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Pseudobacteraemia in a patient with neutropenic fever caused by a novel paenibacillus species: Paenibacillus hongkongensis sp. nov.

AIMS: To characterise a strain of Gram negative aerobic straight or slightly curved rods (HKU3) isolated from the blood culture of a 9 year old Chinese boy with neutropenic fever and pseudobacteraemia. METHODS: The isolate was phenotypically investigated by standard biochemical methods using conventional biochemical tests, scanning electron microscopy, and transmission electron microscopy. Genotypically, the 16S rRNA gene of the bacterium was amplified by the polymerase chain reaction (PCR) and sequenced. The sequence of the PCR product was compared with known 16S rRNA gene sequences in the Genbank by multiple sequence alignment. The G + C content was determined by thermal denaturation. A phylogenetic tree was constructed by the PileUp method. RESULTS: The cells of the bacterial strain were aerobic, sporulating, Gram negative straight or slight curved rods. The bacterium grew on horse blood agar as non-haemolytic, grey colonies of 1 mm in diameter after 24 hours of incubation at 37 degrees C in ambient air. No enhancement of growth was seen in 5% CO(2). It grew at 50 degrees C as pinpoint colonies after 72 hours of incubation, but did not grow at 65 degrees C or on MacConkey agar. It was non-motile. It produced catalase (weakly positive) and cytochrome oxidase. It reduced nitrate, produced beta galactosidase, hydrolysed esculin, and utilised sodium acetate. A scanning electron micrograph of the bacterium showed straight or slightly curved rods. A transmission electron micrograph of the cell wall of the bacterium revealed multiple electron dense layers, including the outer membrane, middle murein layer, and inner cytoplasmic membrane, compatible with its Gram smear appearance. 16S rRNA gene sequencing showed that there were 7.7%, 8.0%, 8.2%, and 8.6% differences between the 16S rRNA gene sequence of the bacterium and those of Paenibacillus macerans, Paenibacillus borealis, Bacillus ehimensis, and Paenibacillus amylolyticus, respectively. The mean (SD) G + C content of the bacterium was 47.6 (2.1) mol%. Phylogenetically, it belongs to the genus paenibacillus (previously called group 3 bacillus). CONCLUSIONS: A bacterium that exhibited phenotypic and genotypic characteristics that are very different from closely related members of paenibacillus was the cause of pseudobacteraemia in a patient with neutropenic fever. A new species, Paenibacillus hongkongensis sp. nov. is proposed, for which HKU3 is the type strain.

Bacillaceae↗

The taxonomy of some new isolates of dissimilatory sulfate-reducing bacteria.

The interrelationships between 92 isolates of sporing and non-sporing sulfate-reducing bacteria were determined. Of the 116 biochemical and physiological characteristics examined, only 25 were useful for discrimination of groups. Responses to most of the test were negative. A similarity coefficient and a principal component factor analysis of these data were made. The deoxyribonucleic acids buoyant densities (DNA) from all strains and the electrophoretic properties of adenylylsulfotransferase (ATP-sulfurylase), adenylphosphosulfate (APS)-reductase, and sulfite reductase of selected isolated were determined. On the basis of these various data eight groups were recognized. Isolated of seven of these groups appeared to be similar to one or more named strains. Isolates of group E(DNA buoyant density, 1.708) were different from previously named strains. Sporins strains were not isolated from the Papua New Guinea location. Halophilic and non-halotolerant strains were isolated from highly saline locations in Australia. Results pertinent to the taxonomy and ecology of the sulfate-reducing bacteria are discussed.

Bacillaceae↗

Cell division in Sporosarcina ureae.

Electron microscopy of thin-sectioned and freeze-etched cells of Sporosarcina ureae demonstrated that division occurred in two or three perpendicular planes. The complex wall consisted of a 12-nm-thick amorphous layer which was adjacent to the plasma membrane (PM) and an overlying 16-nm-thick poroteinaceous array (a regularly structured (RS) layer). Septation proceeded with the ingrowth of the PM and the inner layer in association with division mesosomes. The RS layer remained behind at the initiation site, and buckled and sloughed off to accommodate its continued extension. After the septal annulus had fused, perpendicular septa were initiated. As these secondary septa proceeded to form a tetrad of cells, the RS layer began a gradual peripheral ingrowth along the first division plane. Separation of the cells was incomplete until the centripetal growth of the RS layer had finished; often this was not until a packet of eight cells had been formed.

