Nutritional Requirements of Bacteria PDF

Requirements for Growth 1.Enviromental conditions 2. Nutrients 3. Sources of energy. Important (environmental factors) that affect microbial growth: 1.pH. 2.Temperature. 3.Oxygen requirement. 4. Pressure. 5. Other environmental factors e.g (radiation, water acti...

Requirements for Growth 1.Enviromental conditions 2. Nutrients 3. Sources of energy. Important (environmental factors) that affect microbial growth: 1.pH. 2.Temperature. 3.Oxygen requirement. 4. Pressure. 5. Other environmental factors e.g (radiation, water activities, salt concentration etc). 1  The optimal pH for Growth First: Acidity or (pH) Organisms classified into Three categories according to the optimal pH for growth: 1. Acidophiles: organisms that grow best at low pH (Helicobacter pylori, Thiobacillus thiooxidans). 2. Alkaliphiles: organisms that grow best at high pH (Vibrio cholera). 3. Neutrophiles: organisms that grow best at Neutral pH. Most of pathogenic bacteria are neutrophiles. Each organism has a pH range and a pH optimum. ❖ Acidophiles – optimum in pH range 1-4. ❖ Neutrophiles - optimum in pH range 4- 8.5. ❖ Alkalophiles – optimum in pH range 8.5-11 1 2 3 4 5 6 7 8 9 10 11 Acidophiles Neutrophiles Alkalophiles 2  The optimal Temperature for Growth Second: Temperature Organisms exhibit distinct growth temperatures : 1.Minimum 2.Maximum 3.Optimum Minimum Temperature: Temperature below which growth ceases, or lowest temperature at which microbes will grow. Optimum Temperature: Temperature at which microbial growth rate is the fastest. Maximum Temperature: Temperature above which growth ceases, or highest temperature at which microbes will grow. As temperature influences enzymic reactions it has an important role in promoting or preventing microbial growth. 3  The optimal Temperature for Growth Second: Temperature: Four groups depending on their optimum growth temperature and the temperature range at which they will grow. 1.Hyper thermophiles: have optimum growth at 100 °C and a growth range of (75-120)°C. 2.Thermophiles: have optimum growth at 55 °C and a growth range of (45- 75) °C. 3.Mesophiles: have optimum growth at 35 °C and a growth range of (10 – 45) °C. 4.Psychrophiles: have optimum growth at 15 °C and a growth range of (-5 – 10)°C. -5 5 10 20 30 40 50 60 70 80 90 100 110 120 Psychrophiles Mesophiles Thermophiles Hyper thermophiles  The optimal Oxygen for Growth Third: Oxygen The atmosphere of earth contains about 20% (v/v) of oxygen. 1. Aerobes: the microorganisms capable of growing in the presence of atmospheric oxygen. 2. Obligate Anaerobes: the microorganisms capable of growing in the absence of atmospheric oxygen. They can be harmed by reactive oxygen molecules. 3. Obligate aerobes: the microorganisms that are completely dependent on atmospheric oxygen for growth. 4. Facultative anaerobes: the microorganisms that do not require oxygen for growth but grow well in its presence. 5. Aerotolerant anaerobes: use fermentation to produce ATP. They do not use oxygen, but they can protect themselves from reactive oxygen molecules. 6. Microaerophile: is a microorganism that requires environments containing lower levels of dioxygen than that are present in the atmosphere (i.e. < 21% O2; typically 2–10% O2) for optimal growth. 5  Nutrient Requirements for Growth 1. Macro elements (Macronutrients): Carbon (C), Oxygen (O), Hydrogen (H), Nitrogen (N), Phosphorus (P), and Sulfur (S) required in relatively large amounts. 2. Micronutrients (Trace elements): Potassium (K), Calcium (Ca), Magnesium (Mg) , Iron (Fe), Copper (Cu), Manganese (Mn), Zinc (Zn), Cobalt (Co), Molybdenum (Mo) and Nickel (Ni): required in trace amounts – often supplied in water or in media components. 3. Growth Factors: A. Amino acids: require for protein synthesis. B. Purines and pyrimidines: requires for nucleic acid synthesis. C. Vitamins: enzymatic cofactors. 6  THANK YOU 7