Microbiology, Ch 30, Nester's 9th

The malolactic fermentation of wine is performed by Aspergillus species. Saccharomyces species. Leuconostoc species. Lactobacillus species. acetic acid bacteria.

Leuconostoc species.

The final characteristics of beer such as color, flavor, and foam primarily depend on the alcohol. whey. adjuncts. wort. roasted malt.

roasted malt

On which of the following foods can Staphylococcus aureus multiply with little competition? Bread and jam Milk Bread Jam Salty ham

salty ham Staphylococcus aureus is salt-tolerant p.801 - S.aureus can grow at a LOWER WATER ACTIVITY THEN MORE SPOILAGE BACTERIA. - S. aureus can grow at a water activity of 0.86. Ham is a common vehicle for S. aureus food poisoning.

Foods that have been unacceptably changed due to uncontrolled bacterial growth are called spoiled. refrigerated. preserved. fermented. oxidized.

spoiled

Which of the following foods has the greatest amount of available water? Steak Cake Jam Syrup Bread

steak p.801 - fresh meats and milk have plenty of water to support the growth of many microbes. Bread, nuts and dried foods are relatively dry. Jams, jellies and some other sugar-rich foods are seemingly moist but most of that water is chemically interacting with the sugar, making it unavailable for use by microbes. Similar for salty foods.

The amount of moisture available in foods is designated by the term fluid availability. water activity. dampness quotient. aqueous usability

water activity a subscript-w. For pure water it = 1.0

The most promising sources of single cell protein are bacteria. viruses. worms. yeasts.

yeasts Saw this, don't think it applies to my chapter but hey.

Single cell protein -refers to the use of single-celled organisms as a protein source. - refers to a single-celled protein produced by several different organisms. - is an enzyme. - causes food intoxication.

-refers to the use of single-celled organisms as a protein source.

For growth, most bacteria require water activity levels above 1.00. 0.80. 0.70. 0.90

0.90 - which explains why fresh, moist foods spoil more quickly than dried, sugary or salted foods. Fungi can grow at a water activity as low as 0.80, so forgotten bread, cheese, jam and dried foods often become moldy.

Pure water has a water activity value of ________. 0.90 1.00 0.70 0.80 100

1.00 Most fresh foods have a value above 0.98. Ham has a value of 0.91. Jam has a value of 0.85. some cakes have a value of 0.75

Most large cities have required the pasteurization of milk and milk products since ________. 1800 1850 1920 1985 1900

1900

Most human pathogens grow best at temperatures near 37ºC. 97ºF. 25ºC. 45ºC. 20ºC.

37ºC.

Most bacteria are inhibited by a pH of 6.5. 7.0. 6.0. 7.2. 4.5.

4.5

Naturally occurring microbial chemicals may include benzoic acid. lysozyme. allicin. peroxidase. All of the choices are correct

All of the choices are correct benzoic acid - in cranberries lysozyme - in egg whites allicin - in garlic peroxidase -Peroxidase is an enzyme found in a wide variety of organisms, from plants to humans to bacteria. Its function is to break down hydrogen peroxide (H2O2), which is one of the toxins produced as a byproduct of using oxygen for respiration. (The fact that it's toxic is what makes hydrogen peroxide useful in first aid kits.

Limiting the activity of microbes in food can be accomplished by cold storage. lowering the pH. growth inhibiting substances. pasteurization. All of the choices are correct.

All of the choices are correct.

The growth of microorganisms in a food product is influenced by the availability of acidity. moisture. temperature. nutrients. All of the choices are correct.

All of the choices are correct.

Which of the following produce lactic acid? Lactobacillus Leuconostoc Streptococcus Lactococcus All of the choices are correct.

All of the choices are correct. Know these so you will remember which do and will be better able to choice "Which of the following does NOT produce lactic acid?" if asked.