Bacillaceae↗

Salt extends the upper temperature limit for growth of food-poisoning bacteria.

Inclusion of NaCl into the growth medium raised the upper temperature limit of growth of the following organisms: Staphylococcus aureus (two strains), Salmonella senftenberg, S. typhimurium, Escherichia coli, Streptococcus faecalis, Bacillus cereus, Clostridium sporogenes, C. perfringens (two strains). The magnitude of the response varied with the culture, the largest being 3.5 degrees with B. cereus cells. The spores of B. cereus were not protected by salt but clostridial spores behaved as the vegetative cells (response of 2.5 degrees). The optimal salt concentration for the protective effect varied with the organism ranging from 0.2 M for the Gram-negative organisms to 1.0 M for S. aureus.

Bacillaceae↗

Influence of bacterial strains isolated from lead-polluted soil and their interactions with arbuscular mycorrhizae on the growth of Trifolium pratense L. under lead toxicity.

We isolated two bacterial strains from an experimentally lead (Pb)-polluted soil in Hungary, 10 years after soil contamination. These strains represented the two most abundant cultivable bacterial groups in such soil, and we tested their influence on Trifolium pratense L. growth and on the functioning of native mycorrhizal fungi under Pb toxicity in a second Pb-spiked soil. Our results showed that bacterial strain A enhanced plant growth, nitrogen and phosphorus accumulations, nodule formation, and mycorrhizal infection, demonstrating its plant-growth-promoting activity. In addition, strain A decreased the amount of Pb absorbed by plants, when expressed on a root weight basis, because of increased root biomass due to the production of indoleacetic acid. The positive effect of strain A was not only evident after a single inoculation but also in dual inoculation with arbuscular mycorrhizal fungi. Strain A also exhibited higher tolerance than strain B when cultivated under increasing Pb levels in the spiked soil. Molecular identification unambiguously placed strain A within the genus Brevibacillus. We showed that it is important to select the most tolerant and efficient bacterial strain for co-inoculation with arbuscular mycorrhizal fungi to promote effective symbiosis and thus stimulate plant growth under adverse environmental conditions, such as heavy-metal contamination.

Bacillaceae↗

Isolation, characterization, and identification of Geobacillus thermodenitrificans HRO10, an alpha-amylase and alpha-glucosidase producing thermophile.

Thermophilic and amylolytic aerobic bacteria were isolated from soil through a selective enrichment procedure at 60 degrees C with starch as the carbon source. One of the isolates designated as HRO10 produced glucose aside from limit dextrin as the only hydrolysis product from starch and was characterized in detail. The starch-degrading enzymes produced by strain HRO10 were determined to be alpha-amylase and alpha-glucosidase. Whereas the alpha-amylase activity was detected exclusively in the culture supernatant, alpha-glucosidase occurred intracellular, extracellular, or on the surface of the bacteria depending on the growth phase. The optimum temperature and pH required for the growth of strain HRO10 were about 50 degrees C and pH 6.5 to 7.5. The strain used different carbohydrates as the carbon source, but the maximum production of alpha-amylase occurred when 1.0% (w/v) starch or dextrin was used. The use of organic vs. inorganic nitrogen favored the production of alpha-amylase in strain HRO10. The metal ions Li+, Mg2+, and Mn2+ stimulated the production of both enzymes. Identification of strain HRO10 by physiological and molecular methods including sequencing of the 16S rDNA showed that this strain belongs to the species Geobacillus thermodenitrificans. Biochemically, strain HRO10 differs from the type strain DSM 465 only in its ability to hydrolyze starch.

Bacillaceae↗

Bacillus endophthalmitis: roles of bacterial toxins and motility during infection.

