Noel R. Krieg

Bergey's manual of systematic bacteriology

BCL3 and Sheehy cite Bergeys manual of determinative bacteriology of which systematic bacteriology, first edition, is an expansion. With v.4 the set is complete. The volumes cover, roughly, v.1, the Gram-negatives except those in v.3 (

Phylogenetic study of the genus Campylobacter

87.95); v.2, the Gram-positives less actinomycetes (

Classification of Procaryotic Organisms and the Concept of Bacterial Speciation

71.95); v.

Determining chemotactic responses by two subsurface microaerophiles using a simplified capillary assay method

The phylogenetic relationships of all species in the genus Campylobacter, Wolinella succinogenes, and other gram-negative bacteria were determined by comparison of partial 16S ribosomal ribonucleic acid sequences. The results of this study indicate that species now recognized in the genus Campylobacter make up three separate ribosomal ribonucleic acid sequence homology groups. Homology group I contains the following true Campylobacter species: Campylobacter fetus (type species), Campylobacter coli, Campylobacter jejuni, Campylobacter laridis, Campylobacter hyointestinalis, Campylobacter concisus, Campylobacter mucosalis, Campylobacter sputorum, and “Campylobacter upsaliensis” (CNW strains). “Campylobacter cinaedi,” “Campylobacter fennelliae,” Campylobacter pylori, and W. succinogenes constitute homology group II. Homology group III contains Campylobacter cryaerophila and Campylobacter nitrofigilis. We consider the three homology groups to represent separate genera. However, at present, easily determinable phenotypic characteristics needed to clearly differentiate them are not apparent. The three homology groups are only distantly related to representatives of the alpha, beta, and gamma branches of the purple bacteria, indicating that these bacteria do not belong to any previously defined branch of this phylum.

Wolinella recta, Wolinella curva, Bacteroides ureolyticus, and Bacteroides gracilis are microaerophiles, not anaerobes

Taxonomy is the science of classification of organisms. Bacterial taxonomy consists of three separate, but interrelated areas: classification, nomenclature, and identification. Classification is the arrangement of organisms into groups (taxa) on the basis of similarities or relationships. Nomenclature is the assignment of names to the taxonomic groups according to international rules (International Code of Nomenclature of Bacteria [Sneath, 1992]). Identification is the practical use of a classification scheme to determine the identity of an isolate as a member of an established taxon or as a member of a previously unidentified species.

Deoxyribonucleic and ribonucleic acid homology studies of the genera Azospirillum and Conglomeromonas

A simplified capillary chemotaxis assay utilizing a hypodermic needle, syringe, and disposable pipette tip was developed to measure bacterial tactic responses. The method was applied to two strains of subsurface microaerophilic bacteria. This method was more convenient than the Adler method and required less practice. Isolate VT10 was a strain of Pseudomonas syringae, which was isolated from the shallow subsurface. It was chemotactically attracted toward dextrose, glycerol, and phenol, which could be used as sole carbon sources, and toward maltose, which could not be used. Isolate MR100 was phylogenetically related to Pseudomonas mendocina and was isolated from the deep subsurface. It showed no tactic response to these compounds, although, it could use dextrose, maltose, and glycerol as carbon sources. The chemotaxis results obtained by the new method were verified by using the swarm plate assay technique. The simplified technique may be useful for routine chemotactic testing.

Deoxyribonucleic acid homology of Azospirillum amazonense Magalhães et al. 1984 and emendation of the description of the genus Azospirillum

Although the nonfermentative, asaccharolytic, putative anaerobes Wolinella curva, Wolinella recta, Bacteroides ureolyticus, and Bacteroides gracilis are phylogenetically related to the true campylobacters, the type strains of these species exhibited O2-dependent microaerophilic growth in brucella broth and on brucella agar. The optimum O2 levels for growth of these strains ranged from 4 to 14% in brucella broth and from 2 to 8% on brucella agar, when H2 was provided as the electron donor. No growth occurred under 21% O2, and scant or no growth occurred under anaerobic conditions unless fumarate or nitrate was provided as a terminal electron acceptor. Aspartate, asparagine, and malate also served as apparent electron acceptors. The organisms were catalase negative and, except for B. gracilis, oxidase positive. Catalase added to brucella broth enhanced growth. O2 uptake by all species was inhibited by cyanide and 2-heptyl-4-hydroxyquinoline N-oxide. We concluded that these organisms are not anaerobes but instead are microaerophiles, like their campylobacter relatives.

