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Yeast Media WHAT IS IN YEAST MEDIA ماهو الوسط الغدائي للخميرة Yeast media MUST contain the following components for the yeast to grow: الاوساط الغدائية للخميرة يجب ان يتوفر بها المكونات التالية A carbon source. مصدر كربون A nitrogen source, also called a nutrient base. مصدر نيتروجين بالاضافة الى المكونات الاساسية قد تحتاج الخميرة احد المكونات Various additional nutritional supplements.l مكملات غدائية Various additional "additives", typically drugs or antibiotics. اضافات مثل المضادات الحيوية 2% agar for solid medium (plates) الاجار ليساعد على تصلب الوسط الغدائي.

TYPES OF CARBON SOURCES انواع مصادر الكربون 2% Dextrose, which is the same thing as Glucose. A sugar. Typically abbreviated as "D" or "Dex" or "Glu". This is by far the most common carbon source, and is preferred by the yeast. (Dex" or "Glu 2% دكستروز او جلوكوز وهي سكريات, تختصر بـ ( وهي اكثر مصادر الكربون المفضلة للخمائر 2% Galactose (Gal). Another sugar, typically used for regulated expression of genes. 2& جالاكتوز وهو من السكريات التي تستعمل لتنظيم التعبير الجيني 2% Raffinose (Raf). Yet another sugar. This sugar is non-repressing (i.e. cells behave as if glucose is not present), but does not induce Gal genes. 2% رافينوز, في وجودة الخلايا تتصرف كانة لايوجد جلوكوز, ولكنة لا يحفز جينات الجلاكتوز 1% Potassium Acetate. Acetate requires respiratory growth. Most commonly used in sporulation medium. 1% بوتاسيوم استيت, مهم في عمليات التنفس ويستخدم غالبا في الاوساط الخاصة بالتجرثم 3% Glycerol. Glycerol requires respiratory growth. Most commonly used to verify that yeast are not petite (i.e. that they have mitochondrial function). 3% جليسرول Note that carbon sources may be combined. There are also others that are not listed – those above are the most common. وقد يكون المصدر الكربوني مركب, وهناك غيرها من المصادر ولكن تلك هي العامة.

TYPES OF NITROGEN SOURCES/NUTRIENT BASES 1% Yeast Extract + 2% Peptone (YP). This is a complex nutrient base derived from killed yeast cells. It provides everything yeast need to grow except a carbon source (although it is typically low in adenine), and so makes non-selective rich medium. هدا المعقد مشتق من خلايا الخميرة الميتة, وهو يوفر كل الاحتاجات لنمو الحميرة ماعدا المصدر الكربوني, كما انة فقير بالادنين, ويستخدم لتحضير الاوساط ا الغنية لغير اختارية. Yeast Nitrogen Base with Ammonium Sulfate (YNB + AS). This is a combination of various ingredients that we purchase as a mix from Difco. It is made from purified chemicals, and so is used to make selective media. هدا المصدر النتيروجيني مركب من مجموعة من الماد الكيمائية التي تباع تجاريا, ويستخدم لتحضير الاوساط الاختيارية.

TYPES OF NUTRITIONAL SUPPLEMENTS انواع المكملات الغدائية Individual nutrients. The typical nutrients we use are: – Adenine (Ade, A, 1X = 40 ug/ml). – Arginine (Arg, R, 1X = 50 ug/ml) – Histidine (His, H, 1X = 20 ug/ml) – Leucine (Leu, L, 1X = 100 ug/ml) – Lysine (Lys, K, 1X = 50 ug/ml) – Methionine (Met, M, 1X = 20 ug/ml) – Tryptophan (Trp, W, 1X = 50 ug/ml) – Uracil (Ura, U, 1X = 20 ug/ml)

TYPES OF YEAST MEDIA انواع الاوساط الغدائية هناك نوعين من الاوساط التي تحضر من المكونات التي تكلمنا عنها سابقا والاختاتف بينها يكون في المصدر النيتروجيني There are two principal types of yeast media that are made from the above components – the key difference between them is the nitrogen source/nutrient base: YPAD. This is rich and non-selective medium. All yeast will grow. Its components are: – nutrient base = 1% Yeast Extract + 2% Peptone (YP) – supplement = 1X (40 ug/ml) adenine (A) – carbon source = 2% Dextrose (D) YPD, which is the same but without the additional adenine. Yeast will still all grow, but ade2 yeast will turn red on YPD. YPA with another carbon source. This is again a rich medium, but with a different carbon source substituted for the Dextrose. The most common are YPAGal and YPAGlycerol (YPAG). YPAD with an additive. Many drugs can simply be added to YPAD. The most common for us is YPAD ug/ml G418. Synthetic Defined (SD). This medium is chemically defined. Synthetic defined medium contains the following components. – nutrient base = YNB + AS – a carbon source – a supplement mix (optional).

The most commonly used medium for isolation of yeasts is Sabouraud Dextrose Agar, (SAB agar). This medium is commercially available from many companies including Oxoid. It is a general purpose medium for fungi, not specialised for differentiation of yeast strains and consequently colonies of all strains of Saccharomyces yeasts look rather similar, white, of similar size and with small differences in colonial architecture. The composition of the medium is given below:-Oxoid Formula gm/litre Mycological peptone 10.0 Glucose 40.0 Agar 15.0 pH 5.6 ± 0.2

more specialised medium for use in brewing is Wallerstein Laboratories Nutrient Agar (W.L. Nutrient Agar). This medium is very useful in differentiating between brewing yeast strains. In addition to variations in shape and size between strains colonies vary considerably in colour. The medium contains the dye bromocresol green which different strains take up to different extents, so colonies vary in colour from white/buff through pale green to very deep green.