Investigation of structure and antigenic capacities of Thermococcales cell envelopes and reclassification of ``Caldococcus litoralis'' Z-1301 as Thermococcus litoralis Z-1301

Fourteen strains of hyperthermophilic organotrophic anaerobic marine Archaea were isolated from shallow water and deep-sea hot vents, and four of them were characterized. These isolates, eight previously published strains, and six type strains of species of the order Thermococcales were selected for the study of cell wall components by means of thin sectioning or freeze-etching electron microscopy. The cell envelopes of most isolates were shown to consist of regularly arrayed surface protein layers, either single or double, with hexagonal lattice (p6) symmetry, as the exclusive constituents outside the cytoplasmic membrane. The S-layers studied differed in center-to-center spacing and molecular mass of the constituent protein subunits. Polyclonal antisera raised against the cells of 10 species were found to be species-specific and allowed 12 new isolates from shallow water hot vents to be identified as representatives of the species Thermococcus litoralis. Thermococcus stetteri, Thermococcus chitonophagus, and Thermococcus pacificus. Of the 7 deep-sea isolates, only 1 was identified as a T. litoralis strain. Thus, hyperthermophilic marine organotrophic isolates obtained from deep-sea hot vents showed greater diversity with regard to their S-layer proteins than shallow water isolates

The Phylum dictyoglomi

The phylum Dictyoglomi consists a single genus, Dictyoglomus, with two type strains and several related pure culture isolates. All isolates are thermophilic anaerobic Gram-type negative rods. A major distinguishing phenotypic feature is the formation of spherical bodies in late stationary phase of growth, the function of which is not understood.Most isolates are fermentative using a range of simple carbohydrates, but some isolates are able to grow on crystalline cellulose and chemolithotrophy using carbon monoxide as energy source has been reported for one pure culture. There have been relatively few applications for Dictyoglomus enzymes as a result of a number of factors. Although many of their kinetic properties are exceptional, they have had to be cloned and expressed in standard fermentation strains as hosts, and their low G:C content has required significant genetic manipulation to provide expression. Some of the main applications have required inexpensive enzymes in bulk (e.g., pulp bleaching in paper manufacture), and they have had to be regarded as a replacement for well-established enzymes currently used in the industry. The major applications have involved glycosyl hydrolases, but new uses in value-added products involving drug precursor transformations have been reported recently.10 page(s