Plot No. C40, Road No. 21Y, MIDC, Wagle Industrial Estate,
Thane(W)-400604, MH, India.
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Controlling Fermentation Processes#CC293D
Intended Use
Recommended for isolation and enumeration of wild yeasts in pitching yeasts.
Composition
| Ingredients | g/L |
|---|---|
| Dextrose (Glucose) | 44.500 |
| Potassium dihydrogen phosphate | 1.780 |
| Magnesium sulphate | 0.890 |
| Calcium chloride anhydrous | 0.178 |
| Sodium chloride | 0.089 |
| Adenine | 0.00178 |
| DL-Methionine | 0.000891 |
| L-Histidine | 0.000891 |
| DL-Tryptophan | 0.000891 |
| Boric acid | 0.0000089 |
| Zinc sulphate | 0.0000356 |
| Ammonium molybdate | 0.0000178 |
| Manganese sulphate | 0.0000356 |
| Ferrous sulphate | 0.0002225 |
| L-Lysine | 1.000 |
| Inositol | 0.020 |
| Calcium pantothenate | 0.002 |
| Aneurine | 0.0004 |
| Pyridoxine | 0.0004 |
| p-Amino benzoic acid (PABA) | 0.0002 |
| Nicotinic acid (Niacin) | 0.0004 |
| Riboflavin (Vitamin B2) | 0.0002 |
| Biotin | 0.000002 |
| Folic acid | 0.000001 |
| Agar | 17.800 |
| Final pH (at 25°C) | 5.0±0.2 |
Formula adjusted, standardized to suit performance parameters
Directions
Suspend 6.62 grams in 100 ml purified / distilled water containing 1 ml of 50% potassium lactate (FD123). Heat to boiling to dissolve the medium completely. DO NOT AUTOCLAVE. Cool to 45-50°C, adjust pH to 5.0 with 10% lactic acid and pour into sterile Petri plates.
Principle And Interpretation
Morris and Eddy (1) described this complex medium for the isolation and enumeration of wild yeasts in pitching yeast in the brewery industry. Walters and Thiselton (2) used a liquid synthetic medium containing lysine as sole nitrogen source and found that many types of yeast utilize lysine. Later Morris and Eddy (1) also formulated solid lysine medium. Most of the Saccharomyces strains employed in the brewery industry and other fermentative industries do not use lysine, whereas the wild strains do. Lysine Medium exploits this differential behavior to separate both types of yeasts. The medium contains vitamins and trace elements, which is necessary to support metabolic activities of yeast. Lysine acts as the sole source of nitrogen, which is utilized by many types of yeast. Morris and Eddy (1) recommended surface inoculation of washed aliquots from the yeast mass; 0.2 ml suspension of 107 cells/ml is the best. Sample is incubated at 25°C and examined daily, enumerating all the colonies that have grown (lysine positive). The degree of contamination is expressed as the number of wild yeast cells per million cells of the original inoculum. The number of cells in the inoculum is important as small number of cells about 100 to 1000 grow to a limited extent while 10,000 brewing yeast cells provide a direct measure of contaminant wild yeasts (3).
Type of specimen
Brewery sample
Specimen Collection and Handling
For brewery samples follow appropriate techniques for handling specimens as per established guidelines (1). After use, contaminated materials must be sterilized by autoclaving before discarding.
Warning and Precautions
Read the label before opening the container. Wear protective gloves/protective clothing/eye protection/face protection. Follow good microbiological lab practices while handling specimens and culture. Standard precautions as per established guidelines should be followed while handling specimens. Safety guidelines may be referred in individual safety data sheets.
Limitations
- Individual organisms differ in their growth requirement and may show variable growth patterns on the medium.
Performance and Evaluation
Performance of the medium is expected when used as per the direction on the label within the expiry period when stored at recommended temperature.
Quality Control
Appearance: Off white to yellow homogeneous free flowing powder
Gelling: Firm, comparable with 1.78% Agar gel.
Colour and Clarity of prepared medium: Off white to pale yellow clear to slightly opalescent opalescent gel forms in Petri plates
Reaction: Reaction of 6.6% w/v aqueous solution at 25°C. pH : 5.0±0.2
pH: 4.80-5.20
Cultural Response
Cultural characteristics observed after an incubation at 25-30°C upto 7 days.
| Organism | Growth |
|---|---|
| Pichia fermentans ATCC 10651 | luxuriant |
| Saccharomyces kudriavzevii ATCC 2601 | partial to complete inhibition |
| Saccharomyces cerevisiae ATCC 9763 | partial to complete inhibition |
Storage and Shelf Life
Store between 10-30°C in a tightly closed container and the prepared medium at 20-30°C. Use before expiry date on the label. On opening, product should be properly stored dry, after tightly capping the bottle in order to prevent lump formation due to the hygroscopic nature of the product. Improper storage of the product may lead to lump formation. Store in dry ventilated area protected from extremes of temperature and sources of ignition. Seal the container tightly after use. Product performance is best if used within stated expiry period.
Disposal
User must ensure safe disposal by autoclaving and/or incineration of used or unusable preparations of this product. Follow established laboratory procedures in disposing of infectious materials and material that comes into contact with sample must be decontaminated and disposed of in accordance with current laboratory techniques (4,5).
| Product Name | Lysine Medium Base |
|---|---|
| SKU | M642 |
| Product Type | Regular |
| Physical Form | Powder |
| Origin | Chemically defined |
| Packaging type | HDPE |
| References | 1.Morris E. O. and Eddy A. A, 1957, J. Inst. Brew. 63(1): 34. 2.Walters L. S. and Thiselton M. R., 1953, J. Inst. Brew. 59:401. 3.Fowell R. R., 1965, J. Appl. Bacteriol., 28:373. 4.Jorgensen, J.H., Pfaller, M.A., Carroll, K.C., Funke, G., Landry, M.L., Richter, S.S and Warnock., D.W. (2015), Manual of Clinical Microbiology, 11th Edition. Vol. 1. 5.Isenberg, H.D. Clinical Microbiology Procedures Handbook 2nd Edition |
| Customized Product Available | No |
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50% Potassium Lactate (10 ml per vial)
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