Bacterial Physiology, Microbes, and Infectious Diseases

Posted on Jan 23, 2025 in Biology

Bacterial Physiology

Cytoplasm and ribosomes are also included. Protein synthesis and bacterial DNA is a double-stranded circular structure, usually attached to the mesosome. Additionally, there may be one or several small DNA molecules called plasmids. Flagella allow for localization.

Nutrition

Autotrophs: They produce organic matter from inorganic matter and energy captured from the environment.

  • Photolithotrophs: Capture light energy.
  • Chemolithotrophs: Use the chemical energy of oxidation of inorganic molecules.

Heterotrophs: They use organic material. They are called chemoorganotrophs. Within this group, bacteria can also be saprophytic, parasitic, or symbiotic.

Reproduction

Basically, reproduction is asexual by bipartition. However, bacteria also have parasexual mechanisms through which DNA fragments are exchanged. These are:

  1. Conjunction
  2. Transduction
  3. Transformation

Microbes

Eukaryotes

  • Algae: Photosynthetic. They constitute phytoplankton and are of great importance in the biosphere.
  • Fungi: Heterotrophs, including molds and yeasts.
  • Protozoa: Free-living or parasitic heterotrophs.

Infectious Diseases

Pathogenic microbes are those that directly cause diseases. For this, they must penetrate the living organism (infection), which can occur through wounds, the digestive tract, the respiratory tract, or the genitourinary tract.

Epidemic: When there are many sick individuals in a particular geographic area.

Pandemic: If it affects a large land area.

Reservoir: Places where germs can survive outside of guests and where they can initiate infection.

Vectors: Living beings that carry the pathogenic microbe to the host.

Carriers: Persons who do not have the disease symptoms but carry the pathogen inside and are transmitting the disease.

Virulence: Indicates the pathogenic capacity, consisting of the ability to destroy tissue, produce toxins, and escape the immune response.

Toxins: Substances produced by bacteria that have toxic effects on the host. If they are released, they are called exotoxins; therefore, they lose their toxic effect when heated. If they are not released, they remain in the bacterial cell.

Infection and Examples of Disease Transmission

  1. Direct contact through wounds in the skin (rabies, tetanus)
  2. Through the air (influenza, chickenpox)
  3. Sexual contact (HIV, herpes)
  4. Water and food (salmonellosis, cholera)
  5. Animals (plague, malaria)

Control of Organisms: Physical and Chemical

Antimicrobial agents are chemicals or chemical processes that act on bacteria.

Sterilization: The destruction of all microorganisms in any substrate.

  • Physical agents: High temperatures (autoclave). Not all agencies have the same resistance.
  • Pasteurization: Used in the food industry (milk, wine). It does not destroy all microbes. It consists of submitting the product to 70°C for 15 seconds.
  • Low temperatures inhibit bacterial growth. They are used for food preservation.
  • Ionizing radiation.

Chemical disinfectants: Kill microorganisms but not spores.

Antiseptic: Prevents microbial growth in wounds.

Industrial Microbiology

Industrial processes that use microorganisms to obtain products.

Fermentation process: Large-scale cultivation in fermenters. Deposits with a capacity of 400,000 liters in a liquid culture medium.