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Under conditions of starvation, especially the lack of carbon and nitrogen sources, a single endospore forms within some of the bacteria through a process called sporulation. [15] When a bacterium detects environmental conditions are becoming unfavourable it may start the process of endosporulation, which takes about eight hours.
The wrong decision can be catastrophic: a vegetative cell will die if the conditions are too harsh, while bacteria forming spores in an environment which is conducive to vegetative growth will be out competed. [3] In short, initiation of sporulation is a very tightly regulated network with numerous checkpoints for efficient control. [citation ...
Bacillus subtilis (/ b ə ˈ s ɪ l. ə s s u b ˈ t iː. l i s /), [3] [4] known also as the hay bacillus or grass bacillus, is a gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans and marine sponges.
Some viruses can "hide" within a cell, which may mean that they evade the host cell defenses or immune system and may increase the long-term "success" of the virus. This hiding is deemed latency. During this time, the virus does not produce any progeny, it remains inactive until external stimuli—such as light or stress—prompts it to activate.
Serial passage is the process of growing bacteria or a virus in iterations. For instance, a virus may be grown in one environment, and then a portion of that virus population can be removed and put into a new environment.
The following outline is provided as an overview of and topical guide to concepts related to infectious diseases in humans.. Infection – transmission, entry/invasion after evading/overcoming defense, establishment, and replication of disease-causing microscopic organisms (pathogens) inside a host organism, and the reaction of host tissues to them and to the toxins they produce.
In bacteria capable of forming spores, conditions inducing sporulation often overlap with those inducing competence. [1] [8] Thus cultures or colonies containing sporulating cells often also contain competent cells. Most naturally competent bacteria are thought to take up all DNA molecules with roughly equal efficiencies. [1]
A virus must now enter the cell, which is covered by a phospholipid bilayer, a cell's natural barrier to the outside world. The process by which this barrier is breached depends upon the virus. Types of entry are: Membrane fusion or Hemifusion state: The cell membrane is punctured and made to further connect with the unfolding viral envelope.