The polymerase chain reaction (PCR) is used to produce many copies of a specific sequence of DNA.Source: OpenStax Microbiology OpenStax Microbiology Most methods of DNA analysis, such as restriction enzyme digestion and agarose gel electrophoresis, or DNA sequencing require large amounts of a specific DNA fragment. In the past, large amounts of DNA were produced … Continue reading The Polymerase Chain Reaction (PCR)
(a) Alkylating agents replace hydrogen atoms with alkyl groups. Here, guanine is alkylated, resulting in its hydrogen bonding with thymine, instead of cytosine. (b) The chemical structures of several alkylating agents.Source: OpenStax Microbiology OpenStax Microbiology The alkylating agents are a group of strong disinfecting chemicals that act by replacing a hydrogen atom within a molecule … Continue reading The Alkylating Agents
(a) The CDC recommends five steps as part of typical handwashing for the general public. (b) Surgical scrubbing is more extensive, requiring scrubbing starting from the fingertips, extending to the hands and forearms, and then up beyond the elbows, as shown here. (credit a: modification of work by World Health Organization) OpenStax Microbiology Handwashing is … Continue reading The Proper Handwashing Technique
Soaps are the salts (sodium salt in the illustration) of fatty acids and have the ability to emulsify lipids, fats, and oils by interacting with water through their hydrophilic heads and with the lipid at their hydrophobic tails.Source: OpenStax Microbiology OpenStax Microbiology Surface-active agents, or surfactants, are a group of chemical compounds that lower the … Continue reading The Surfactants
(a) Ethyl alcohol, the intoxicating ingredient found in alcoholic drinks, is also used commonly as a disinfectant. (b) Isopropyl alcohol, also called rubbing alcohol, has a related molecular structure and is another commonly used disinfectant. (credit a photo: modification of work by D Coetzee; credit b photo: modification of work by Craig Spurrier) Alcohols make … Continue reading Alcohols as Disinfectants and Antiseptics
(a) Betadine is a solution of the iodophor povidone-iodine. (b) It is commonly used as a topicalantiseptic on a patient’s skin before incision during surgery. (credit b: modification of work by Andrew Ratto) OpenStax Microbiology Halogens iodine, chlorine, and fluorine are the chemicals commonly used for disinfection. Iodine works by oxidizing cellular components, including sulfur-containing … Continue reading The Antimicrobial Activity of Halogens
Heavy metals denature proteins, impairing cell function and, thus, giving them strong antimicrobial properties. (a) Copper in fixtures like this door handle kills microbes that otherwise might accumulate on frequently touched surfaces. (b) Eating utensils contain small amounts of silver to inhibit microbial growth. (c) Copper commonly lines incubators to minimize contamination of cell cultures … Continue reading Heavy Metals as Disinfectants and Antiseptics
Triclosan is a common ingredient in antibacterial soaps despite evidence that it posesenvironmental and health risks and offers no significant health benefit compared to conventional soaps. (credit b, c: modification of work by FDA) OpenStax Microbiology Hand soaps and other cleaning products are often marketed as “antibacterial,” suggesting that they provide a level of cleanliness … Continue reading Triclosan: Antibacterial Overkill?
Phenol and phenolic compounds have been used to control microbial growth. (a) Chemical structure of phenol, also known as carbolic acid. (b) o-Phenylphenol, a type of phenolic, has been used as a disinfectant as well as to control bacterial and fungal growth on harvested citrus fruits. (c) Hexachlorophene, another phenol, known as a bisphenol (two … Continue reading What is Phenolics?
(a) Foods are exposed to gamma radiation by passage on a conveyor belt through a radiation chamber. (b) Gamma-irradiated foods must be clearly labeled and display the irradiation symbol, known as the “radura.” (credit a, b: modification of work by U.S. Department of Agriculture) OpenStax Microbiology Of all the ways to prevent food spoilage and … Continue reading Irradiated Food: Would You Eat That?