Microbial Nutrition and Growth Study Chapter 6 PDF
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Greenville Technical College
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This document discusses microbial nutrition and growth, including essential nutrients, environmental factors affecting microbes, and various types of microbial interactions. It covers aspects like temperature, gases, and pH. The document also includes the stages in the bacterial growth curve.
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Chapter 6: Microbial Nutrition and Growth Microbial Nutrition Essential nutrient: **any substance that must be provided to organism** - a. b. c. d. e. Macronutrients: quantity nutrient is requiered Micronutrients: also known as trace element - Environmental Factors that Influence...
Chapter 6: Microbial Nutrition and Growth Microbial Nutrition Essential nutrient: **any substance that must be provided to organism** - a. b. c. d. e. Macronutrients: quantity nutrient is requiered Micronutrients: also known as trace element - Environmental Factors that Influence Microbes Temperature Cardinal temperatures: the range of temperatures for the growth of a given microbial species - - - Microbes can be divided into 5 categories based on their temperature range. How each is important to human health.) (Fig 6.4) - - - - - - 1. 2. 3. 4. 1. 2. 3. 4. 5. 6. Gases The atmospheric gases that most influence microbial growth are O~2~ and CO~2~ - - As oxygen enters cellular reactions, it is transformed into several toxic products: 1. 2. Most cells have developed enzymes that scavenge and neutralize reactive oxygen byproducts. Many cells have a two-step process requires two enzymes: - - Organisms are divided into groups based on their ability to grow in the presence of oxygen - - - - - - - - - pH The majority of organisms are neutrophils 7 Many molds and yeasts tolerate acid Acidophiles: look like archea pH1,2 C: \>7 Osmotic Pressure Most microbes exist under isotonic or slightly hypotonic conditions Osmophiles: microbes exist under hypotonic or isotonic conditions They live high solute concentration. Halophiles: prefer high concentration of high concentration of salt Obligate halophiles: require at least 9% NaCl. Optimum 25% NaCl - - Other Organisms In all but the rarest instances, microbes live in shared habitats Interactions can be beneficial, harmful, or have no effect. Interactions can be obligatory or nonobligatory to the members. Often involve nutritional interactions Strong Partnerships: Symbioses Symbiosis: "living together" - Three main types of symbiosis occur 1. 2. 3. Associations But Not Partnerships Antagonism*:* - - - - A relationship where microorganisms compete for survival in a common environment is known as antagonism Synergism: think of colonies like gum disease - - Biofilms: The Epitome of Synergy - a. b. c. - - - - - - - - - +-----------------+-----------------+-----------------+-----------------+ | Lag | Log | Stationary | Death | +=================+=================+=================+=================+ | - | - | - - - | - | +-----------------+-----------------+-----------------+-----------------+ | - | - | - | - | +-----------------+-----------------+-----------------+-----------------+ | | - | | | +-----------------+-----------------+-----------------+-----------------+ | | | | | +-----------------+-----------------+-----------------+-----------------+ | | | | | +-----------------+-----------------+-----------------+-----------------+ The Study of Bacterial Growth Binary fission: Fig 6.8 Stages in the Normal Growth Curve (Fig 6.11) Lag phase - - Logarithmic (or log, exponential) phase: - - - Stationary growth phase: - - - Death phase: - - The Practical Importance of the Growth Curve - - - - -  
