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PubMed1980

[Histological study of Xenopsylla cheopis fleas infected with the ulegeic subspecies of the plague microbe, Yersinia pestis ulegeica].

The plague microbe of the Ulegei subspecies is able to cause the stable infection of fleas of X. cheopis, which is accompanied by the formation of "block" in most individuals. The preservation of the plague agent in these ectoparasites is characterized by its variation in the number that undergoes cyclic changes depending on the feeding rate and digestion. The bloodsucking is accompanied by the excretion of some microbes and by the reproduction of the remaining ones in the midgut and proventriculus which lasts the whole 1 st stage while dense clots of erythrocytes are preserved in the intestine. In the course of blood digestion the reproduction of microbes is replaced by their dying off and when the digestion is over the quantity of microbes increases again. In this period small cocci, which form dense clots in the midgut and proventriculus, are the dominant form of microbes.

Animals↗

PubMed1994

[Virulence of rifampicin and quinolone resistant mutants of strains of plague microbe with Fra+ and Fra- phenotypes].

Experiments with 15 highly virulent antigenically typical strains (Fra+) and 3 fraction-free strains (Fra-) of the plague microbe were conducted. It was demonstrated that a single exposure of the plague microbe to rifampicin or nalidixic acid (100 micrograms/ml) resulted in the formation of mutants (Rifr or Nalr) resistant to the drugs. The mutation frequency was 10(-10)-10(-8). All the Nalr mutants showed cross resistance to ciprofloxacin, a 3rd generation quinolone. A comparative study of the virulence of the clones in the population of the initial strains of the plague microbe and the cultures of the Rifr and Nalr mutants revealed that the predominating majority of the variants resistant to rifampicin and the quinolone preserved their high virulence. The resistance level of the mutants was sufficient for inducing the infection development in the albino mice at the background of the therapy with rifampicin, nalidixic acid or ciprofloxacin: no statistically significant differences in the values of the LD50 of the culture for the treated and nontreated animals were recorded. The Rifr and Nalr variants of the fraction-free strains of the plague microbe preserved their ability to overcome the specific immunity in the albino mice. The experimental data indicated that the rifampicin or quinolone monotherapy required a caution and the combined etiotropic therapy was more advantageous since it decreased the risk of the complications due to the drug resistant virulent variants of the plague microbe forming during the treatment.

4-Quinolones↗

PubMed2001

X-ray absorption spectroscopy study shows that the rapid selenium volatilizer, pickleweed (Salicornia bigelovii Torr.), reduces selenate to organic forms without the aid of microbes.

In many plant species, selenium (Se) volatilization is limited by the reduction of selenate and its chemical conversion to organic Se compounds, a process that may be facilitated by rhizosphere microbes. This study was conducted to determine if pickleweed (Salicornia bigelovii Torr.), which is characterized by having high rates of Se volatilization from selenate, is able to reduce selenate into organic forms of Se axenically, or whether it requires the presence of microbes. X-ray absorption spectroscopy analysis showed that shoots and roots of pickleweed plants supplied with 50 microM selenate accumulated Se predominantly in organic Se forms (about 65-75% of the total accumulated Se), regardless of whether the plants were grown axenically or in the presence of microbes. The results suggest that, unlike other species for which selenate reduction appears to be rate limiting. e.g. Indian mustard (Brassica juncea L.) and broccoli (Brassica oleracea L.), pickleweed is unusual in that it has an enhanced capacity to reduce selenate to organic forms that is independent of the presence of rhizosphere microbes.

Chenopodiaceae↗

PubMed2003

Gingival colonization with selective HACEK microbes in children with congenital heart disease.

It was previously shown that children with congenital heart disease (CHD) harbored Hemophilus, Actinobacillus, Cardiobacter, Eikenella, and Kingella (HACEK) microbes to a greater extent and had more severe gingival inflammation than a normal group of children. The purpose of this study was to determine if HACEK microbes are more prevalent in children with CHD than in normal children when there is no difference in gingival inflammation. Two groups of 12 children were matched with respect to gingival inflammation. Each child had a gingival index recorded as described by Massler. The experimental group consisted of 12 children with CHD 2.5-10 years old (average 5.5) and the control group consisted of 12 healthy children 2-13 years old (average 5.6). Subgingival samples were obtained and cultured for HACEK microbes. Fischer's exact test was performed with the significance level defined at P<0.05. The average gingival indices for the experimental and control groups were 6.5 and 6.4, respectively (N.S.). Nine of 12 children with CHD had Eikenella corrodens (E.c.) compared to 3/12 control patients ( P<0.05). Three of 12 CHD patients but no control patient had Actinobacillus actinomycetemcomitans (A.a.) (N.S.). There were no significant differences in E.c. or A.a. presence between cyanotic and acyanotic CHD patients. This study found that the greater extent of specific HACEK microbes harbored by children with CHD is not associated with cyanosis or the degree of gingival inflammation. Further study is needed to delineate fully the medical significance of this observation.

