"Carbon Group" (36 results)

Reinforced Clostridial Agar is recommended for the cultivation and enumeration of anaerobes, particularly Clostridium, and other microorganisms in foods and clinical specimens. Hirsch and Grinstead formulated Reinforced Clostridial Medium (Cat. CL-1007) and found that this medium is superior to others in supporting growth and producing high cell counts of Clostridia. When incubated anaerobically, this medium grows various anaerobes and other bacteria. It has also been demonstrated that it can be used to develop vegetative cells in assays of Clostridium perfringens. Peptone and beef extract provide nitrogen, vitamins, minerals, and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group. Dextrose is the fermentable carbohydrate providing carbon and energy. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Starch in the medium acts as a growth factor, probably functioning like a colloid protector and neutralizes toxic products that form during the development of the organisms. L-Cysteine hydrochloride is the reducing agent and Sodium acetate is the buffer. Bacteriological agar is the solidifying agent. Since it is a non-selective enrichment medium, it allows the growth of various anaerobic microorganisms and facultative bacteria when incubated anaerobically.

Brilliant Green Agar (BGA) is used for the selective isolation of Salmonella spp, other than S. typhi, in foods and clinical specimens, via Lactose/Sucrose fermentation. The Peptone mixture provides nitrogen, vitamins, minerals, and amino acids essential for growth. Yeast extract is a source of vitamins, particularly the B-group. Sucrose and Lactose are fermentable carbohydrates providing carbon and energy. Phenol red is the pH indicator, turning the medium a yellow colour with the formation of acid because of Lactose/Sucrose fermentation. Brilliant green inhibits Gram-positive bacteria and most Gram-negative bacilli, other than Salmonella spp. Lactose/Sucrose fermenters are usually inhibited. Sodium chloride supplies essential electrolytes for transport and osmotic balance and bacteriological agar is the solidifying agent.

The medium, which has a coffee colour at the beginning will change to red during incubation at 35-37 ºC. A probable presence of Salmonellae is indicated by small, transparent, either colourless or pink or opaque-white colonies, often surrounded by a pink or red zone. Some of the uninhibited Gram-negative, Lactose/Sucrose fermenting organisms present opaque green-yellow colonies, surrounded by a yellow halo. Other lactose negative microorganisms, such as Proteus spp., form colonies of a pale pink or red colour, transparent and surrounded by a brilliant red halo.

Reinforced Clostridial Medium is a semi-solid medium that is recommended for the cultivation and enumeration of anaerobes, particularly Clostridium and other microorganisms in goods and clinical specimens. Hirsch and Grinstead formulated it in 1954 and their work demonstrated that the medium outperformed other media when supporting the growth of Clostridium from small inoculum and produced higher viable cell counts. Peptone and beef extract provide nitrogen, vitamins, minerals, and amino acids that are essential for growth. Yeast extract is the source of vitamins, particularly of the B-group and dextrose is the fermentable carbohydrate providing carbon and energy.

Sodium chloride supplies essential electrolytes for transport and osmotic balance. Starch in the medium acts as a growth factor, probably functioning like a colloid protector, and neutralizes toxic products that form during the development of the organisms. L Cysteine hydrochloride is the reducing agent and sodium acetate is the buffer. Since the medium is a non-selective enrichment one, it allows the growth of various anaerobic microorganisms and facultative bacteria when incubated under anaerobic conditions. The European Pharmacopoeia, USP, recommends the Reinforced Clostridial Medium for “Microbiological examination of non-Sterile products: test for specified microorganisms” for the testing of Clostridia in products.

Listeria Enrichment Broth with Supplements is the modified version of Listeria Fraser Broth ISO Cat. CL-1182. The medium is used for the selective enrichment and enumeration of Listeria monocytogenes and other Listeria species in all food types, including milk and dairy products, and environmental samples. The antibiotics are already included in the formula. Listeria monocytogenes is the bacterium that causes the infection listeriosis which is an illness that is vital when it comes to food safety. The control of this bacterium is important as it has the ability to grow at temperatures as low as 3°C. Listeria is killed by cooking and pasteurization so can be found in raw milk and foods made from raw milk as cheeses (particularly soft-ripened varieties) or ice cream as they do not require cooking. It can also live in food processing plants and contaminate a variety of processed meats.

