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Fpathogens > 19 - Molds > Flashcards

19 - Molds Flashcards

1
Q

Mycotoxins: _____________ which when ingested, inhaled, or absorbed through the skin can cause disease in humans and domestic animals, including birds.

A

fungal metabolites

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2
Q

Specific mycotoxins are produced by only ___________, usually a few species

A

specific fungi

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3
Q

T or F: a particular species of fungus may produce more than one mycotoxin

A

T

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4
Q

T or F: the presence of spores indicates the presence of mycotoxin

A

F

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5
Q

Mycotoxin production occurs only as a result of _________

A

fungal growth

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6
Q

Fungal growth and toxin production can occur at any point in the _________________

A

food production chain: growing, harvesting, drying, or storage

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7
Q

Mycotoxins are usually very ______ once formed and may persist in the food, even after processing destroys the fungi that produced them

A

stable

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8
Q

Molecular structures of mycotoxins ______ widely

A

vary

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9
Q

The effects of mycotoxins on health vary and include:

A
  • neurotoxins
  • teratogens
  • nephrotoxins
  • hepatotoxins
  • immunosuppressive agents
  • carcinogens
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10
Q

IMPORTANTLY, toxicity due to mycotoxins is almost never ______, effects are ___________ over a long period of time

A

acute

cumulative

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11
Q

T or F: the health effects of mycotoxins are among the most neglected areas in medical science

A

T

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12
Q

Name 5 mycotoxins:

A
  • Aflatoxin
  • Ochratoxin A
  • Fumonisins
  • Deoxynivalenol
  • Zearalenone
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13
Q

Aflatoxin can cause _________ (Aflatoxicosis)

A

acute toxicity

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14
Q

Describe a typical aflatoxin outbreak:

A

India, consumption of contaminated corn, outbreaks occur when drought or famine cause exceptionally high levels of aflatoxins to be eaten at high-levels in substandard food

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15
Q

Name the 4 naturally occuring Aflatoxins:

A
  • B1
  • B2
  • G1
  • G2
  • named based on their flurescence under UV light
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16
Q

When aflatoxins are ingested by lactating cows, they are excreted as aflatoxins ___ and ___

A

M1

M2

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17
Q

Aflatoxins are produced by (2):

A
  • Aspergillus flavus

- Aspergillus parasiticus

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18
Q

Aspergillus flavus grows from _______

A

10-48C

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19
Q

What is the pH range of A.flavus:

A

2.1-11.2

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20
Q

The required aw of A.flavus depends on temperature, describe it:

A

A.flavus is better adapted to high temperatures so less water is required at higher temp and more water is required at lower temp

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21
Q

T or F: Pasteurization readily kills A.flavus cells

A

T

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22
Q

A.flavus is common in food crops in ______ and _____ temperate areas of the world

A

tropical

warm

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23
Q

A.flavus tends to be associated with peanuts, _________

A

corn and tree nuts (pistachios and Brazil nuts)

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24
Q

A.parasiticus is more _________ limited, its growth is associated with ________, and appears uncommonly elsewhere

A

geographically

peanuts

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25
Q

T or F: Under inadequate storage conditions, other grains may also permit growth and aflatoxin production

A

T

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26
Q

T or F: n peanuts it appears that Aspergillus infection while the nuts are still in the ground is a prerequisite for high levels of aflatoxins

A

T

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27
Q

If pre-harvest infection is ______ and nuts are dried quickly then aflatoxin free nuts can be produced

A

absent

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28
Q

What are major contributors to pre-harvest infections in peanuts?

A
  • high spore numbers
  • plant stress (drought)
  • high soil temperatures
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29
Q

Control of spore numbers can be achieved by _________ and __________

A

crop rotation

irrigation

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30
Q

Biocontrol is also used as an effective strategy to reduce aflatoxin infection, explain:

A
  • only 40% of A.flavus produce toxin

- fields are inoculated with non-toxic strains to compete with toxins

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31
Q

Aflatoxin can be reduced in peanuts by manually _______ kernels after shelling

A

sorting

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32
Q

If the ground is too ___ Aspergillus grows and produces aflatoxin (this causes discoloration)

A

dry

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33
Q

If peanuts are _______ to remove the skin they can be sorted to remove discolored kernels

