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Bacteria

About: Bacteria is a research topic. Over the lifetime, 23676 publications have been published within this topic receiving 715990 citations. The topic is also known as: eubacteria.


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Journal ArticleDOI
TL;DR: The phylogenetic characterization of small subunit rRNA gene sequences obtained by polymerase chain reaction (PCR) amplification of mixed population DNA extracted directly from soil in a soybean field without culturing the organisms suggests a global distribution of this archaeal group.
Abstract: Summary We report here the phylogenetic characterization of small subunit rRNA gene sequences obtained by polymerase chain reaction (PCR) amplification of mixed population DNA extracted directly from soil in a soybean field without culturing the organisms. The phylogenetic analysis of 17 soil clones by the neighbour-joining method shows that the soil sample contained broadly diverse prokaryotes; a clone related to archaea, a clone to gram-positive bacteria with high G+C contents, two clones to green sulphur bacteria, four clones to proteobacteria, and nine clones were not in clusters of any previously reported bacterial groups, which suggests they belong to members of novel groups in Bacteria. In addition, the archaeal sequence, FIE16, is phylogenetically similar to ANTARCTIC 12, a clone obtained from surface waters of Antarctica by PCR. Their occurrence in both the ocean and soil suggests a global distribution of this archaeal group. In conclusion, rRNA gene sequences recovered from soil biomass document the occurrence of many more bacterial lingeages than have been recognized previously through cultivation-based techniques.

156 citations

Journal ArticleDOI
TL;DR: Intracellular breakdown was primarily dependant upon the composition of the ingested particle rather than on the type or source of the phagocyte, and evidence is presented for the reincorporation of bacterial constituents into leucocyte lipid.
Abstract: The intraleucocytic fate of a variety of P32- and C14-labeled bacteria has been studied in both polymorphonuclear leucocytes and macrophages. Both cell types brought about extensive degradation of bacterial lipids, nucleic acids, and proteins. Intracellular breakdown was primarily dependant upon the composition of the ingested particle rather than on the type or source of the phagocyte. Evidence is presented for the reincorporation of bacterial constituents into leucocyte lipid. More than 50 per cent of the acid-soluble degradation products of P32-labeled bacteria appear as inorganic phosphate. Bacterial RNA is degraded more readily than DNA. Following phagocytosis, labeled bacteria lose their pool of small molecular weight intermediates. This is followed by the degradation of acid-insoluble constituents. The majority of bacterial breakdown products are then excreted by the leucocyte and appear in the medium. Heat-killed bacteria were more readily broken down than viable organisms. Only small amounts of C14-labeled bacteria were completely oxidized by leucocytic enzymes to C14O2. Acid extracts of polymorphonuclear leucocyte granules, which were highly bactericidal, liberated the acid-soluble constituents of labeled bacteria but did not significantly degrade bacterial macromolecules.

156 citations

Journal ArticleDOI
TL;DR: A second pathway for acetyl-CoA oxidation was found and it is shown that sulfur-reducing bacteria and one genus of sulfate reducers use a modified citric-acid cycle with a novel anaplerotic sequence as pathway of terminal respiration, while all other anaerobes use an alternative pathway.
Abstract: Many anaerobic bacteria can completely oxidize organic matter to CO2 with either sulfur, sulfate, or protons as electron acceptor The sulfur-reducing bacteria and one genus of sulfate reducers use a modified citric-acid cycle with a novel anaplerotic sequence as pathway of terminal respiration All other anaerobes use an alternative pathway, in which carbon monoxide dehydrogenase is a key enzyme and in which acetyl-CoA is cleaved into two C1 units at the oxidation level of CH3OH and CO Thus almost 50 years after the discovery of the citric acid cycle by Hans Krebs in 1937, a second pathway for acetyl-CoA oxidation was found

156 citations

Journal ArticleDOI
TL;DR: Evidence from scanning electron microscopy pointed to a general lack of colonization of the gut wall: instead, microorganisms were abundant in the intestinal contents, and aerobic bacteria were generally resistant to the antibiotics in use.
Abstract: Populations of aerobic and anaerobic heterotrophic bacteria occurring in the gastrointestinal tract of healthy rainbow trout were estimated using a dilution plate technique. Data revealed a progressive decline in numbers of aerobic bacteria along the digestive tract from oesophagus to lower intestine. However, the highest numbers were recovered from the intestinal contents and faeces. Anaerobes were generally restricted to the upper intestine and intestinal contents. The aerobic component of the bacterial microflora from the digestive tract was equated with Acinetobacter calcoaceticus, Aeromonas hydrophila, Bacillus circulans, Bac. megaterium, coryneforms, Grampositive irregularly shaped rods, Flavobacterium sp., Kurthia sp., Microhacterium sp., Providencia stuartii, Pseudomonas spp., Ps.fluorescens and Ps. pseudoalcaligenes. Evidence from scanning electron microscopy pointed to a general lack of colonization of the gut wall: instead, microorganisms were abundant in the intestinal contents. Antimicrobial compounds, i.e. oxolinic acid, oxytetracycline and sulphafurazole (which are commonly used to combat infections by Gramnegative bacterial fish pathogens), caused an increase in bacterial numbers throughout the digestive tract, with maximal numbers in the lower intestine. The bacteria, comprising an essentially different range of taxa, were generally resistant to the antibiotics in use. Conversely, erythromycin and penicillin G, which are used to treat some diseases caused by Gram-positive bacteria, caused a rapid reduction in bacterial numbers within the gastrointestinal tract.

156 citations

Journal ArticleDOI
TL;DR: Fourteen isolates of soil bacteria, including two known plant growth promoting rhizobacteria (PGPR) strains, Azotobacter vinelandii Mac 259 and Bacillus cereus UW 85, were tested in vitro and found to have IAA- and siderophore-producing traits.
Abstract: Fourteen isolates of soil bacteria, including two known plant growth promoting rhizobacteria (PGPR) strains, Azotobacter vinelandii Mac 259 and Bacillus cereus UW 85, were tested in vitro Parameters assessed were indoleacetic acid (IAA) production, phosphate solubilization, dinitrogen fixation, and siderophore (Fe-III chelating agent) production IAA production was assayed colorimetrically using ferric chlorideperchloric acid reagent Phosphate-solubilization and siderophore production were tested qualitatively by plating the bacteria in Pikovskaya and chrome azurol S agar, respectively The ability to fix dinitrogen was measured based on nitrogenase activity of the bacteria by gas chromatography The results showed that twelve isolates produced IAA, ranged from 209 to 3328 µmol ml-1 The ability to solubilize precipitated phosphate was positively exhibited by four isolates (BS 58, BTS, TCaR 61, and BTCaRe 65) Seven isolates including Mac 259 positively produced siderophore None of the isolates showed nitrogenase activity Only one isolate (TS 3) did not exhibit any of the traits tested Isolate TCeRe 60 and reference strain Mac 259 were found to have IAA- and siderophore-producing traits Four P-solubilizing bacteria (BS 58, BTS, TCaR 61, and BTCaRe 65) were also IAA- and siderophore-producing bacteria Potential use of these PGPR isolates needs further test in enhancing plant growth

156 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20242
20235,286
202210,729
20211,047
20201,096
20191,044