Module 6 Flashcards
1
Q
Bacterial Growth
A
the increase in the number of microbial cells in a population.
2
Q
Growth
A
an orderly increase of all the chemical constituents of the cell.
3
Q
Growth Rate
A
the change in cell number or cell mass per unit time.
4
Q
Exponential Growth
A
pattern of population increase.
5
Q
Generation Time (Doubling Time)
A
the time interval for the formation of two daughter cells from one.
6
Q
Binary Fission
A
the process by which bacteria reproduce, involving the duplication of DNA and division of the parent cell into two daughter cells.
7
Q
Asexual Reproduction - Budding
A
a form of asexual reproduction where a new organism develops from an outgrowth or bud on the parent.
8
Q
Asexual Reproduction - Fragmentation
A
a form of asexual reproduction where an organism breaks into fragments, each capable of growing into a new organism.
9
Q
Asexual Reproduction - Spore Formation
A
the process by which certain bacteria reproduce by forming spores.
10
Q
Bacterial Growth by Binary Fission
A
a process coordinated by the bacterial membrane where DNA is replicated and the cell divides into two progeny cells.
11
Q
Bacterial Cultivation
A
a method of multiplying microorganisms by letting them grow and reproduce in artificial culture media under controlled laboratory conditions.
12
Q
Culture Medium
A
a nutrient material prepared for the growth of microorganisms in a laboratory.
13
Q
In Vitro
A
the process of inoculating bacteria in a pre-determined culture medium and growing them in a laboratory controlled environment.
14
Q
Synchronous Growth
A
a type of bacterial growth where all cells divide at the same time.
15
Q
Continuous Culture
A
a method of culturing microorganisms where fresh medium is continuously added and waste is continuously removed.
16
Q
Measurements of Growth
A
various methods used to quantify the growth of bacterial cultures.
17
Q
Nutritional Requirements for Microbial Growth
A
the essential nutrients needed for the growth and reproduction of microorganisms.
18
Q
Nutritional Classification of Microorganisms
A
the categorization of microorganisms based on their electron, energy, and carbon requirements.
19
Q
Nutritional Categories among Microorganisms
A
the different groups of microorganisms classified according to their nutritional needs.
20
Q
Physical Requirements for Microbial Growth
A
the environmental conditions necessary for the growth of microorganisms.
21
Q
Bacterial Growth Curve
A
a graphical representation of the growth of a bacterial population over time.
22
Q
Inoculum
A
When microbes are introduced into a culture medium to initiate growth.
23
Q
Culture
A
The microbes that grow and multiply in or on a culture medium.
24
Q
Main purposes of bacterial cultivation
A
Bacterial cultivation has three main purposes: 1. To grow and isolate all bacteria present in an infection. 2. To determine which of the bacteria that grow are most likely causing infection and which are likely contaminants or colonizers. 3. To obtain sufficient growth of clinically relevant bacteria to allow identification and characterization.
25
Nutrients
All chemicals required by microorganisms are raw materials for their metabolism and reproduction.
26
Nutrition
All such events used in biosynthesis and energy production.
27
Mineral Nutrients
Essential nutrients that include micro-nutrients and macro-nutrients.
28
Micro-Nutrients
Trace elements required by microorganisms in small amounts.
29
Macro-Nutrients
Nutrients required by microorganisms in larger amounts.
30
Growth Factors
Substances that bacteria require to build proteins and structural membranes and drive biochemical processes.
31
Sources of carbon, nitrogen, phosphorous, iron
Essential elements that bacteria require for growth and metabolism.
32
Micro-Nutrients
Essential trace elements required in small amounts for microbial growth.
33
Cobalt
A micro-nutrient that is essential for certain microbial enzymes.
34
Copper
A micro-nutrient that plays a role in various enzymatic reactions.
35
Manganese
A micro-nutrient involved in enzyme function and photosynthesis.
36
Molybdenum
A micro-nutrient necessary for nitrogen fixation in some bacteria.
37
Nickel
A micro-nutrient that is a component of certain enzymes.
