Micro Chapter 26

In an ONPG/MUG test, both bottles exhibit a color. This result most accurately indicates which of the following?

E. coli is present

best method for preservation of cheese

High-heat treatment for a short period of time (pasteurization)

Which of the following microorganisms associated with food poisoning thrives in cold storage?

Listeria monocytogenes

Acidophiles

Organism that can be found growing at pH values below 4

Hyperthermophiles

Organisms that thrive in environments above 80 degrees C.

Thermophiles

Organisms that thrive in environments between 50 and 60 degrees C.

The presence of what of the following can substitute for nitrogen fertilizers in legume crops?

Rhizobium

What is a nitrogen fixing bacterium that forms associations with the roots of plants?

Rhizobium species

What best describes the primary role of microorganisms in food production?

Some microbes are responsible for food spoilage, whereas others are used to increase the flavoring of the food or to produce the food product itself.

Why are "fortified" foods more likely to spoil than are unfortified foods?

The added vitamins and minerals can promote microbial growth.

What best explains how the fermentation process in these two organisms, although similar in nature, produce two very different products? (wine and cheese)

The bacteria produce acids as a metabolic by-product hat give the cheese its characteristic flavor and aroma, whereas the yeasts produce alcohols that give the wine its characteristic flavor and aroma.

There are over 250 foodborne illness that have been characterized, _______ like Salmonella enterica, E. coli, and Taxoplasma gondii can all cause disease.

microorganisms

A new inductrial park in your community dumps its wastewater into a large aerated pond, to which nutrients are added. The water from this pond makes its way into a nearby marsh, which eventually drains into a slow moving stream. This is an example of...

natural bioremediation

Halophiles

organisms that thrive in salt concentrations of more than 25%

BOD is highest during which of the following phases of municipal wastewater treatment?

primary treatment removes only 25 to 35% of the BOD in the water

Food poisoning is usually accompanied by signs like diarrhea, fever, and fatigue. These are all _______ that either toxins or _______ may have been ingested.

symptoms; microorganisms

What is a specific example of bioremediation?

the degradation of crude oil spilled into the Gulf of Mexico

Which aquatic zone in a lake will have the highest nutrient levels and therefore the densest microbial populations?

the littoral zone

Food microbiology applies to

the use of microorganisms to make food and the control microbial activity to prevent foodborne illness.

What results when ethanol is allowed to oxidize to acetic acid following the fermentation of fruit, grain, or vegetables?

vinegar

What are situations that are examples o fa symbiotic relationship?

- Fungi growing on the root hairs of plants. - E, coli growing in the large intestine of humans. - Staphylococcus epidermidis growing on the skin. Normal flora

What are some situations that are examples of biogeochemical cycling?

- Plants and bacteria incorporate sulfates to become part of sulfar-containing amino acids for humans and their animals. - Some microbes decompose proteins from dead cells and waste products to their amino acid subunits, which are ultimately converted into ammonia. - Photoautotrophs incorporate carbon dioxide into organic matter using energy from sunlight

Examples of external factors of food microbiology

-Humidity of the storage environment. -Preservations, such as salt and sugar. -Temperature of food storage during processing. -Handling of food by manufacturers. -Presence of gases, such as CO2 during packaging. Deals with how the food is handled during processing.

Correct statements about fermentation

-Lactic acid is produced by certain microorganisms and aids in fermentation -Fermentation allows for sugars to be broken down or metabolized to make food such as bread, vegetables, and cheese. -Starter cultures are used to initiate the process of fermentation in modern food processing. -Some grains, fruits, and vegetables have their own microbes that facilitate fermentation.

Examples of internal factors of food microbiology

-Moisture content or water activity. -pH of the food. -Nutrient content (vitamins and minerals) -Protective structure of food, such as feathers, hide, and skin. -Presence of antimicrobial compounds. Factors dealing with the food itself.

Examples of commercial microbial products?

-baker's yeast, Rhizobium, and Bt-toxin -amylase, glucose isomerase, proteases, and rennin -antibiotics, vaccines, and steroids -glutamic acid, lysine, methionine, and phenylalanine

What is the acceptable level of colifrom bacteria per 100 ml of drinking water?

0 No colifrom should be in drinking water

The steps in cheese production...

1. an enzyme is added to the milk that causes clumping and the formation of curd. 2. Lactic-acid-producing bacteria provide the characteristics flavors and aromas of fermented dairy products. 3. The curd must be separated from the whey. 4. The solid portion of the cheese is out into pieces, drained completely, and compressed for the ripening process. 5. The cheese is allowed to age

What microorganism can be used as a biological insecticide?

Bacillus thuringiensis produces a toxin that kills many insect pests

True or False Cold is preferred for storing food because it retards microbial growth by slowing down metabolic processes.

True

best method for preservation of soup

Use of more than one food processing type (canning and use of preservatives)

best method for preservation of peas

Use of more than one food processing type (ex. canning and use of preservatives)

best method for preservation of bacon

Use of salt or sugar to draw water out of foods (preservatives)

Municipal water treated with chlorine compounds contains

a decreased microbial load

Agricultural runoff that deposits large amounts of phosphate into rivers and lakes results in which of the following?

autrophication

Which of the following statements about extremophiles is FALSE? a. Extremophines can be found in environments with high salinity, such as the Great Salt Lake, or with low temps, such as the Antarctic. b. Extremophiles can include members of the Bacteria or Archaea that live in extreme environments. c. Extremophiles are generally pathogenic to humans. d. Extremophiles use specialized enzymes in their metabolic pathways.

c. Extremophiles are generally pathogenic to humans.

Which of the following pairs is mismatched? a. whiskey; cereal grains b. vodka; potatoes c. white wine; must d. brandy; fruit juice e. beer; malt

c. white wine; must

What additive helps preserve food as well as enhancing flavor?

cinnamon, garlic, and salt

In a ________, a single food sources is responsible for many individuals getting sick.

common source epidemic

Potable water is water that

contains low amounts of microorganisms and is considered safe to drink

What microbial product is neede to produce "gasohol"?

ethanol

Alum is a chemical necessary for which of the following stages of drinking water treatment?

flocculation

A _______ is caused by the consumption of living ________.

food infection; microorganisms

When toxins are consumed instead of live microorganisms, this is considered _________.

food intoxication

During treatment of water to make it potable, about 90% of the microbes are removed

in the filtration step

Pickling is an effective means of food preservation involving...

increasing salt concentration or reducing pH or both.