Dust-borne bacteria in animal sheds, schools and children's day care centres

A total of 316 bacterial strains, including psychrophiles, mesophiles and thermophiles, were isolated and identified from indoor dusts in schools, children's day care centres and animal sheds. Several species which had not previously been reported from indoor environments were found: Sphingomonas, Brevibacterium, Nocardiopsis, Deinococcus and Rhodococcus/Gordona. A new psychrophilic actinomycete genus was also found in animal sheds, representing a new undescribed peptidoglycan type and an unusual whole-cell fatty acid composition. The indoor dusts of animal sheds contained mainly the Gram-negative genera Pseudomonas, Pantoea, Flavobacterium and Xanthomonas early in the indoor feeding season, but changed to a composition dominated by Bacillus, Micrococcus and mesophilic and thermophilic actinomycetes towards the end of the season. The dust contained, and air-borne bacterial flora in schools and day care centres were dominated by, Gram-positive bacilli and actinomycetes, notably Bacillus cereus, Brevibacillus brevis, B. licheniformis, B. subtilis and species of Arthrobacter, Corynebacterium, Rhodococcus/Gordona, Nocardiopsis sp., Deinococcus, Staphylococcus and Micrococcus. Indoor air and dust contained Klebsiella oxytoca, Acinetobacter calcoaceticus, Ac. lwoffi, Bacillus cereus and Nocardiopsis dassonvillei with the status of hazard group II. Indoor dusts of animal sheds contained eight different 3-hydroxy fatty acids, the 2-hydroxy fatty acid 14:0 and two 10-methyl fatty acids, whereas in dusts from schools and day care centres, these were below the detection level (< 3.5 ng mg-1). The 3-and 2-hydroxy fatty acids could be assigned to one or more of the dust-contained cultivable strains, but 10-methyl C16:0 was not present in any of the strains isolated. The dusts from schools and children's day care centres contained 0.2-0.3 ng of endotoxin mg-1 and 0.5-1.4 ng of beta-D-glucan mg-1, whereas the dusts from animal sheds contained more 0.3-41 ng mg-1 and 8-35 ng mg-1, respectively.

Meiothermus cerbereus sp. nov., a new slightly thermophilic species with high levels of 3-hydroxy fatty acids

Strains of Meiothermus cerbereus sp. nov. were isolated from the hot springs within the Geysir geothermal area of Iceland. The strains of Meiothermus cerbereus produce red-orange-pigmented colonies, have an optimum growth temperature of about 55 degrees C, and have higher levels of 3-OH fatty acids than the strains of the other species of the genus Meiothermus. These strains, unlike all other strains of the species of the genus Meiothermus examined previously, required cysteine, thiosulfate, or thioglycolate for growth in liquid Thermus medium, but not in the corresponding medium solidified with agar. Several strains belonging to Meiothermus silvanus, isolated from Geysir, also required reduced sulfur compounds for growth in liquid medium, leading to the hypothesis that this requirement is not a taxonomic characteristic of the new species. The new species represented by strains GY-1T and GY-5 can be distinguished from the other species of the genus Meiothermus by biochemical characteristics, fatty acid composition, DNA-DNA reassociation values, and 16S ribosomal DNA sequence. The type strain for Meiothermus cerbereus is GY-1 (= DSM 11376).

Bacteria, molds, and toxins in water-damaged building materials

Microbial toxins and eukaryotic cell toxicity from indoor building materials heavily colonized by fungi and bacteria were analyzed. The dominant colonizers at water-damaged sites of the building were Stachybotrys chartarum (10(3) to 10(5) visible conidia cm-2), Penicillium and Aspergillus species (10(4) CFU mg-1), gram-negative bacteria (10(4) CFU mg-1), and mycobacteria (10(3) CFU mg-1). The mycobacterial isolates were most similar to M. komossense, with 98% similarity of the complete 16S rDNA sequence. Limulus assay of water extracts prepared from a water-damaged gypsum liner revealed high contents of gram-negative endotoxin (17 ng mg-1 of E. coli lipopolysaccharide equivalents) and beta-D-glucan (210 ng mg-1 of curdlan equivalents). High-performance liquid chromatography analysis of the methanol extracts showed that the water-damaged gypsum liner also contained satratoxin (17 ng mg-1). This methanol-extracted substance was 200 times more toxic to rabbit skin and fetus feline lung cells than extract of gypsum liner sampled from a non-water-damaged site. The same extract contained toxin(s) that paralyzed the motility of boar spermatozoa at extremely low concentrations; the 50% effective concentration was 0.3 microgram of dry solids per ml. This toxicity was not explainable by the amount of bacterial endotoxin, beta-D-glucan, or satratoxin present in the same extract. The novel in vitro toxicity test that utilized boar spermatozoa as described in this article is convenient to perform and reproducible and was a useful tool for detecting toxins of microbial origin toward eukaryotic cells not detectable in building materials by the other methods.

