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Geobacillus stearothermophilus V ubiE gene product is involved in the evolution of dimethyl telluride in Escherichia coli K-12 cultures amended with potassium tellurate but not with potassium tellurite.

A 3.8-kb fragment of chromosomal DNA of Geobacillus stearothermophilus V cloned in pSP72 (p1VH) confers resistance to potassium tellurite (K(2)TeO(3)) and to potassium tellurate (K(2)TeO(4)) when the encoded genes are expressed in Escherichia coli K-12. The nt sequence of the cloned fragment predicts three ORFs of 780, 399, and 600 bp, whose encoded protein products exhibit about 80% similarity with the SUMT methyltransferase and the BtuR protein of Bacillus megaterium, and with the UbiE methyltransferase of Bacillus anthracis A2012, respectively. In addition, E. coli/p1VH cells evolved dimethyl telluride, which was released into the headspace gas above liquid cultures when amended with K(2)TeO(3) or with K(2)TeO(4). After 48 h of growth in the presence of these compounds, a protein of about 25 kDa was found at a significantly higher level when crude extracts were analyzed by SDS-PAGE. The N-terminal amino acid (aa) sequence of this protein, obtained by Edman degradation, matched the deduced aa sequence predicted by the G. stearothermophilus V ubiE gene. This gene was amplified by PCR, subcloned in pET21b, and transformed into E. coli JM109(DE3). Interestingly, DMTe evolution occurred when these modified cells were grown in K(2)TeO(4) - but not in K(2)TeO(3) - amended media. These results may be indicative that the two Te oxyanions could be detoxified in the cell by different metabolic pathways.

Anions↗

Metabolism of chloride in halophilic prokaryotes.

While much understanding has been achieved on the intracellular sodium and potassium concentrations of halophilic and halotolerant microorganisms and on their regulation, we know little on the metabolism of anions. Archaea of the family Halobacteriaceae contain molar concentrations of chloride, which is pumped into the cells by cotransport with sodium ions and/or using the light-driven primary chloride pump halorhodopsin. Most halophilic and halotolerant representatives of the bacterial domain contain low intracellular ion concentrations, with organic osmotic solutes providing osmotic balance. However, some species show a specific requirement for chloride. In Halobacillus halophilus certain functions, such as growth, endospore germination, motility and flagellar synthesis, and glycine betaine transport are chloride dependent. In this organism the expression of a large number of proteins is chloride regulated. Other moderately halophilic Bacteria such as Halomonas elongata do not show a specific demand for chloride. A very high requirement for chloride was demonstrated in two groups of Bacteria that accumulate inorganic salts intracellularly rather than using organic osmotic solutes: the anaerobic Halanaerobiales and the aerobic extremely halophilic Salinibacter ruber. It is thus becoming increasingly clear that chloride has specific functions in haloadaptation in different groups of halophilic microorganisms.

Bacillaceae↗

Halobacillus locisalis sp. nov., a halophilic bacterium isolated from a marine solar saltern of the Yellow Sea in Korea.

A Gram-positive, motile, endospore-forming and rod-shaped halophilic bacterial strain MSS-155 (KCTC 3788 and KCCM 41687) was isolated from a marine solar saltern of the Yellow Sea in Korea and was subjected to a polyphasic taxonomic study. This organism grew at temperature of 10.0-42.0 degrees C with an optimum of 35 degrees C. Strain MSS-155 grew optimally in the presence of 10% NaCl and did not grow in the absence of NaCl. The cell wall peptidoglycan type of strain MSS-155 was A4beta based on l-Orn- d-Asp. Strain MSS-155 was also characterized chemotaxonomically by having menaquinone-7 (MK-7) as the predominant isoprenoid quinone and anteiso-C15:0 as the major fatty acid. The DNA G + C content was 44.0 mol%. Phylogenetic analysis based on 16S rDNA sequences showed that strain MSS-155 falls within the radiation of the cluster comprising Halobacillus species. Levels of 16S rDNA sequence similarity between strain MSS-155 and the type strains of four Halobacillus species were in the range 97.6-98.8%. Strain MSS-155 exhibited levels of DNA-DNA relatedness of 6.2-11.2% to the type strains of Halobacillus species described previously. On the basis of phenotypic properties, phylogeny, and genomic data, strain MSS-155 should be placed in the genus Halobacillus as a member of a novel species, for which we propose the name Halobacillus locisalis sp. nov.

