5.3
Métodos físicos para el control del crecimiento microbiano: radiación y filtración
La radiación y la filtración son herramientas fundamentales para el control microbiano, ya que actúan sobre los microorganismos mediante mecanismos di…
La radiación mata o inhibe el crecimiento de microorganismos.
Los gabinetes de seguridad utilizan radiación UV no ionizante, que daña el ADN y desinfecta las superficies, el aire y el agua, pero su penetración limitada evita que desinfecte artículos a granel como alimentos enlatados.
La radiación ionizante, como los rayos X y los rayos gamma, penetra profundamente y destruye las endosporas, esteriliza los antibióticos, los suministros hospitalarios y los alimentos.
El plasma frío, el cuarto estado de la materia que emite rayos UV, se ha convertido en un potente agente antimicrobiano utilizado para esterilizar dispositivos médicos y conservar alimentos.
La filtración elimina la mayoría de los microbios y se utiliza para esterilizar líquidos y gases sensibles al calor.
Los filtros de membrana con poros de 0,2 μm, hechos de ésteres de celulosa o polímeros plásticos, eliminan la mayoría de los microbios y esterilizan los medios de cultivo, las vacunas y los antibióticos.
Los filtros de profundidad, como los filtros HEPA utilizados en cabinas de seguridad, quirófanos y unidades de quemados, atrapan el 99,97% de las partículas, incluidos los virus, dentro de su matriz porosa.
Del mismo modo, las mascarillas N95 bloquean el 95% de las partículas en el aire por encima de 0,3 μm.
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Q1: How does UV radiation kill microorganisms in safety cabinets?
UV radiation, a non-ionizing radiation type, is absorbed by microbial DNA, causing defects that kill or inhibit microorganisms. Safety cabinets use UV radiation to disinfect surfaces, air, and water effectively. However, UV radiation has limited penetration depth, making it unsuitable for sterilizing bulk items like canned foods.
Q2: What is the difference between ionizing and non-ionizing radiation for microbial control?
Non-ionizing UV radiation damages DNA but cannot penetrate thick layers, limiting its use to surfaces and air. Ionizing radiation, such as X-rays and gamma rays, penetrates deeply and destroys all microbes, including highly resistant endospores. This makes ionizing radiation ideal for sterilizing vaccines, antibiotics, hospital supplies, and food products.
Q3: Why is filtration preferred for sterilizing heat-sensitive liquids and antibiotics?
Filtration is a chemical-free method that removes microorganisms without applying heat or chemicals, making it ideal for heat-sensitive materials. Membrane filters with 0.2 μm pores, made of cellulose esters or plastic polymers, effectively remove most microbes from culture media, vaccines, and antibiotics while preserving their integrity.
Q4: How do HEPA filters and N95 masks protect against airborne microbes?
HEPA filters trap 99.97% of particles, including viruses, within their porous matrix through adsorption, making them critical for sterile environments in operating rooms and burn units. N95 masks block 95% of airborne particles larger than 0.3 μm, providing essential personal protection against microbial threats in healthcare and daily settings.
Q5: What is cold plasma and how does it sterilize medical devices?
Cold plasma is the fourth state of matter that emits UV rays and exhibits remarkable antimicrobial properties. It is increasingly used for sterilizing medical devices and preserving food, offering a versatile and effective solution for microbial control that complements traditional radiation and filtration methods.
Q6: Why can't UV radiation sterilize canned foods while gamma rays can?
UV radiation has limited penetration depth and cannot pass through thick layers or opaque materials like metal cans. Gamma rays, an ionizing radiation type with wavelengths shorter than 1 nm, penetrate deeply into objects and destroy all microbes, including endospores, making them effective for sterilizing packaged food products.
Q7: What pore size do membrane filters use to remove most microorganisms?
Membrane filters use pore sizes as small as 0.2 μm to effectively remove most microorganisms from liquids and gases. These filters, made from cellulose esters or plastic polymers, are widely used for sterilizing culture media, vaccines, and antibiotics, providing reliable microbial removal without damaging heat-sensitive materials.