A

blanched

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34
Q

Aflatoxin removal by heat depends on which type of heat: boiling and autoclaving ________________, dry roasting removes up to ______, the alkali process used to make peanut oil removes _________

A

doesn’t help (less than 25% of toxin destroyed)

80%

all aflatoxin

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35
Q

Aflatoxin toxicity have 5 primary toxic effects:

A
  • acute toxicity (indian example)
  • liver carcinogenicity
  • liver cirrhosis
  • immunosuppression
  • growth retardation in children
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36
Q

T or F: liver carcinogenicity (less obvious) than acute toxicity is the development of liver cancer from the sustained consumption of lower levels of aflatoxin over longer priods of time

A

T

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37
Q

If you are infected with ____________________, you are 30 times more likely to develop liver cancer due to the consumption of aflatoxin (they are synergistic)

A

Hepatitis B

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38
Q

In the liver, enzymes convert aflatoxin to _________.

A

epoxide

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39
Q

Epoxide binds liver ________ leading to liver failure

Epoxide binds _____ which is a precursor to liver cancer

A

proteins

DNA

40
Q

Aflatoxin exposure before birth and during childhood is associated with _________

A 
stunted growth (also observed in birds and other mammals)
*mechanism is unknown
41
Q

__________________ have been shown to suppress the cell- mediated immune response.
Effects include: ________________(3)

A

Aflatoxins

  • decreases in the phagocytic activity of macrophages
  • increased susceptibility to infection
  • reduced response to vaccines
42
Q

The accepted safe level of aflatoxin consumption in humans is ________

A

15ug/kg

43
Q

Ochratoxin A is produced by 3 well defined groups of fungi:

A

1- The ocher-colored aspergilli
2- The black aspergilli
3- Penicillium species

44
Q

Ochratoxin A is a _____________ that affects kidney function

A

nephrotoxin

45
Q

T or F: OTA also has carcinogenic properties

A

T

46
Q

OTA readily enters the blood stream through the intestine and can circulate for up to __________

A

3 weeks

47
Q

T or F: As a result of the long half-life most people who regularly consume OTA in food will have detectable levels in their blood

A

T (mostly in Northern Europe, Northern North America, and Northern Asia)

48
Q

The mechanism of action of OTA is still unclear, but it is likely related to _____________ metabolism

A

phenylalanine

49
Q

People in North America are probably exposed to OTA via ________________ OTA production

A

P.verrucosum

50
Q

Products involved with exposure of OTA include:

A
  • barley
  • wheat
  • meat
  • beer
  • wine
  • coffee
  • cocoa
  • chocolate
  • dried vine fruits
51
Q

OTA intake is much lower in ________ and ___________ regions

A

tropical and subtropical

52
Q

The tolerable weekly intake of OTA is __________ of body weight

A

100 ng/kg

53
Q

T or F: rapid drying is difficult but it prevents OTA production

A

T

54
Q

____________ is a known producer of OTA especially in Wine

A

A. carbonarius

55
Q

Levels of OTA in wine are generally low because:

A

fermentation stops fungal growth (production of alcohol)

56
Q

OTA producing fungal growth can be prevented by:

A
  • proper irrigation
  • regular pruning (air flow)
  • use of crop cover
  • fungiside applications
57
Q

Slow drying of coffee beans can lead to ___________

A

OTA formation, effective sun drying or mechanical dehydration provide effective control

58
Q

OTA is largely removed in winemaking process when solid fractions are removed, _____ wines maintain OTA more than _____

A

red

white

59
Q

Dependent on the temperature of roasting _____ of OTA will be removed in coffee

A

8-98%

60
Q

______ and ____ removal can affect OTA levels in flour

A

bran

germ

61
Q

________ to produce white flour creates 65% reduction in OTA

A

Milling

62
Q

A further 10% decrease in OTA is observed after _______

A

backing

63
Q

T or F: whole wheat bread shows less of a reduction in OTA since less of the grain is discarded

A

T

64
Q

Fumonisins are produced by _____________________

A
  • Fusarium verticilloides
  • Fusarium proliferatum
  • A.niger
65
Q

T or F: Fusarium species are always present on corn and sorghum, even in healthy kernels

A

T

66
Q

A.niger is associated with fumonisins in _________________

A

grapes, raisins and coffee

*this is of particular concern since A.niger can also produce OTA, the co-occurence of OTA and fumonisins is scary

67
Q

Fumonisins is associated with which color?

