FMB - Lecture 5 Flashcards
(111 cards)
1
Q
Factors affecting the growth of bacteria:
A
Physical
- pH
- Temperature
- Oxygen concentration
- Moisture
- Hydrostatic pressure
- Osmotic pressure
- Radiation
Nutritional
- Carbon
- Nitrogen
- Sulfur
- Phosphorus
- Trace elements
- Vitamins
1
Q
A measure of how acidic/basic water is.
A
pH
2
Q
____ ranges from 0 to 14, with 7.0 being neutral.
A
pH
3
Q
Acidity is inversely related to pH.
A
- A system with high acidity has a low pH.
- A system with low acidity has a high pH.
4
Q
Most bacteria grow between pH _______.
A
pH 6.5 AND 7.5
5
Q
Molds and yeast grow between pH _______.
A
pH 5 and 6
6
Q
They grow in acidic enviroment.
A
Acidophiles
7
Q
Examples of acidophiles.
A
- Sulfolobus spp.
- Lactobacillus spp.
8
Q
Examples of neutrophiles.
A
- Escherichia coli
- Salmonella
9
Q
They grow at a pH level of 7.0 - 11.5, 12.0
A
Alkaliphiles
10
Q
Example of alkaliphiles.
A
- Vibrio cholerae
- Alcaligenes faecalis (9.0 - higher)
- Agrobacterium (soil microorganisms, 12.0 pH)
11
Q
Cause peptic ulcer.
A
Helicobacter pylori
12
Q
_____ is neutrophile, however, its ability to survive low pH of the stomach would seem to suggest that it is an extreme acidophile.
A
H. pylori
13
Q
The ammonium ion raises the pH of the immediate environment (NH4+ and CO2).
A
H. pylori
14
Q
Effects of pH in growth of bacteria:
A
- Protection.
- Inhibits growth.
- Denaturation of enzymes and other proteins.
- Metabolic by-products.
15
Q
It is a major environmental factor controlling microbial growth and is accomplished through enzymatic reactions.
A
Temperature
16
Q
Because _____________ influences enzyme reactions, it has an important role in microbial growth in food.
A
Temperature
17
Q
Must meet required environmental conditions.
A
Obligate
18
Q
Adjust and tolerate / thrive in other environmental conditions, and can adapt.
A
Facultative
19
Q
Cold loving microorganisms (cold temperature optima). Most extremes representative inhabit permanently in cold environments.
A
Psychrophiles
20
Q
Growth temperature of 15 - 20 degree celsius and 0 - 20 degree celsius.
A
Psychrophiles
21
Q
Example of obligate psychrophiles.
A
Bacillus globisporus - 20 degree celsius.
22
Q
Example of facultative psychrophiles.
A
Xanthomonas pharmicola - below 20 degree celsius but can grow above 20 degree celsius.
23
Q
Moderate loving microorganisms (midrange temperature optima). Found in warm-blooded animals and in terrestrial and aquatic environments in temperature and tropical latitudes.
A
Mesophiles
24
Growth temperature of 20 - 45 degree celsius / 25 - 40 degree celsius. Also considered as human pathogen because it grow best in human temperature (37 degree celsius).
Mesophiles
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Growth temperature optima between 45 - 80 degree celsius / 50 - 60 degree celsius / 50 - 80 degree celsius.
Thermophiles
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It can be seen in compost pits and hot springs. They are also called as heat loving microorganisms.
Thermophiles
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Obligate thermophiles temperature:
Above 37 degree celsius
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Facultative thermophiles temperature:
Both above and below 37 degree celsius.
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Example of thermophiles.
Bacillus stearothermophilus
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Optima greater than 80 degree celcius. These organisms inhabit hot environments including boiling hot springs, as well as undersea hydrothermal vents that can have temperature in excess of 100 degree celcius.
Hyperthermophiles
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Example of hyperthermophiles:
Thermus aquaticus
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Live as mesophiles but can live at a higher temperature for a short period of time.
Thermoduric
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Growth temperature of 0 - 30 degree celcius. Cannot grow in 4. degree celcius. Low temperature food spoilage.
Psychrotrophs
34
Three cardinal temperature.
1. Minimum Temperature
2. Optimum Temperature
3. Maximum Temperature
35
Temperature below which growth ceases, or lowest temperature at which microbes will grow.
Minimum Temperature
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Temperature at which its growth rate is the fastest.
Optimum Temperature
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Temperature above which growth ceases, or highest temperature at which microbes will grow.