Aggregatibacter actinomycetemcomitans↗

PubMed2004

Metagenomics--the key to the uncultured microbes.

It is widely accepted that up to 99.8% of the microbes present in many environments are not readily culturable. 'Metagenome technology' tries to overcome this bottleneck by developing and using culture-independent approaches. From the outset, metagenome-based approaches have led to the accumulation of an increasing number of DNA sequences, but until this time the sequences retrieved have been those of uncultured microbes. These genomic sequences are currently exploited for novel biotechnological and pharmaceutical applications and to increase our knowledge on microbial ecology and physiology of these microbes. Using the metagenome sequences to fully understand how complex microbial communities function and how microbes interact within these niches represents a major challenge for microbiologists today.

Bacteria↗

PubMed2005

Exploring novel bioactive compounds from marine microbes.

The historical paradigm of the deep ocean as a biological 'desert' has shifted to one of a 'rainforest' owing to the isolation of many novel microbes and their associated bioactive compounds. Recently, there has been an explosion of information about novel bioactive compounds that have been isolated from marine microbes in an effort to further explore the relatively untapped marine microbes and their secondary metabolites for drug discovery. The microbes are recovered and purified from the ocean by both conventional and innovative isolation methods to obtain those previously thought to be 'uncultivable'. To overcome the difficulties and limitations associated with cultivation techniques, several DNA-based molecular methods have been developed to bypass the culture-dependent bottleneck. Bioactive compounds isolated using the above strategies have not only shown importance in biotechnological and pharmaceutical applications but have also increased our understanding of the diversity of marine microbiota, ecosystem functions and the exploitable biology.

Anti-Infective Agents↗

PubMed1997

Microscopic study of migration of microbes in food-packaging paper and board.

The microbiological barrier properties of food-packaging paperboards, coated with polyethylene, mineral pigment or a biodegradable polymer and of high-density paper were examined with confocal laser scanning microscopy. The results show that the spatial distribution of microscopically observable bacterial cells was uneven inside the paperboard. The concentration in the interface between the polyethylene coating and the cellulose fibers was 100-200 times higher than inside the cellulose matrix. The bacteria in the interface and the mineral coating layer grew in response to access to food and moisture, whereas no growth was observed inside the fiber web, not even after extended exposure for up to 90 days. The paper and paperboards studied contained soluble nutrients (C:N:P 54:9:1 to 309:3:1) and no measurable antimicrobial activity. The factor limiting growth and migration of bacteria inside the fiber web was most likely limited access to free water, even under conditions of extensive wetting. The studied paperboards functioned as efficient barriers against translocation of microbes. The microbes residing between the paperboard and its polymer coating facing food, was the only potential site from which microbes could leak into food. This emphasizes the need for high hygienic quality of surface-sizing chemicals. Mineral-coating pigments were a source of microbes and their application behind the PE coating facing food is contraindicated.

Bacteria↗

PubMed1994

Microbes at work: micro-organisms, the D.S.I.R. and industry in Britain, 1900-1936.

The study of micro-organisms in Britain in the early twentieth century was dominated by medical concerns, with little support for non-medical research. This paper examines the way in which microbes came to have a place in industrial contexts in the 1920s and early 1930s. Their industrial capacity was only properly recognized during World War I, with the development of fermentation processes to make required organic chemicals. Post-war research sponsored by chemical and food industries and the D.S.I.R established the industrial significance of microbes. The primary focus here is the D.S.I.R. work which aimed to pull microbes away from medical concerns and promote the role of microbes in British industry.

Chemical Industry↗

PubMed2004

Regulation of intestinal ontogeny: effect of glucocorticoids and luminal microbes on galactosyltransferase and trehalase induction in mice.

