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An essay is presented on the world of microorganisms at the Yellowstone National Park in the United States. The author notes that in the thermal features of the park, visitors can witness a visual display of microorganisms, and even smell and taste the metabolic efforts of these creatures. The author claims that the national park not only provided a refuge for dwindling population of wildlife, but also prevented exploitation of geothermal resources, preserving a microscopic world.

AbstractOf 73 essential oils tested for antibacterial activity against Streptococcus pneumoniaeR36A (an unencapsulated strain) with a paper disk diffusion assay, three oils were highly inhibitory, fifteen moderately inhibitory and the remainder weakly or non-inhibitory. Three oils from each group were selected and tested with a broth assay in which each oil was added to growing cultures of S. pneumoniaeR36A and optical densities (OD) were measured over time. The oils with high antibacterial activity; oregano, thyme and rosewood, induced rapid lysis of R36A as indicated by a decrease in OD, and appearance of dechaining and considerable cell debris within 30 min of addition. The lytic response of R36A to the three oils with moderate activity was variable but all induced some lysis. Oils that were weak inhibitors generally caused slowing of growth but little or no lysis. Several oils were also tested against an encapsulated isolate, S. pneumoniaeIC2. Both disk assay and broth results were similar to those obtained with R36A, except that the oils were slightly less effective. Disk assay results showed some correlation with the broth assay, but were not always predictive of an oil's ability to induce bacterial lysis. Essential oils that induce lysis in S. pneumoniaemay have potential as an alternative treatment for infections caused by drug resistant pneumococci.

Mitomycin C was used to induce temperate bacteriophage from three strains of Pediococcus acidilactici.The new bacteriophage, designated pa97, pa40, and pa42, were characterized based on morphology, DNA homology, and major protein profiles.Morphological attributes (small isometric heads with non-contractile tails) place these bacteriophages within the B1 group of the family Siphovirdae.Restriction endonuclease digests suggested that the bacteriophage genomes were linear molecules without cohesive ends, and between 33 and 37 kilobases in length.All three bacteriophages possessed one major protein with an estimated mass of 30 to 35 kilodaltons.Bacteriophage pa42 also contained a second major protein of approximately 47 kilodaltons.DNA-DNA hybridization showed bacteriophages pa40 and pa42 were homologous to each other, but not to pa97, suggesting that Pediococcus acidilacticibacteriophage fall into at least two different species.

Reduced fat Mozzarella cheese was produced usingStreptococcus thermophilusandLactobacillus helveticus, and either total or partial replacement ofL. helveticuswithLactobacillus caseissp.casei. Stretch, melt and cook colour were determined at 1, 7, 14, and 28 d. All cheeses decreased in stretch during the first 7 d of storage, but there were no significant differences between culture types. Reduced fat cheese made withL. helveticusandS. thermophilusshowed the greatest stretch at both 1 and 7 d. After 14 d, all cheeses showed the same level of stretch. Storage time significantly affected stretch and melt. All reduced fat cheeses showed less melt through 14 d than the control cheese. Reduced fat cheese made with partial or total replacement ofL. helveticuswithL. caseissp.caseihad more stretch and less cook colour at day 1 than the part-skim Mozzarella. At 28 d of storage, all cheeses showed the same levels of melt and stretch with the reduced fat cheeses having less cook colour. Both scanning and transmission electron microscopy showed substantial differences between reduced fat and part-skim Mozzarella cheese during the manufacturing process. Reduced fat Mozzarella had a much more dense protein matrix with fewer small vacuoles (voids left in the cheese upon removal of fat with chloroform, particularly after stretching). TEM showed that after set, the reduced fat cheese had much larger protein strands where casein micelles had formed dense aggregates. Overall, the physical properties of reduced fat Mozzarella cheese made in this study, including those made with theL. caseiculture adjunct, compared favourably to part-skim Mozzarella cheese made with conventional thermophilic cultures.