The taxonomy of the genus Gluconobucter has undergone many changes during the past 40 years. Based on phenotypic properties, this genus has changed from numerous species to one species containing five subspecies and then to a single species, Gluconobucter oxyduns, with no subspecies. The present study was designed to test the validity of this latter view. Nucleotide sequence similarites were determined for 54 strains of Gluconobucter by using an S1 nuclease procedure. Three distinct deoxyribonucleic acid homology groups were obtained. The average level of relatedness among these groups was 16%. Homology group I contained 32 strains and included the type strain of G . oxyduns and the type strains of all previously recognized subspecies. Homology group I1 contained 12 strains that had an intragroup homology level of 44 to 87% (average, 65%) with reference strain IF0 3264. Homology group 111 contained six strains with an average intragroup homology level of 86% with reference strain IF0 3276a. Reference strains IF0 3264 and IF0 3276 were previously recognized as G.oxyduns. The remaining four strains of Gluconobucter had from 0 to 23% homology with reference strains used to delineate the three homology groups. Although these data show that the genus Gluconobucter is composed of at least three species, they also support elimination of the previously designated subspecies. Three isolates implicated in pink disease of pineapples were shown either not to be gluconobacters or to be mixed with gluconobacters. The occurrence of colony variants within many of the Gluconobucter strains is described, and the significance of this observation is discussed.The genus Gluconobacter is composed of strictly aerobic, gram-negative rods that (i) have the ability to oxidize a wide variety of polyols (17, 25), (ii) lack a complete tricarboxylic acid cycle (21), and (iii) grow at low pH (12). Although these unique features aid in the separation of gluconobacters from other bacteria, the subgeneric taxonomy of this genus has not been clearly established.Asai (2-5), Vaughn (36), Asai and Shoda (8), and De Ley and Frateur (12) proposed various taxonomic schemes for Gluconobacter. All of these proposals were based upon phenotypic data, such as acid production from various carbohydrates, pigmentation, and production of gammapyrones from carbohydrates (11,12). The number of subgeneric taxa proposed by these authors varied from 1 to 13 species (6). In Bergey ' * Corresponding authorThe purpose of this investigation was to determine the nucleotide sequence similarity among Gluconobacter strains by using a S1 nuclease procedure. MATERIALS AND METHODSBacterial strains. The strains used in the homology experiments and their sources are listed in Table 1. Escherichia coli strain B was included in all experiments as a nonhomologous control.Purity of strains, Prior to use, each strain listed in Table 1 was streaked onto media adjusted to pH 6.0 with HC1 and containing 5% sorbitol, 1% yeast extract, 1% peptone, and 1.5% agar (5% sorbitol agar); this w...

In Bergey's Manual of Systematic Bacteriology, vol. 1, only one species is listed in the genus Gluconobacter. One other species, Gluconobucter cerinus, was proposed by Yamada and Akita in 1984. However, recent deoxyribonucleic arid-deoxyribonucleic acid homology studies have produced evidence of at least three distinct homology groups that are believed to represent three species within this genus. In this paper we report results obtained by using 35 strains and 58 phenotypic characteristics. Three tests were useful in differentiating the three Gluconobacter species. Homology group I strains grew to an optical density (OD) of only 0.5 U or less on medium containing ribitol or arabitol as the primary carbon source, and they grew to an OD of only 0.5 U or less after three passages (24 h of incubation each) in nicotinate-deficient media. We propose that the name Gluconobacter oxyduns (Henneberg 1897) De Ley 1961 be retained for these strains. Homology group I1 strains grew to an OD of more than 1.0 U on medium containing ribitol or arabitol as the primary carbon source, and they grew to an OD of more than 1.0 U after three passages (24 h of incubation each) in nicotinate-deficient media. We propose that the group I1 gluconobacters be named Gluconobacter frateurii sp. nov. All of the typical strains of homology group 111 grew to an OD of 0.5 U or less on medium containing ribitol or arabitol as the primary carbon source, but they grew to an OD of 1.0 U or more after three passages (24 h of incubation each) in nicotinate-deficient ^media. We propose that the group I11 gluconobacters be named Cluconobacter asaii sp. nov.