Lactic acid bacteria are used to ferment and produce foods from A.dairy. B.vegetables. C.meat. D.All of these can be fermented by lactic acid bacteria to make foods

All of these can be fermented by lactic acid bacteria to make foods

Soy sauce is made by fermentation of soybeans and wheat by - lactic acid bacteria. - Saccharomyces. - Aspergillus. - lactic acid bacteria AND Saccharomyces.

Aspergillus. Soy sauce is made by inoculating equal parts of cooked soybeans and roasted cracked wheat with a culture of either Aspergillus oryzae or Aspergillus sojae. The mixture (called KOJI) stands for several days while carbs and proteins in soybeans are broken down - making a yellow-green liquid full of fermentable sugars, peptides and amino acids. This is added to a solution of 18% NaCl (brine) where salt-tolerant microbes grow and produce flavor changes over time. Microorganisms involved in this stage of fermentation: lactobacilli, pediococci, and yeasts. The brine sits for 8-12 months, then the liquid soy sauce is removed and the remaining solids are used as animal feed.

You are cleaning out your pantry and find that your bread has spoiled. Which organism caused the spoilage, and why? Bread is spoiled by bacteria because it does not have enough water available for mold growth. Pseudomonas aeruginosa—this bacterium is the primary cause of spoilage in grain products. Bread is spoiled by mold because it does not have enough water available for bacterial growth. Bread is spoiled by both bacteria and mold simultaneously—these organisms always act synergistically in spoilage. Bread is spoiled by mold because there is too much water present for bacterial growth.

Bread is spoiled by mold because it does not have enough water available for bacterial growth.

Why would the use of a known, reliable starter culture improve the safety of fermented meat products? a) We need to be very careful which microbes are introduced into a food product. Some microbes can interact with microbes already present in the food, producing toxins and toxic byproducts that might harm human beings. b) By using pure starter cultures, we KNOW what we're adding in, and how much. We can control the microbial fermentation precisely to best prepare the food product. c) It doesn't. All fermented meat products are inherently unsafe since we can't determine what fermentation products are left behind in the food. Some of them may be toxic. d) It doesn't. Every fermenting microbe ferments the same way, producing the same products. Whatever we start with, the outcome is the same.

By using pure starter cultures, we KNOW what we're adding in, and how much. We can control the microbial fermentation precisely to best prepare the food product.

Which statement regarding canning and pasteurization is TRUE? Canning and pasteurization are essentially the same process—one is used on fresh food while the other is used on preserved food; both result in sterilization of the product. Pasteurization uses a process that destroys all microorganisms that can grow under normal storage conditions; the resulting product is commercially sterile. Canning significantly decreases the number of spoilage microbes and eliminates pathogens; however, viable organisms still remain. Canning and pasteurization both use a process that destroys all microorganisms that can grow under normal storage conditions; the resulting products are commercially sterile. Canning and pasteurization both significantly decrease the number of spoilage microbes and eliminates pathogens; however, viable organisms still remain. Canning uses a process that destroys all microorganisms that can grow under normal storage conditions; the resulting product is commercially sterile. Pasteurization significantly decreases the number of spoilage microbes and eliminates pathogens; however, viable organisms still remain.

Canning uses a process that destroys all microorganisms that can grow under normal storage conditions; the resulting product is commercially sterile. Pasteurization significantly decreases the number of spoilage microbes and eliminates pathogens; however, viable organisms still remain. WRONG!!! Pasteurization uses a process that destroys all microorganisms that can grow under normal storage conditions; the resulting product is commercially sterile. Canning significantly decreases the number of spoilage microbes and eliminates pathogens; however, viable organisms still remain.