Bacillaceae↗

A rapid and effective method of extracting fully intact RNA from thermophilic geobacilli that is suitable for gene expression analysis.

Extraction of intact RNA is essential for quantitative gene expression analysis. Isolating high quality RNA from gram-positive bacteria is known to be problematic particularly from organisms that have optimal growth temperatures greater than 45 degrees C. We report a novel extraction protocol for the rapid isolation of fully intact RNA from thermophilic Geobacillus thermoleovorans using a lysing matrix containing a mixture of ceramic and glass beads, triisopropylnaphthalene sulfonic acid (TNS), and p-4-aminosalicyclic acid (PAS). Combining both detergents, TNS and PAS, appeared to increase denaturation of RNases at thermophilic temperatures. Gel electrophoresis revealed that only RNA isolated using the TNS-PAS procedure demonstrated sharp, undegraded 23S, 16S, and 5S ribosomal RNA bands. RNA extracted from geobacilli using commercially available kits was extensively degraded and was not suitable for detecting gene expression. Total RNA yields extracted with the TNS-PAS protocol were greater than eightfold higher than those obtained with available kits. Critically, it was also shown that only RNA isolated with the TNS-PAS-based method was suitable for monitoring thermophile gene expression patterns using RT-PCR analysis.

Aminosalicylic Acid↗

Genomic characterization of thermophilic Geobacillus species isolated from the deepest sea mud of the Mariana Trench.

The thermophilic strains HTA426 and HTA462 isolated from the Mariana Trench were identified as Geobacillus kaustophilus and G. stearothermophilus, respectively, based on physiologic and phylogenetic analyses using 16S rDNA sequences and DNA-DNA relatedness. The genome size of HTA426 and HTA462 was estimated at 3.23-3.49 Mb and 3.7-4.49 Mb, respectively. The nucleotide sequences of three independent lambda-phage inserts of G. stearothermophilus HTA462 have been determined. The organization of protein coding sequences (CDSs) in the two lambda-phage inserts was found to differ from that in the contigs corresponding to each lambda insert assembled by the shotgun clones of the G. kaustophilus HTA426 genome, although the CDS organization in another lambda insert is identical to that in the HTA426 genome.

Bacillaceae↗

Isolation and characterization of a cellulolytic Geobacillus thermoleovorans T4 strain from sugar refinery wastewater.

A novel, cellulolytic, bacterial thermophilic strain, T4, was isolated from sugar refinery wastewater in southern Taiwan. This isolate, a Gram-negative, motile, aerobically growing sporulating rod, can secrete thermostable endocellulase (endo-1,4-beta-D-glucanase, EC 3.2.1.4) and hydrolyze carboxymethylcellulose (CMC), phosphoric acid-swollen cellulose, Avicel, filter paper, and salicin. When strain T4 was grown in CMC medium, the cellulolytic enzyme activity in culture supernatants was stable up to 70 degrees C. More than 10% of the original activity was still detectable after heating to 100 degrees C with a pH 7.0 for 1 h. Based on 16S rDNA sequence analysis, DNA base composition, phenotypic and physiological characteristics, as well as DNA-DNA hybridization, strain T4 was classified as Geobacillus thermoleovorans T4 (DSM 14791 = CCRC 17200). We also demonstrated that the type species G. stearothermophilus (DSM 22 = ATCC 12980) could hydrolyze amorphous and crystalline (filter paper) celluloses at a rate of 13 and 14%, respectively, in comparison with strain T4.