Thermosyntropha lipolytica gen. nov., sp. nov., a lipolytic, anaerobic, alkalitolerant, thermophilic bacterium utilizing short- and long-chain fatty acids in syntrophic coculture with a methanogenic archaeum

Three strains of an anaerobic thermophilic organoheterotrophic lipolytic alkalitolerant bacterium, Thermosyntropha lipolytica gen. nov., sp. nov. (type strain JW/VS-265T; DSM 11003), were isolated from alkaline hot springs of Lake Bogoria (Kenya). The cells were nonmotile, non-spore forming, straight or slightly curved rods. At 60 degrees C the pH range for growth determined at 25 degrees C [pH25 degrees C] was 7.15 to 9.5, with an optimum between 8.1 and 8.9 (pH60 degrees C of 7.6 and 8.1). At a pH25 degrees C of 8.5 the temperature range for growth was from 52 to 70 degrees C, with an optimum between 60 and 66 degrees C. The shortest doubling time was around 1 h. In pure culture the bacterium grew in a mineral base medium supplemented with yeast extract, tryptone, Casamino Acids, betaine, and crotonate as carbon sources, producing acetate as a major product and constitutively a lipase. During growth in the presence of olive oil, free long-chain fatty acids were accumulated in the medium but the pure culture could not utilize olive oil, triacylglycerols, short- and long-chain fatty acids, and glycerol for growth. In syntrophic coculture (Methanobacterium strain JW/VS-M29) the lipolytic bacteria grew on triacylglycerols and linear saturated and unsaturated fatty acids with 4 to 18 carbon atoms, but glycerol was not utilized. Fatty acids with even numbers of carbon atoms were degraded to acetate and methane, while from odd-numbered fatty acids 1 mol of propionate per mol of fatty acid was additionally formed. 16S rDNA sequence analysis identified Syntrophospora and Syntrophomonas spp. as closest phylogenetic neighbors.

Description of chlorophenol-degrading Pseudomonas sp. strains KF1T, KF3, and NKF1 as a new species of the genus Sphingomonas, Sphingomonas subarctica sp. nov

Gram-negative polychlorophenol-degrading bacterial strains KF1T (T = type strain), KF3, and NKF1, which were described previously as Pseudomonas saccharophila strains, were studied by chemotaxonomic, genetic, and physiological methods and by electron microscopy and compared with selected xenobiotic compound-degrading bacteria. These strains contained sphingolipids with d-18:0, d-20:1, and d-21:1 as the main dihydrosphingosines, ubiquinone 10 as the main respiratory quinone, and spermidine as the major polyamine, and the DNA G + C content was 66 mol%. The cellular fatty acids included about 60% octadecenoic acid, 9% 2-hydroxymyristic acid, 14% cis-9-hexadecenoic acid, and 10% hexadecanoic acid. These strains exhibited less than 97% 16S ribosomal DNA sequence similarity to all of the other taxa studied. In the DNA-DNA reassociation studies the highest levels of reassociation between these strains and previously described species were less than 40%. Thin sections of cells of strains KF1T, KF3, and NKF1 were examined by electron microscopy, and the results showed that the cells had peculiar concentrically arranged layered membranous blebs that extruded from the outer membrane, especially at the cell division points. On the basis of the results of this study, polychlorophenol-degrading strains KF1T, KF3, and NKF1 are considered members of a new species of the genus Sphingomonas, Sphingomonas subarctica. The polycyclic aromatic hydrocarbon-degrading organism Sphingomonas paucimobilis EPA 505 was closely related to Sphingomonas chlorophenolica as determined by chemotaxonomic, phylogenetic, and physiological criteria. The xenobiotic compound degraders Alcaligenes sp. strain A175 and Pseudomonas sp. strain BN6 were identified as members of species of the genus Sphingomonas.