Intestinal maturation can be influenced by intrinsic factors (glucocorticoid hormones) and by extrinsic factors (resident microflora); their relative roles in ontogeny of mouse intestinal trehalase expression, a marker of general gut development, and of beta1,4-galactosyltransferase (beta GT), a marker of glycosyltransferase development, were investigated. In conventional (CONV) mice, beta GT and trehalase gene expression rapidly increased to adult levels by the fourth postnatal week. In germ-free (GF) mice, beta GT expression remained at initial low levels and was rapidly induced on reintroduction of luminal microbes of the adult gut but not of microbes characteristic of the suckling gut. Similar developmental patterns were observed for colonic galactosyl beta1,4-linked glycoconjugates, products of beta GT activity. These results indicate an essential role for microbes in the ontogeny of beta GT. In both CONV and GF mice, cartisone acetate (CA) precociously accelerated the ontogeny of beta GT and trehalase until maturation of the gut occurred (day 22). In the mature gut of CONV mice, both beta GT and trehalase are elevated and insensitive to CA; in GF mature mice, the expression of beta GT remains low, whereas the expression of trehalase was at mature levels, regardless of CA treatment. These changes in enzyme activity were accompanied by parallel changes in mRNA, implying transcriptional regulation. Thus both microbes and cortisone regulate gut ontogeny, but only suckling gut responds to CA, an intrinsic factor, whereas adult gut beta GT expression remains sensitive to microflora, an extrinsic factor. However, induction of the adult pattern of glycosyltransferase expression in mature gut requires colonization by microflora typical of adult gut, suggesting an essential role for intestinal colonization in the ontogeny of normal intestinal mucosal cell surface glycoconjugate receptors.

Animals↗

PubMed1991

Comparison of the ability of two sperm preparation techniques to remove microbes.

The ability of a new sperm preparation method--self migration in sodium hyaluronate (SH)--to remove microbes from samples was compared to that of the traditional method of centrifugation/swim up (CS). Two 1-ml aliquots were taken from 20 semen samples used for inseminations, and prepared by each of the methods. Samples for culture were taken immediately before wash and at 2 and 24 h after. Microbes were found in all raw semen samples with a mean concentration of 47.8 x 10(3) colony forming units per ml (c.f.u./ml). After preparation and 2 h incubation with and without penicillin, both CS and SH were found greatly to reduce the number of isolates. There were no differences between the ability of the two methods to reduce microbe concentration, although SH recovered more progressive motile spermatozoa than CS (P less than 0.05). When penicillin preparation was omitted, both the CS and SH methods resulted in significantly more isolates after 24 h of incubation. This effect of penicillin preparation was also evident after only 2 h of incubation with CS, but not with SH. No clinical signs of infection were observed among women receiving treatment. We conclude that sperm preparation by self migration in sodium hyaluronate is a simple and safe method to remove microbes and to recover motile spermatozoa.

Bacteriological Techniques↗

PubMed1993

Binding of streptavidin to bacteria or fungi and its applications in detecting these microbes.

We have investigated the characteristics and utilities of streptavidin-binding to gram-negative and gram-positive bacteria and Candida spp. The pre-treatment of these microbes with chemical reagents such as CHCl3, NaOH, and Tween 20 have allowed colorimetric visualization under light microscopy or quantitation on nitrocellulose membranes, using streptavidin/biotinylated alkaline phosphatase conjugates. Analysis of this binding was confirmed by western blot. These binding reactions were due to the specific interaction of streptavidin with biotinylated proteins present in the microbes. Competition assays with free biotin or inhibition by an antibiotin antibody confirmed binding to these proteins. With knowledge of these strongly specific interactions, we attempted to reveal the biotinylated proteins within these microbes using clinical specimens. Using phagocyte-smears from blood, urine, and ascites, these intracellular microbes were easily detected by light microscopy. One of the septic blood samples stained by our technique revealed semi-digested microbial signals despite the absence of a signal with routine staining. This detection system, which combines streptavidin as a probe and biotinylated proteins as a microbial marker, is useful in staining for intracellular bacteria or fungi (e.g., microbial infections in phagocyte-smears).

Alkaline Phosphatase↗

PubMed2006

Enrichment for microbes living in association with plant tissues.

AIMS: To investigate a cultivation-independent method of enrichment for microbes living in association with plant tissues. METHODS AND RESULTS: A large quantity of leaves or seeds was enzymatically hydrolyzed, and the pellets were collected by differential centrifugation. Enzyme concentration, buffer and incubation time were optimized for release of plant-associated microbes. The relative abundance of plant nuclear DNA and bacterial DNA in the enriched sample was estimated by PCR amplification of genome-specific marker genes. The efficiency of microbe enrichment was estimated from the proportion of bacterium-derived clones and their restriction fragment length polymorphism (RFLP) types as detected by 16S rRNA gene-based techniques. With a higher ratio of bacterial to plant nuclear DNA, the enriched samples showed a considerably enhanced proportion of bacterium-derived clones and a wider sequence diversity of those clones. CONCLUSIONS: The method described here proved to be remarkably effective in enriching for bacteria living in association with plant tissues. SIGNIFICANCE AND IMPACT OF THE STUDY: The method can be applied to study plant-associated microbes in the field of environmental molecular ecology and environmental metagenomics.