Bacillaceae↗

Thermoactive extracellular proteases of Geobacillus caldoproteolyticus, sp. nov., from sewage sludge.

A proteolytic thermophilic bacterial strain, designated as strain SF03, was isolated from sewage sludge in Singapore. Strain SF03 is a strictly aerobic, Gram stain-positive, catalase-positive, oxidase-positive, and endospore-forming rod. It grows at temperatures ranging from 35 to 65 degrees C, pH ranging from 6.0 to 9.0, and salinities ranging from 0 to 2.5%. Phylogenetic analyses revealed that strain SF03 was most similar to Saccharococcus thermophilus, Geobacillus caldoxylosilyticus, and G. thermoglucosidasius, with 16S rRNA gene sequence identities of 97.6, 97.5 and 97.2%, respectively. Based on taxonomic and 16S rRNA analyses, strain SF03 was named G. caldoproteolyticus sp. nov. Production of extracellular protease from strain SF03 was observed on a basal peptone medium supplemented with different carbon and nitrogen sources. Protease production was repressed by glucose, lactose, and casamino acids but was enhanced by sucrose and NH4Cl. The cell growth and protease production were significantly improved when strain SF03 was cultivated on a 10% skim-milk culture medium, suggesting that the presence of protein induced the synthesis of protease. The protease produced by strain SF03 remained active over a pH range of 6.0-11.0 and a temperature range of 40-90 degrees C, with an optimal pH of 8.0-9.0 and an optimal temperature of 70-80 degrees C, respectively. The protease was stable over the temperature range of 40-70 degrees C and retained 57 and 38% of its activity at 80 and 90 degrees C, respectively, after 1 h.

Bacillaceae↗

Gene replacement of adenylate kinase in the gram-positive thermophile Geobacillus stearothermophilus disrupts adenine nucleotide homeostasis and reduces cell viability.

Thermophilic bacteria are of great value for industry and research communities. Unfortunately, the cellular processes and mechanisms of these organisms remain largely understudied. In the present study, we investigate how the inactivation of adenylate kinase (AK) affects the adenine nucleotide homeostasis of a gram-positive moderate thermophile, Geobacillus stearothermophilus strain NUB3621-R. AK plays a major role in the adenine nucleotide homeostasis of living cells and has been shown to be essential for the gram-negative mesophile Escherichia coli. To study the role of AK in the maintenance of adenylate energy charge (EC) and cell viability of G. stearothermophilus, we generated a recombinant strain of this organism in which its endogenous gene coding for the essential protein adenylate kinase (AK) has been replaced with the adk gene from the mesophile Bacillus subtilis. PCR, DNA sequencing and Southern analysis were performed to confirm proper gene replacement and preservation of neighboring genes. The highest growing temperature for recombinant cells was almost 20 degrees C lower than for wild-type cells (56 vs. 75 degrees C). This temperature-sensitive phenotype was secondary to heat inactivation of B. subtilis AK, as evidenced by enzyme activity assays and EC measurements. At higher temperatures (65 degrees C), recombinant cells also had lower EC values (0.09) compared to wild-type cells (0.45), which reflects a disruption of adenine nucleotide homeostasis following AK inactivation.

Adenine Nucleotides↗

Isolation of uncultivated anaerobic thermophiles from compost by supplementing cell extract of Geobacillus toebii in enrichment culture medium.

Several researchers have reported that microorganisms can be cultivated only in the presence of other microorganisms. We suggest that a portion of uncultivated microorganisms might be cultivated in the presence of cellular components released from bacteria in their natural environments. In this study, the cell extract of Geobacillus toebii was used to enrich uncultivated thermophiles from compost. In the process of enrichment cultures, cell extract supplementation apparently changed the community composition. This change was monitored by PCR-DGGE targeting 16S rRNA gene. Five novel groups of microorganisms (similarity of 16S rRNA gene to the closest relative <96%) were specifically isolated from enrichment cultures by using cell extract-supplemented culture media. Their growth was found to be dependent on the addition of extract of G. toebii. Putting these findings together, we suggest that the extracts of bacteria could be one of the growth factors in the thermal ecosystem with a possibility of extending other ecological niches.