Thermobrachium celere gen. nov., sp. nov., a rapidly growing thermophilic, alkalitolerant, and proteolytic obligate anaerobe

More than 40 isolates of a novel, ubiquitous, proteolytic, moderately alkaliphilic, thermophilic obligate anaerobe were obtained from geothermally and anthropogenically heated environments and mesobiotic environments located on three continents. Whole-cell protein sodium dodecyl sulfate gel electrophoresis revealed that most of these organisms are very similar. Eight of the isolates were characterized in detail; this analysis included 16S ribosomal DNA sequence analysis. The cells of those organisms are (depending on the isolate) 0.5 to 0.8 micron in diameter and 1.5 to 13 microns long, exhibit tumbling motility, and have a positive Gram stain reaction. The temperature range for growth is 43 degrees to 75 degrees C (optimum temperature, 66 degrees C), and the pH range for growth is 5.4 to 9.5 (optimum pH, 8.2); the shortest doubling time is around 10 min. Yeast extract is required for growth, and (depending on the strain) glucose, sucrose, fructose, galactose, and ribose are utilized. The fermentation products from glucose in the presence of yeast extract are CO2, H2, acetate, formate, and ethanol. The G + C content is 30 to 31 mol%. On the basis of these properties, which differentiate these strains from all alkalitolerant thermophiles described previously, and the results of a comparison of the 16S ribosomal DNA sequences of these organisms with previously described sequences, we propose that our isolates be placed in a single species of the new genus Thermobrachium; strain JW/YL-NZ35 is the type strain of the the type species, Thermobrachium celere.

Spirochaeta alkalica sp. nov., Spirochaeta africana sp. nov., and Spirochaeta asiatica sp. nov., alkaliphilic anaerobes from the Continental Soda Lakes in Central Asia and the East African Rift

During a study of microbial communities in athalassic bodies of water, three new species within the genus Spirochaeta were described. These are alkaliphilic Spirochaeta alkalica sp. nov. Z-7491 (DSM 8900) and halophilic S. africana sp. nov. Z-7692 (DSM 8902) from the soda-depositing Lake Magadi in Central Africa and haloalkaliphilic S. asiatica sp. nov. Z-7591 (DSM 8901) from Lake Khatyn, Central Asia. These mesophilic spirochetes develop at pHs of > 9 as anaerobic saccharolytic dissipotrophs. The DNA base compositions (moles percent G+C) of the strains were as follows: S. alkalica Z-7491, 57.1; S. africana Z-7692, 56.1; and S. asiatica Z-7591, 49.2. The optimum growth parameters (temperature, pH, and NaCl concentration [percent, wt/vol], respectively) were as follows: for S. alkalica Z-7491, 35 degrees C, 9.2, and 5 to 7%; for S. africana Z-7692, 35 degrees C, 9.3, and 5 to 7%; and for S. asiatica Z-7591, 35 degrees C, 8.9, and 3 to 6%. The products of glucose fermentation were acetate, hydrogen, ethanol, and lactate, in different proportions, for S. alkalica and S. africana; for S. asiatica, they were acetate, ethanol, and lactate. S. asiatica is strictly anaerobic, while S. alkalica and S. africana are rather aerotolerant. All three species group within the radiation of the majority of the species of the genus Spirochaeta. Studies of the genes encoding 16S rRNA indicate a possible fanning out of the phylogenetic tree of spirochetes.

Thermocrispum gen. nov., a new genus of the order Actinomycetales, and description of Thermocrispum municipale sp. nov. and Thermocrispum agreste sp. nov

Ten strains of thermophilic actinomycetes were isolated from waste and mushroom composts, as well as from the air of compost plants and a refuse incineration plant in Germany. These organisms produce white aerial mycelia and form hyphae with so-called pseudosporangia that fragment into rod-like structures. The organisms have type III cell walls (meso-diaminopimelic acid and whole-cell sugar type C), the phospholipid type is type PII, and mycolic acids are not present. The major menaquinone is MK-9(H4), and the fatty acids are mainly iso- and anteiso-branched fatty acids, hydroxy fatty acids, and 10-methyl-branched fatty acids. The guanine-plus-cytosine content of the DNA is 69 to 73 mol%. The chemotaxonomic markers (especially whole-cell sugar type C) and 16S ribosomal DNA sequence data indicated that these organisms represent a new genus of the order Actinomycetales, for which the name Thermocrispum is proposed. On the basis of phylogenetic and phenotypic data, this new genus is closely related to members of the family Pseudonocardiaceae and related taxa and contains two species: Thermocrispum municipale sp. nov. and Thermocrispum agreste sp. nov. The type species of the genus is T. municipale, with type strain MKD 35 (= DSM 44069), and the type strain of T. agreste is CHB 77 (= DSM 44070).