midterm - food microbiology

What are the five kingdoms of life?

Monera, Protista, Fungi, Plantae, Animalia

What is the main difference between prokaryotes and eukaryotes?

Prokaryotes lack a true nucleus and membrane-bound organelles eukaryotes have both.

What are examples of prokaryotic organisms?

Bacteria and Archaea

What are examples of eukaryotic organisms?

Fungi, algae, protozoa, plants, and animals

What are autotrophs?

Organisms that produce their own food using light or chemical energy

What are heterotrophs?

Organisms that obtain nutrients by consuming organic matter

What is binomial nomenclature?

System of naming organisms with genus and species (e.g., *Escherichia coli*)

What is the function of the bacterial cell wall?

Maintains shape and prevents osmotic lysis

What is peptidoglycan?

Polymer of N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM) cross-linked by peptides

What are Gram-positive bacteria?

Have thick peptidoglycan and teichoic acids

What are Gram-negative bacteria?

Have thin peptidoglycan and an outer membrane containing lipopolysaccharides (LPS)

What is the function of the cell membrane?

Selective barrier for transport, energy generation, and biosynthesis

What are plasmids?

Small circular DNA molecules carrying non-essential genes (e.g., antibiotic resistance)

What are ribosomes responsible for?

Protein synthesis

What are flagella?

Tail-like structures for motility

What are pili and fimbriae?

Pili transfer DNA (conjugation) fimbriae help in adhesion

What are endospores?

Highly resistant dormant structures formed by Bacillus and Clostridium

Why are spores important in food safety?

They survive heat, drying, and chemicals, causing spoilage or illness.

What are the four phases of bacterial growth?

Lag, Log (Exponential), Stationary, Death (Decline);

What is generation time?

Time required for one cell to divide into two;

What environmental factors affect microbial growth?

Temperature, pH, water activity, oxygen, and nutrients;

What are psychrophiles?

Grow best at −5°C to 20°C;

What are mesophiles?

Grow best at 10°C to 45°C;

What are thermophiles?

Grow best at 45°C to 70°C;

What are psychrotrophs?

Grow at refrigeration temps (0–7°C) but prefer 20–30°C;

What is the temperature danger zone?

5°C–60°C (41°F–140°F);

What is water activity (aw)?

Availability of water for microbial growth (scale 0–1);

At what aw do most bacteria grow?

Above 0.90;

What is the minimum pH for Clostridium botulinum growth?

pH 4.6;

What is oxidation–reduction potential (Eh)?

Tendency of a food to gain or lose electrons;

What are obligate aerobes?

Require oxygen for growth;

What are obligate anaerobes?

Cannot tolerate oxygen;

What are facultative anaerobes?

Can grow with or without oxygen;

What are microaerophiles?

Require low oxygen levels (2–10%);

What enzymes protect bacteria from oxygen toxicity?

Superoxide dismutase (SOD), catalase, peroxidase;

What is hurdle technology?

Combining preservation factors (pH, aw, temperature, atmosphere) to prevent growth;

What is fermentation?

Microbial conversion of sugars into acids, alcohols, or gases under anaerobic conditions

What are the purposes of fermentation?

Preservation, flavor, texture, and safety improvement

What are lactic acid bacteria (LAB)?

Gram-positive bacteria that ferment sugars to lactic acid

Examples of LAB?

Lactobacillus, Leuconostoc, Streptococcus, Pediococcus

What microorganisms are used in yogurt fermentation?

*Lactobacillus bulgaricus* and *Streptococcus thermophilus*

What relationship exists between yogurt cultures?

Symbiotic (mutualistic)

What microorganisms are used in cheese fermentation?

*Lactococcus lactis*, *Propionibacterium freudenreichii*, *Penicillium* species

What are fermented vegetables?

Sauerkraut, kimchi, pickles

What microorganisms ferment vegetables?

*Leuconostoc mesenteroides*, *Lactobacillus plantarum*

What are fermented soy products?

Miso, soy sauce, tempeh, natto

What mold is used in soy fermentation?

*Aspergillus oryzae*

What is alcoholic fermentation?

Conversion of sugars to ethanol and CO₂ by yeasts

What yeast is used in bread, beer, and wine fermentation?

*Saccharomyces cerevisiae*

What is spoilage?