38
Selenium
A micro-nutrient that is important for antioxidant enzymes.
39
Tungsten
A micro-nutrient that can substitute for molybdenum in some enzymes.
40
Zinc
A micro-nutrient that is crucial for the structure and function of many proteins.
41
Macro-Nutrients
Essential elements required in larger quantities for microbial growth.
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Oxygen
A macro-nutrient that is essential for aerobic respiration.
43
Hydrogen
A macro-nutrient that is a component of water and organic compounds.
44
Carbon
A macro-nutrient that is the primary building block of life.
45
Nitrogen
A macro-nutrient that is essential for amino acids and nucleic acids.
46
Phosphorous
A macro-nutrient that is a component of nucleic acids and ATP.
47
Sulfur
A macro-nutrient that is important for certain amino acids and vitamins.
48
Calcium
A macro-nutrient that is important for cell wall stability.
49
Iron
A macro-nutrient that is crucial for oxygen transport and electron transport chains.
50
Amino Acids
Building blocks of proteins that are essential for microbial growth.
51
Purines and Pyrimidines
Nucleotides that are essential for nucleic acid synthesis.
52
Vitamins
Organic compounds that are essential for various metabolic processes.
53
Autotroph
Organisms that produce their own food using CO₂ and sunlight.
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Heterotroph
Organisms that require preformed food from other organisms.
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Phototrophs
Organisms that capture light energy to produce food.
56
Chemotrophs
Organisms that obtain energy by oxidizing chemical compounds.
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Lithotrophs
Organisms that use reduced inorganic compounds as electron donors.
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Organotrophs
Organisms that use organic compounds as electron donors.
59
PHOTOAUTOTROPHS
Organisms that use light as an energy source and carbon dioxide as the principal carbon source.
60
PHOTOHETEROTROPHS
Organisms that use light as an energy source and reduced, preformed, organic molecules from other organisms.
61
CHEMOHETEROTROPHS
Organisms that obtain chemical energy from the oxidation of reduced inorganic compounds.
62
CARDINAL TEMPERATURES
The minimum, optimum, and maximum temperatures that define the growth conditions for microorganisms.
63
MINIMUM TEMPERATURE
The lowest temperature at which the organisms grow.
64
OPTIMUM TEMPERATURE
The temperature at which the highest growth rate occurs.
65
MAXIMUM TEMPERATURE
The highest temperature at which growth occurs.
66
MEMBRANE GELLING
The process where the lipid bilayer of a bacterial cell membrane solidifies due to exposure to low temperatures.
67
Loss of Membrane Fluidity
At low temperatures, the lipids in the membrane pack tightly together, restricting the movement of proteins and other membrane components.
68
Impact on Cellular Function
A gelled membrane reduces the efficiency of essential processes such as enzyme activity and metabolic reactions.
69
Cold Stress and Bacterial Survival
When bacteria are exposed to extreme cold, membrane gelling can inhibit growth or even lead to cell death.
70
Effects of Low Temperature
At very low temperatures, metabolic rates are very slow and cells will survive for long periods.
71
Effects of Rising Temperature
As temperature rises, enzymatic reactions inside the cell proceed at faster rates and growth becomes more rapid until optimum growth rate is achieved.
72
Denaturation of Cell Components
Just above the optimum temperature, proteins, DNA, RNA, and other critical cell components become irreversibly denatured.
73
Growth Rate of Bacteria
The growth rate varies among different types of bacteria based on their temperature preferences.
74
PSYCHROPHILES/CRYOPHILES
Organisms that are able to grow at 0°C or lower but grow best at higher temperatures (Range: -20°C to 10°C).
75
MESOPHILES
Microorganisms that grow best in moderate temperatures, typically in the range of 20°C to 45°C.
76
Examples of Psychrophiles
Members of the genera Pseudomonas, Flavobacterium, and Alcaligenes.
77
Examples of Mesophiles
E. coli, Streptococcus pneumoniae, and other microorganisms that thrive at body temperature (37°C).
78
THERMOPHILES
Heat-loving microorganisms that grow best at temperatures above 45°C, with an optimum between 50°C and 80°C.
