M-Yeast and Mould Broth

M-Yeast and Mould Broth is used for counting yeasts and moulds in samples by membrane filter technique.

Composition**

Final pH (at 25°C): 4.6±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 7.32 grams in 100 ml distilled water. Mix thoroughly. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Mix well and dispense as desired.

Principle And Interpretation

M-Yeast and Mould Broth is used for counting yeasts and moulds in samples by membrane filter method. It can also be used for cultivating other aciduric microorganisms in sugars (1).

Cerelose; a refined dextrose which is easily fermented by the moulds is included in the medium along with the amylolytic enzyme diastase. Biopeptone and yeast extract provide sufficient nitrogenous nutrients for the growth of the moulds. Thiamine (vitamin B1) functions in intermediate carbohydrate metabolism in the coenzyme form. Magnesium sulphate supplies the ions for fungal growth. The acidic pH of the medium favours the growth of moulds, yeasts and aciduric microorganisms. The medium is used to saturate sterile absorbent cotton pads. Membrane filters through which sample has been passed is aseptically placed on these saturated cotton pads. Incubation is carried out at 30°C for 48-72 hours.

Quality Control

Appearance: Cream to yellow homogeneous free flowing powder

Colour and Clarity of prepared medium: Light yellow coloured clear solution without any precipitate

Reaction: Reaction of 7.3% w/v aqueous solution at 25°C. pH : 4.6±0.2

pH: 4.40-4.80

Cultural Response

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

Storage and Shelf Life

Store below 30°C in tightly closed container and the prepared medium at 2-8°C. Use before expiry date on the label.

Reference

1. MacFaddin J. F., 1985, Media for Isolation-Cultivation-Identification-Maintenance of Medical Bacteria, Vol. 1, Williams and Wilkins, Baltimore.