PURPOSE: Bacillus endophthalmitis is a highly explosive infection of the eye that commonly results in rapid inflammation and vision loss, if not loss of the eye itself, within a few days. Quorum-sensing-controlled toxins are essential to virulence during infection. Another unique characteristic of this disease is the ability of Bacillus to replicate rapidly and migrate to all parts of the eye. This study was conducted to determine the combined roles of toxins and motility during Bacillus endophthalmitis. METHODS: Rabbit eyes were injected intravitreally with approximately 100 cfu of wild type, nonmotile, or nonmotile/quorum-sensing-deficient Bacillus thuringiensis. Infection courses were analyzed by biomicroscopy, histology, electroretinography, and quantitation of bacteria and inflammatory cells. RESULTS: Infection with wild type B. thuringiensis resulted in complete retinal function loss by 18 hours after infection, whereas nonmotile B. thuringiensis infections required 30 hours to achieve a reduction of >90% in retinal function. Further attenuation of infection resulted from infection with the nonmotile/quorum-sensing-deficient B. thuringiensis strain, with approximately 90% retinal function loss occurring at 36 hours. Overall, the nonmotile and nonmotile/quorum-sensing-deficient mutants were significantly less virulent than wild-type B. thuringiensis. CONCLUSIONS: The results demonstrate that, in addition to quorum-sensing-controlled toxin production, bacterial migration within the eye contributed to the rapidly fulminant and destructive course of Bacillus endophthalmitis. Motility and quorum-sensing may therefore represent possible targets for the development of therapies designed to attenuate the devastating effects of Bacillus in the eye during endophthalmitis.

Animals↗

Degradation of blood group antigens in human colon ecosystems. I. In vitro production of ABH blood group-degrading enzymes by enteric bacteria.

Human feces contain enzymes produced by enteric bacteria that degrade the A, B, and H blood group antigens of gut mucin glycoproteins. We have studied their production in fecal cultures to determine if such cultures can be a source for enzyme purification and to explore how blood group antigen-degrading enzymes are adapted in individual human colon ecosystems. They were present in fecal cultures from each of 27 healthy subjects, including ABH nonsecretors. Heat-sensitive obligate anaerobes are their major source. From 39 to 85% of the total enzyme activity produced by growing cultures was extracellular. Commercial hog gastric mucin and salivary glycoproteins, including Lea saliva which lacks A, B, and H antigens, enhance production of A-, B-, and H-degrading activity in anaerobic fecal cultures irrespective of the glycoprotein's blood group specificity. There is evidence that the host's ABO blood type and secretor status affects the specificity of blood group-degrading enzymes produced by his fecal bacteria in vitro. Thus, fecal inocula from B secretors incubated with hog gastric mucin (A and H specificity) or with Lea saliva produced greater levels of B-degrading than A- or H-degrading activity, and inocula from A secretors in similar media produced greater levels of A-degrading than B- or H-degrading activity. Blood group-degrading enzymes produced in fecal cultures are glycosidases and not proteases. The B-degrading enzyme cleaves the B antigenic determinant alpha-D-galactose from the oligosaccharide side chains of mucin glycoproteins with B specificity. Anaerobic fecal cultures containing blood group substances are a feasible source for purifying blood group antigen-degrading enzymes. Prior adaptation to blood group antigens in the gut mucins of type A and type B secretors affects the specificity of the enzymes produced in vitro.

ABO Blood-Group System↗

Degradation of blood group antigens in human colon ecosystems. II. A gene interaction in man that affects the fecal population density of certain enteric bacteria.

The autosomal dominant ABH secretor gene together with the ABO blood type gene control the presence and specificity of A, B, and H blood group antigens in human gut mucin glycoproteins. Certain obligate anaerobes in feces produce extracellular antigen-specific glycoside structures. We estimated the populations of these bacteria in feces of 22 healthy subjects by determining the greatest dilution of feces that yielded A, B, or H blood group-degrading enzyme activity after 24 h incubation in anaerobic cultures. Comparatively small populations of fecal bacteria produce blood group-degrading enzymes; their estimated populations were 10(8) per g or less in 21 subjects. Fecal populations of B-degrading bacteria were stable over time, and their population density averaged 50,000-fold greater in blood group B secretros than in other subjects. We present evidence that the greater fecal populations of B-degrading bacteria in B secretors is due in part to a competitive nutritional advantage gained by their ability to enzymatically cleave the B antigenic determinant alpha-D-galactose from gut mucins of B secretors. Fecal populations of bacteria producing A and H antigen-degrading enzyme activities were comparable in all subjects to the fecal population of B-degrading bacteria in B secretors. The large populations of fecal anaerobes may be an additional source of A antigen substrate for A-degrading bacteria; thus, antigens cross-reacting with A antigen were detected on cell walls of anaerobic bacteria from 3 of 10 cultures inoculated with 10(-10) g feces. Bacteria producing B-degrading activity likely represent a separate population from those producing A- or H-degrading activity since their fecal populations differed numerically in 14 subjects. These findings suggest that adaptation of blood group-degrading enzymes to mucin structures in human colon ecosystems is chiefly by mutation-selection of comparatively small populations of constitutive enzyme-producing strains rather than by substrate induced enzyme synthesis in many strains.

