Malt Yeast Agar

Intended Use

Recommended for the cultivation of yeast and moulds.

Composition**

Final pH (at 25°C): 6.2±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 41 grams in 1000 ml purified / distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 121°C for 15 minutes. Cool to 45-50°C. Mix well and pour into sterile Petri plates.

Principle And Interpretation

Media based on malt extract may be considered as general growth substrates due to their richness and nutrient balance. Malt yeast Agar is formulated by Wickerham for the isolation, cultivation and maintenance of yeast and moulds and other aciduric microorganisms (1). Malt Agar is included in Official Methods of Analysis of AOAC International (2). Malt Yeast Agar is recommended by MTCC for cultivation and maintenance of Saccharomyces cerevisiae.(3)

Malt Yeast Agar contains malt extract, which provides carbon, protein and nutrient sources required for the growth of microorganisms. Peptone and yeast extract provides nitrogen compounds, vitamin B complex and other growth nutrient.

Type of specimen

Clinical samples - skin scrapings, nail scrapings etc.; Food and dairy samples.

Specimen Collection and Handling

For clinical samples follow appropriate techniques for handling specimens as per established guidelines (4,5).

For food and dairy samples, follow appropriate techniques for sample collection and processing as per guidelines (6-8).

After use, contaminated materials must be sterilized by autoclaving before discarding.

Warning and Precautions

In Vitro diagnostic Use. For professional use only. 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 clinical specimens. Safety guidelines may be referred in individual safety data sheets.

Limitations

1. Individual organisms differ in their growth requirement and may show variable growth patterns on the medium.
2. Each lot of the medium has been tested for the organisms specified on the COA. It is recommended to users to validate the medium for any specific microorganism other than mentioned in the COA based on the user’s unique requirement.
3. Overheating of the medium may result in low productivity and softening of gel.

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: Cream to brownish yellow homogeneous free flowing powder

Gelling: Firm, comparable with 2% Agar gel

Colour and Clarity of prepared medium: Light amber coloured clear to slightly opalescent gel forms in tubes or Petri plates

Reaction: Reaction of 4.10% w/v aqueous solution at 25°C. pH : 6.2±0.2

pH: 6.00-6.40

Cultural Response: Cultural characteristics was observed after an incubation at 25 - 30°C for 48 - 72 hours.

Key : (*) Corresponding WDCM numbers. (#) - Formerly known as Aspergillus niger

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).

Reference

1. Wickerham, J. Tropical Med. Hyg., 42, 176 (1939)
2. Williams, (Ed.), 2005, Official Methods of Analysis of the Association of Official Analytical Chemists, 19th Ed., AOAC, Washington, D.C.
3. Microbial Type Culture Collection and Gene Bank (MTCC ) Institute of Microbial Technology, Chandigarh.
4. Isenberg, H.D. Clinical Microbiology Procedures Handbook 2nd Edition.
5. 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.
6. American Public Health Association, Standard Methods for the Examination of Dairy Products, 1978, 14th Ed., Washington D.C.
7. Salfinger Y., and Tortorello M.L. Fifth (Ed.), 2015, Compendium of Methods for the Microbiological Examination of Foods, American Public Health Association, Washington, D.C.
8. Wehr H. M. and Frank J. H., 2004, Standard Methods for the Microbiological Examination of Dairy Products, 17th Ed., APHA Inc., Washington, D.C.