Cell Nucleus↗

PubMed1974

Habitat, succession, attachment, and morphology of segmented, filamentous microbes indigenous to the murine gastrointestinal tract.

Some indigenous microorganisms localize on epithelial surfaces in various areas of the digestive tracts of animals. One of these, a segmented, filamentous microbe, localizes on the epithelium in the small bowels of mice and rats. These filamentous microbes colonize mice at weaning time and persist in adult animals for at least 2 months. Results of the study of light and electron micrographs suggest that the microorganisms are procaryotic, and that they interact with small bowel epithelial cells to form an attachment site. This site consists of modified epithelial cell membrane and apical cytoplasm adjacent to the attached bacterium. The microbe fills the site with part of its first segment. This segment has a nipple-like appendage on the end inserted into the epithelial cell. The other segments, which compose the rest of the filament, are usually separated by septa. Many of the individual segments contain intrasegmental bodies that appear to be procaryotic cells. Some of these intrasegmental bodies are similar in morphology to the first segment of each filament inserted into an epithelial cell. These intracellular bodies may be components in the life cycle of the microorganism. The organism has not yet been cultured in recognizable form. Therefore, such a hypothesis cannot be proved as yet, nor can the microbe be classified with certainty. Because it localizes in an epithelial habitat in the small bowel, however, it may be a particularly important microbial type in the gastrointestinal ecosystem of laboratory rodents.

Animals↗

PubMed1965

UTILIZATION OF EXTERNAL GROWTH FACTORS BY INTRACELLULAR MICROBES: MYCOBACTERIUM PARATUBERCULOSIS AND WOOD PIGEON MYCOBACTERIA.

Wheeler, William C. (Johns Hopkins University-Leonard Wood Memorial Leprosy Research Laboratory, Baltimore, Md.), and John H. Hanks. Utilization of external growth factors by intracellular microbes: Mycobacterium paratuberculosis and wood pigeon mycobacteria. J. Bacteriol. 89:889-896. 1965.-The extent to which the intracellular growth of microbes is dependent upon capacities for growth in vitro has been investigated by use of organisms which require a specific factor, mycobactin, for isolation and growth on conventional mycobacterial media. Similarities between growth on bacteriological media and within tissue cells have been demonstrated by examining the responses of Mycobacterium paratuberculosis and wood pigeon mycobacteria to mycobactin, iron, CO(2), and glycerol, and to the low pH which characterizes phagocytic vacuoles. The results indicate that success of intracellular infections depends upon the independent growth of microbes and that the phagocytic vacuoles of sheep and mouse macrophages seem to be freely accessible to bacterial growth factors, minerals, and substrates. Because these factors did not modify the appearance, overall metabolism, or surface properties of macrophages, it was concluded that the intracellular growth of microbes is not determined solely by the components, metabolism, or immunological properties of host cells, but is influenced to an important degree by compounds and conditions provided by extracellular environments.

Animals↗

PubMed2002

Metabolic diversity in aromatic compound utilization by anaerobic microbes.

A vast array of structurally diverse aromatic compounds is continually released into the environment due to the decomposition of green plants and as a consequence of human industrial activities. Increasing numbers of bacteria that utilize aromatic compounds in the absence of oxygen have been brought into pure culture in recent years. These include most major metabolic types of anaerobic heterotrophs and acetogenic bacteria. Diverse microbes utilize aromatic compounds for diverse purposes. Chlorinated aromatic compounds can serve as electron acceptors in dehalorespiration. Humic substances serve as electron shuttles to enable the use of inorganic electron acceptors, such as insoluble iron oxides, that are not always easily reduced by microbes. Substituents that are attached to aromatic rings may serve as carbon or energy sources for microbes. Examples include acyl side chains and methyl groups. Finally, aromatic compounds can be completely degraded to serve as carbon and energy sources. Routes by which various types of aromatic compounds, including toluene, ethylbenzene, phenol, benzoate, and dihydroxylated compounds, are degraded have been elucidated in recent years. Biochemical strategies employed by microbes to destabilize the aromatic ring in preparation for degradation have become apparent from this work.

Anaerobiosis↗

PubMed2005

Design and development of a DNA array for rapid detection and genotyping of seven kinds of pathogenic microbes.