A 37-year-old man is admitted to the hospital where you work with dizziness, dry mouth, blurred vision, and slurred speech. In addition, he reports abdominal symptoms, including pain, nausea, vomiting, and diarrhea. The patient's family tells you that he was recently at a church potluck, where he ate bread, streak, homemade tomato-beef stew and home-canned green beans. Based on the patient's signs and symptoms, the physician with whom you are working suspects botulism, and the patient is immediately given botulinum antitoxin. He develops breathing difficulty and is placed on a mechanical ventilator.A stool sample from the patient is cultured, and confirms the presence of Clostridium botulinum. In addition, the stool sample as well as leftover stew and green beans are tested for botulinum toxin—toxin is present in the green beans and in the stool sample, but not in the stew. These results confirm the diagnosis of foodborne botulism. You are one of the RNs taking care of the patient—he remains in the hospital for several weeks, before being discharged. Please select the statement that does NOT apply to botulism. The causative agent is an obligate anaerobe. Vegetative Clostridium cells release botulinum toxin, a potent neurotoxin. Boiling home-canned foods for 10 minutes will destroy any botulinum toxin present. The causative agent is Clostridium botulinum. Clostridium endospores can germinate in food with an acidic pH.

Clostridium endospores can germinate in food with an acidic pH. Not true - this is why acidic foods don't need such stringent canning procedures - Clostridium endospores are inhibited by low/acidic pH. Clostridium botulinum - Gram positive, anaerobe, motile, endospore former.

What is the purpose of the mashing step in beer making? Mashing is required to remove residual solids, leaving wort that can be fermented by bacteria. During mashing, the enzymes of malted barley degrade starches, converting them to fermentable sugars. During mashing, the enzymes of malted barley degrade fermentable sugars, converting them to starches. Mashing increases the surface area available for microbes to adhere to during the fermentation process. All of the answer choices are correct.

During mashing, the enzymes of malted barley degrade starches, converting them to fermentable sugars.

The bacteria associated with hemolytic uremic syndrome is Lactobacillus. Campylobacter jejuni. Escherichia coli O157:H7. Salmonella cholerasuis. Pseudomonas aeruginosa.

Escherichia coli O157:H7.

The connection between unpasteurized milk and brucellosis in humans was made by Pasteur. Evans. Fleming. Ehrlich. Koch.

Evans

Egg white is rich in the antimicrobial lysosome. T/F

False

Aflatoxin is a potent carcinogen produced by certain bacteria. T/F

False - Aspergillus flavus (fungus) grows on peanuts and other grains, producing AFLATOXIN, a potent carcinogen monitored by the FDA. What makes it false is that aflatoxin is produced by a fungus, not bacteria. p.808

Foodborne intoxication requires the ingestion of living organisms. T/F

False Foodborne intoxication involves ingesting toxins and foodborne infection is ingesting the living cells.

High concentrations of nucleic acids in the diet may lead to high levels of uric acid in the blood. T/F

False Proteins might but false.

The water activity in foods with high levels of salt or sugar is high. T/F

False Seems like it should be but any water is tied up with the salt/sugar and unavailable for use by spoilage organisms.

Which of the following are most likely to be found growing on salted or dried foods? Fungi Viruses Bacteria Fungi AND bacteria Protozoa

Fungi

Why might a large number of competing microorganisms in a food sample result in lack of sensitivity of culture methods for detecting pathogens? a) The sheer number of microbes present might shut down the growth/replication of a pathogenic microbe in a food sample due to a 'starving out' effect. If it can't grow/replicate, it won't be detectable by a culturing method test. b) Many microbes secrete compounds that can be toxic for their competitors. If you need a pathogenic microbe to grow in a culture in order to detect it, these toxic compounds might inhibit the growth of the pathogen and impede the test AND culture methods often rely on biochemical changes taking place in medium for identification. With multiple microbes present, you may not be sure that the biochemical change observed is from the presence of a pathogen or from some other non-dangerous bacterium that also induces the biochemical change. c) Many microbes secrete compounds that can be toxic for their competitors. If you need a pathogenic microbe to grow in a culture in order to detect it, these toxic compounds might inhibit the growth of the pathogen and impede the test. d) You can't obtain a pure culture from a food sample that has a large number of microbes present. It would be impossible to detect only one from within the sample. e) Culture methods often rely on biochemical changes taking place in medium for identification. With multiple microbes present, you may not be sure that the biochemical change observed is from the presence of a pathogen or from some other non-dangerous bacterium that also induces the biochemical change.