Soy peptone and tryptone provide nitrogen, vitamins, minerals, and amino acids essential for growth. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Dextrose is the fermentable carbohydrate providing carbon and energy. Yeast extract is source of vitamins, particularly the B-group essential for bacterial growth. Potassium phosphates act as a buffer system. Nalidixic acid blocks the DNA replication of susceptible bacteria and acts against many Gram-negative bacteria. The Acriflavine and cicloheximide are the Gram-positive selective components.

WL Differential Agar is a selective medium for the isolation and enumeration of microbial flora used together with WL Nutrient Agar (Cat. CL-1086) for the control of the manufacture of beer and other fermentation processes by yeasts. Both media are widely used in the industries of vinegar, bread yeasts, grape and wine-growing and distilled spirits. In the production of yeasts for the bakery and distillery industries, the pH of the media is adjusted to 6.5. The medium allows the selective multiplication of yeasts in fermentation liquids, which contain a microflora mix consisting of fungi and bacteria. When the number of yeasts present is relatively small, certain bacteria can also be detected.

Tryptone provides nitrogen, vitamins, minerals, and amino acids essential for growth. Dextrose is the fermentable carbohydrate providing carbon and energy. Yeast extract is a source of vitamins, particularly of the B-group and monopotassium phosphate is the buffer. Potassium, Calcium and Ferric chlorides all provide essential ions for the osmotic balance. Magnesium and Manganese sulphates are sources of divalent cations. Bromocresol purple is the pH indicator and bacteriological agar is the solidifying agent. The addition of 0.004 grams of Cycloheximide converts the WL Nutrient formula into a differential medium, which inhibits the development of yeasts and moulds while permitting the notable proliferation of the bacteria present in the fermentation liquids and subsequent identification and enumeration.

Endo LES Agar Base is a modification of Endo Agar Base (Cat. CL-1118), for testing water by the membrane filter technique. It uses Lauryl Sulphate Broth (Cat.CL- 1310) as an enrichment to obtain greater growth. LES stands for Lawrence Experimental Station which is a standard formula for testing waters and is also specified in the coliform’s fermentation technique.

Like Endo Agar, it uses fuchsin to differentiate between positive lactose-fermenting and lactose non-fermenting bacteria. Acetaldehyde production by lactose fermenting organisms such as Escherichia coli produce characteristic red colonies and a red surrounding area, marked by its reaction with Sodium sulphite in the presence of fuchsin. Lactose non-fermenters form colourless, transparent colonies.

Casein and Meat peptones, and Tryptose provide nitrogen, vitamins, minerals, and amino acids that are essential for growth. Yeast extract is a source of vitamins, particularly of the B-group and lactose is the fermentable carbohydrate providing carbon and energy. Potassium phosphates act as a buffer system. Sodium deoxycholate inhibit growth of gram-positive bacteria. Sodium lauryl sulphate partially inhibits organisms other than coliforms. Sodium chloride supplies essential electrolytes for transport and osmotic balance and bacteriological agar is the solidifying agent.

Note: Basic fuchsin is a potential carcinogen and precautions should be taken to avoid inhalation of the dye powder as well as contact with skin.

Yersinia Select Agar Base is a selective and differential medium when used with supplements. The formula is based on the CIN Agar described by Schiemann and is recommended by ISO 10273 for the isolation and detection of presumptive pathogenic Yersinia enterocolitica from a variety of clinical and food samples. Antibiotics are added as a supplement to inhibit the accompanying flora. The growth of Yersinia is promoted by pyruvate as well as by the nutrients content in the base.

Yersinia degrades the mannitol of the medium to an acid form. This makes the colonies turn to a red colour due to the neutral red indicator. Mannitol fermentation in the presence of neutral red produces a characteristic “bull’s-eye” colony, colourless with a red centre. Mannitol is the fermentable carbohydrate, source of carbon and energy. Enzymatic digest of gelatin and the enzymatic digest of casein and animal tissues provide nitrogen, vitamins, minerals, and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group.

Sodium pyruvate is added as a source of energy and as a protective substance to overcome oxygen toxicity biologically produced by the organisms. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Magnesium sulphate is an ion required in a large variation of enzymatic reactions, including DNA replication. Neutral red is the pH indicator. Selective inhibition of Gram-negative and Gram-positive organisms is obtained through crystal violet, sodium desoxycholate and Irgasan (triclosan). Cefsulodin and novobiocin improve the inhibition of normal enteric organisms.

