One-step detection of pathogens and cancer biomarkers by the naked eye based on aggregation of immunomagnetic beads

This report shows that immunomagnetic beads (IMBs) can act as the optical readout for assays, in addition to serving as the carrier for purification/separation. Under the influence of an external magnet, IMBs are attracted to coat one side of a test tube. IMBs specifically bound to targets can form a narrow brown stripe, whereas free IMBs will form a diffuse, yellow coating on the side of the test tube. Target analytes can aggregate initially dispersed IMBs in a sample concentration-dependent manner, yielding a color change from yellow to brown that can be seen with the naked eye. This assay combines the convenience of a lateral flow assay, allowing a one-step assay to finish within 15 min, with the sensitivity of an enzyme-linked immonosorbent assay.

[Two new species of microaerophilic sulfur spirilla, Spirillum winogradskii sp. nov. and Spirillum kriegii sp. nov]

New microaerophilic sulfur-oxidizing spirilla were isolated from hydrogen sulfide sludge of wastewater treatment plants. Strains D-427 and D-430 have spiral cells that are highly motile due to bipolar flagellum bundles covered with mucous sheaths. Under a phase-contrast microscope, these bundles are visible as single polar flagella. Spheroplasts are formed in the stationary growth phase. Both strains are obligate organotrophs able to oxidize a number of reduced sulfur compounds. The oxidation of sulfide and polysulfide leads to the formation of intracellular globules of elemental sulfur; thiosulfate oxidation results in tetrathionate accumulation in the medium. The cells are unable to utilize reduced sulfur compounds in the energy metabolism; their oxidation is caused by a chemical interaction with H2O2 and O2, synthesized in the electron transport chain. Both strains are obligate microaerophiles with an optimal oxygen concentration in the gas phase of 2 and 0.8% for strains D-427 and D-430, respectively. The strains utilize a limited number of organic acids as growth substrates, mainly tricarboxylic-acid-cycle intermediates. The DNA G+C content is 38.0 mol % (T(m)) for strain D-427 and 38.9 mol % for strain D-430. Phylogenetic analysis, based on the comparison of 16S rRNA gene sequences, revealed that the new isolates of sulfur spirilla are the most closely related to Spirillum volutans, the type species of the genus (97.4% similarity). They were assigned to the genus Spirillum within the class Beta-proteobacteria as two new species, S. winogradskii sp. nov. (D-427T = DSM 12756T) and S. kriegii sp. nov. (B-430T = BKM B-2372T). The emended description of the genus Spirillum is provided.

Bacterial diversity in the bacterioneuston (sea surface microlayer): the bacterioneuston through the looking glass

The bacterioneuston is defined as the community of bacteria present within the neuston or sea surface microlayer. Bacteria within this layer were sampled using a membrane filter technique and bacterial diversity was compared with that in the underlying pelagic coastal seawater using molecular ecological techniques. 16S rRNA gene libraries of approximately 500 clones were constructed from both bacterioneuston and the pelagic water samples and representative clones from each library were sequenced for comparison of bacterial diversity. The bacterioneuston was found to have a significantly lower bacterial diversity than the pelagic seawater, with only nine clone types (ecotaxa) as opposed to 46 ecotaxa in the pelagic seawater library. Surprisingly, the bacterioneuston clone library was dominated by 16S rRNA gene sequences affiliated to two groups of organisms, Vibrio spp. which accounted for over 68% of clones and Pseudoalteromonas spp. accounting for 21% of the library. The dominance of these two 16S rRNA gene sequence types within the bacterioneuston clone library was confirmed in a subsequent gene probing experiment. 16S rRNA gene probes specific for these groups of bacteria were designed and used to probe new libraries of 1000 clones from both the bacterioneuston and pelagic seawater DNA samples. This revealed that 57% of clones from the bacterioneuston library hybridized to a Vibrio sp.-specific 16S rRNA gene probe and 32% hybridized to a Pseudoalteromonas sp.-specific 16S rRNA gene probe. In contrast, the pelagic seawater library resulted in only 13% and 8% of 16S rRNA gene clones hybridizing to the Vibrio sp. and Pseudoalteromonas sp. probes respectively. Results from this study suggest that the bacterioneuston contains a distinct population of bacteria and warrants further detailed study at the molecular level.