79
HYPERTHERMOPHILES
Microorganisms that thrive in extremely hot environments, with a temperature range of 80°C to 113°C.
80
pH
Refers to the negative logarithm of Hydrogen ion concentration, which strongly affects microbial growth.
81
ACIDOPHILES
Microorganisms that grow between pH 0 and 5.5.
82
NEUTROPHILES
Microorganisms that grow between pH 5.5 to 8.0.
83
ALKALIPHILES
Microorganisms that grow between pH 8 to 14.
84
Optimum pH for microbial growth
The middle of the pH range from pH 6 to 8.
85
Most Bacteria pH tolerance
Minimum pH 4, maximum pH 9.
86
Molds and Yeasts pH tolerance
Broader pH range with optimum pH 5 to 6.
87
AEROBES
Organisms that can survive and grow in an oxygenated environment, typically in standard air atmosphere (21%).
88
ANAEROBES
Microorganisms which may be poisoned by oxygen and cannot grow in an air atmosphere.
89
TOLERANT ANAEROBES
Anaerobes that can tolerate low concentrations of oxygen.
90
STRICT ANAEROBES
Anaerobes that are killed by brief exposure to oxygen.
91
FACULTATIVE ANAEROBES
Anaerobic bacteria that do not require oxygen for growth but may use it for energy production if available.
92
MICROAEROPHILES
Organisms that can use oxygen but cannot withstand the level present in the air (21%) and usually grow best at oxygen levels between 1% and 15%.
93
HYDROSTATIC PRESSURE
The pressure exerted on the cells by the movement of water resting on top of them.
94
Barophiles
Pressure-dependent microbes that need a high-pressure environment in order to grow.
95
Deep-sea environment
An environment where pressure exceeds 380 atm, such as ocean floors and deep lakes.
96
Bacterial growth curve
A characteristic growth curve that shows the growth pattern of bacteria when a suitable liquid medium is inoculated and incubated.
97
Lag phase
The time period in which bacteria are metabolically active but do not divide; characterized by no increase in the number of cells.
98
Log phase or exponential phase
A phase during which bacteria divide continuously at a constant rate, leading to exponential growth.
99
Stationary phase
A phase where bacterial growth reaches a state with no net increase in population, maintained by a balance between cell division and cell death.
100
Death phase or decline phase
A phase where the number of bacteria decreases continuously and exponentially, often due to depletion of nutrition and accumulation of toxic wastes.
101
Generation time
The time it takes for a bacterial population to double in number, usually determined during the log phase.
102
Nutrient depletion
A condition that can induce the stationary phase due to lack of essential nutrients in the growth medium.
103
Toxic metabolic wastes
Substances that accumulate in the growth medium and can contribute to the transition into the stationary and death phases.
104
Viable count
The measurement of live bacteria in a population, which decreases during the death phase.
105
Total count
The measurement of all bacteria in a population, including both live and dead cells.
106
Bacterial population
The total number of bacteria present in a given environment or culture.
107
Metabolically active
A state in which bacteria are engaged in metabolic processes but are not dividing.
108
Cell division
The process by which a bacterial cell divides to form two new cells, occurring primarily during the log phase.
109
Physiological activities
The various metabolic processes that bacteria must carry out, which require enzyme and co-enzyme synthesis during the lag phase.
110
Environmental adaptation
The process by which microorganisms adjust to new conditions in their environment, particularly during the lag phase.
111
Balanced growth
A state during the log phase where the rate of cell division equals the rate of cell death.
112
Exponential growth
A rapid increase in bacterial numbers during the log phase, characterized by constant division rates.
113
Bacterial density
The concentration of bacteria in a given volume, which can affect growth phases.
114
Bacterial cell death
The process by which bacterial cells lose viability, contributing to the decline phase.
115
Adjustment phase
The period during the lag phase where bacteria prepare for division by synthesizing necessary components.
116
Logarithm (10) of Viable Cells
A mathematical function used to express the number of viable cells in a population.
117
Lag phase
The initial phase where bacteria have the maximum cell size before division.
