PPT-Lecture 6 Microbial Nutrition, Growth and Control (II)

Microbiology Outline Microbial growth in natural environments Measurement of microbial population size Principles of microbial control Physical chemical and biological control. in vitro. CLS 212: Medical Microbiology. . Microbicidal. or . Microbistatic. ?. . Microbicidal. . Microbicidal. . is . the process . or . an agent . that . kills. the microorganism. . A. Metabolism. 1. Anabolism. A) synthesis reactions (building up). 2. Catabolism. A) lysis reactions (breaking down). B. Enzymes. 1. proteins that facilitate chemical reactions. Microbial Metabolism. Batch culture and Kinetics of Microbial growth in batch culture. After inoculation the growth rate of the cells gradually increases.. The cells grow at a constant, maximum, rate and this period is known as the . Eric J. Raes, P.E. ., LSRP. Engineering and Land Planning . Dora Ogles, Brett Baldwin, Kate Clark & . Anita Biernacki. Microbial Insights Inc.. Kerry Sublette, Ph.D., Kate Key. University of Tulsa. THE ORIGIN AND EVOLUTION OF MICROBIAL LIFE. HOW DID LIFE ORIGINATE?. SPONTANEOUS GENERATION. LIFE ARISING FROM NON-LIVING MATTER. LONG BELIEVED AS THE ACCEPTED EXPLANATION OF ORIGINATION OF LIFE. EXPERIMENTS EVENTUALLY SHOWED IT TO BE IMPOSSIBLE. A. Microbial Reproduction. 1. binary (transverse) fission. A) parent cell enlarges and duplicates all its genetic material. B) DNA copies move to opposite ends of parent and attach to a section of the cell membrane as it begins to pinch together at the center. A. Structure of DNA. 1. discovered by James Watson and Francis Crick in 1953. 2. stores genetic information for the production of proteins. 3. composed of nucleotides. A) a nucleotide is composed of a nitrogenous base, sugar, and phosphate. In the Environment. Table 9.1 Terminology of Microbial Control. Figure 9.1 A plot of microbial death rate.. Basic Principles of Microbial Control. Action of Antimicrobial Agents. Alteration of cell walls and membranes. Dr.. P. . Fandamu. Chief Veterinary Research Officer. Presentation outline. Background. Objective of the programme. Materials and Method. Preliminary results. Conclusion. Background. An important aspect food safety (animal derived food) is the control of residues. Microbiology. Microbial Growth. Microbial requirements for growth:. 1. . Physical. A. . Temperature. Optimal growth temperature. Permissible range. human pathogens optimal = . 37°C. Microbial Growth. Musafer. PhD. Microbial growth defined as an increase in cellular constituents resulting an increase in a microorganism size, population number or both.. 1-Lag phase. When M.O are inoculated into fresh culture medium, will not reproduce immediately, therefore this period is called the lag phase. . 1. Temperature. 2. . PH. 3. . Water activity. 4. . Oxygen and redox. Temperature. Minimum Temperature. . The temperature below which no growth occurs.. At temperature below the minimum the properties of cell membranes change so that they can no longer transport materials into the cell. 9. Figure 9.1 A plot of microbial death rate.. Constant percentage. of the extant population. is killed each minute. Basic Principles of Microbial Control. Action of Antimicrobial Agents. Alteration of cell walls and membranes. . Kinetics. Growth Curve. Log CFU/ml. Optical Density. Lag. First Order Kinetics. Food microbiology is concerned with all phases. Of microbial growth (. lag,log. , stationary, death phase).Growth curves are normally plotted as the number of cells on a log scale or log10 cell number versus time..