The Protective Effect of Skin Microecology on Skin
The sebaceous glands secrete lipids, which are metabolized by microorganisms to form an emulsified lipid film. These lipid films contain free fatty acids, also known as acid films, which can neutralize alkaline substances contaminated on the skin and inhibit foreign bacteria (passing bacteria). , fungi and other pathogenic microorganisms grow, so the first function of the normal skin flora is an important protective effect.
Invaginations of the skin and appendages, including sweat glands (sweat glands), sebaceous glands, and hair follicles, have their own unique flora. The sebaceous glands connect the hair follicles to form the follicular sebaceous unit, which secretes a rich lipid substance called sebum. Sebum is a hydrophobic protective film that protects and lubricates the skin and hair and acts as an antibacterial shield. The sebaceous glands are relatively hypoxic, supporting the growth of facultative anaerobic bacteria such as P. acnes, which contains P. acnes lipase that degrades sebum, hydrolyzes triglycerides in sebum, and releases free fatty acids. Bacteria can adhere to these free fatty acids, which help explain the colonization of the sebaceous glands by P. acnes, and these free fatty acids also contribute to the acidity of the skin surface (pH of 5). Many common pathogenic bacteria, such as Staphylococcus aureus and Streptococcus pyogenes, are inhibited in an acidic environment and thus are favorable for the growth of coagulase-negative staphylococci and coryneform bacteria. However, occlusion of the skin results in an increase in pH that will favor the growth of S. aureus and S. pyogenes. Because humans produce more sebum triglycerides than other animals, more P. acnes colonizes human skin.
Post time: Jun-27-2022
