logging in or signing up CULTURE MEDIA dhariniariya Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: Embed: Flash iPad Copy Does not support media & animations WordPress Embed Customize Embed URL: Copy Thumbnail: Copy The presentation is successfully added In Your Favorites. Views: 2533 Category: Education License: All Rights Reserved Like it (1) Dislike it (0) Added: January 25, 2011 This Presentation is Public Favorites: 2 Presentation Description No description available. Comments Posting comment... Premium member Presentation Transcript CULTURE MEDIA & CULTURE METHODS : CULTURE MEDIA & CULTURE METHODS Slide 2: Bacteria have to be grown (cultured) for them to be identified. By appropriate procedures they have to be grown separately (isolated) on culture media and obtained as pure for study. History The original media used by Louis Pasteur – urine or meat broth Liquid medium – diffuse growth Solid medium – discrete colonies. Slide 3: Colony – macroscopically visible collection of millions of bacteria originating from a single bacterial cell. Cooked cut potato by Robert Koch – earliest solid medium Gelatin – not satisfactory - liquefy at 24oC Slide 4: Agar Frau Hesse Used for preparing solid medium Obtained from seaweeds. No nutritive value Not affected by the growth of the bacteria. Melts at 98oC & sets at 42oC 2% agar is employed in solid medium Types of culture media : Types of culture media Based on their consistency a) solid medium b) liquid medium c) semi solid medium Based on the constituents/ ingredients a) simple medium b) complex medium c) synthetic or defined medium d) Special media Slide 6: Special media Enriched media Enrichment media Selective media Indicator media Differential media Sugar media Transport media Based on Oxygen requirement - Aerobic media - Anaerobic media Slide 7: Solid media – contains 2% agar Colony morphology, pigmentation, hemolysis can be appreciated. Eg: Nutrient agar, Blood agar Liquid media – no agar. For inoculum preparation, Blood culture, for the isolation of pathogens from a mixture. Eg: Nutrient broth Semi solid medium – 0.5% agar. Eg: Motility medium Slide 9: Simple media / basal media - Eg: NB, NA - NB consists of peptone, yeast extract, NaCl, - NB + 2% agar = Nutrient agar Slide 10: Complex media Media other than basal media. They have added ingredients. Provide special nutrients Synthetic or defined media Media prepared from pure chemical substances and its exact composition is known Eg: peptone water – 1% peptone + 0.5% NaCl in water Slide 11: Enriched media Substances like blood, serum, egg are added to the basal medium. Used to grow bacteria that are exacting in their nutritional needs. Eg: Blood agar, Chocolate agar Slide 12: Blood agar Chocolate agar Slide 13: Enrichment media Liquid media used to isolate pathogens from a mixed culture. Media is incorporated with inhibitory substances to suppress the unwanted organism. Eg: Selenite F Broth – for the isolation of Salmonella, Shigella Alkaline Peptone Water – for Vibrio cholerae Slide 14: Selective media The inhibitory substance is added to a solid media. Eg: Mac Conkey’s medium for gram negative bacteria TCBS – for V.cholerae LJ medium – M.tuberculosis Wilson and Blair medium – S.typhi Potassium tellurite medium – Diphtheria bacilli Slide 15: TCBS Mac Conkey’s medium Slide 16: Potassium Tellurite media LJ media Slide 17: Indicator media These media contain an indicator which changes its colour when a bacterium grows in them. Eg: Blood agar Mac Conkey’s medium Christensen’s urease medium Slide 19: Urease medium Slide 20: Differential media A media which has substances incorporated in it enabling it to distinguish between bacteria. Eg: Mac Conkey’s medium Peptone Lactose Agar Neutral red Taurocholate Distinguish between lactose fermenters & non lactose fermenters. Slide 21: Lactose fermenters – Pink colonies Non lactose fermenters – colourless colonies Slide 22: Sugar media Media containing any fermentable substance. Eg: glucose, arabinose, lactose, starch etc. Media consists of 1% of the sugar in peptone water. Contain a small tube (Durham’s tube) for the detection of gas by the bacteria. Slide 24: Transport media Media used for transporting the samples. Delicate organisms may not survive the time taken for transporting the specimen without a transport media. Eg: Stuart’s medium – non nutrient soft agar gel containing a reducing agent Buffered glycerol saline – enteric bacilli Slide 25: Anaerobic media These media are used to grow anaerobic organisms. Eg: