MICROBIAL GROWTH DR CHANDER ARORA WHAT IS MICROBIAL

MICROBIAL GROWTH DR. CHANDER ARORA

WHAT IS MICROBIAL GROWTH Microbial growth is the increase in number of cells, not cell size Dr. Arora - Microbial Growth

THE REQUIREMENTS FOR GROWTH: TEMP REQUIREMENTS §Temperature §Minimum growth temperature §Optimum growth temperature §Maximum growth temperature Dr. Arora - Microbial Growth

POPULATION GROWTH Dr. Arora - Microbial Growth

PSYCHROTROPHS Grow between 0°C and 20 -30°C Cause food spoilage Dr. Arora - Microbial Growth

THE REQUIREMENTS FOR GROWTH: PHYSICAL REQUIREMENTS p. H § Most bacteria grow between p. H 6. 5 and 7. 5 § Molds and yeasts grow between p. H 5 and 6 § Acidophiles grow in acidic environments Dr. Arora - Microbial Growth

THE REQUIREMENTS FOR GROWTH Dr. Arora - Microbial Growth

THE REQUIREMENTS FOR GROWTH: TRACE ELEMENTS §Trace elements §Inorganic elements required in small amounts §Usually as enzyme cofactors Dr. Arora - Microbial Growth

CHEMICAL REQUIREMENTS §Oxygen (O 2): Aerobes, Anaerobes: Obligate, Facultative §Obligate anaerobes grow in completer lack of free oxygen. DRAWING DEPLICTS 1. Obligate aerobic 2. Obligate anaerobic 3. Facultative Anaerobic 4. Microaerophiles 5. Aerotolerant anaerobes Dr. Arora - Microbial Growth

GROWTH: CHEMICAL FACTORS §Organic growth factors §Organic compounds obtained from the environment §Vitamins, amino acids, purines, and pyrimidines Dr. Arora - Microbial Growth

CULTURE MEDIA §Culture medium: Nutrients prepared for microbial growth §Sterile: No living microbes §Inoculum: Introduction of microbes into medium §Culture: Microbes growing in/on culture medium Dr. Arora - Microbial Growth

ANAEROBIC CULTURE METHODS §Reducing media §Contain chemicals (thioglycollate or oxyrase) that combine O 2 §Heated to drive off O 2 Dr. Arora - Microbial Growth

ANAEROBIC JAR Dr. Arora - Microbial Growth

ANAEROBIC CULTURE METHODS CONT. Dr. Arora - Microbial Growth

CAPNOPHILES REQUIRE HIGH CO 2 Dr. Arora - Microbial Growth

SELECTIVE MEDIA Supress unwanted microbes and encourage desired microbes Dr. Arora - Microbial Growth

STREAK PLATE Dr. Arora - Microbial Growth

BINARY FISSON Dr. Arora - Microbial Growth

GENERATIONS Generation Number of cells Amount Produced 0 1 5 32 10 1, 024 15 32, 768 16 65, 536 17 131, 072 18 262, 144 19 524, 288 20 1, 048, 576 Dr. Arora - Microbial Growth

COLONY GROWTH CURVE Dr. Arora - Microbial Growth

BACTERIAL POPULATION GROWTH Dr. Arora - Microbial Growth

COPYRIGHT – SLIDE 23 Dr. Arora - Microbial Growth

PLATE COUNT AFTER INTUBATION Dr. Arora - Microbial Growth

DIRECT MEASUREMENT OF MICROBIAL GROWTH Dr. Arora - Microbial Growth

MEASURING MICROBIAL GROWTH Direct methods §Plate counts §Filtration §MPN §Direct microscopic count §Dry weight Dr. Arora - Microbial Growth

MEASURING MICROBIAL GROWTH CONT. Direct methods Indirect methods §Plate counts §Turbidity §Filtration §Metabolic activity §MPN §Dry weight §Direct microscopic count §Dry weight Dr. Arora - Microbial Growth