Maximum Temperature
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Effects of temperature in growth of bacteria:
1. Enzyme activity.
2. Preventing growth.
3. Preservations
39
Microbes that use molecular oxygen produce more energy from nutrients
Aerobes (Oxygen)
40
Microbes that do not use oxygen.
Anaerobes (Oxygen)
41
Require an atmosphere oxygen in concentrations comparable to 20%–21%.
Obligate aerobes
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Example of Obligate aerobes:
Pseudomonas
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Not require oxygen for life and reproduction.
Obligate anaerobes
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Example of Obligate anaerobes:
Clostridium botulinum
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They prefer an atmosphere containing about 5% oxygen.
Microaerophilic aerobes
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Examples of Microaerophilic aerobes:
Campylobacter
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They are capable of surviving in either the presence or absence of oxygen.
Facultative anaerobes
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Examples of Facultative anaerobes:
Staphylococcus, E. coli
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Does not require oxygen, grows better in the absence of oxygen, but can survive in O2 atmospheres.
Aerotolerant anaerobes
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Example of Aerotolerant anaerobes:
Lactobacillus
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They grow best in the presence of increased concentrations of CO2 (usually 5 to 10%)
Capnophilic organisms
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Microorganisms obtain almost all their nutrients in solution from the surrounding water.
Moisture
53
Require water for growth, and their composition is 80- 90% water.
Moisture
54
Most foods have a water activity above 0.95 and that will provide sufficient moisture to support the growth of bacteria, yeasts, and mold.
The amount of available moisture can be reduced to a point which will inhibit the growth of the organisms.
Water Activity
55
Each microbial species (or group) has an optimum, maximum, and minimum AW level for growth.
- most molds –0.8, with xerophilic molds as low as 0.6
- most yeasts, 0.85, with osmophilic yeasts, 0.6–0.7
- most Gram-positive bacteria, 0.90
- Gram-negative bacteria, 0.93
56
Organisms which thrive in high pressure
Barophiles (Hydrostatic pressure)
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Organisms which tolerate high pressure
Barotolerant (Hydrostatic pressure)
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Organisms which thrive in high solute
Osmophiles (Osmotic pressure)
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Organisms which tolerate high solute
Osmotolerant (Osmotic pressure)
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Organisms which thrive in high salt
Extreme halophiles (Osmotic pressure)
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(Osmotic pressure) At least 30% of salt concentration to live.
Obligate Halophiles
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(Osmotic pressure) From 2% and can tolerate up to 15% salt concentration.
Facultative Halophiles
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Organisms which tolerate high salt
Halotolerant
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Some microorganisms have pigments that screen ___________ and help to prevent DNA damage.
Radiation
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Enzyme systems that can repair certain kinds of DNA damage.
Radiation
66
Nutritional Factors:
- Carbon
- Nitrogen
- Sulfur
- Phosphorus
- Trace elements
- Vitamins
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(Nutrient Content) Required by all organisms, necessary to support life.
carbohydrates
proteins
lipids
minerals
vitamins
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Elements required in fairly large amounts.
Macronutrients
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Macronutrients
Carbon, oxygen, hydrogen, nitrogen, phosphorus, potassium, sulfur, calcium, iron, sodium, chlorine, magnesium and a few other elements.
70
Metals and organic compounds needed in very small amounts.
Micronutrients
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Micronutrients
Mn, Co, Zn, Cu, Ni and Mo.
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The structural backbone of living matter.
Carbon
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It is needed for all the organic compounds that make up a living cell.
Carbon
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Source of cellular energy (ATP or related compounds) to drive metabolic reactions.
Carbon
75
Half the dry weight of a typical bacterial
cell is ___________.
Carbon
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All organisms, including microorganisms, need this to synthesize enzymes, other proteins, and nucleic acids.
Nitrogen
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* In amino acids, vitamins: thiamine, biotin
* Most bacteria decompose proteins
* Some bacteria use SO4 2- or H2S
Sulfur
78
* In DNA, RNA, ATP, and membranes
* PO4 3- is a source of phosphorus
Phosphorus
79
Very little amount is needed but critical to cell function. Often used as enzyme cofactors.
Micronutrients (Trace elements)
80
It plays a major role in cellular respiration, being a key component of cytochromes and iron sulfur proteins involved in electron transport.
Iron
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Iron-binding agents that cells produce to obtain iron from various insoluble minerals.
Siderophores
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Organic compounds which are required in very small amount. Used as coenzyme.