Many microbes secrete compounds that can be toxic for their competitors. If you need a pathogenic microbe to grow in a culture in order to detect it, these toxic compounds might inhibit the growth of the pathogen and impede the test AND culture methods often rely on biochemical changes taking place in medium for identification. With multiple microbes present, you may not be sure that the biochemical change observed is from the presence of a pathogen or from some other non-dangerous bacterium that also induces the biochemical change.

Which strain of Escherichia coli may be involved in foodborne infection? HB101 O157:H7 M309 AB220 O7:H157

O157:H7

Which of the following is often associated with poultry products? Salmonella AND Pseudomonas Campylobacter AND Lactobacilllus Lactobacillus AND Salmonella Salmonella AND Campylobacter Pseudomonas AND Campylobacter

Salmonella AND Campylobacter

Why might the presence of Apsergillus flavus in grain products be a problem? Some species of Aspergillus cause systemic infections in animals that consume them. Some species of Aspergillus produce aflatoxin, a potent carcinogen. All species of Aspergillus produce aflatoxin, a potent carcinogen. Presence of Aspergillus indicates a highly contaminated environment. Some species of Aspergillus produce aflatoxin, which kills plants and causes crop loss.

Some species of Aspergillus produce aflatoxin, a potent carcinogen. - it produces AFLATOXIN, a potent carcinogen monitored by the FDA. Aflatoxin mycotoxins are toxic to humans and even more toxic to animals. They also cause cancer in humans and animals

Why is ham is a common vehicle for S. aureus food poisoning? Ham is a particularly moist meat, so encourages the growth of the staphylococci, which can only survive on foods with a high aw. Ham is an untreated raw meat. As such, it is prone to contamination by the staphylococci that thrive on meat, resulting in food poisoning. Staphylococci are able to act synergistically with the normal microbiota of pigs, creating toxins that result in food poisoning. S. aureus is part of the normal microbiota of cows, so is a frequent cause of S. aureus food poisoning. Staphylococci are adapted to salty conditions and thrive with little competition on cured meats such as ham.

Staphylococci are adapted to salty conditions and thrive with little competition on cured meats such as ham.

Which of the following organisms can grow at a lower water activity than most spoilage bacteria? Pseudomonas sp. most yeasts Streptococcus pyogenes Staphylococcus aureus

Staphylococcus aureus It faces too much competition normally but it is salt tolerant and can grow on salty ham where there will be less competition from other spoilage bacteria. (salty foods have a reduced water availability but S. aureus tolerates salt so it's fine.)

A 37-year-old man is admitted to the hospital where you work with dizziness, dry mouth, blurred vision, and slurred speech. In addition, he reports abdominal symptoms, including pain, nausea, vomiting, and diarrhea. The patient's family tells you that he was recently at a church potluck, where he ate bread, streak, homemade tomato-beef stew and home-canned green beans. Based on the patient's signs and symptoms, the physician with whom you are working suspects botulism, and the patient is immediately given botulinum antitoxin. He develops breathing difficulty and is placed on a mechanical ventilator.A stool sample from the patient is cultured, and confirms the presence of Clostridium botulinum. In addition, the stool sample as well as leftover stew and green beans are tested for botulinum toxin—toxin is present in the green beans and in the stool sample, but not in the stew. These results confirm the diagnosis of foodborne botulism. You are one of the RNs taking care of the patient—he remains in the hospital for several weeks, before being discharged. How did the antitoxin help the patient? The antitoxin is a mixture of antibodies that bind to and thereby neutralize the different serotypes of botulinum toxin. The antitoxin binds to and destroys Clostridium botulinum cells, preventing them from releasing botulinum toxin. The antitoxin stimulates phagocytes to neutralize botulinum toxin type A. The antitoxin contains antibodies to botulinum toxin type A, which is the type that causes illness. The antitoxin is a mixture of antigens that bind to and thereby neutralize the different serotypes of botulinum toxin.