A

Fuschia

68
Q

Levels of F. verticillioides and F. proliferatum are influenced by _______ during or near harvest

A

climate

69
Q

T or F: Colonization of the kernel is usually symptomless, but when the plant is stressed it leads to a disease- / mycotoxin producing interaction

A

T

70
Q

Stress can be caused by:

A
  • drought stress
  • heat stress
  • insect predation
71
Q

Fumonisins affect________________ metabolism, and cause depletion of complex sphingolipids

his interferes with the function of some membrane proteins, including the inhibition of ____________

A

sphingolipid

folate binding

72
Q

There is a dramatic disease in horses called ___________________

  • it rapidly progresses and turns the horse brain to mush
  • if feed contains more than 10mg/kg of fumonisin there is a risk of developing this disease
A

equine leukoencephalomalacia

73
Q

In pigs fumonisin in feed leads to ________
In rats ____________
in humans, _____________ and ___________ in infants

A

heart failure
liver cancer
esophageal cancer, and neural tube defects such as spina bifida in infants (probably due to inhibition of folate binding)

74
Q

Harvested corn should be rapidly dried to avoid fungal growth (Fusarium species do not grow below ____), this level of drying can occur in the field before harvest if the field is not over irrigated

A

Aw 0.9

75
Q

T or F: most corn lost are inspected for fungal damage, and tested for levels of fumonisins

A

T

76
Q

What is nixatmalization?

A
  • Process used in central america
  • Corn or other grains are soaked and cooked in an alkaline solution
  • This process removes almost all fumonisins
  • Processed products in these areas such as tortillas and other corn products are essentially fumonisin free
77
Q

If product is processed above ______, fumonisin levels are decreased (breakfast cereal, snack)

A

150C

78
Q

Deoxynivalenol (DON) is produced by Fusarium __________, F. _______

A

graminearum

culmorum

79
Q

T or F: Only some F. graminearum produce DON and all F. culmorum produce DON

A

T

80
Q

F. graminearum occurs in ____, and F. gaminearum and F. culmorum occur in _________, especially wheat and barley

A

corn

small grains

81
Q

DON inhibits ____________

A

protein synthesis

82
Q

DON toxicosis is rare, but it does cause _____________ and __________ in humans

A

intestinal symptoms

immunotoxicity

83
Q

T or F: DON production on corn is the most prevalent in cooler and wet climates

A

T (Canada and Argentina are where rates are highest)

84
Q

USDA allows ________ of DON for grains for human consumption and _______ for bovine feed

A

1 mg/Kg

10 mg/Kg

85
Q

__________ can be used to control DON production, __________ helps reduce the risk

A

Fungicides

irrigation

86
Q

T or F: Forecasting systems have been developed in Canada to warn producers when the weather poses a DON production risk

A

T

87
Q

T or F: ZEA is produced by the same Fusarium species that produce DON, and generally under the same conditions

A

T

88
Q

Zearalenone has a __________ toxicity

A

low acute

89
Q

Zearalenone metabolites possess estrogenic activity in agricultural animals:

A
  • pigs
  • cattle
  • sheep
90
Q

Symptoms of ZEA in pigs include:

A
  • vulvovaginitis

- vaginal and rectal polapse

91
Q

ZEA is considered:

  • hepatotoxic (toxic to the liver cells)
  • ___________ (toxic to red blood cells)
  • ________________
  • ______________ (may be involved in cancer)
A

hematotoxic
immunotoxic
genotoxic

92
Q

ZEA estrogenic activity has also been implicated in _________ and ___________ of girls in Hungary and Italy

A

early puberty

advanced growth

93
Q

Out of all mycotoxins, which one are considered carcinogenic?

A

-Aflatoxin B and G

94
Q

___________, _________, and__________are the mold genera most commonly associated with foods

A

Aspergillus
Penicillum
fusarium

95
Q

Toxigenic molds are mostly found as contaminates of ________ foods

A

plant derived

96
Q

T or F: Developed countries tend to have regulations on the allowable levels of mycotoxins in foods

A

T

Fpathogens (23 decks)

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