Titanospirillum velox: a huge, speedy, sulfur-storing spirillum from Ebro Delta microbial mats

A long (20-30 micrometer), wide (3-5 micrometer) microbial-mat bacterium from the Ebro Delta (Tarragona, Spain) was grown in mixed culture and videographed live. Intracellular elemental sulfur globules and unique cell termini were observed in scanning-electron-microprobe and transmission-electron micrographs. A polar organelle underlies bundles of greater than 60 flagella at each indented terminus. These Gram-negative bacteria bend, flex, and swim in a spiral fashion; they translate at speeds greater than 10 body lengths per second. The large size of the spirillum permits direct observation of cell motility in single individual bacteria. After desiccation (i.e., absence of standing water for at least 24 h), large populations developed in mat samples remoistened with sea water. Ultrastructural observations reveal abundant large sulfur globules irregularly distributed in the cytoplasm. A multilayered cell wall, pliable and elastic yet rigid, distends around the sulfur globules. Details of the wall, multiflagellated termini, and large cytoplasmic sulfur globules indicate that these fast-moving spirilla are distinctive enough to warrant a genus and species designation: Titanospirillum velox genus nov., sp. nov. The same collection techniques at a similar habitat in the United States (Plum Island, northeast Essex County, Massachusetts) also yielded large populations of the bacterium among purple phototrophic and other inhabitants of sulfurous microbial-mat muds. The months-long survival of T. velox from Spain and from the United States in closed jars filled with mud taken from both localities leads us to infer that this large spirillum has a cosmopolitan distribution.

Spiral bacterium associated with gastric, ileal and caecal mucosa of mice

A spiral shaped bacterium was seen in smears and histological sections (stained by carbolfuchsin) of gastric, ileal and caecal mucosa as well as in stool smears from mice. A significant correlation between the presence of the spiral bacterium and the occurrence of gastritis was observed but the ileal and caecal mucosa seemed unaffected. The bacterium was Gram negative and grew on BHM and Skirrow's medium, under microaerophilic conditions, at 37 degrees C. Its major biochemical characteristics included positive catalase and oxidase reactions and a rapidly positive urease test. There were 2 or 3 spiral turns per cell and a tuft of up to 12 sheathed flagella on each pointed end. Entwined, braided periplasmic fibrils covered the surface of the cell. This spiral bacterium seemed to be part of the normal intestinal flora but was associated with gastritis.

[Sodoku--a case report]

Rat-bite fever results from an infection with the organism Spirillum minus. The authors report a symptomatic patient with fever, malaise, and ulcer in forehead after a rodent exposure. The organism was identified in darkfield examination of the ulcer exudate. Penicillin was the drug used with clinical improvement of symptoms.

'Gastrospirillum hominis', another gastric spiral bacterium

'Gastrospirillum hominis' is a 'new' tightly coiled gram-negative bacterium carrying bundles of sheathed polar flagella. It has been rather infrequently detected in antral and, even more rarely, in fundic mucosa samples removed at endoscopy from patients investigated for Helicobacter pylori colonization. Until now, it has remained noncultivable but has successfully been maintained in laboratory mice. Its identity with similar bacteria found in the stomachs of cats, dogs, monkeys, pigs, and other animals is uncertain. It was probably already seen by early investigators in the first half of this century. Preliminary data published in case reports suggest that it is associated with more or less active chronic antral gastritis, that it is restricted to the gastric epithelium, and that it possesses a urease, thus limiting the specificity of urease tests for H. pylori. There is hitherto no solid proof that it can induce inflammation although it seems capable of invading parietal and other glandular cells and causing ultrastructural changes. Similar organisms spontaneously colonizing the stomachs of rhesus monkeys were shown to increase gastric acid secretion.

Azospirillum irakense sp. nov., a nitrogen-fixing bacterium associated with rice roots and rhizosphere soil

A new species of nitrogen-fixing bacteria, Azospirillum irakense, was found associated with roots and the rhizosphere of rice in the region of Diwaniyah (Qadisya), Iraq. The seven isolates, on which the species description is based, have vibrioid to S-shaped cells with one polar flagellum in liquid medium. Additional lateral flagella are seen on cells grown on nutrient agar. Poly-beta-hydroxybutyrate granules are present in cells. Nitrogen fixation occurs in microaerobic conditions. The phenotypic characters were found to be very close to those of A. amazonense with the following differences: growth occurred in the presence of 3% NaCl, and at pH 5.5 and 8.5, myo-inositol was not utilized as sole source of carbon and energy and pectin was slowly (6 to 9 days) hydrolysed. The seven studied strains formed a DNA-relatedness group distinct from other Azospirillum and Herbaspirillum species. The G + C content of the DNA was 64 to 67 mol %. The type strain is KBC1 (CIP 103311).

