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ADNAN MENDERES UNIVERSITY
Department of Food Engineering
FE 206 Food Microbiology I
Lecture #1
Cisem Bulut Albayrak, Ph.D.
FE 206 Food Microbiology I
• Section I
• Section II
• Tuesdays
• Thursdays
• Lecture 08:30-10:15
• Lecture 08:30-10:15
• Lab 10:30-12:15
• Lab 10:30-12:15
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Textbook
• Doyle and Buchanan, Food Microbiology:
Fundamentals and Frontiers, 2013, 4th ed.
ASM Press, ISBN: 978-1555816261
• Available in University Library as e-book
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Grading
Grades will be determined as follows:
•Laboratory grade: 20%
•Quizzes: 10 %
•Homeworks: 10%
•Midterm: 20%
•Participation: 10%
•Final exam: 30%
Total: 100%
Grade
90-100
85-90
75-84
70-74
60-69
55-59
50-54
0-49
Letter
AA
BA
BB
CB
CC
DC
DD
FF
Laboratory will be graded by:
Laboratory reports: 70 %
Lab Exam: 30 %
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Attendance
• Student attendance is mandatory and
students must attend all sessions
• Small tolerance may be shown
• At least 70 % attendance in lectures and
80% in labs are expected
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Binomial nomenclature
• Saccharomyces cerevisiae
• Escherichia coli
• Homo sapiens
• S. cerevisiae
• E. coli
• H. sapiens
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Types of Microorganisms in Food
• Important Microorganisms in Foods
– Fungi
– Bacteria
– Parasites
– Viruses
– Algae
– Prions
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Fungus - Fungi
• Chytridiomycetes-Members are found in soil,
fresh water, and saline estuaries.
• Zygomycetes- fungi that reproduce sexually by
forming zygospores
• Ascomycetes
• Basidiomycetes
• Deuteromycetes (Fungi Imperfecti): No known
sexual growth
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Fungus physiology and structure
• Most fungi are multicellular, forming a network of hyphae
(sing. hypha)
• Hyphae that extend above the surface can produce asexual
spores called conidia (sing. conidium)
– Conidia are often pigmented and resistant to drying
• Hyphae form compact tufts called mycelia
• Most fungal cell walls are made of chitin
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Conidium
(spore)
Conidia
(spores)
Germination
Conidiophore
Aerial hyphae
Subsurface
Hypha
Hyphae
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Fungal Diseases
• Fungi can cause disease (mycosis) in plants
and animals
– Mycoses in humans range in severity from
"athlete's foot"
to
histoplasmosis
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Fungal Reproduction and Phylogeny
• Asexual reproduction in three forms
– Growth and spread of hyphal filaments
– Asexual production of spores
– Simple cell division (budding yeasts)
• Some fungi produce spores as a result of sexual
reproduction
– Sexual spores can originate from the fusion of two haploid cells to form a
diploid cell (ascospores, basidiospores, zygospores)
– Spores are resistant to drying, heating, freezing, and chemicals
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Ascomycetes
• Key genera: Saccharomyces, Aspergillus, Penicillium,
Microsporum, Morchella
• Around 50,000 species of molds, yeasts, an plant parasites
• Also known as (aka) Sac fungi
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Budding Yeast
Saccharomyces cerevisiae budding
Time-lapse movie
https://www.youtube.com/watch?v=FcV1ydls9hg
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Basidiomycetes
• Key genera: Agaricus, Amanita
• Over 30,000 described species
• Many are recognizable as mushrooms and
toadstools
– Also yeasts and pathogens of plants and humans
• Undergo both vegetative and sexual
reproduction
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Gills
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Zygomycetes
• Key genera: Rhizopus, Mucor, Encephalitozoon
– Known primarily for food spoilage
– Commonly found in soil and decaying plant material
– All are coenocytic (multi nuclei)
– Sexual spores are called zygospores
• Rhizopus stolonifer (black bread mold) is representative
• Microsporidia: unicellular, obligate parasites
– Often infect immune-compromised individuals
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Rhizopus stolonifer
Microsporidia
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Important Bacterial Groups
• Lactic acid bacteria (LAB)
– Gram (+), non-sporulating rods/cocci, produce
lactic acid
– Lactobacillus, Lactococcus
• Acetic acid bacteria
– Gram (-), obligate aerobic, chemoorganotrophic
– Acetobacter
• Butyric acid bacteria
– Spore forming anaerobes
– Clostridium butyricum
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Important Bacterial Groups
•
•
•
•
•
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Proteolytic bacteria
Lipolytic bacteria
Thermophilic bacteria
Psychrophilic bacteria
Halophilic bacteria
Sporeformers
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Sources of Microorganisms in Foods
• Water
– Water used in production
– Washwater
• Plants and Plant Products
– Human pathogens from contaminated soil, water
– Mold from soil
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Sources of Microorganisms in Foods
• Food Utensils and Packaging Materials
– Open served foods
• Intestinal Tract of the Human and Animals
– Pathogens
– E. coli, Salmonella
– Candida
– Enteroviruses
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Sources of Microorganisms in Foods
• Food Handlers
– Personal hygiene
• Food Ingredients
– Chemicals
– Spores
• Sewage!!!
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Sources of Microorganisms in Foods
• Animals, Birds, and Fish
– Natural flora of animals
• Air, Dust, and Soil
– Bacterial spores
– Fungus spores
• Miscellaneous Sources
• Animal feeds, Rodents, Insects
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Primary Sources of Microorganisms
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Pathogenic Escherichia coli – intestine
Salmonella – intestine, poultry, eggs
Campylobacter jejuni – poultry
Staphylococcus aureus – nasal cavity
Streptococcus pyogenes – nasal cavity
Listeria monocytogenes – cheese, milk, fish
Bacillus cereus – starchy foods, rice, pasta
Brucella – raw milk and products
Clostridium perfringens – soil
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Resources
• Brock Biology of Microorganisms, Pearson
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