Chapter 6B

Announcements, Thurs. Sept 23 : 

Announcements, Thurs. Sept 23 Today: continue Chapter 6 Microbial Nutrition Sunday: Review session 6:30, Room 206 Kivett, covering exams from Miles and Thomas Sept 12 (Sunday): Group Tutoring 6:30, Room 206 Kivett, Covering Chapter 3

Today’s Lecture : 

Today’s Lecture Review different types of media Isolation of pure cultures Colony growth and morphology Nutritional requirements/types of microbes

What is the purpose of the media, give an example of each : 

What is the purpose of the media, give an example of each 3 Table 6.4

Review: Small Group DiscussionComplete this table in 5 minutes, using Tuesday’s notes : 

Review: Small Group DiscussionComplete this table in 5 minutes, using Tuesday’s notes

Diagnostic or Research Microbiology: Working with a Sample : 

Diagnostic or Research Microbiology: Working with a Sample Collect a sample Isolate a single colony visible growth or cluster of microorganisms Obtain a pure culture population of cells arising from a single cell 5

What techniques have you learned to isolate pure cultures? : 

What techniques have you learned to isolate pure cultures?

What techniques have you learned to isolate pure cultures? : 

What techniques have you learned to isolate pure cultures? Techniques to obtain a pure culture Streak plate Dilutions and spread plates Dilutions and pour plates

Streak Plate Technique: resterilize inoculating loop after each step, pattern may vary : 

Streak Plate Technique: resterilize inoculating loop after each step, pattern may vary 8 Figure 6.10

Serial Dilutions: prior to spread or pour plates : 

Serial Dilutions: prior to spread or pour plates How/why did we do this differently in lab? 9 Figure 6.12

The Pour Plate : 

The Pour Plate sample is diluted several times diluted samples are mixed with liquid agar mixture of cells and agar are poured into sterile culture dishes 10

Spread Plate Technique : 

Spread Plate Technique 11 Dispense diluted cells onto medium in Petri dish Sterilize spreader in alcohol Flame sterilize and cool spreader Spread cells across surface Figure 6.11 (a)

Appearance of a Spread Plate How will a pour plate look different? : 

Appearance of a Spread Plate How will a pour plate look different? 12 Figure 6.11 (b)

How are the goals (intended results) of the Streak Plate, Spread Plate, and Pour Plate similar? : 

How are the goals (intended results) of the Streak Plate, Spread Plate, and Pour Plate similar?

The Streak Plate and Spread Plate : 

The Streak Plate and Spread Plate involve spreading a mixture of cells on an agar surface so that individual cells are well separated from each other For a Pour Plate the cells are mixed with agar, but results are similar 14

Colony Growth : 

Colony Growth most rapid at edge of colony oxygen and nutrients are more available at edge slowest at center of colony colony morphology is sometimes useful in identifying organisms 15

Slide 16: 

16 Bacterial Colony Morphology Figure 6.13 (a)

Bacterial Colony Morphology : 

Bacterial Colony Morphology 17 Figure 6.13 (b): common and (c) unusual colony morphology; (c) B. subtillis in poor nutrient conditions

The Common Microbe Nutrient Requirements : 

The Common Microbe Nutrient Requirements Macroelements (macronutrients) C, O, H, N, S, P, (structural) K, Ca, Mg, and Fe (cations) required in relatively large amounts Micronutrients (trace elements) Mn, Zn, Co, Mo, Ni, and Cu required in trace amounts often supplied in water or in media components 18

All Organisms Require C, Energy and an Electron Source : 

All Organisms Require C, Energy and an Electron Source Carbon: backbone of all organic components present in cell Energy: to do work Electrons: energy production and biosynthesis 19

Requirements for Carbon, Energy and Electrons : 

Requirements for Carbon, Energy and Electrons often satisfied together carbon source often provides, energy and electrons Heterotrophs (most common) C source =organic molecules Energy source usually as C source Autotrophs C source = CO2 Energy usually comes from a different source 20

Sources of Carbon, Energy and Electrons : 

Sources of Carbon, Energy and Electrons 21 Table 6.1

Nutritional Types of Microorganisms : 

Nutritional Types of Microorganisms 22 Table 6.2

Illustration of Microorganism Nutritional types: Chemoogranoheterotroph : 

Illustration of Microorganism Nutritional types: Chemoogranoheterotroph If your last name starts with a J, K, L, M, N, O, P: 15 people you are the most abundant type, Chemoorganoheterotroph You get all your carbon, energy and electrons from the same food source: organic compounds Includes most non-photosynthetic microbes

Illustration of Microorganism Nutritional types: Chemolithoheterotroph : 

