ADNAN MENDERES UNIVERSITY Department of Food Engineering FE

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 II • Tuesdays • Thursdays • Lecture 08: 30 -10: 15 • Lab 10: 30 -12: 15 FE 206 Food Microbiology I 2

Textbook • Doyle and Buchanan, Food Microbiology: Fundamentals and Frontiers, 2013, 4 th ed. ASM Press, ISBN: 978 -1555816261 • Available in University Library as e-book FE 206 Food Microbiology I 3

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 % FE 206 Food Microbiology I 4

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 FE 206 Food Microbiology I 5

Binomial nomenclature • Saccharomyces cerevisiae • Escherichia coli • Homo sapiens • S. cerevisiae • E. coli • H. sapiens FE 206 Food Microbiology I 6

Types of Microorganisms in Food • Important Microorganisms in Foods – Fungi – Bacteria – Parasites – Viruses – Algae – Prions FE 206 Food Microbiology I 7

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 FE 206 Food Microbiology I 8

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 FE 206 Food Microbiology I 9

Conidium (spore) Conidia (spores) Germination Conidiophore Aerial hyphae Subsurface Hyphae FE 206 Food Microbiology I 10

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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 FE 206 Food Microbiology I 12

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 FE 206 Food Microbiology I 13

Ascomycetes • Key genera: Saccharomyces, Aspergillus, Penicillium, Microsporum, Morchella • Around 50, 000 species of molds, yeasts, an plant parasites • Also known as (aka) Sac fungi FE 206 Food Microbiology I 14

Budding Yeast Saccharomyces cerevisiae budding Time-lapse movie https: //www. youtube. com/watch? v=Fc. V 1 ydls 9 hg FE 206 Food Microbiology I 15

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 FE 206 Food Microbiology I 16

Gills FE 206 Food Microbiology I 17

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 FE 206 Food Microbiology I 18

Rhizopus stolonifer Microsporidia FE 206 Food Microbiology I 19

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 FE 206 Food Microbiology I 20

Important Bacterial Groups • • • Proteolytic bacteria Lipolytic bacteria Thermophilic bacteria Psychrophilic bacteria Halophilic bacteria Sporeformers FE 206 Food Microbiology I 21

Sources of Microorganisms in Foods • Water – Water used in production – Washwater • Plants and Plant Products – Human pathogens from contaminated soil, water – Mold from soil FE 206 Food Microbiology I 22

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 FE 206 Food Microbiology I 23

Sources of Microorganisms in Foods • Food Handlers – Personal hygiene • Food Ingredients – Chemicals – Spores • Sewage!!! FE 206 Food Microbiology I 24

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 FE 206 Food Microbiology I 25

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 FE 206 Food Microbiology I 26

Resources • Brock Biology of Microorganisms, Pearson FE 206 Food Microbiology I 27