Experimental infection and abortion of pregnant guinea pigs with a unique spirillum-like bacterium isolated from aborted ovine fetuses

Study was made of the pathogenicity of a spirillum-like, anaerobic, gram-negative bacterium, originally isolated from aborted lambs, for pregnant guinea pigs. Reproducible conditions for propagation and preservation of the bacterium were determined as requisite for the preparation of cultures for animal inoculation. A preliminary experiment was done with 10 pregnant guinea pigs to test for an infective dose of organisms that would produce abortion. High-passage cultures (n = 50) were used to inoculate these guinea pigs intraperitoneally. Six of 10 guinea pigs aborted, and the organism was cultured from fetal tissues of 5 guinea pigs. Isolates from 3 of the 6 guinea pigs were propagated through 4 passages on blood agar and used to infect 3 groups, each of 5 guinea pigs. A 4th group of 5 guinea pigs was inoculated with the original culture. Three of 5 animals in the first 3 groups, which had been given the low-passage cultures from the preliminary trial, and 2 of 5 guinea pigs in the 4th group, which had been given the original culture, aborted. Antibody against the spirillum was detected in 19 of 30 inoculated guinea pigs. The major microscopic lesions were acute suppurative placentitis and splenitis. This bacterium retained pathogenic properties sufficient to cause infection, abortion, and microscopic lesions in two-thirds of the guinea pigs, in spite of high in vitro passage. The organism has unique ultrastructures, and its genus and species are yet to be determined.

Anaerobiospirillum species isolated from humans with diarrhoea

Flagellated anaerobic motile spiral bacteria were isolated from the faeces of two patients with diarrhoea. They were recovered by the microaerophilic culture method used to detect campylobacters but demanded anaerobic conditions for subculture. Electron microscopy and other investigations showed them to be closely related to Anaerobiospirillum succiniproducens first described in beagle dogs and subsequently in three humans with bacteraemia.

Large intestine bacterial flora of nonhibernating and hibernating leopard frogs (Rana pipiens)

The bacteria in the large intestines of 10 northern leopard frogs (Rana pipiens) were enumerated and partially characterized. Four nonhibernating frogs were collected in the summer, four hibernating frogs were collected in the winter, and two frogs just emerged from hibernation were collected in the spring. All frogs had about 10(10) bacteria per g (wet weight) of intestinal contents and about 10(9) bacteria per g (wet weight) of mucosal scraping, although the counts from the winter frogs were slightly less than those from the other two groups of frogs. Another group of 14 summer frogs, after treatment to induce hibernation, showed a drop in bacterial counts accompanied by a change in the composition of the flora. In most frogs, Bacteroides was the dominant organism. Other bacteria repeatedly isolated at high dilutions were strict anaerobes, including butyrigenic and acetogenic helically coiled bacteria; fusobacteria; and acetogenic, small, gram-positive bacilli. These data indicate that the intestinal flora of frogs is similar to that of mammals and birds and that this flora can be maintained at temperatures close to freezing.

Isolation and pure culture of a freshwater magnetic spirillum in chemically defined medium

A bipolarly flagellated magnetotactic spirillum containing intracellular chains of single domain-sized magnetite crystals was isolated by applying a magnetic field to sediments from a freshwater swamp. The organism was cultured in a chemically defined medium containing ferric quinate and succinate as sources of iron and carbon, respectively. Nonmagnetic variants of this isolate were maintained in chemically defined medium lacking ferric quinate. In contrast to magnetic cells, these had less iron and lacked measurable magnetic remanence and the intracytoplasmic crystals. In other respects, including moles percent guanine plus cytosine content, growth characteristics, nutrition, and physiology, the two types were similar. The isolate reduced nitrate without accumulating nitrite and produced ammonia during growth. Nitrate or ammonium ions served as a nitrogen source. The organism was microaerophilic and did not grow anaerobically with nitrate in the medium. In chemically defined medium, cells synthesized magnetite only if the initial O2 concentration in the atmosphere of sealed cultures was 6% (vol/vol) or less.

Isolation of Azospirullum from diverse geographic regions

We have isolated Azospirillum (Spirullum lipoferum) from roots of grasses of several genera collected from a number of tropical and subtropical-temperate locations. Pure cultures were obtained from a small percentage of samples; no higher percentage was secured from tropical than from other grasses. Acetylene reduction and distinctive growth in N-free soft agar deeps were inadequate to identify this genus, although helpful in initial screening. Fluorescent antibody tests with antiserum against characterized strains were helpful. There is some evidence that this genus of bacteria may be favored in the rhizoplane.

