FE 206 Food Microbiology I Lecture #1 ( Dr. Çisem Bulut ALBAYRAK )


    Department of Food Engineering

  • FE 206 Food Microbiology I

  • Lecture #1

  • Cisem Bulut Albayrak, Ph.D.

  • FE 206 Food Microbiology I

  • Section I

  • Tuesdays

  • Lecture 08:30-10:15

  • Lab 10:30-12:15

  • Textbook

  • Doyle and Buchanan, Food Microbiology: Fundamentals and Frontiers, 2013, 4th ed. ASM Press, ISBN: 978-1555816261

  • Available in University Library as e-book

  • Grading

  • 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

  • Binomial nomenclature

  • Saccharomyces cerevisiae

  • Escherichia coli

  • Homo sapiens

  • Types of Microorganisms in Food

  • Important Microorganisms in Foods







  • 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

  • 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

  • Fungal Diseases

  • Fungi can cause disease (mycosis) in plants and animals

–Mycoses in humans range in severity from “athlete’s foot”     to       histoplasmosis

  • 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

  • Ascomycetes

  • Key genera: Saccharomyces, Aspergillus, Penicillium, Microsporum, Morchella

  • Around 50,000 species of molds, yeasts, an plant parasites

  • Also known as (aka) Sac fungi

  • Budding Yeast

  • 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

  • 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

  • Important Bacterial Groups

  • Lactic acid bacteria (LAB)

–Gram (+), non-sporulating rods/cocci, produce lactic acid

Lactobacillus, Lactococcus

  • Acetic acid bacteria

–Gram (-), obligate aerobic, chemoorganotrophic


  • Butyric acid bacteria

–Spore forming anaerobes

Clostridium butyricum

  • Important Bacterial Groups

  • Proteolytic bacteria

  • Lipolytic bacteria

  • Thermophilic bacteria

  • Psychrophilic bacteria

  • Halophilic bacteria

  • Sporeformers

  • Sources of Microorganisms in Foods

  • Water

–Water used in production


  • Plants and Plant Products

–Human pathogens from contaminated soil, water

–Mold from soil

  • Sources of Microorganisms in Foods

  • Food Utensils and Packaging Materials

–Open served foods

  • Intestinal Tract of the Human and Animals


E. coli, Salmonella



  • Sources of Microorganisms in Foods

  • Food Handlers

–Personal hygiene

  • Food Ingredients



  • Sewage!!!

  • 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

  • Primary Sources of Microorganisms

  • 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

  • Resources

  • Brock Biology of Microorganisms, Pearson

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