The antitoxin is a mixture of antibodies that bind to and thereby neutralize the different serotypes of botulinum toxin. This is from a scenario question in the text! p.811 - this is the first line of the first discussion question answer. :)

A wide variety of fungi spoil food including species of Rhizopus, Alternaria, Penicillium, Aspergillus, Botrytis. T/F

True

T/F -pH determines production of toxins (i.e. they are not produced below a pH of 4.5)

True

The toxin produced by Staphylococcus aureus is heat-stable. T/F

True - heat stable and survives cooking

Lactobacillus acidophilus can potentially colonize the intestinal tract. T/F

True - in the discussion of Acidophilus milk on slide 30

Yeast alone cannot convert grain to alcohol. T/F

True Beer production - p.806 yeast lacks the enzymes needed to digest starch, the primary carb of grains. Have to have sprouted or germinated barley to get the enzymes to do so.

The bacteria associated with hemolytic uremic syndrome is Escherichia coli O157:H7. T/F

True This strain and other STEC (shiga-toxin producing E. coli) can cause HUS.

The most prevalent cause of wine spoilage is the presence of sulfur dioxide. ethanol. carbon dioxide. lactic acid bacteria. acetic acid bacteria.

acetic acid bacteria. Add sulfur dioxide (SO2) to inhibit growth of other microbes on the grapes - including these else your wine could become expensive vinegar.

Clostridium botulinum typically does not produce its toxin under conditions that are anaerobic. alkaline. neutral. acid.

acid It's why high acid things like pickles don't have to worry about Clostridium endospores - too acidic. - Clostridium botulinum is a Gram-positive, rod-shaped, anaerobic, spore-forming, motile bacterium with the ability to produce the neurotoxin botulinum.

C. botulinum toxin is - heat-stable. - an exotoxin. - endotoxin. - heat-sensitive. - an exotoxin AND heat-sensitive.

an exotoxin AND heat-sensitive.

As an added safety precaution, low-acid, home canned foods should be - eaten with spoons. - boiled at least 15 minutes before consumption. - frozen for 1 hour before consumption. - dried prior to eating.

boiled at least 15 minutes before consumption.

Human disease(s) from milk may include amoebiasis AND tuberculosis. brucellosis AND tuberculosis. brucellosis AND anthrax. anthrax AND amoebiasis. tuberculosis AND anthrax.

brucellosis AND tuberculosis.

Egg white is rich in the antimicrobial hydrogen peroxide. lysosome. benzoic acid. lysozyme. allicillin.

lysozyme

Slow cooking for a long time and then storage at room temperature would tend to favor the growth of anaerobes AND endospore-formers. thermophiles AND anaerobes. mesophiles AND thermophiles. endospore-formers AND thermophiles. endospore-formers AND mesophiles.

endospore-formers AND mesophiles. mesophiles like 25-45 degrees Celsius

Foods that have been altered due to the carefully controlled growth of microorganisms are called controlled. fermented. cooked. spoiled. preserved.

fermented

What is the difference between fermented food and spoiled food?

fermented: foods intentionally altered during production by carefully controlling bacteria, yeasts, or molds spoiled: unintentional growth of bacteria on foods leading to quality deterioration

Growth of pathogens in a food generally does not result in perceptible changes in the quality of the food but the ingestion of this food can result in spoilage. foodborne illness. toxin infection. respiratory illness. aging.

foodborne illness - 2 types: foodborne intoxication from ingesting a toxin, and foodborne infection from ingesting live cells

Foods such as acidic fruits are often spoiled by fungi. protozoans. viruses. bacteria

fungi Bacteria can't hack it at pH less than 4.5. Acidic fruit? Fungi is your spoiler.