Brucella Agar is rich in nutrients and growth factors which makes it suitable to grow and isolate fastidious microorganisms. It can be used to successfully isolate Brucella from diverse specimens contaminated with microflora, both saprophytes and commensals in clinical samples as well as in food. The medium is used to produce clostridial toxins and can be utilised in the isolation of many anaerobes of human and animal origin. Food samples can be inoculated directly on the plates of Brucella Agar, while clinical specimens are more convenient as suspensions or macerations in sterile saline solutions.

Meat peptone and casein peptone provide nitrogen, vitamins, minerals. and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group. Sodium bisulphite is the reducing agent; Sodium chloride supplies essential electrolytes for transport and osmotic balance. Dextrose is the fermentable carbohydrate providing carbon and energy. The addition of blood provides extra growth factors for fastidious microorganisms. Bacteriological agar is the solidifying agent. The addition of the Brucella Supplement (Cat. CL-6017) enhances the medium’s selectivity for the growth of Brucella. For a better growth, Polyenrichment Supplement (Cat. CL-6011) and Polyenrichment CC Supplement (Cat. CL-6071) may be added if required. Brucella species are level 3 pathogens and cause brucellosis, a zoonotic disease. It is usually transmitted through milk, dairy products, meat, and direct contact with infected animals.

Note: To obtain an excellent medium for anaerobes, add 5 mg/ml of hemin and 10 μg/ml of vitamin K1 (fitomenadione) to the basal medium. Inoculate and incubate in anaerobic conditions.

Vogel-Johnson Agar is a selective and differential medium used for the early detection of Staphylococcus aureus by identifying the coagulase-positive and mannitol-fermenting strains. The medium is well suited for the detection of staphylococci carriers as well as studies of sanitary concern. S. aureus reduce the potassium tellurite to the metal tellurium and result in the growth of black colonies. The fermentation of mannitol is indicated by the yellow zones around the black colonies and changes the red colour of the medium to yellow.

Tryptone provides nitrogen, vitamins, minerals, and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group. Mannitol is the fermentable carbohydrate providing carbon and energy potassium tellurite, lithium chloride and the high glycine concentration inhibit most microorganisms other than staphylococci. Phenol red is the pH indicator. Dipotassium phosphate is a buffer and bacteriological agar is the solidifying agent.

Vogel-Johnson Agar plates can be streaked heavily with a swab and incubated at 35±2 °C for 24-48 hours. It is important to look for the black colonies that are surrounded by a yellow zone. In the first 24 hours, most microorganisms except for coagulase-positive staphylococci are totally or markedly inhibited. In the 48-hour period, many coagulase-negative staphylococci, mannitol-positive and mannitol-negative begin to appear. Staphylococcus epidermidis, almost always inhibited early, forms small greyish-black colonies without yellow zones. Coagulase-positive staphylococci form black colonies on the red medium. If they ferment mannitol, the colonies are surrounded by a yellow zone. Mannitol-negative organisms do not change the red colour of the medium.

Bismuth Sulfite Agar (Wilson Blair) is a modification of the Wilson Blair Medium, and generally accepted as routine for the detection of most Salmonella, in particular Salmonella typhi. Peptone and beef extract provide nitrogen, vitamins, minerals, and amino acids essential for growth. Dextrose is the fermentable carbohydrate providing carbon and energy, Bismuth sulphite indicator and brilliant green are inhibitors of Gram-positive bacteria and members of the coliform group. Disodium phosphate acts as a buffer system and bacteriological agar is the solidifying agent. Ferrous sulphate is included for detection of H2S production. When H2S is present, Salmonella spp reduces the iron salts to iron sulphate, which produces a black colony and turns the bismuth indicator to metallic bismuth, surrounding the area of the colonies with a bright sheen. The colonies of S. typhi are black surrounded by a black or brownish zone, with a metallic sheen. In heavy growth areas, these may appear as light green colonies whereas in other strains of Salmonella produce black to green colonies with little or no darkening of the surrounding medium. Shigella spp, other than Shigella flexneri and Shigella sonnei, do not grow. Those colonies that do grow are brown to green, raised with a crater-like appearance. E. coli is partially inhibited, occasionally growing with brown or greenish glistening colonies. A few Enterobacter strains may grow with raised, mucoid colonies, having a silvery sheen lighter than S. typhi. Colonies of coliforms that produce H2S form colonies similar in appearance to S. typhi. These may be readily differentiated as they produce gas with lactose media, e.g. TSI Agar (Cat.CL-1046) or Kligler Iron Agar (Cat. CL-1042). The hydrolysis of urea in Urea Broth (Cat. CL-1226) or Urea Agar Base (Cat. CL-1110) may be used to identify Proteus spp.

