Microbiology in society: Eat, Drink

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Microbiology in societyEat, Drink Sleep
Microbes
Kevin F. Kelly Department of Biology McMaster
University
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Microbes in SocietyThe Power of Numbers
Microbes are EVERYWHERE, you are probably
inhaling them right now.
5 broad classes
rod-shaped bacteria

• Bacteria (gt5000 sp.!)
• Fungi (moulds, yeast)
• Algae
• Viruses
• Protozoa (amoeba)

amoeba
budding yeast
viral particles
threadlike algae
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Many, Many disease-causing foodborne Microbes

• Most common, caused by bacteria
• Campylobacter fever, diarrhea, abdominal cramps.
  Lives in
• the gut of healthy birds (E.g. chicken).
• Salmonella more fever, diarrhea, abdominal
  cramps. If enters
• bloodstream, can be fatal. Present in or on
  birds, reptiles and
• mammals.
• E. coli O157H7 Bloody diarrhea, painful
  abdominal cramps.
• Present in cattle and other animals often
  ingested through cow feces.

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Many, Many Beneficial foodborne Microbes
Microbes are used in the generation of various
foods, including

• Hams (involved in the curing process)
• Beans, other veggies (N2 fixation)
• Pickles
• Chocolate
• Milk and Cheese

and on and on
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Making
Beer

Yogurt
using Yeast
using Bacteria
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Beer in Canadapart of our identity?
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Beer in Canadapart of our identity?

• First introduced to Canadians by European
  settlers in the
• 17th century
• In the absence of refrigeration, Canada had an
  ideal climate
• for beer-making
• First brewery was in Québec city in 1668
• Prohibition in Canada was largely over by the mid
  1920s
• (apart from the P.E.I, where it ran from 1901 to
  1948)
• Largest Canadian breweries are Labatt Molson

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Making Beer
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The Making of Beer
Four, and only four, ingredients required Hops,
water, yeast, and barley.
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Step 1 Sprouting the Barley

• Soak barley in water for several days
• drain, hold barley at 60 degrees F for
• 5 days
• husks will open and barley will sprout
• now called green malt
• now ready for the mash

Barley
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Step 1.1 grinding the BarleyThe Mash

• Converts the barley starches into
• fermentable sugars
• malted barley is crushed through
• rollers
• heated water is sprayed onto the barley
• grains as they enter the mash
• wet grains stay in the mash for 1 hour
• at 150 degrees F.
• Optimal temperatures and mashing releases
• enzymes capable of converting starches to
• sugars

The Mash
at-home brewing
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Step 2 Time for the Wort (wert)

• Liquid drained off of mash is added to a
• huge brew kettle
• brought to a vigorous boil for 90 mins.

Brew Kettle
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Step 2.1 Hop to it

• At start of boil, hops are added
• member of the hemp family
• contain acid, give beer its
• bitter flavour
• inhibits growth of unwanted
• bacteria

Hops
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Step 3 Separate the Solids

• Wort is pumped from the kettle, then forced back
  into kettle through a jet nozzle
• The unique flow of liquid initiates a whirlpool
  all of the hops and other solids move to the
  centre of the kettle
• The liquids (wort) are drained out, leaving the
  solids (in a cone shape) behind

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Step 4 The Beauty of BiochemistryYeast
Fermentation

• Cooled wort is transferred to fermentation vessel
  already containing the yeast
• Type of yeast ultimately determines the type of
  beer

Lager kept at 48 degrees F for 6 weeks! Ale
kept at 68 degrees F for two weeks
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Step 4 Using Yeast for Alcohol Fermentation
released to atmosphere
The source of alcohol in beer!
Alcohol Dehydrogenase
C6H12O6?2(CH3CH2OH) 2(CO2)
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Yeast Fermentation in a brewery
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Step 5 Cooling to bottling/Kegging