ABO Blood-Group System↗

Naturally occurring Tyzzer's disease in a puppy.

A naturally occurring case of Tyzzer's disease due to infection with Bacillus piliformis in a wolf-dog hybrid resulted in widely disseminated lesions, including severe myocarditis, hepatitis, enterocolitis, intestinal leiomyositis, and adrenal cortical adenitis. Previously reported lesions for canine Tyzzer's disease have been limited to hepatic necrosis and a necrotizing enterocolitis.

Animals↗

Pathogenicity of cilia-associated respiratory (CAR) bacillus isolates for F344, LEW, and SD rats.

We conducted experiments to test whether rats of F344, LEW, and SD strains differ in susceptibility to mycoplasma-free isolates of cilia-associated respiratory (CAR) bacillus, whether Mycoplasma pulmonis can affect expression of CAR bacillus disease, and whether isolates of CAR bacillus differ in virulence for rats. In the first experiment, 24 rats of each strain were inoculated intranasally with 10(7) bacilli of CAR bacillus X1428D/AS, and 24 rats of each strain were inoculated with sterile medium (controls). Eight weeks later, eight inoculated rats and eight control rats of each strain were euthanatized, eight inoculated and eight control rats were given 10(6.5) colony-forming units of M. pulmonis X1428D, and eight inoculated rats and eight control rats were sham inoculated. Four rats of each group were euthanatized 4 or 8 weeks after the second inoculation. Severity of lesions in nasal passages, middle ear, trachea, and lungs was assessed by scoring. Rats of all three strains given CAR bacillus had typical lesions of similar severity; M. pulmonis X1428D was avirulent and did not exacerbate CAR bacillus disease. In the second experiment, groups of eight rats of F344 and SD strains were given 10(5) or 10(7) CAR bacillus X1328E, X1428D/AS, or X2450D and euthanatized 8 or 16 weeks later. Isolates X1428D/AS and X2450D caused similar lesions in rats of both strains and at both doses, but CAR bacillus X1328E was avirulent. Rats of the tested strains are similarly susceptible to CAR bacillus disease, but CAR bacillus isolates differ in virulence.

Animals↗

Colonization of the tracheal epithelium of pigs by filamentous bacteria resembling cilia-associated respiratory bacillus.

Warthin Starry staining revealed filamentous bacteria colonizing the tracheal epithelium of 41 of 88 (46.6%) pigs submitted for necropsy at 2 midwestern veterinary diagnostic laboratories. The bacteria were interspersed between and oriented parallel to the cilia. In 4 of 4 colonized pig tracheas, filamentous bacteria were demonstrated by transmission electron microscopy. The bacteria were approximately the same length and diameter as cilia, and in areas of heavy colonization the bacteria outnumbered cilia. The filamentous bacteria were similar in location and morphologic characteristics to cilia-associated respiratory (CAR) bacilli of rats, mice, rabbits, and cattle. Results of immunoperoxidase staining and polymerase chain reaction analysis indicated that the pig CAR bacillus is a different bacterium than the rat CAR bacillus. Rat CAR bacillus causes chronic respiratory disease in rats and mice. The association, if any, between pig CAR bacillus and swine respiratory disease is unknown.

Animals↗

The genomic resource of Lysinibacillus fusiformis KBD-5, a biocontrol agent with antifungal activity against Botrytis cinerea.

Lysinibacillus fusiformis strain KBD-5, previously known for its antiviral activity against Tobacco mosaic virus, was investigated for its biocontrol potential against the fungal pathogen Botrytis cinerea. In plate assays, conducted with three independent biological replicates and incubated at 28 °C for 5 days, KBD-5 significantly inhibited the mycelial growth of B. cinerea by 76.42%. Whole-genome sequencing revealed a 4.69 Mb genome with a GC content of 37.28%, encoding 4719 proteins. Bioinformatics analysis identified genes involved in antimicrobial functions, including 195 carbohydrate-active enzymes (potentially aiding in fungal cell wall degradation) and 8 gene clusters for secondary metabolite synthesis (e.g., T3PKS with 30% similarity to bacillibactin biosynthetic clusters and NRPS), indicating the production of antifungal metabolites like bacillibactin-like polyketides. The strain also showed a high safety profile with no significant virulence or drug resistance risks. These findings indicate that genomic analysis of KBD-5 reveals the potential for multiple biocontrol mechanisms, supporting its potential development as a biocontrol agent. The draft genome sequence is available under NCBI accession PRJNA1335659.