Triple Sugar Iron Agar (TSI) comes as 500g and is a differential medium used to differentiate enteric Gram-negative Enterobacteria based on carbohydrate fermentation and H2S production. It is used as an aid in the identification of pathogenic and saprophytic Enterobacteria isolated from routine bacteriological analysis of material samples such as faeces. This medium is used to initiate the identification of Enterobacteria in some FDA schemas.

Peptone mixture and the Beef extract provide nitrogen, vitamins, minerals, and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group. TSI contains three carbohydrates (Dextrose, Sucrose and Lactose) as sources of carbon and energy. When these are fermented, the acid production is indicated by the Phenol red indicator, being the colour changes yellow for acid production and red for alkalinization. Sodium thiosulfate is reduced to hydrogen sulphide, which reacts with the iron salt to give the black iron sulphide. Ferric ammonium citrate is an H2S indicator. Sodium chloride supplies essential electrolytes for transport and osmotic balance and bacteriological agar is the solidifying agent.

The mode of action is like Kligler Iron Agar (Cat. CL-1042) which contains two sugars. The addition of 1% Sucrose in TSI Agar allows differentiating between Proteus and Salmonella. The fermentation of sucrose by Proteus turns the colour of the Phenol red indicator in the slant from red to yellow. Dextrose-positive and lactose-negative members of the genus Salmonella all cause a reddening of the slant and acidify the depths of the agar tubes. The presence of salmonellae is provisionally confirmed if in the deep inoculation, but not in the surface culture, there is a change of colour from red to yellow and, usually, a formation of gas, with or without production of hydrogen sulphide in the agar. Precise confirmation may be carried out by the appropriate biochemical and serological tests.

Chapman Stone Agar is used for the isolation of pathogenic Staphylococci in foods. It is like Staphylococcus N° 110 Agar (Cat. CL-1032) but contains ammonium sulphate to detect the gelatinase activity (Stone’s reaction), and sodium chloride concentration is reduced to 5.5%. The main modification of this medium is the inclusion of ammonium sulphate that allows the direct observation of gelatin hydrolysis instead of adding reagents to the plate medium. Due to the presence of ammonium sulfate in the medium itself, there is no need to flood the plate with the ammonium solution to detect the gelatin liquefaction (Stone’s method). Ammonium sulphate precipitates unhydrolyzed gelatin, so a transparent halo will appear around the gelatinase (+) colonies. Casein peptone provides nitrogen, vitamins, minerals, and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group. D-Mannitol is the fermentable carbohydrate providing carbon and energy. Sodium chloride, in high concentrations, inhibits most bacteria except Staphylococci.

Gelatin is a protein derived by the hydrolysis of collagen, found abundantly in bones, skin, tendons, cartilage, and animal tissue. It is used in culture media to determine gelatinolysis by bacteria. The gelatinoses produced by the microorganisms hydrolyse, the gelatin liquefying a solid medium or preventing the gelation of a medium containing gelatin. Bacteriological agar is the solidifying agent. The staphylococcal colonies are yellow, yellow-gold or orange, ferment mannitol, coagulase-positive, produce beta-haemolysis in media such as Blood Agar (Cat. CL-1108) and are gelatinase-positive. Any pigmented colony that is surrounded by a clear zone is probably a pathogenic Staphylococcus. Pale colonies, practically lacking in colour or not producing pigment, should not be considered as positives, even if they are surrounded by a clear zone (halo), and are presumptively identified as S. epidermidis colonies. It is recommended to pick the colony and inoculate it in 0,1-0,2 ml of Brain Heart Infusion Broth (Cat. CL-1400) and perform the coagulase test. At the same time, add a drop of Bromocresol purple to the colony site to determine mannitol fermentation: a yellow colour formation is a positive reaction. The zones of clear halos around the colonies indicate degradation by the enzyme gelatinase (gelatin hydrolysis).