 The ultimate outcome of metabolic activity is reproduction  Growth refers to an increase in population which is a discrete colony  Nutrients are chemicals  And are used for energy

How do bacteria get energy?  Autotrophs-make their own food  Heterotrophs-get food from other organisms  Chemotrophs-food from chemicals  Phototrophs-food from light  The most common chemical element in cells (never a limiting nutrient) is Hydrogen

Bacterial Environments  Organotrophs-get e- from organic molecules  Lithotrophs-get e- from inorganic molecules  Obligate Aerobes-have to have oxygen  Obligate Anaerobes-oxygen is deadly  Facultative anaerobes-aerobes that can use anaerobic pathways ex: fermentation

Most microbes can be placed in 1 of 5 categories  Photolithoautotrophy  Photoorganoheterotrophy  Chemolithoautotrophy  Chemolithoheterotrophy  Chemoorganoheterotrophy

Bacterial Environments  Aerotolerant anaerobes- don’t normally use oxygen but can Ex: lactobacilli (cucumbers>pickles) (milk>cheese)  Microaerophiles-use small amounts of Oxygen Ex: heliobacter pylori- stomach ulcers  Capnophile – needing high concentrations of CO 2  Four toxic forms of oxygen 1.singlet O 2 - have lost e- during metabolism 2. superoxide radical (O 2 -) 3.peroxide anion (O 2 2- ) 4.Hydroxyl radical (OH. )

Nitrogen  What element is often a growth-limiting nutrient- Nitrogen, needed to make proteins  Few organisms can utilize nitrogen gas.  These four make up more than 95% of the dry weight of cells C,H,O,N

Definitions  Trace elements- required in small amounts  Growth factors- vitamins  Minimum growth temperature- lowest temp needed to survive  Maximum growth temperature-highest temp capable of surviving at  Optimum growth temperature-desired temp

Loving Environments  Psychrophiles- super cold Ex: ice, freezer, refrigerators, cold water, cause food spoilage  Mesophiles-best at C (human body 37C) Ex: human pathogens  Thermophiles- hot Ex: hot springs, don’t cause disease  Hyperthermophiles-Archae, extremely hot Ex: hydrothermal vents, volcanic necks  Neutrophiles- pH , human body  Acidophiles- acidic habitats

3 features of hyperthermophiles that enable them to remain intact 1. Cytoplasmic membranes don’t contain fatty acids so they don’t melt 2. DNA is unique heat-stable supercoils 3. Enzymes are heat stable

2 regions of body that acidity reduces microbes and what happens if malfunctions 1. Stomach Heliobacter pylori- neutralizes stomach acid and causes ulcers 2. Vagina -disruption causes yeast infection ex:antibiotics

How can microbes survive in dry conditions 1. Cell wall retain water for months 2. Spores & cysts can cease metabolic activity for years

 Hypertonic- greater amount of solutes  Hypotonic- lower amount of solutes  Plasmolysis- shriveling of cytoplasm  Obligate halophiles-high osmotic pressure- Great Salt Lake, Dead Sea  Barophiles- extreme pressure

Relationships  Antagonistic relationships- one organism harms or kills another  Synergistic relationships- each receive benefits  Symbiotic relationships- interdependent on each other rarely live outside the relationship

 Biofilms- complex community of bacteria Reading page 174  Quorum sensing-bacteria cell to cell communication  Ufr8VPA Ufr8VPA

Culturing Microorganisms  medical labs must grow pathogens  sample called inoculum is introduced into a collection of nutrients called medium  Culture- cultivating microorganisms

Inocula  1. Environmental- ponds, streams, soil, air  2. previous specimens kept in storage  3. Clinical- from patients (feces, saliva, blood) -very important that they are handled correctly, prevent contamination of sample and themselves -universal precautions (CDC)

Pure Cultures (axenic) - cultures composed of cells arising from a single progenitor (may be single cell or group of related cells) -termed colony-forming unit (CFU) -want it to be sterile- free of any microbial contamination How? 1. Streak Plates- inoculating loop spreads on Petri dishes -incubation- time for growth 2. Pour Plates- isolated colonies

Culture Media-pg 178 Nutrient Broth or Agar (solid)  1.most microbes can't digest agar  2. powdered agar dissolves in water at 100C  3. Agar solidifies at temps below 40C  4. Doesn't melt below 100C- can culture thermophiles  -make Petri plates or slant tubes

 1. Defined- exact chemical composition is known  2. Complex- nutrients released by the partial digestion of yeast, beef, -soy, or proteins, exact makeup unknown, blood often added -supports many organisms ex: soy agar, nutrient broth  3. Selective- substances that either favor growth of microbes wanted or inhibit growth of unwanted, differentiates between 2 species ex: large NaCl for halophiles

 4. Differential- either the presence of visible changes in media or differences in colony appearance ex: may make color if digest certain chemical  5. Anaerobic- protected from free oxygen -stab cultures- into media -reducing media- chemically combine with free oxygen and remove it from the medium  6. Transport- carry clinical specimens

Special Culture Techniques  1. Animals & Cells Mycobacterium leprae in armadillos, parasites in bird eggs  2. Low-Oxygen carbon dioxide incubators, candle jars, chemicals ex: capnophiles- grow best at high CO2  3. Enrichment- uses selective media, keep isolating wanted bacteria ex: oil -cold enrichment- some survive, some don't, ex: stool specimens

Preserving  1. Refrigeration  2. Deep-freezing  3. Lyophilization- removing water from frozen culture w/ vacuum, preserves for years

Reproduction  Binary Fission 1. Cell replicates DNA 2. Cell grows, DNA moves apart 3. Forms a cross wall 4. 2 new daughter cells

 Spores Reproductive cells that can make a clone of original organism  Budding Outgrowth of original cell receives genetic material and enlarges

Endospore formation 1. Replicates DNA 2. Cytoplasm splits 3. Membrane grows to make spore coat 4. Endospore is released

Exponential Growth Occurs under ideal conditions... Unlimited resources or no predation Bacteria reproduce on average every 20 minutes. Starting with minutes – 2 bacteria 40 minutes – 4 bacteria 1 hour – 8 bacteria 2 hours – 64 bacteria 4 hours – 512 bacteria 1 day – 4,720,000,000,000,000,000,000 bacteria! If this population growth went unchecked, bacteria would cover the planet!

Carrying capacity- largest number of individuals that a given environment can support

Phases of Growth  1. Lag Phase- adjusting to new environment, synthesize enzymes to use nutrients  2. Log Phase- rapid chromosome replication, growth, reproduction -population increases logarithmically  3. Stationary Phase- nutrients depleted, wastes increase,rate decreases # dying = #produced  4. Death Phase- nutrients not added, wastes not removed # dying › # produced

Measuring  1. Viable Plate Counts count the colonies on plates, multiply the number of bacteria Determines the number of living cells in a culture per ml of the original culture  2. Membrane Filtration large sample poured through a filter small enough to trap cells  3. Microscopic Counts sample on cell counter (gridded slide), # per square  4. Electronic Counters count cells as they interrupt an electrical current  5. Most probable number stats based on more bacteria in sample, more dilutions required to reduce # to 0

Indirect  1. Metabolic Activity  2. Dry Weight  3. Turbidity- Spectrophotometer