Botrytis↗

Ontogeny and behaviour of early macrophages in the zebrafish embryo.

In the zebrafish embryo, the only known site of hemopoieisis is an intra-embryonic blood island at the junction between trunk and tail that gives rise to erythroid cells. Using video-enhanced differential interference contrast microscopy, as well as in-situ hybridization for the expression of two new hemopoietic marker genes, draculin and leucocyte-specific plastin, we show that macrophages appear in the embryo at least as early as erythroid cells, but originate from ventro-lateral mesoderm situated at the other end of the embryo, just anterior to the cardiac field. These macrophage precursors migrate to the yolksac, and differentiate. From the yolksac, many invade the mesenchyme of the head, while others join the blood circulation. Apart from phagocytosing apoptotic corpses, these macrophages were observed to engulf and destroy large amounts of bacteria injected intravenously; the macrophages also sensed the presence of bacteria injected into body cavities that are isolated from the blood, migrated into these cavities and eradicated the microorganisms. Moreover, we observed that although only a fraction of the macrophage population goes to the site of infection, the entire population acquires an activated behaviour, similar to that of activated macrophages in mammals. Our results support the notion that in vertebrate embryos, macrophages endowed with proliferative capacity arise early from the hemopoietic lineage through a non-classical, rapid differentiation pathway, which bypasses the monocytic series that is well-documented in adult hemopoietic organs.

Animals↗

Novel squalene-hopene cyclase inhibitors derived from hydroxycoumarins and hydroxyacetophenones.

Squalene-hopene cyclase (SHC) is a useful model enzyme for predicting molecular interactions with oxidosqualene cyclase (OSC). Structure--activity relationships were investigated for numerous coumarin-derived inhibitors of SHC, and structural simplifications are suggested. Both umbelliferone and 2,4-dihydroxyacetophenone provide convenient starting nuclei for the design of SHC inhibitors. Derivatives bearing an omega-epoxyfarnesyl moiety or just a plain alkyl chain showed an inhibitory effect on a recombinant SHC from Alicyclobacillus acidocaldarius expressed in Escherichia coli.

Acetophenones↗

Two novel cyclodextrin-degrading enzymes isolated from thermophilic bacteria have similar domain structures but differ in oligomeric state and activity profile.

In this paper, we present the expression and characterization of two novel enzymes from the alpha-amylase family exhibiting cyclomaltodextrinase specificity. The nucleotide sequences encoding the enzymes were isolated from the genomic DNA of two thermophilic bacterial strains originating from Icelandic hot springs and belonging to the genera Anoxybacillus (AfCda13) and Laceyella (LsCda13). The genes were amplified using a consensus primer strategy utilizing two of the four conserved regions present in glycoside hydrolase family 13. No identifiable signal peptides were present in open reading frames encoding the enzymes, indicating an intracellular location of both enzymes, and their physiological function to be intracellular cyclodextrin degradation. The domain structures of both enzymes were also similar, including an N-terminal domain, the catalytic module composed of the A- and B-domains, and a C-terminal domain. Despite the similarity in domain composition, the two enzymes displayed differences in the oligomeric state with AfCda13 being a dimeric protein, whereas LsCda13 was monomeric. The two enzymes also displayed significantly different activity profiles, despite being active on the same range of substrates. It was shown that the enzyme displaying the highest activity on cyclodextrin was dimeric (AfCda13). Moreover, a fraction of the dimeric enzyme could be converted to a monomeric state in the presence of KCl and this fraction retained only 23% of its activity on alpha-cyclodextrin while its activity on starch was not significantly affected, indicating that the oligomeric state is an important factor for a high activity on cyclodextrin substrates.

Amino Acid Sequence↗

Identification and characterization of salt-inducible polypeptide in Paenibacillus sp., a moderately halophilic bacterium.

In response to salt, Paenibacillus sp. strain XII expresses a 21.4 kDa polypeptide. N-terminal sequencing and sequence homology analysis indicate homology between the N-terminal sequence of the polypeptide and a segment of the N-terminus of the spore coat associated protein CotN of Oceanobacillus iheyensis, an extremely halotolerant bacteria of the deep-sea.

Bacillaceae↗