The primary structures of the 16S rRNAs of Bacillus anthracis, Bacillus cereus, Bacillus mycoides, and Bacillus thuringiensis were determined by using the reverse transcription-dideoxy sequencing method. All of the strains exhibited very high levels of sequence similarity T (T = type strain) by only a single nucleotide. The 16S rRNA sequences of B. mycoides and B. thuringiensis differed from each other and from the sequences of B. anthracis and B. cereus by four to nine nucleotides.

Comparative analysis of Bacillus anthracis, Bacillus cereus, and related species on the basis of reverse transcriptase sequencing of 16S rRNA

Members of the Bacillus cereus group of organisms include Bacillus cereus, Bacillus anthracis and Bacillus thuringiensis. Collectively, these organisms represent microbes of high economic, medical and biodefense importance. Given this significance, this group contains the highest number of closely related fully sequenced genomes, giving the unique opportunity for thorough comparative genomic analyses. Much of the disease and host specificity of members of this group can be attributed to their plasmids, which vary in size and number. Chromosomes exhibit a high level of synteny and protein similarity, with limited differences in gene content, questioning the speciation of the group members. Genomic data have spurred functional studies that combined microarrays and proteomics. Recent advances are reviewed in this article and highlight the advantages of genomic approaches to the study of this important group of bacteria.

Genomics of the Bacillus cereus group of organisms

Bacillus cereus food poisoning and its toxins.

A system is described for the rapid and accurate identification of Bacillus isolates using a matrix of results from tests in the API 20E and API 5OCHB strips and from supplementary tests. API System tests have been shown to be more reproducible than the classical tests. A taxonomy based upon API tests is in good agreement with those obtained by other methods. The results matrix can also be used in computer assisted identification.

Identification of Bacillus Strains Using the API System

SUMMARY: Scientific classification is virtually a branch of mathematics which describes the overall similarities of organisms. Catalogues do not do this. Many schemes of bacterial taxonomy are not classifications but catalogues. Similarity is best measured by the number of features in common between two strains, while division into taxa is based on correlated features. Other criteria for these two basic ideas are unsatisfactory and cause confusion, and there seems to be no logical reason why any one feature should be given greater weight in classification than any other. Hierarchical systems are a practical necessity, and simple mathematical methods are useful in bacterial classification. It is not necessary to know the evolutionary history of organisms in order to classify them in a scientific manner.

Some thoughts on bacterial classification.

Aerobic sporeforming bacteria

Aerobic mesophilic sporeforming bacteria

The collection of 621 strains of aerobic mesophilic sporeforming bacteria studied by Smith, Gordon, and Clark (1946) included 8 strains that grew slowly, if at all, at 28 C and required a higher temperature than the others for maximum growth. They were closely related and as a group were distinguishable in several respects from the other species. Pending the investigation of more strains the 8 were assigned to the speciesBacillus coagulans Hammer (1915), withwhichBacillus thermoacidurans Berry (1933) is in synonymy. Our interest in acquiring and examining additional strains of this poorly represented species was twofold. In the first place, a larger number was needed to give a more complete characterization of the species, for only through the study of an adequate number of strains can a reliable description of a species be prepared. Also, as an apparent intermediate between the mesophilic and thermophilic sporeformers, Bacillus coagulans seemed from the data available to be an inviting preliminary step toward the study of the so-called thermophilic group. Thermophilic bacteria have been characterized by different workers in a variety of ways. Prickett (1928) ably summarized the various definitions and accepted the following one of Cameron and Esty (1926): Cultures growing at 55 C but not at 37 C were classified as obligate thermophiles, and those growing at both 55 C and 37 C, as facultative thermophiles. According to this definition none of the strains studied by Smith, Gordon, and Clark (1946) were obligate thermophiles; but 7 of the 8 strains of Bacllus coagulans and a few of Bacillus subtilis were facultative. Approximately 60 different species of aerobic thermophilic sporeforming bacteria have been named and described. In the sixth edition of Bergey's Manual (Breed et al., 1948, p. 707), Smith offered this apology: \"The data on the species of this group are so meager that it is not possible to offer a rational system of classification. Many of the characters used for separating the various species are probably as variable in this group as they have been found to be in the mesophilic group. Lacking a knowledge of the limits of variability and lacking other pertinent data, the present arrangement is regarded as temporary only.\" It was the purpose of thiswork, therefore, to studyBacillus coagulans more thoroughly, to characterize the species growing at still higher temperatures, and,

Aerobic sporeforming bacteria capable of growth at high temperatures.

Glycerol is a major by-product from biodiesel production, and developing new uses for glycerol is imperative to overall economics and sustainability of the biodiesel industry. With the aim of producing xylitol and/or arabitol as the value-added products from glycerol, 214 yeast strains, many osmotolerant, were first screened in this study. No strains were found to produce large amounts of xylitol as the dominant metabolite. Some produced polyol mixtures that might present difficulties to downstream separation and purification. Several Debaryomyces hansenii strains produced arabitol as the predominant metabolite with high yields, and D. hansenii strain SBP-1 (NRRL Y-7483) was chosen for further study on the effects of several growth conditions. The optimal temperature was found to be 30°C. Very low dissolved oxygen concentrations or anaerobic conditions inhibited polyol yields. Arabitol yield improved with increasing initial glycerol concentrations, reaching approximately 50% (w/w) with 150 g/L initial glycerol. However, the osmotic stress created by high salt concentrations (≥50 g/L) negatively affected arabitol production. Addition of glucose and xylose improved arabitol production while addition of sorbitol reduced production. Results from this work show that arabitol is a promising value-added product from glycerol using D. hansenii SBP-1 as the producing strain.

Production of Arabitol from Glycerol: Strain Screening and Study of Factors Affecting Production Yield

Species of the Dictyosteliaceae, a group of pseudoplasmodiumforming slime molds, are not uncommon in nature and can be readily isolated from soils, from decaying vegetation and from the dung of various animals. In contrast to the Myxogastrales which possess true plasmodia, the Dictyosteliaceae are characterized by myxamoebae which retain their identity throughout the whole life cycle of the organisms. During the vegetative stage these myxamoebae are free-living and feed by the ingestion and digestion of bacterial cells. With the exhaustion of the available food supply, the myxamoebae collect into aggregates termed pseudoplasmodia, and collectively build fruiting structures, or sorocarps. In these structures some myxamoebae become transformed into sterile, supportive cells to form a stalk, or sorophore, while others become differentiated into fertile spores forming a spore head, or sorus. The ubiquitous species Dictyostelium mucoroides Bref. has been more widely studied than other members of the group and from the work of Vuillemin (1902), Potts (1902), Pinoy (1903 and 1907), and Schuckmann (1924) a limited bacterial "host range" embracing twelve different species has been reported for it.

Nathan R. Smith

Papers

Aerobic sporeforming bacteria

Aerobic mesophilic sporeforming bacteria

Aerobic sporeforming bacteria capable of growth at high temperatures.

Production of Arabitol from Glycerol: Strain Screening and Study of Factors Affecting Production Yield

The Growth of Dictyostelium discoideum upon Pathogenic Bacteria.