• Most important thing is to maintain sterility
  limit exposure to
• yeasts, microbes in the environment prior to
  packaging
• empty bottles are sterilized with a chlorine
  solution and rinsed
• beer added to CO2-pressurized bottles
• bottles are capped

rinsing
WHAT IS THE MOST DIFFICULT PART OF ALL THIS?
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Getting the label to stick
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Processing of Yeast amino acids yields various
compounds affecting the scent and taste of beer
(aromas)
(aromas)
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A Skunk walked into a bar
Over 1,000 chemical compounds in beer Some of
these compounds are generated when beer becomes
exposed to light creating skunky
aromas 3-methylbut-2-ene-1-thiol is one
culprit Studying the chemical constituents of
beer is "like looking at the night sky," he
says. "The closer you look, the more stars you
can see."
Morten C. Meilgaard
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Brewing at home Give it a try!
Affordable, enjoyable, but not
reproducible! Sterility is the main concern here
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Once you have the beer, you need something to eat.
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Making yogurtDoing It at Home
Bring the milk to 85C (185F) over a stove and
keep it there for two minutes, to kill any
undesirable microbes. Pour the re-pasteurised
milk into a tall, sterile container and allow to
cool to 43C (110F) Mix in 120ml of warmed
yogurt and cover tightly. After about six hours
of incubation at precisely 43C (110F) the
entire mixture will have become a very plain but
edible yogurt with a loose consistency.

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Making yogurtthe co-operation of two bacteria
Streptococcus thermophilus and Lactobacillus
bulgaricus
S. thermophilus
L. bulgaricus
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Bacterial Lactic Acid Fermentation
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Streptococcus thermophilus produces lactic
acid?lowers the pH, changing the form of the
milk proteins and causing the mixture to thicken
Lactobacillus bulgaricus produce acetaldehyde,
acetic acid, volatile fatty acids, ethanol,
carbon dioxide and various other products which
influence flavor and aroma
If Streptococci outgrow the Lactobacilli, the
result is a harsh, sour yogurt due to
overproduction of lactic acid relative to flavor
components.
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Neat Yogurt Facts -a good source of calcium,
riboflavin and protein. -has a fine curd which
makes it more easily digestible than sweet milk.
-lactose is converted to lactic acid this
makes digestion easier on lactose- intolerant
people -lactic acid bacteria fight pathogenic
organisms Salmonella typhi die, E. coli are
unable to develop, and S. paratyphi and
Corynebacteriae diphtheriae lose their
pathogenic properties. -fermented milk cultures
have been reported to help treat peptic ulcer,
diarrhea, and dysentery. -Freshly prepared
yogurt contains 10,000,000,000 (109) bacteria per
gram!!
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Other FoodborneMicrobes

Campylobacter jejuni is one of the major causes
of diarrhea in humans
Streptococcus lactis and other lactic acid
bacteria are used to make cheese. They ripen the
cheese and provide characteristic flavour.
Streptococcus thermophilus is one of the major
yogurt-forming bacteria. The other is
Lactobacillus bulgaricus
Salmonella infection of meat is one of the major
causes of food poisoning.
Bifidobacteria are beneficial to the
gastro-intestinal tract. Also called probiotic
bacteria.
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ConclusionsThe good bad of microbes

• We exploit microbes for the purpose of bettering
  our food industry,
• creating medicines etc
• Also, at times, microbes exploit us for bettering
  their living
• environments
• Important to understand which microbes are
  beneficial, and which
• are undesirable

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Glycolysis
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What is Cenosillicaphobia the fear of?
Answer  Fear of an empty glass
What was the length of Prohibition? 
Answer  Prohibition lasted 13 years, 10 months,
19 days, 17 hours, 32 1/2 minutes
What is the best selling brand in the Western
Hemisphere outside of the United States? What
country is it brewed in?
Answer Brahma Beer. It is brewed in Sao Paulo,
Brazil.
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While in some countries the penalty for driving
while intoxicated can be death (yes, death), in
Uruguay intoxication is a legal excuse for having
an accident while driving. "Please believe me
officer, I really was drunk. There are more
breweries in the US than any other country in the
world. There is more than 200 styles of beer
produced throughout the world today. Anheuser-Bus
ch consumes about 15 of the entire U.S. rice
crop for brewing beer. The average American
annually consumes 23.1 gallons of beer.