Studies conducted on the ultrastructurc of Cyanophora paradoxa Korschikoff (a cryptomonad) have shown that its intracellular symbiont is closely related to unicellular blue-green algae. Due to its peculiar habitat, the intracellular symbiont lacks the characteristic cyanophyccan double-layered cell wall, but is surrounded by a thin protoplasmic membrane. The protoplasm itself is differentiated into a lamellated chromatoplasm containing photosynthetic pigments, polyphosphate granules, and possible oil droplets, and a non-lamellar centroplasm with a large centrally located electron-opaque body surrounded by a fibril-containing halo. 2-his halo-central body complex may be nuclear in nature. Binary fission of the organism is described. Since this cyanelle has not yet been classified, we name it Cyanocyta korschikofftana nov. gen. nov. sp.; and because of its structural peculiarities, we find it necessary to create a new family for it, Cyanocytaceae, in the order Chroococcales.

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Gluconobacter oxydans is well known for the limited oxidation of compounds and rapid excretion of industrially important oxidation products. The dehydrogenases responsible for these oxidations are reportedly bound to the cell's plasma membrane. This report demonstrates that fully viable G. oxydans differentiates at the end of exponential growth by forming dense regions at the end of each cell observed with the light microscope. When these cells were thin sectioned, their polar regions contained accumulations of intracytoplasmic membranes and ribosomes not found in undifferentiated exponentially growing cells. Both freeze-fracture-etched whole cells and thin sections through broken-cell envelopes of differentiated cells demonstrate that intracytoplasmic membranes occur as a polar accumulation of vesicles that are attached to the plasma membrane. When cells were tested for the activity of the plasma membrane-associated glycerol dehydrogenase, those containing intracytoplasmic membranes were 100% more active than cells lacking these membranes. These results suggest that intracytoplasmic membranes are formed by continued plasma membrane synthesis at the end of active cell division.

The morphological features of the cell wall, plasma membrane, protoplasmic constituents, and flagella of Acetobacter suboxydans (ATCC 621 ) were studied by thin sectioning and negative staining. Thin sections of the cell wall demonstrate an outer membrane and an inner, more homogeneous layer. These observations are consistent with those of isolated, gramnegative ccU-wall ghosts and the chemical analyses of gram-negative cell walls. Certain functional attributes of the cell-wall inner layer and the structural comparisons of gramnegative and gram-positive cell walls arc considered. The plasma membrane is similar in appearance to the membrane of the cell wall and is occasionally found to bc folded into the cytoplasm. Certain features of the protoplasm are described and discussed, including the diffuse states of the chromatinic material that appear to be correlated with the length of the cell and a polar differentiation in the area of expected flagellar attachment. Although the flagella appear hollow in thin sections, negative staining of isolated flagella does not substantiate this finding. Severe physical treatment occasionally produces a localized penetration into the central region of the flagellum, the diameter of which is much smaller then that expected from sections. A possible explanation-of this apparent discrepancy is discussed.

Ultrastructural studies conducted on the intracellular symbiont of Glaucocystis nostochinearum Itz., a unicellular alga with a debated taxonomic position, have shown that the endosymbiont, although somewhat aberrant, is a blue-green alga. Due possibly to its intracellular habitat, it lacks the characteristic cyanophycean double-layered cell wall and the cells appear to be completely naked, bound only by a single plasma membrane. The protoplasm of the cell is differentiated into the lamellated chromatoplasm, which contains the photosynthetic pigments and polyphosphate granules, and a nonlamellar ccntroplasm, in which the nucleic material is dispersed. The usual cyanophycean organelles, as well as the different vacuoles and granules, with the exception of the formed bodies, are missing. Approximately 10% of the cells sliows a peculiar homogeneous area at one tip, the nature of which is unknown. Binary fission of the organism is mentioned. Since this cyanelle has not yet been classified, we name it Skujapelta nuda nov. gen., nov. sp.; and because of its structural peculiarities we find it necessary to create a new family for it, Skujapeltaceae in the order Chroococcales.