Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ingested by an organism and assimilated by the organism's cells in an effort to produce energy, maintain life, or stimulate growth.
Historically, people secured food through two methods: hunting and gathering, and agriculture. Today, most of the food energy consumed by the world population is supplied by the food industry.
Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain (commonly safranin) is added after the crystal violet, coloring all gram-negative bacteria with a red or pink color. The counterstain is used to visualize the otherwise colorless gram-negative bacteria whose much thinner peptidoglycan layer does not retain crystal violet. The test itself is useful in classifying two distinct types of bacteria based on the structural differences of their bacterial cell walls. Gram-positive bacteria retain the crystal violet dye when washed in a decolorizing solution. Compared with gram-positive bacteria, gram-negative bacteria are more resistant against antibiotics, despite their thinner peptidoglycan layer, because of their additional, relatively impermeable lipid membrane.
The pathogenic capability of gram-negative bacteria is often associated with certain components of gram-negative cell envelope, in particular, the lipopolysaccharide layer (also known as LPS or endotoxin layer). In humans, LPS triggers an innate immune response characterized by cytokine production and immune system activation. Inflammation is a common result of cytokine (from the Greek cyto, cell and kinesis, movement) production, which can also produce host toxicity. The innate immune response to LPS, however, is not synonymous with pathogenicity, or the ability to cause disease. In fact, the innate immune response is triggered by LPS alone, isolated from bacteria.
Hospitality is the relationship between the guest and the host, or the act or practice of being hospitable. This includes the reception and entertainment of guests, visitors, or strangers.