Lecture 12: Cultivation of Bacterial at Atmospheric Condition PDF

LECTURE 12 CULTIVATION OF BACTERIAL AT ATMOSPHERIC CONDITION SBGA_020724 Mar-Aug24  CO2 Anaerobiosis  Explain the principle of Epsilometer test (E test). Provide a direct quantification of antimicrobial susceptibility of microorganisms. It is a quantitative method that...

LECTURE 12 CULTIVATION OF BACTERIAL AT ATMOSPHERIC CONDITION SBGA_020724 Mar-Aug24  CO2 Anaerobiosis  Explain the principle of Epsilometer test (E test). Provide a direct quantification of antimicrobial susceptibility of microorganisms. It is a quantitative method that applies both the dilution of antibiotics and the diffusion of antibiotics into the medium. More precisely, the test combines a disk diffusion pattern with the determination of Minimum Inhibitory Concentration (MIC) which is considered as the lowest concentration of an antimicrobial that inhibits the visible growth of a microorganism. The E-test uses rectangular plastic strips with the predefined, continuous and exponential gradient of antibiotic concentration (one side of the strip contains the antimicrobial agent concentration gradient and the other side of the strip contains a numeric scale that indicates the drug concentration). Read more at: https://microbenotes.com/epsilometer-test-e-test/  Cultivate – to nurture and help grow (bacteria) Bacteria culture/ cultivation: is a biological activity wherein microorganisms multiply themselves in a predetermined culture media under laboratory conditions OR a method that allows the multiplication of bacterial cells in or on a culture medium under controlled laboratory conditions. Most bacteria can grow Species that are naturally found in low to some extent in the oxygen environments, such as in deep presence of oxygen, wounds or abscesses or the deep ocean, known as aerobic will typically grow best in the absence of culture oxygen – anaerobic culture. Species example? skin surface Staph. epidermidis Staph. aureus upper respiratory tract Streptococcus pneumoniae Haemophilus influenza Moraxella catarrhalis  Microorganism can be found as normal flora in the nasopharynx of healthy individuals? Human non-sterile sites and normal flora in health, by Basicmedical Keys.  cannot grow in the presence of oxygen at The growth of bacteria with varying oxygen requirements all. e.g. Fusobacterium B & Bacteroides cannot grow in the absence of oxygen. A e.g. Pseudomonas & Mycobacterium tuberculosis can grow in either aerobic or anerobic conditions, switching from aerobic respiration to fermentation or anaerobic respiration if oxygen is absent. e.g. E. coli, Salmonella, Listeria & Staphylococci C https://ecampusontario.pressbooks.pub/microbio/chapter/oxygen-requirements-for-microbial-growth/  The term “aerotolerant” pertains to an An organism that achieves optimal organism that does not require oxygen for growth at low oxygen concentrations, but growth but can tolerate its presence. An not in the complete absence of oxygen. aerotolerant organism is classified as an anaerobe. e.g. Strep. pyogenes (harmful) & Lactobacillus (beneficial) CSI211 – Clinical Microb. I GBS GAS  Cultivation of Aerobic Bacteria Aerobic bacteria require oxygen for survival. They are present in aerated moist soil containing organic carbon sources. There are two main types of aerobic bacteria: 1. The obligate aerobes that compulsorily require oxygen for deriving energy, growth, reproduction, and cellular respiration. These organisms do not survive in the absence of oxygen or flooding. 2. Facultative and Microaerophile aerobes: Facultative bacteria behave both aerobically and anaerobically, according to the prevailing conditions. In reduced environments, they acquire energy via anaerobic pathways, whereas in oxidative environments, they develop aerobic pathways. The microaerophilic bacteria require oxygen but in very low concentrations.  Cultivation of Anaerobic Bacteria There are mainly three methods of cultivation of anaerobic bacteria such as an atmosphere free of oxygen, an anaerobic indicator, and an anaerobic jar with a catalyst. An anaerobic jar is pictured Openings in the side of an anaerobic box that is holding nine Petri are sealed by glove-like sleeves that allow plates supporting cultures for the handling of cultures inside the box. Inoculated plates or tubes are placed inside the chamber, and anaerobic conditions are created by adding water to a gas generator envelope (GasPak) that is placed in the jar just before sealing. A candle jar is a container into which a lit candle is introduced before sealing the container's airtight lid. The candle's flame burns until extinguished by oxygen deprivation, which creates a carbon dioxide-rich, oxygen-poor atmosphere in the jar. End of Lecture 12