A DNA array for rapid detection and genotyping of the pathogenic microbes of epidemic hemorrhagic fever, tsutsugamushi disease, leptospirosis, malaria, schistosomiasis, cholera, and hemorrhagic colitis was developed. The specific and relatively conserved PCR primers and DNA probes were screened from the characteristic genes of the pathogenic microbes. The PCR or RT-PCR methods were established for amplifying and labeling the DNA fragments of the pathogenic microbes. All the probes with the same Tm value were synthesized chemically and modified with an NH2 at their 5' terminus, they were printed on glass slides for fabrication of a oligonucleotide DNA array. The developed DNA array could be used for detecting and genotyping the pathogenic microbes simultaneously, and they had a high sensitivity and specificity.

Animals↗

PubMed2006

Metabolic engineering of microbes for oligosaccharide and polysaccharide synthesis.

Metabolic engineering has recently been embraced as an effective tool for developing whole-cell biocatalysts for oligosaccharide and polysaccharide synthesis. Microbial catalysts now provide a practical means to derive many valuable oligosaccharides, previously inaccessible through other methods, in sufficient quantities to support research and clinical applications. The synthesis process based upon these microbes is scalable as it avoids expensive starting materials. Most impressive is the high product concentrations (up to 188 g/L) achieved through microbe-catalyzed synthesis. The overall cost for selected molecules has been brought to a reasonable range (estimated $30-50/g). Microbial synthesis of oligosaccharides and polysaccharides is a carbon-intensive and energy-intensive process, presenting some unique challenges in metabolic engineering. Unlike nicotinamide cofactors, the required sugar nucleotides are products of multiple interacting pathways, adding significant complexity to the metabolic engineering effort. Besides the challenge of providing the necessary mammalian-originated glycosyltransferases in active form, an adequate uptake of sugar acceptors can be an issue when another sugar is necessary as a carbon and energy source. These challenges are analyzed, and various strategies used to overcome these difficulties are reviewed in this article. Despite the impressive success of the microbial coupling strategy, there is a need to develop a single strain that can achieve at least the same efficiency. Host selection and the manner with which the synthesis interacts with the central metabolism are two important factors in the design of microbial catalysts. Additionally, unlike in vitro enzymatic synthesis, product degradation and byproduct formation are challenges of whole-cell systems that require additional engineering. A systematic approach that accounts for various and often conflicting requirements of the synthesis holds the key to deriving an efficient catalyst. Metabolic engineering strategies applied to selected polysaccharides (hyaluronan, alginate, and exopolysaccharides for food use) are reviewed in this article to highlight the recent progress in this area and similarity to challenges in oligosaccharide synthesis. Many naturally occurring microbes possess highly efficient mechanisms for polysaccharide synthesis. These mechanisms could potentially be engineered into a microbe for oligosaccharide and polysaccharide synthesis with enhanced efficiency.

Journal Article↗

PubMed2000

Increased susceptibility to gingival colonization by specific HACEK microbes in children with congenital heart disease.

It is well established that infective endocarditis (IE) involving the HACEK (Hemophilus, Actinobacillus, Cardiobacter, Eikenella, Kingella) group of microbes occurs in patients with congenital heart defects (CHD) and in those with prosthetic grafts. Dental caries and gingival disease have been presumed to be the focus of microbial shedding. The purpose of this study was to determine if children with CHD had a more severe gingival inflammatory condition and harbored the HACEK group of microbes to a greater extent than normal children. Two groups of 12 age and sex matched children were selected for this study. The experimental group consisted of twelve children with CHD, 1-1/2 to 8 years of age. The control group consisted of 12 healthy children 2 to 8 years of age. Each child had a gingival index score recorded as described by Massler. Subgingival cultures were obtained. Gingival samples were cultured for HACEK microbes and total Streptococcus (spp) using standard techniques. Fisher's exact test was performed with significance defined at P < 0.05. Children with CHD had more severe gingival inflammatory index than the control group (P < 0.05). 8/12 CHD patient had Actinobacillus actinomycetemcomitans (A.a.) as compared with 2/12 controls (P < 0.05). Furthermore, all cyanotic CHD patients (4/4) had A.a. whereas, only 2/12 controls did (P < 0.05). 4/12 CHD patients harbored Eikenella corrodens (E.c.) compared to 1/12 controls (N.S.). There was no significant difference in colonization with E.c. or A.a. between cyanotic and acyanotic patients. No significant difference in total Streptococcus (spp) was found between the two groups. This study suggests that children with CHD have a more severe gingival inflammatory index and are colonized with specific HACEK microbes more so than normal children.

Actinobacillus↗