Ecological distribution of Spirillum lipoferum Beijerinck

A survey in various countries revealed that the N2-fixing Spirillum lipoferum Beijerinck is a very common root and soil inhabitant in the tropics. More than half of the grass root and soil samples collected in tropical countries (four African countries and Brazil) contained abundant S. lipoferum populations, while less than 10% of the samples collected in temperate South Brazil, Kenya, and the U.S.A. contained the organism. There is a pronounced vegetation effect. Panicum maximum seems the most favorable among the forage grasses, while few positive samples were found under virgin tropical forest. Legume roots contained less S. lipoferum than adjacent soils. More than 80% of the samples from cereal roots (maize, sorghum, wheat, and rye) grown in fields fertilized with PK and Mo, in Rio de Janeiro State, were positive. Maize and sorghum grown under similar conditions in Wisconsin contained less than 10% of positive samples, but when maize fields were inoculated 90% of the root samples contained S. lipoferum. Alluvial soils were more favorable than eroded hill soils. Occurrence in soil was strongly pH-dependent with a pH around 7, being optimal (correlation coefficient r = 0.90). Sporadic occurrence was observed even in soils with pH 4.8. Surface-sterilized P. maximum roots collected from soils with pH ranging from 4.8 to 7.2 contained high S. lipoferum numbers which did not correlate with soil pH (r = 0.41). Amendment with malate of acid soils was not very effective in increasing nitrogenase (N2-ase) activity, but in two soils with pH above 6.4, high N2-ase activity was obtained after 16 to 48 h of incubation. In two soils from a temperate climate region, inoculation with S. lipoferum increased N2-ase activity produced through malate amendment.

Biology of the chemoheterotrophic spirilla

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Spirillum endocarditis

A case of Spirillum endocarditis causing severe aortic regurgitation in a 26-year-old man is reported. The infection responded to treatment with oxytetracycline followed by ampicillin, but the valvular damage led to progressive left ventricular failure. The valve was replaced with a fresh nutrient homograft and the patient made a good recovery. A normal aortic valve appeared to have been infected.

Isolation and identification of rumen bacteria capable of anaerobic rutin degradation

Fifteen strains of bacteria capable of degrading rutin anaerobically were isolated from bovine rumen contents and identified by morphological and biochemical evidence as strains of Butyrivibrio sp. Three cultures from a laboratory collection of 53 strains of rumen bacteria also used rutin anaerobically. Two, Butyrivibrio fibrisolvens D1 and Selenomonas ruminantium GA192, cleaved the glycosidic bond of rutin and fermented the sugar but did not degrade the insoluble aglycone produced; the third strain, Peptostreptococcus sp. B178, degraded the substrate to soluble products. Butyrivibrio sp. C3 degraded rutin, quercitrin, and naringin to water-soluble products, showing that the organism cleaved the heterocyclic ring of these compounds. Butyrivibrio sp. C3 fermented the sugar moiety of hesperidin but did not cleave the heterocyclic ring. It did not attack quercetin, taxifolin, protocatechuic acid, or phloroglucinol. In a medium containing rumen fluid, Butyrivibrio sp. C3 degraded rutin more than twice as fast as it did in a medium containing enzymatic casein hydrolyzate, volatile fatty acids, yeast extract, and hemin in place of rumen fluid.The observations reported in this paper are believed to represent the first recorded demonstration of degradation of the heterocyclic ring structure of rutin and other bioflavonoids in pure cultures of anaerobic bacteria.

A method for isolating leptospires from natural surface waters

A method for isolation of leptospirae from natural surface waters with initial inoculation under field conditions is described. Leptospirae were isolated from 19 of 51 water samples obtained from five Iowa streams. The problem of coincidental contamination was successfully resolved by using Millipore filtration schema and serum containing liquid and semisolid media.

Isolation and characterization of filterable marine bacteria

Anderson, J. I. W. (Northeast Shellfish Sanitation Research Center, Narragansett, R.I.), and W. P. Heffernan. Isolation and characterization of filterable marine bacteria. J. Bacteriol 90:1713-1718. 1965.-By a process of double filtration of seawater, first through a membrane filter with a pore diameter of 0.45 mu and then through a membrane filter with a pore diameter of 0.22 mu, it was possible to isolate on the surface of the latter membrane a group of marine organisms not usually encountered by conventional techniques of pour plates or one-stage filtration. Many of the isolates could not be identified, but the largest single group belonged to the genus Spirillum; other isolates were placed in the genera Leucothrix, Flavobacterium, Cytophaga, and Vibrio. A group of four organisms which was not identified was characterized by the formation of large, club-shaped cells, 20 to 30 mu long. Of the 25 strains studied in detail, 22 required seawater for growth and 8 retained their filterable property after cultivation. No filterable bacteria were isolated from terrestrial samples.