Isolation and characterization of Aquaspirillum fasciculus sp. nov., a rod-shaped, nitrogen-fixing bacterium having unusual flagella

Ribosomal ribonucleic acid (RNA) homology studies indicated that there is 90 to 96% homology between Azospirillum lipoferum and Azospirillum brasilense and 64 to 70% homology between these two species and Azospirillum amazonense. These findings support the inclusion of these three species in the genus Azospirillum. In contrast, “Azospirillum seropedicae” strains showed very little homology with the other Azospirillum species ( 65% RNA homology); Gluconobacter oxydans and Beijerinckia indica exhibited 30 to 60% RNA homology with Azospirillum species. Deoxyribonucleic acid studies indicated that Conglomeromonas largomobilis subsp. largomobilis was related to Azospirillum lipoferum at a level of deoxyribonucleic acid homology of >45% and at a level of RNA homology of 99%; moreover, this organism was found to be a microaerophilic nitrogen fixer. Thus, C. largomobilis subsp. largomobilis is a subjective synonym of Azospirillum lipoferum. In contrast, deoxyribonucleic acid homology studies indicated that C. largomobilis subsp. parooensis is not related to C. largomobilis, Azospirillum lipoferum, or any other species tested, and its taxonomic position is uncertain. Several strains of azospirilla which form unique star-shaped colonies were identified as Azospirillum lipoferum by deoxyribonucleic acid homology.

Identification of Procaryotes

The results of deoxyribonucleic acid homology experiments with the type strains of Azospirillum lipoferum, Azospirillum brasilense, and Azospirillum amazonense and 19 additional strains of A. amazonense confirmed that A. amazonense is a distinct new species. The description of the genus Azospirillum is emended to accommodate A. amazonense.

3 – Phenotypic and Physiological Characterization Methods

In 1971, Strength and Krieg reported the isolation of a gram-negative freshwater rod which exhibited bipolar flagellar fascicles clearly visible by dark-field microscopy. The flagellar fascicles exhibited helical wave propagation, basal bending, and an ability to coil up like springs. Despite the flagellar activity, the cells were apparently unable to swim freely. Such organisms appeared to be similar morphologically to an organism previously described by Houwink in 1953 and Jarosch in 1969. The present report describes a reliable isolation method for such organisms based on the use of L-proline and semisolid agar. Upon isolation, the organisms grew in flocs, from which a highly viscous matrix could be separated by high-speed centrifugation. After many transfers, the growth gradually became homogeneous and turbid, and the viscous substance could no longer be demonstrated. Under certain conditions of growth, steady straight-line motility could be observed and photographed within viscous flocs. Straight-line, free-swimming motility occurred in viscous suspensions of cells prepared by homogenization of flocs. In 8- to 12-h-old cultures in the nonviscous homogeneous condition, some cells could swim slowly in irregular, circular paths; other could move about on surfaces. When the viscosity of the medium was increased, nearly every cell could swim freely and steadily in straight paths. A viscosity of 200 centipoise was optimal for strain XI, whereas 10 centipoise was optimal for strains X and XII. These results suggest that the organisms may be highly adapted to life within viscous flocs. The organism exhibited nitrogenase activity when tested by methods developed by Dobereiner and her colleagues for “Spirillum” lipoferum; Aquaspirillum peregrinum also was found to possess nitrogenase activity. Investigation of the physiology and deoxyribonucleic acid base composition of strains X, XI, and XII has indicated that even though the organisms are straight rods, they are probably members of the genus Aquaspirillum. Important taxonomic considerations include: Coccoid body or “microcyst” formation, possession of a “polar membrane” similar to that occurring in certain spirilla, bipolar tufts of flagella, a strictly respiratory metabolism, inability to attack carbohydrates, positive catalase and oxidase reactions, and a deoxyribonucleic acid base composition of 62 to 65 mol% guanine plus cytosine. The organisms were assigned to a new species, Aquaspirillum fasciculus, and the type strain was deposited with the American Type Culture Collection under the number 27740.