Definition of courier: An individual responsible for the exchange of items between two or more parties. Couriers are usually employed by a company that charges a flat rate to the party using the courier service. Federal Express, UPS, DHL, and the United States Post Office all employ couriers to deliver mail and packages.
At least 3 bacterial morphotypes, as well as fungal mycelia, thelastomatid nematodes, and ingested material are found in the hindgut. At annual molt, the lumen bacteria virtually disappear; presumably they are replaced from anterior gut regions, ingested exuvium, and ingested soil.
Gram-negative bacteria are a group of bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall sandwiched between an inner cytoplasmic cell membrane and a bacterial outer membrane. Gram-negative bacteria are spread worldwide, in virtually all environments that support life.