Bacillaceae↗

Anoxybacillus kamchatkensis sp. nov., a novel thermophilic facultative aerobic bacterium with a broad pH optimum from the Geyser valley, Kamchatka.

A facultative aerobic, moderately thermophilic, spore forming bacterium, strain JW/VK-KG4 was isolated from an enrichment culture obtained from the Geyser valley, a geo-thermally heated environment located in the Kamchatka peninsula (Far East region of Russia). The cells were rod shaped, motile, peritrichous flagellated stained Gram positive and had a Gram positive type cell wall. Aerobically, the strain utilized a range of carbohydrates including glucose, fructose, trehalose, proteinuous substrates, and pectin as well. Anaerobically, only carbohydrates are utilized. When growing on carbohydrates, the strain required yeast extract and vitamin B(12). Anaerobically, glucose was fermented to lactate as main product and acetate, formate, ethanol as minor products. Aerobically, even in well-aerated cultures (agitated at 500 rpm), glucose oxidation was incomplete and lactate and acetate were found in culture supernatants as by-products. Optimal growth of the isolate was observed at pH(25 C) 6.8-8.5 and 60 degrees C. The doubling times on glucose at optimal growth conditions were 34 min (aerobically) and 40 min (anaerobically). The G+C content was 42.3 mol% as determined by T(m) assay. Sequence analysis of the 16S rRNA gene indicated an affiliation of strain JW/VK-KG4 with Anoxybacillus species. Based on its morphology, physiology, phylogenetic relationship and its low DNA-DNA homology with validly published species of Anoxybacillus, it is proposed that strain JW/VK-KG4 represents a new species in the genus Anoxybacillus as A. kamchatkensis sp. nov. The type strain for the novel species is JW/VK-KG4(T) (=DSM 14988, =ATCC BAA-549). The GenBank accession number for the 16S rDNA sequence is AF510985.

Aerobiosis↗

Characterization of Exiguobacterium isolates from the Siberian permafrost. Description of Exiguobacterium sibiricum sp. nov.

Three Gram-positive bacterial strains, 7-3, 255-15 and 190-11, previously isolated from Siberian permafrost, were characterized and taxonomically classified. These microorganisms are rod-shaped, facultative aerobic, motile with peritrichous flagella and their growth ranges are from -2.5 to 40 degrees C. The chemotaxonomic markers indicated that the three strains belong to the genus Exiguobacterium. Their peptidoglycan type was A3alpha L-Lys-Gly. The predominant menaquinone detected in all three strains was MK7. The polar lipids present were phosphatidyl-glycerol, diphosphatidyl-glycerol and phosphatidyl-ethanolamine. The major fatty acids were iso-C13:0, anteiso-C13:0, iso-C15:0, C16:0 and iso-C17:0. Phylogenetic analysis based on 16S rRNA and six diverse genes, gyrB (gyrase subunit B), rpoB (DNA-directed RNA polymerase beta subunit), recA (homologous recombination), csp (cold shock protein), hsp70 (ClassI-heat shock protein-chaperonin) and citC (isocitrate dehydrogenase), indicated that the strains were closely related to Exiguobacterium undae (DSM 14481(T)) and Exiguobacterium antarcticum (DSM 14480(T)). On the basis of the phenotypic characteristics, phylogenetic data and DNA-DNA reassociation data, strain 190-11 was classified as E. undae, while the other two isolates, 7-3 and 255-15, comprise a novel species, for which the name Exiguobacterium sibiricum sp. nov. is proposed.

Bacillaceae↗

Biosynthesis of a thermostable gellan lyase by newly isolated and characterized strain of Geobacillus stearothermophilus 98.