Robertson’s cooked meat medium, Thioglycolate medium. CULTURE METHODS : CULTURE METHODS Culture methods employed depend on the purpose for which they are intended. The indications for culture are: To isolate bacteria in pure cultures. To demonstrate their properties. To obtain sufficient growth for the preparation of antigens and for other tests. For bacteriophage & bacteriocin susceptibility. To determine sensitivity to antibiotics. To estimate viable counts. Maintain stock cultures. Slide 27: Culture methods include: Streak culture Lawn culture Stroke culture Stab culture Pour plate method Liquid culture Anaerobic culture methods Slide 28: STREAK CULTURE Used for the isolation of bacteria in pure culture from clinical specimens. Platinum wire or Nichrome wire is used. One loopful of the specimen is transferred onto the surface of a well dried plate. Spread over a small area at the periphery. The inoculum is then distributed thinly over the plate by streaking it with a loop in a series of parallel lines in different segments of the plate. On incubation, separated colonies are obtained over the last series of streaks. Slide 31: LAWN CULTURE Provides a uniform surface growth of the bacterium. Uses For bacteriophage typing. Antibiotic sensitivity testing. In the preparation of bacterial antigens and vaccines. Lawn cultures are prepared by flooding the surface of the plate with a liquid suspension of the bacterium. Slide 32: Antibiotic sensitivity testing Slide 33: STROKE CULTURE Stroke culture is made in tubes containing agar slope / slant. Uses Provide a pure growth of bacterium for slide agglutination and other diagnostic tests. Slide 34: STAB CULTURE Prepared by puncturing a suitable medium – gelatin or glucose agar with a long, straight, charged wire. Uses Demonstration of gelatin liquefaction. Oxygen requirements of the bacterium under study. Maintenance of stoke cultures. Slide 35: Gelatin liquefaction Oxidation – Fermentation medium Slide 36: POUR PLATE CULTURE Agar medium is melted (15 ml) and cooled to 45oC. 1 ml of the inoculum is added to the molten agar. Mix well and pour to a sterile petri dish. Allow it to set. Incubate at 37oC, colonies will be distributed throughout the depth of the medium. Uses Gives an estimate of the viable bacterial count in a suspension. For the quantitative urine cultures. Slide 37: LIQUID CULTURES Liquid cultures are inoculated by touching with a charged loop or by adding the inoculum with pipettes or syringes. Uses Blood culture Sterility tests Continuous culture methods Disadvantage It does not provide a pure culture from mixed inocula. Slide 38: Blood culture bottles ANAEROBIC CULTURE METHODS : ANAEROBIC CULTURE METHODS Anaerobic bacteria differ in their requirement and sensitivity to oxygen. Cl.tetani is a strict anaerobe – grows at an oxygen tension < 2 mm Hg. Methods: Production of vacuum Displacement of oxygen with other gases Chemical method Biological method Reduction of medium Slide 40: Production of vacuum: Incubate the cultures in a vacuum desiccator. Displacement of oxygen with other gases Displacement of oxygen with hydrogen, nitrogen, helium or CO2. Eg: Candle jar Slide 42: Chemical method Alkaline pyrogallol absorbs oxygen. McIntosh – Fildes’ anaerobic jar Consists of a metal jar or glass jar with a metal lid which can be clamped air tight. The lid has 2 tubes – gas inlet and gas outlet The lid has two terminals – connected to electrical supply. Under the lid – small grooved porcelain spool, wrapped with a layer of palladinised asbestos. Slide 44: Working: Inoculated plates are placed inside the jar and the lid clamped air tight. The outlet tube is connected to a vacuum pump and the air inside is evacuated. The outlet tap is then closed and the inlet tube is connected to a hydrogen supply. After the jar is filled with hydrogen, the electric terminals are connected to a current supply, so that the palladinised asbestos is heated. Act as a catalyst for the combination of hydrogen with residual oxygen. Slide 45: Gaspak Commercially available disposable envelope. Contains chemicals which generate H2 and CO2 on addition of water. Cold catalyst – in the envelope Indicator is used – reduced methylene blue. Colourless – anaerobically Blue colour – on exposure to oxygen Slide 47: Biological method Absorption of oxygen by incubation with aerobic bacteria, germinating seeds or chopped vegetables. Reduction of oxygen By using reducing agents – 1% glucose, 0.1% Thioglycolate You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.