Food Microbiology FINAL EXAM

covers molds and mycotoxins, viruses, spoilage of meat, poultry, and seafood, produce and grains, microbial control in food and fermentation yeast, fermentation lactic acid bacteria.

What is Spontaneous Generation?

Disproven idea that life arises from non-living matter

Germ theory states that

microbes cause diseases.

The scientific method includes what six steps?

  Observe -> Question -> hypothesis -> experiment -> results -> repeat

Taxonomy is

organizing, classifying, and naming living things

Reservoir in terms of infectious disease means refers to:

where a pathogen naturally lives

Source in terms of infectious disease refers to:

immediate origin of infection

Food infection occurs from:

consuming live microbes

Food intoxication occurs from:

consuming toxins produced by microbes

molds and mycotoxins are what type of pathogens?

fungal pathogens

Distribution: Found in soil, plants, and decaying matter

- Humans are relatively resistant

- Fungi are common plant pathogens.

-Fungal cells can switch from hyphal cells (long filamentous) to yeast cells (round ovoid)

thermal dimorphism refers to:

fungal pathogens ability to grow as yeast 37C (warm) or mold 30C (cold)

portals of entry for fungal pathogens

1. Skin (cutaneous Entry): through cuts, abrasions, or wounds

2. Respiratory tract (inhalation): inhalation of fungal spores from the air.

3. Gastrointestinal Tract (ingestion): Consumption of contaminated food or water.

4. Mucous Membrane (eye, mouth, nose): early through mucosal surfaces during exposure to contaminated environments.

5. Systemic (opportunistic Entry): occurs in immunocompromised individuals, leading to systemic fungal infections,

What are the five mycotoxins studies in this course?

• Aflatoxins: found in grains, peanuts, (produced by aspergillus), stable in heat, cause liver damage

• Ochratoxin: found in cereals, coffee (aspergillus and penicillium), targets kidney

• Patulin: found in apples, causes gastrointestinal issues

• Fumonisins: Found in corn, affects the nervous system

• Deoxynivalenol (DON): found in wheat, causes vomiting

What are mycotoxins?

toxic secondary metabolites produced by filamentous fungi or molds

HARMFUL TO ANIMALS AND HUMANS

1. Aflatoxins:

• found in grains, peanuts

• produced by aspergillus flavus

• stable in heat

• cause liver damage

• can screen for toxin, detect discolored kernels

• MYCOTOXINS/AFLATOXINS MAY BEPRODUCED IN STORED PRODUCTS IN HIGH HUMID ENVIRONMENTS

Aspergillosis is:

serious opportunistic threat; infection usually occurs in lungs

2. Ochratoxin

• found in raisins, dried fruit, nuts, wine, coffee, barley and wheat

• Produced by: aspergillus ochraceus WARM and penicillium verrucosum COOLER

• fairly heat stable

• targets kidney

  ROASTING DESTROYS TOXIN** CAN SURVIVE COOKING AND MASHING

3. Patulin

• found in apples

• produced by penicillum expansum

• causes gastrointestinal issues

4. Fumonisins

• Found in corn

  • Highest levels: corn products receiving only physical process

  • Lowest levels: highly processed corn products

  • Possibly low: fresh and canned sweet corn, popcorn

• affects the nervous system

• Equine Leukoencephalomalacia ELEM: fatal brain disease in horses

5. Deoxynivalenol (DON) AKA VOMITOXIN

• produced by Fusarium graminearum

• associated with cereal grains

• Illness: vomiting, gastroenteritis, suppression of immunity, kidney disease

Mycotoxin grow best under what conditions?

• Moisture Content: High water activity (aw > 0.7) promotes mold growth.

• Temperature: Warm temperatures (25-30°C) accelerate production.

• Oxygen Availability: Aerobic conditions encourage fungal growth.

• Storage Time: Longer storage increases the risk of mycotoxin buildup.

• Grain Damage: Damaged or improperly harvested grains are more susceptible

Mycotoxin control

• controlled primarily in field

• DIFFICULT to prevent mycotoxins during production and storage

• keep at cool temp; molds grow in 75-100F or 25-35C

• MYCOTOXINS/AFLATOXINS MAY BEPRODUCED IN STORED PRODUCTS IN HIGH HUMID ENVIRONMENTS

What size are viruses typically?

Size ranges from 20-300 nm however, MOST ARE <0.2 UM

REQUIRES ELECTRON MICROSCOPE

What is the structure of a virus?

• capsids: protein coat that

• SOME have envelope (lipid layer) that have spikes for attachment

  those without envelope are NAKED

  Both protects nucleic acid. attachment and penetration

What are the six virus multiplication steps?

1. Adsorption: virus binds to specific molecule on host
cell
2. Penetration: genome enters host cell
3. Uncoating: viral nucleic acid released from the capsid
4. Synthesis: viral components produced
5. Assembly: new viral particles constructed
6. Release: assembled viruses released by budding
(exocytosis) or cell lysis (bursting)

Host range in viruses refers to:

range of hosts it can infect

Tropism in viruses refers to:

host cell specificity

Viruses can penetrate in which of two ways?

1. Fusion: enveloped viruses; fuses directly with host membrane

   1. Endocytosis: enveloped or naked viruses; entire virus penetrates and is enclosed in a vesicle or vacuole

ALL food-associated viruses are what type ?

RNA viruses

Where does synthesis occur for DNA and RNA viruses?

• DNA occurs in the nucleus

• RNA occurs in the cytoplasm

Two types of releases of viruses include:

1. enveloped: through budding/exocytosis

   1. naked and complex: through lysis

TRUE OR FALSE: Naked viruses are more environmentally resistant, spread through harsh environments

TRUE

TRUE OR FALSE: Enveloped Viruses are more vulnerable to external conditions but better at evading the immune system

TRUE

What are some potential food sources containing viruses?

1. fresh produce

2. shellfish

3. ready-to-eat foods

4. ground beef/meat

What are the two types of viral infections learned in this course?

1. Lytic infections: virus is assembled and released with destruction of host cell. Many exit the body quickly

2. Persistent infection: virus does not destroy the cell LAST YEARS OR A LIFETIME; 2 types:

   1. Latent: virus is in dormant phase, can’t be detected

   2. Chronic: virus is detectable; symptoms are mild or absent

picornaviruses is a family that contains _______ both of which are _______ RNA viruses.

enteroviruses; non-enveloped

• Enteroviruses are a genus within this family, known for causing various human diseases, especially through fecal-oral transmission.

Poliovirus is a type of enterovirus what are its characterisitcs?

• naked

• resistant to acid, bile and detergent

• fecal-oral route

Poliovirus symptoms include what four types?

1. 90% Asymptomatic Infections

2. 5% Minor Symptoms: fever, headache, malaise, sore throat

3. 2% Nonparalytic polio: invades meninges/CNS, spasms and muscle pain

4. 3% Paralytic polio: invades spinal cord/motor cortex, limits nerve impulse conduction

SYMPTOMS DEPEND ON TYPE OF VIRUS, ID, AGE AND HEALTH

Prevention: Inactivated polio vaccine (IPV) Salk Vaccine

TRUE OR FALSE: Many viruses do NOT survive on foods or processing, but are relatively acid resistant

TRUE