The thermophilic strain able to degrade gellan was isolated from Bulgarian hot spring. According to its morphological and biochemical properties and by partial sequencing of its 16S rDNA, it was classified as Geobacillus stearothermophilus. It grew in a synthetic medium with gellan as the only carbon source with a specific growth rate of 0.69 h(-1) and generation time of 60 min. The strain produced thermostable gellan lyase extracellularly during exponential phase. Its synthesis was inducible; the enzyme was not registered in culture liquid without gellan. The enzyme activity was increased tenfold in conditions of continuous cultivation compared to data from batch fermentations and enzyme productivity was almost sixfold higher. The enzyme showed optimal activity at 75 degrees C in a very large pH area 4-8.5. This enzyme is the first reported thermostable gellan lyase, its residual activity was 100% after 24 h incubation at 60 degrees C and its half-life was 60 min at 70 degrees C.

Bacillaceae↗

Isolation and characterization of two novel ethanol-tolerant facultative-anaerobic thermophilic bacteria strains from waste compost.

In a search for potential ethanologens, waste compost was screened for ethanol-tolerant thermophilic microorganisms. Two thermophilic bacterial strains, M5EXG and M10EXG, with tolerance of 5 and 10% (v/v) ethanol, respectively, were isolated. Both isolates are facultative anaerobic, non-spore forming, non-motile, catalase-positive, oxidase-negative, Gram-negative rods that are capable of utilizing a range of carbon sources including arabinose, galactose, mannose, glucose and xylose and produce low amounts of ethanol, acetate and lactate. Growth of both isolates was observed in fully defined minimal media within the temperature range 50-80 degrees C and pH 6.0-8.0. Phylogenetic analysis of the 16S rDNA sequences revealed that both isolates clustered with members of subgroup 5 of the genus Bacillus. G+C contents and DNA-DNA relatedness of M5EXG and M10EXG revealed that they are strains belonging to Geobacillus thermoglucosidasius. However, physiological and biochemical differences were evident when isolates M5EXG and M10EXG were compared with G. thermoglucosidasius type strain (DSM 2542(T)). The new thermophilic, ethanol-tolerant strains of G. thermoglucosidasius may be candidates for ethanol production at elevated temperatures.

Bacillaceae↗

Isolation and characterization of novel denitrifying alkalithermophiles, AT-1 and AT-2.

Two novel denitrifying alkalithermophilic bacteria, AT-1 and AT-2, were isolated from manure-amended soil. The isolates grew at 35-65 degrees C with an optimum temperature at 50-60 degrees C, and pH 6.5-10.0 with an optimum pH at 9.5. Both isolates were Gram-positive, facultative anaerobic, non-motile rod-shaped bacteria. A phylogenetic analysis based on 16S rRNA sequence data indicated that both AT-1 and AT-2 are members of the genus Anoxybacillus. DNA-DNA hybridization revealed moderate relatedness between AT-1 and AT-2 and one phylogenetically related strain, A. pushchinensis K1 (69.5 and 69.1%, respectively). Comparative analysis of morphology and biochemical characteristics of the two isolates also showed similarity to A. pushchinensis K1. Based on these results, we identified AT-1 and AT-2 as A. pushchinensis. To our knowledge, this is the first report of denitrifying bacterium isolated from alkalithermophilic Anoxybacillus spp.

Bacillaceae↗

Isolation of Thermoanaerobacter keratinophilus sp. nov., a novel thermophilic, anaerobic bacterium with keratinolytic activity.