Vitamins
83
Some microorganisms tend to create their own ______.
Example: E. coli - is producing vitamin A in the body for blood clothing factor.
Vitamins
84
Factors affecting the growth of fungi:
1. Environmental Factors
2. Chemical Factors
3. Biological Factors
85
Environmental Factors
1. pH
2. Temperature
3. Atmospheric gases
4. Photoperiod, light intensity
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Chemical Factors
1. Type of substrate
2. Antifungal agents
87
Biological Factors
1. Competing microflora
2. Inoculum size
3. Strain variability
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Temperature:
- Psychrotolerant
- Psychrophilic
- Mesophilic
- Thermotolerant
- Thermophilic
- Psychrotolerant – growth above 20 °C
- Psychrophilic – maximum of 20 °C or below
- Mesophilic - growth between 25 and 30.
- Thermotolerant – growth at 30 to 45 °C
- Thermophilic – growth above 45 °C
89
Fungi have a wide range of acid/alkaline needs for growth, ranging from pH 3.0 to more than pH 8.0, with an ideal pH of approximately pH 5.0.
Hydrogen Ion concentration / pH
90
- Almost all molds. (Food spoilage molds)
- Colonize the surface of the food (most oxygen demanding)
- Inside the food (less demand for oxygen)
Obligate aerobes (Availability of oxygen)
91
Most fungi are _________
obligate aerobes
92
Most yeasts are __________
Facultative anaerobes
93
MOISTURE LEVEL
- If there are no cold-condensing surfaces and the relative humidity (RH) is maintained below 60 %indoors, there will not be enough water in those materials for mold to grow.
- However, if the RH stays above 70% indoors for extended periods of time, mold will almost certainly grow.
- Fungi need water for all stages of life or RH of >90%.
- Normal yeasts require a minimum water activity of 0.85 or a RH of 88%.
94
__________ are the most common osmophilic microorganisms.
Yeast
- usually the cause of spoilage of high-sugar foods, including jams, molasses, corn syrup, flavored syrups and toppings, honey, concentrated fruit juices, chocolate candy with soft centers.
95
__________ are more resistant to osmotic pressures.
Fungi
- production of osmoprotectant compounds such as glycerol, reorganization of the cytoskeleton, and cell wall biogenesis.
- NaCl
96
__________ grow optimally in low light conditions.
Fungi
- Many molds flourish in dark spaces but some prefer an alternate light pattern – some light, and some dark.
97
___________ do not need sunlight to grow.
Yeast
- Many molds flourish in dark spaces but some prefer an alternate light pattern – some light, and some dark.
98
Types of Fungi:
1. Field Fungi
2. Storage Fungi
3. Advanced Deterioration Fungi
99
Invade crops while it's still on the field (pre-harvest). High requirements of water.
Field Fungi
100
Examples of field fungi:
Fusarium, some Aspergillus, Alternaria and Cladosporium
101
Lower requirement of humidity. Presence before harvest but multiply during storage period.
Storage fungi
102
Examples of storage fungi:
Aspergillus and Penicillium
103
Easily attack damaged one and require high moisture content.
Advanced Deterioration Fungi
104
Examples of advanced deterioration fungi:
A. clavatus, A. fumigatus, Rhizopus, and Mucor
105
Presence of different microorganisms. Biological pest control agents.
Competing Microflora
106
(Biological Factors) Trichoderma harzianum produces a lytic enzyme _______.
Chitinase
107
Production of mycotoxins is influenced by both genotype (strain) and the environment.
Strain Variability
108
Mostly found in soil. Spores, Sclerotia, or fragments of mycelium.
Inoculum
109
NUTRITIONAL FACTORS
- Use of Carbon source to fill their carbon needs for the synthesis of macromolecules.
- Oxidation of sugars, alcohols, proteins, lipids, and polysaccharides for their source of energy.
- Fungi requires source of nitrogen for synthesis of amino acids to proteins
- Other MAJOR nutrients are sulfur, phosphorus, magnesium, and potassium which can be supplied to most fungi as salts.
- TRACE elements like iron, copper, manganese, zinc, and molybdenum are required by nearly all fungi as cofactors for enzymes.
- High amounts of trace elements can become toxic for some fungi.
110
ADAPTATION TO LIMITED NUTRIENTS
1. By increasing the quantities of enzymes that they produce.
2. By making enzymes to metabolize another available nutrient.
3. By adjusting their metabolic activities to grow at a rate
consistent with availability of nutrients.