Which of the following organisms may grow at pH 2.2? Clostridium Streptococcus fungi lactic acid bacteria fungi AND lactic acid bacteria

fungi Even lemons can go moldy. White and green fungi = yum...not

Which of the following organisms may grow at pH 3.5? Streptococcus AND lactic acid bacteria Clostridium AND fungi fungi AND lactic acid bacteria lactic acid bacteria AND Clostridium fungi AND Streptococcus

fungi AND lactic acid bacteria

Staphylococcus aureus toxin is an endotoxin AND heat-sensitive. an exotoxin AND heat-sensitive. heat-stable AND an exotoxin. heat-stable AND an endotoxin. None of the answer choices is correct.

heat-stable AND an exotoxin.

The conditions normally present in food such as moisture, acidity, and nutrients are referred to as: extrinsic factors. intrinsic factors. endogenous factors. exogenous factors

intrinsic factors Things about the food itself not about it's environment.

Irradiation of foods - involves the use of gamma radiation. - is used on all foodstuffs. - changes the taste of foods. - is not regulated by the government. - involves the use of gamma radiation, changes the taste of foods AND is not regulated by the government.

involves the use of gamma radiation. Gamma radiation is used to kill microbes without changing the taste of the food.

In a cow's udder, milk: contains Lactococcus. contains Lactobacillus. is sterile. is acidic.

is sterile Microbes are introduced as and after the milk leaves the udder.

The unique flavor of yogurt is due to the production of A.lactic acid and acetaldehyde. B.casein and alcohol. C.rennin and coagulated protein. D.curd and whey

lactic acid and acetaldehyde. Possible that this isn't from this course...

The tart taste of yogurt, pickles, and sharp cheeses is due to the presence of acetic acid. benzoic acid. lactic acid. sorbic acid. hydrochloric acid.

lactic acid. p.803

The water activity in foods that have high levels of salt or sugar is high. dense. low. osmotic

low It may have a lot of moisture but that water is chemically tied up by the sugar or salt and is not available for use by the spoilage bacteria.

The resulting solids and juices of grapes used to make wine are termed its skin. malt. germinater. mash. must.

must

The toxin of botulism is classified as a(n) - enterotoxin - endotoxiin - neurotoxin - toxoid

neurotoxin

Why do bacteria generally predominate on fresh meats?

p.801 - as a general rule, bacteria will predominate in fresh meats and other moist, pH neutral, nutrient-rich foods. Yeasts and molds can also grow in these foods but the more rapid increase in bacteria overwhelms the competitors. When conditions such as lack of moisture or high acidity restrict the growth of bacteria, fungi predominates despite their relatively slow growth.

Lactic acid bacteria consume lactic acid, allowing them to grow on foods such as yogurt. produce lactic acid, allowing them to produce foods such as yogurt. are important spoilage organisms. can grow on lemons. produce lactic acid, allowing them to produce foods such as yogurt AND are important spoilage organisms

produce lactic acid, allowing them to produce foods such as yogurt AND are important spoilage organisms

Sugar is used in the making of fermented sausages to help preserve the sausage. provide raw material for the fermentation process. sweeten the taste. counteract the action of the salt in the sausage.

provide raw material for the fermentation process.

Which of the following is most likely to grow at refrigerator temperatures? mesophiles psychrophiles thermophiles acidophiles

psychrophiles They like -5-15 degrees Celsius. - The ideal refrigerator temperature is 35° F (1.6° C) Mesophiles like 20-45 degrees Celsius (people are 37C) Thermophiles like 45 to 70 degrees Celsius - hot tubs and compost piles. Acidophiles - organisms are those that thrive under highly acidic conditions (usually at pH 2.0 or below).