Several thermophilic anaerobic bacteria with keratinolytic activity growing at temperatures between 50 degrees C and 90 degrees C were isolated from samples collected on the island of São Miguel in the Azores (Portugal). On the basis of morphological, physiological, and 16S rDNA studies, the isolate 2KXI was identified as a new species of the genus Thermoanaerobacter, designated Thermoanaerobacter keratinophilus. This strain, which grows optimally at 70 degrees C, pH 7.0, and 0.5% NaCl, is the first member of the genus Thermoanaerobacter that has been described for its ability to degrade native keratin. Around 70% of native wool was solubilized after 10 days of incubation under anaerobic conditions. The strain was shown to possess intracellular and extracellular proteases optimally active at 60 degrees C, pH 7.0, and 85 degrees C, pH 8.0, respectively. Keratin hydrolysis was demonstrated in vitro using a sodium dodecyl sulfate gel containing feather meal. The extracellular protease responsible for breaking down keratin fibers was purified to homogeneity in only one step by applying hydroxyapatite column chromatography. The enzyme belongs to the serine-type proteases and has a molecular mass of 135 kDa.

Bacillaceae↗

Bacillus cereus pneumonia in a patient with acute lymphoblastic leukemia.

Reported here is a case of Bacillus cereus pneumonia that occurred in a patient with acute lymphoblastic leukemia. The presentation was severe, essentially marked by respiratory distress and pleuritic chest pain. Classic empirical treatment initiated for febrile neutropenia did not cover this rare pathogen and appropriate therapy was therefore delayed. B. cereus is most often a culture contaminant, but it can also be responsible for self-limited gastrointestinal intoxication and, more rarely, severe systemic diseases. Virulence in the case of systemic disease is attributed to tissue necrosis mediated by toxin release. B. cereus pneumonia, as described in the English-language literature, mainly affects immunocompromised patients and most often has a fatal outcome. Thus, the identification of B. cereus in clinical specimens of severely ill immunocompromised patients should lead physicians to question its clinical significance.

Adult↗

Pyogenic infections of the central nervous system secondary to dental affections--a report of six cases.

Pyogenic infections of the central nervous system of dental origin are quite uncommon in industrialized countries. We report six cases with intracerebral (n = 4) and intraspinal (n = 2) infections treated in our hospital. The microbial pathogen was successfully isolated in all patients. Fusobacterium nucleatum as well as Streptococcus species were found in three cases. Bacillus species were identified in two patients. Actinomyces was the etiologic agent in one case. All patients suffered from dental pathologies, so that after clinical and radiological exclusion of other sources an oral focus was presumed. Therapeutic management consisted of an operative procedure in order to obtain decompression, as well as evacuation of the pus on the one hand, followed by targeted antibiotics on the other. Clinical improvement was achieved in all patients, with one patient lost to follow-up. On magnetic resonance tomography, the inflammatory changes also disappeared in all cases. We recommend that oral infection with recurrent bacteraemia should always be considered in the pathogenesis of the so-called "cryptic" intracerebral and intraspinal infections.

Abscess↗

Production of exopolysaccharides from a thermophilic microorganism isolated from a marine hot spring in flegrean areas.

A thermophilic strain isolated from sea sand at Maronti, near Sant' Angelo (Ischia), is described. The organism grows well at an optimal temperature of 60 degrees C at pH 7.0. The thermophilic bacterium, named strain 4004, produces an exocellular polysaccharide (EPS) in yields of 90 mg/l. The EPS fraction was produced with all substrates tested, although a higher yield was obtained with sucrose or trehalose as sole carbon source. During growth, the EPS content was proportional to the biomass. Three fractions (EPS1, EPS2, EPS3) were obtained after purification. Quantitative monosaccharide analysis of the EPSs revealed the presence of mannose:glucose:galactose in a relative ratio of 0.5:1.0:0.3 in EPS1, mannose:glucose:galactose in a relative ratio of 1.0:0.3:trace in EPS2, and galactose:mannose:glucosamine:arabinose in a relative ratio of 1.0:0.8:0.4:0.2 in EPS3. The average molecular mass of EPS3 was determined to be 1x10(6) Da. From comparison of the chemical shift values in (1)H and (13)C spectra, we conclude that EPS3 presents a pentasaccharide repeating unit.

Bacillaceae↗