Unwanted microbial growth that changes odor, texture, or taste of food

What are spoilage organisms in refrigerated foods?

*Pseudomonas*, *Brochothrix*, and yeasts

What are common preservation methods?

Heating, cooling, drying, irradiation, and use of preservatives

What is pasteurization?

Heat treatment below 100°C to destroy pathogens

What is sterilization?

Destruction of all microorganisms including spores

What is irradiation?

Use of ionizing radiation (gamma, electron beam, X-ray) to kill microbes

What is modified atmosphere packaging (MAP)?

Packaging with altered gas composition (low O₂, high CO₂/N₂)

What are chemical preservatives?

Benzoates, sorbates, propionates, nitrites, sulfites

What are biological preservatives?

Fermentation products and bacteriocins (e.g., nisin)

What is biopreservation?

Use of natural or controlled microbiota to extend shelf life and safety

What are foodborne infections?

Illness from ingestion of live pathogenic microbes that grow in the body

What are foodborne intoxications?

Illness from pre-formed toxins in food

What are toxin-mediated infections?

Pathogens grow in intestines and produce toxins there

What are examples of foodborne infections?

Salmonella, Listeria, E. coli O157:H7, Campylobacter

What are examples of foodborne intoxications?

Staphylococcus aureus, Clostridium botulinum, Bacillus cereus (emetic type)

What are characteristics of Salmonella?

Gram-negative rod, causes diarrhea and fever, from eggs, poultry, meat

What are characteristics of Listeria monocytogenes?

Gram-positive rod, psychrotrophic, grows in refrigerated foods, causes miscarriage and meningitis

What are characteristics of Staphylococcus aureus?

Gram-positive cocci producing heat-stable toxins

found in skin and nasal passages

What are characteristics of Clostridium botulinum?

Gram-positive spore-former, anaerobic, produces neurotoxin causing paralysis

What are characteristics of Bacillus cereus?

Gram-positive spore-former causing emetic or diarrheal food poisoning

What are characteristics of E. coli O157:H7?

Shiga-toxin producing, causes bloody diarrhea and hemolytic uremic syndrome (HUS)

What are characteristics of Campylobacter jejuni?

Microaerophilic curved rod causing gastroenteritis from poultry

What are characteristics of Vibrio species?

Halophilic bacteria from seafood, cause diarrhea and wound infections

What are foodborne viruses?

Norovirus, Hepatitis A – cause gastroenteritis

What are major foodborne parasites?

*Giardia lamblia*, *Toxoplasma gondii*, *Trichinella spiralis*

How can foodborne illness be prevented?

Proper cooking, refrigeration, and avoidance of cross-contamination

What is the danger zone for food safety?

Between 5 °C and 60 °C (41–140 °F)

What is sanitation?

Maintaining clean conditions to prevent contamination

What is cleaning?

Physical removal of dirt, food, and microbes from surfaces

What is sanitizing?

Reduction of microbes to safe levels after cleaning

What are examples of chemical sanitizers?

Chlorine, iodophors, quaternary ammonium compounds (QACs), peracetic acid, hydrogen peroxide

What are the steps in cleaning and sanitizing?

Pre-rinse → Detergent → Rinse → Sanitize → Dry

What is CIP (Clean-In-Place)?

Automated cleaning system for equipment without disassembly

What is SSOP?

Sanitation Standard Operating Procedures – written steps for cleaning and sanitizing

What is GMP?

Good Manufacturing Practice – general hygiene and facility requirements

What is HACCP?

Hazard Analysis and Critical Control Point – system to identify and control hazards in food production

What are the seven HACCP principles?

Hazard analysis, CCP identification, limits, monitoring, corrective action, verification, documentation

What are biological hazards?

Pathogens like bacteria, viruses, parasites

What are chemical hazards?

Toxins, cleaning residues, allergens

What are physical hazards?

Foreign objects like glass, metal, plastic

What is food safety culture?

Shared commitment by all employees to prioritize food safety

What are personal hygiene practices in food safety?

Handwashing, clean uniforms, hair restraints, no jewelry, illness reporting

What are indicator organisms in sanitation verification?

Coliforms, Enterobacteriaceae, total aerobic counts

What is ATP bioluminescence used for?

Rapid detection of organic residues and contamination on surfaces

Why is sanitation important?

Prevents contamination, maintains product quality, and ensures compliance.