During a 2-year study, samples of various types of soils were collected from 115 fields that had not previously been tested with Bacillus thuringiensis and which were remote from any large-scale aggregations of lepidopterous insects in rearing or grain-storage areas. An average of about 400 isolates were examined from each soil, and, of 46 373 isolates examined, only 250 (0.5%) were identified as B. thuringiensis. While it was almost impossible to insure that a field had never been treated with B. thuringiensis or that drift from some nearby application had not reached the field, it is noteworthy that of the 250 isolates, 156 (62.4%) were not var. kurstaki, the only variety that has been used commercially in the United States in about 10 years. This is a strong indication that the B. thuringiensis isolates observed were present naturally. To verify the procedures used, samples were taken from two adjacent experimental plots which had been treated about 12 months previously with formulations of var. kurstaki and var. galleriae, respectively. With practically no exception, the variety recovered from each plot was the variety applied, indicating that the varietal status of B. thuringiensis is stable in the soil.

A strain of bacteria has been isolated which rapidly and efficiently utilizes the herbicide glyphosate ( N -phosphonomethylglycine) as its sole phosphorus source in a synthetic medium. The strain (PG2982) was isolated by subculturing Pseudomonas aeruginosa ATCC 9027 in a synthetic broth medium containing glyphosate as the sole phosphorus source. Strain PG2982 differs from the culture of P. aeruginosa in that it is nonflagellated, does not produce pyocyanin, and has an absolute requirement for thiamine. Strain PG2982 has been tentatively identified as a Pseudomonas sp. strain by its biochemical activities and moles percent guanine plus cytosine. Measurements of glyphosate with an amino acid analyzer show that glyphosate rapidly disappears from the medium during exponential growth of strain PG2982. In batch culture at 30�C, this isolate completely utilized 1.0 mM glyphosate in 96 h and yielded a cell density equal to that obtained with 1.0 mM phosphate as the phosphorus source. However, a longer lag phase and greater generation time were noted in the glyphosate-containing medium. Strain PG2982 can efficiently utilize glyphosate as an alternate phosphorus source.

Various groups of ureolytic organisms have been investigated from the point of view of taxonomic considerations (Viehover, 1913) or with special emphasis on nutritional requirements (Gibson, 1934; Knight and Proom, 1950). However, less attention has been paid to the charactexization of bacterial urease despite the fact that the enzyme has been reported to occur in 200 species of bacteria (Sumner and Somers, 1947). Sizer (1941) determined the kinetics of bacterial urease, and in an earlier study Pasmore and Yudkin (1937) investigated the relationship of growth on diverse substrates to the final level of urease in the harvested organisms. In both of these studies, intact cells of Proteus vulgaris were used as a source of enzyme. So far as we are aware, no report has ever appeared on the purification and properties of urease of bacteria. The present work is a report on such a purification and a comparison of the properties of highly active bacterial urease with urease from other sources. MATERIALS AD METODS Numerous strains of ureolytic bacilli were examined, and since BaciUlu pasteurii (U.S.D.A. 673, Gibson no. 22) possessed relatively high enzymatic activity, it was employed throughout this study. The urea incorporated into all media was sterilized by filtration or intermittent steaming and added to the autoclaved media. Organisms were subcultured on two per cent urea meat infusion slants at room temperature. For growing cells in quantity 40 liters of medium (yeast extract, 0.7 per cent; polypeptone, 1.0 per cent; urea, 2 per cent) were distributed in 12 liter carboys and inoculated with the 24 hour growth

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To isolate intact flagella with basal complexes from Vibrio cholerae, a rhamnolipid hemolysin from Pseudomonas aeruginosa was used to disrupt the cell envelope and flagellar sheath. The nonionic detergent, Triton X-100, provided similar results for Campylobacter fetus. Each of these basal complexes possessed, in addition to the four classical rings, concentric membrane rings (CMR's) similar to those found in Aquaspirillum serpens. Through the use of stereo imaging (which allows structures to be visualized in three dimensions) of thin sections of cells which had been sequentially treated with a number of envelope perturbants (i.e., ethylenediaminetetraacetate, lysozyme, Triton X-100, rhamnolipid hemolysin, and sodium dodecyl sulfate), we have progressively exposed the component parts of the basal organelles in V. cholerae and C. fetus. Since the action of these envelope perturbants has been well documented, we have been able to determine the associations of the exposed portions of the flagellar basal complex and the layer of the cell envelope in which they would normally reside. From our observations we have concluded that in both V. cholerae and C. fetus the L ring is embedded in the outer membrane and the P ring is associated with the peptidoglycan. The CMR's are bracketed by the L and P rings and are sandwiched between the outer membrane and the peptidoglycan. Elements of both the S and M rings appear to be associated with the plasma membrane.

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A flagellar sheath protein of Vibrio cholerae CA401 (Inaba) was characterized. Purity of the preparation was indicated by a single band on polyacrylamide gel electrophoresis gels and on Ouchterlony plates prepared with antibody against crude sheath material. The sheath protein was composed of three polypeptides with minimal molecular weights of 61,500, 60,000, and 56,500. The presence of sheath protein on the flagellum as well as on the outer membrane of the cell was demonstrated by ferritin labeling experiments with antiserum. Sheath protein antibody reacted similarly in labeling experiments and agglutination tests with a classical Ogawa strain and two nonagglutinating V. cholerae isolates, indicating that the sheath protein may represent the common Vibrio H antigen. Antibody specific for lipopolysaccharide labeled the cell but not the sheathed flagellum, which demonstrated that the sheath is not a simple extension of the outer membrane of the cell.

During the course of studying the terminal respiration of Pseudomonas fluorescens, detailed adaptive patterns were worked out with particular respect to compounds conceivably con