Molecular biology of bacterial bioluminescence.

The genus Shewanella has been studied since 1931 with regard to a variety of topics of relevance to both applied and environmental microbiology. Recent years have seen the introduction of a large number of new Shewanella-like isolates, necessitating a coordinated review of the genus. In this work, the phylogenetic relationships among known shewanellae were examined using a battery of morphological, physiological, molecular and chemotaxonomic characterizations. This polyphasic taxonomy takes into account all available phenotypic and genotypic data and integrates them into a consensus classification. Based on information generated from this study and obtained from the literature, a scheme for the identification of Shewanella species has been compiled. Key phenotypic characteristics were sulfur reduction and halophilicity. Fatty acid and quinone profiling were used to impart an additional layer of information. Molecular characterizations employing small-subunit 16S rDNA sequences were at the limits of resolution for the differentiation of species in some cases. As a result, DNA-DNA hybridization and sequence analyses of a more rapidly evolving molecule (gyrB gene) were performed. Species-specific PCR probes were designed for the gyrB gene and used for the rapid screening of closely related strains. With this polyphasic approach, in addition to the ten described Shewanella species, two new species, Shewanella oneidensis and 'Shewanella pealeana', were recognized; Shewanella oneidensis sp. nov. is described here for the first time.

Polyphasic taxonomy of the genus Shewanella and description of Shewanella oneidensis sp. nov

The shewanellae are aquatic microorganisms with worldwide distribution. Their hallmark features include unparalleled respiratory diversity and the capacity to thrive at low temperatures. As a genus the shewanellae are physiologically diverse, and this review provides an overview of the varied roles they serve in the environment and describes what is known about how they might survive in such extreme and harsh environments. In light of their fascinating physiology, these organisms have several biotechnological uses, from bioremediation of chlorinated compounds, radionuclides, and other environmental pollutants to energy-generating biocatalysis. The ecology and biotechnology of these organisms are intertwined, with genomics playing a key role in our understanding of their physiology.

Ecology and Biotechnology of the Genus Shewanella

Phylogeny of the Vibrionaceae, and recommendation for two new genera, Listonella and Shewanella

Approximately 30 years have elapsed since Dr. Fujino's original discovery that Vibrio parahaemolyticus (then termed Pasteurella parahemolytica) was the cause of "summer diarrhea" in Japan. Since that finding, V. parahaemolyticus has been established as a cause of gastroenteritis in numbers and places approaching global proportions. It has been isolated in marine and estuarine areas almost worldwide and despite its halophilic nature, V. parahaemolyticus has been isolated from saline-free waters. The relationship of this organism to the environment reveals a close association with other marine organisms especially copepods on which the Vibrios depend for survival in winter months and growth in summer months. There is a uniquely provocative disparity between human strains of V. parahaemolyticus which are Kanagawa phenomenon (KP) positive and the environmental strains which to a large extent are KP negative, the significance being that pathogenicity is measured according to the Kanagawa phenomenon (hemolytic activity) reaction. The hemolysin of the pathogenic strains is a thermostable, cardiotoxic protein, which thus far has not been implicated in the mechanism(s) which causes human gastroenteritis. The interest in this organism has been widened in recent years by the finding that similar organisms, V. alginolyticus, lactose positive vibrios and group F vibrios also cause serious disease in humans.

Vibrio Parahaemolyticus and Related Halophilic Vibrios

Eleven marine luminous isolates, which could not be identified with previously studied species of luminous marine bacteria, were subjected to an extensive characterization. The results indicated that these strains were phenotypically similar, had a G+C content in their DNA of 45 mol%, and differed from all previously characterized luminous species by their inability to ferment sugars. On the basis of these and other properties, the 11 luminous strains were assigned to the genusAlteromonas and given the species designationA hanedai. Strain 281 (ATCC 33224) has been designated as the type strain of this new species.

Characterization ofAlteromonas hanedai (sp. nov.), a nonfermentative luminous species of marine origin

Twenty-two isolates belonging to group F of Lee, Donovan, and Furniss were submitted to an extensive phenotypic characterization. The results of a numerical analysis of the data indicated that this group consisted of two biotypes which were phenotypically distinct from 22 previously characterized species ofBeneckea andPhotobacterium as well as from 3 species ofvibrio. The guanine-plus-cytosine content in the DNAs from 8 strains of group F was found to be 50.8±0.2 mol%. A set of 10 readily determinable phenotypic properties was proposed for the differentiation of strains of group F from other related species.

M. Mandel

Papers

Characterization ofAlteromonas hanedai (sp. nov.), a nonfermentative luminous species of marine origin

Characterization of facultatively anaerobic marine bacteria belonging to group F of Lee, Donovan, and Furniss