Illustration of Microorganism Nutritional types: Chemolithoheterotroph If your last name starts with an A: 2 people you are the least abundant type, Chemolithoheterotroph You get all your carbon from organic compounds, but energy and electrons from inorganic sources Includes some sulfur-oxidizing bacteria

Illustration of Microorganism Nutritional types: Photoogranoheterotroph : 

Illustration of Microorganism Nutritional types: Photoogranoheterotroph If your last name starts with a B or C (4 people) you are not a very abundant type, Photooganoheterotroph You get all your carbon and electrons from organic compounds, but your energy from the sun Includes purple sulfur bacteria

Illustration of Microorganism Nutritional types: Photolithoautotroph : 

Illustration of Microorganism Nutritional types: Photolithoautotroph If your last name starts with a D, E or F (6 people) you are a fairly abundant type, Photolithoautotroph You get all your carbon from CO2 and electrons from inorganic compounds, but your energy from the sun Includes cyanobacteria

Illustration of Microorganism Nutritional types: Chemolithoautotroph : 

Illustration of Microorganism Nutritional types: Chemolithoautotroph If your last name starts with a S,T,U,V, W (7 people) you are a fairly abundant type, Chemolithoautotroph You get all your carbon from CO2 and electrons and energy from inorganic compounds Includes nitrifying bacteria; methanogens, sulfur-, hydrogen- and iron-oxidizing bacteria

Requirements for Other Macroelements : 

Requirements for Other Macroelements O: needed for organic compounds H: needed for organic compounds N: amino acids P: phospholipids and nucleic acids S: amino acids cysteine and methionine 28

Sources for Other Elements : 

Sources for Other Elements H, O, N organic molecules Nitrogen ammonia nitrate via assimilatory nitrate reduction nitrogen gas via nitrogen fixation Phosphorus inorganic phosphorus is usually directly incorporated into microbe cells Sulfur Sulfate is usually reduced by assimilatory sulfate reduction 29

Growth Factors : 

Growth Factors organic compounds essential cell components (or their precursors) that the cell cannot synthesize 30

Classes of Growth Factors : 

Classes of Growth Factors amino acids needed for protein synthesis purines and pyrimidines needed for nucleic acid synthesis vitamins function as enzyme cofactors 31

Slide 32: 

32 Table 6.3

Practical Applications of Growth Factors : 

Practical Applications of Growth Factors many microorganisms are used to manufacture vitamins needed for human use e.g., vitamin C produced by Gluconobacter

Uptake of Nutrients by the Cell : 

Uptake of Nutrients by the Cell Some nutrients enter by passive diffusion Most nutrients enter by: facilitated diffusion active transport group translocation 34

Passive Diffusion : 

Passive Diffusion molecules move from region of higher concentration to one of lower concentration, with rate dependent on size of the concentration gradient between the cell exterior and interior H2O, O2 and CO2 often move across membranes this way 35

Facilitated Diffusion : 

Facilitated Diffusion similar to passive diffusion movement of molecules is not energy dependent direction of movement is from high concentration to low concentration size of concentration gradient impacts rate of uptake 36

Facilitated Diffusion…cont’d : 

Facilitated Diffusion…cont’d differs from passive diffusion uses carrier molecules (permeases) that transport closely related solutes smaller concentration gradient is required for significant uptake of molecules effectively transports glycerol, sugars, and amino acids more prominent in eukaryotic cells than in prokaryotic cells 37

Slide 38: 

Copyright © McGraw-Hill companies, Inc. Permission required for reproduction or display. 38 Figure 6.3 rate of facilitated diffusion increases more rapidly and at a lower concentration diffusion rate in facilitated diffusion reaches a plateau when carrier becomes saturated

Slide 39: 

39 note conformational change of carrier Figure 6.4 Possible mechanism of action of permease used for facilitated diffusion; movement is down the gradient; note higher concentration of transported molecule on outside of cell

Active Transport : 

Active Transport energy-dependent process ATP or proton motive force used moves molecules against the concentration gradient concentrates molecules inside cell involves carrier proteins (permeases) carrier saturation effect is observed at high solute concentrations 40

ABC Transporters : 

ABC Transporters ATP-binding cassette transporters observed in Bacteria, Archaea, and eucaryotes 41 Figure 6.5

Slide 42: 

42 Figure 6.6

Group Translocation : 

Group Translocation chemically modifies molecule as it is brought into cell best known system is the phosphoenolpyruvate: sugar phosphotransferase system (PTS) transports a variety of sugars while phosphorylating them using phosphoenolpyruvate (PEP) as the phosphate donor 43

Group Translocation : 

Group Translocation energy-dependent process 44 Figure 6.7

Iron Uptake : 

Iron Uptake ferric iron is very insoluble so uptake is difficult microorganisms use siderophores to aid uptake siderophore complexes with ferric ion complex is then transported into cell 45 Figure 6.8