of either pathogenic or beneficial STM's as a criterion for mate choice. There were few significant differences between males with pathogen-infected semen and those without pathogens in their semen in measures of size, morphology, and ectoparasite score and feather damage. Likewise, there were few significant differences between males with beneficial Lactobacilli spp. in their semen and those without Lactobacilli spp. in their semen in measures of size, morphology, and ectoparasite score and feather damage. We were unable to determine if there was a relationship between microbe presence and prevalence on reproductive performance.

Animals↗
PubMed2000

Natural transfer of viable microbes in space.

The possibility and probability of natural transfer of viable microbes from Mars to Earth and Earth to Mars traveling in meteoroids during the first 0.5 Ga and the following 4 Ga are investigated, including: --radiation protection against the galactic cosmic ray nuclei and the solar rays, dose rates as a function of the meteorite's radial column mass (radius x density), combined with dose rates generated by natural radioactivity within the meteorite; and survival curves for some bacterial species using NASA's HZETRN transport code --other factors affecting microbe survival: vacuum; central meteorite temperatures at launch, orbiting, and arrival; pressure and acceleration at launch; spontaneous DNA decay; metal ion migration --mean sizes and numbers of unshocked meteorites ejected and percentage falling on Earth, using current semiempirical results --viable flight times for the microbe species Bacillus subtilis and Deinococcus radiodurans R1 --the approximate fraction of microbes (with properties like the two species studied) viably arriving on Earth out of those ejected from Mars during the period 4 Ga BP to the present time, and during the 700 Ma from 4.5 to 3.8 Ga. Similarly, from Earth to Mars. The conclusion is that if microbes existed or exist on Mars, viable transfer to Earth is not only possible but also highly probable, due to microbes' impressive resistance to the dangers of space transfer and to the dense traffic of billions of martian meteorites which have fallen on Earth since the dawn of our planetary system. Earth-to-Mars transfer is also possible but at a much lower frequency.

Bacillus subtilis↗
PubMed1998

Do microbes with peptides mimicking myelin cause multiple sclerosis if the T cell response to their unique peptides is limited?

This hypothesis for the pathogenesis of multiple sclerosis is based upon assumptions about the response of the T cell repertoire to pathogens. Immunologic and epidemiologic observations of several conditions suggest that activation of T cells formed in early life mediate injury to the central nervous system. Early in life, selection of lymphocytes by the thymus produces a weakly autoreactive T cell repertoire which, with the help of transient maternally-derived defenses, recognizes pathogens. These responses later are supplemented by pathogen-specific responses, acquired as microbes are encountered. As the thymus involutes, the diversity of pathogen-specific responses to microbial epitopes is progressively fixed. Reduced and delayed pathogen exposure, common in developed societies, limits the repertoire of memory T cells, which can efficiently eliminate pathogens. Due to their small number, pathogen-specific lymphocytes which mature extrathymically may not be able to rapidly eliminate most pathogens, and without the editing of the thymus, they may be autoreactive. In this setting, novel pathogens with epitopes mimicking myelin may elicit a T cell response which is autoreactive. Peptides of common microbes are known to activate T cells recognizing dominant antigens of myelin. It is postulated that at the equator, intense, non-seasonal encounters with microbes elicit an immune repertoire that produces resistance to autoimmunity, while, in temperate climates, moderate, seasonal exposures increase susceptibility to it. The differences in responses to microbes between populations with a low or high prevalence of multiple sclerosis suggests that T cell repertoires are divergent in these groups. An exuberant innate response, postulated to diminish as the load of enteric microbes falls and sanitation improves in relation to the distance from the equator, may increase resistance to multiple sclerosis by eliminating the need for T cell activation. Human herpesvirus-6 and respiratory syncytial virus are possible prototypes of microbes which activate myelin-directed T cells.

Antigens, Viral↗
PubMed2004

The weapon potential of a microbe.

The designation of a microbe as a potential biological weapon poses the vexing question of how such a decision is made given the many pathogenic microbes that cause disease. Analysis of the properties of microbes that are currently considered biological weapons against humans revealed no obvious relationship to virulence, except that all are pathogenic for humans. Notably, the weapon potential of a microbe rather than its pathogenic properties or virulence appeared to be the major consideration when categorizing certain agents as biological weapons. In an effort to standardize the assessment of the risk that is posed by microbes as biological warfare agents using the basic principles of microbial communicability (defined here as a parameter of transmission) and virulence, a simple formula is proposed for estimating the weapon potential of a microbe.

Bacteria↗