118
Log phase
The phase where cells are smaller and stain uniformly.
119
Stationary phase
A phase where cells are Gram variable and show irregular staining due to intracellular storage granules; sporulation occurs.
120
Decline phase
The phase where involution forms are common.
121
Generation time
The time interval required for the cells (or population) to divide.
122
Generation time formula
G=t/n, where G is generation time, t is time, and n is the number of generations.
123
Bacterial growth equation
B = Bx2n, representing growth by binary fission.
124
Logarithmic growth calculation
Log b = log B + n log2, used to solve for n.
125
Generation time calculation
G = t / (3.3 log b/B), used to solve for G.
126
Example of generation time calculation
For a population increasing from 10,000 to 10,000,000 cells in four hours, G = 24 minutes.
127
Direct cell counts
A method to measure bacterial growth by counting cells directly under a microscope.
128
Viable cell counts
A method to measure the number of living cells in a population.
129
Measuring biomass
A method to quantify the total mass of microorganisms in a sample.
130
Measuring cell products
A method to assess the metabolic products produced by cells.
131
Direct Microscopic Count
A method where a measured volume of bacterial suspension is placed on a microscope slide.
132
Hemocytometer
A device used for counting eukaryotic microorganisms in direct microscopic counts.
133
Petroff-Hausser Counting Chamber
A device specifically designed for counting bacteria.
134
Disadvantages of direct cell counts
Difficult to distinguish living cells from dead cells and requires large populations for accurate results.
135
Electronic counting chambers
Devices that count numbers and measure size distribution of cells.
136
Coulter counter
An electronic device that gives accurate results with larger cells but is not useful for counting bacteria.
137
Microscopic count method
Counting all cells in several large squares and averaging the numbers.
138
Bacterial suspension
A liquid containing bacteria used for counting and measuring.
139
Grid with 25 large squares
A feature of a hemocytometer used for counting cells.
140
Flow cytometer
A device used to analyze the physical and chemical characteristics of cells or particles in a fluid as they pass through a laser.
141
Coulter Counter
An electronic device that counts and sizes particles suspended in a fluid based on the Coulter Principle.
142
Viable count
A measurement of the number of living cells capable of multiplication in a sample.
143
Colony Forming Unit (CFU)
A unit used to estimate the number of viable bacteria or fungal cells in a sample, where each CFU represents a colony that can grow from a single viable cell.
144
Plating Techniques
Methods that involve spreading a sample of a culture on a nutrient agar surface to count viable cells.
145
Spread-plate method
A technique where a diluted sample is pipetted onto the surface of an agar plate and spread evenly.
146
Pour-plate method
A technique where a sample is pipetted into a sterile plate, mixed with molten agar, and then allowed to solidify.
147
Turbidity Measurements
A method that uses light scattering to determine the concentration of cells in a suspension.
148
Optical density
A measure of how much light is scattered by a suspension of cells, directly related to cell mass or number.
149
Spectrophotometry
A technique that measures the absorbance of light by a sample to determine bacterial concentration.
150
Standard curve
A graph that relates the optical density of a suspension to the actual cell concentration, used for calibration.
151
Dry Weight Measurements
A method of measuring the dry weight of microbial cells after centrifugation to assess biomass.
152
Microbial Dry Weight Determination
A technique for measuring the growth of fungi by assessing the dry weight of cells in liquid samples.
153
Incubation
The process of maintaining environmental conditions suitable for the growth of microorganisms.
154
Sensitivity of turbidity measurements
Limited to about 10^7 cells per ml for most bacteria.
155
Light Source in Spectrophotometer
The component that emits light to be transmitted through the sample in a spectrophotometer.
156
Detector in Spectrophotometer
The component that measures the amount of light transmitted through the sample.
157
Monochromator
An optical device that isolates specific wavelengths of light for analysis in a spectrophotometer.
158
Cuvette
A small, transparent container used to hold samples for spectrophotometric analysis.
159
Digital Display in Spectrophotometer
The component that shows the absorbance readings from the spectrophotometric analysis.
160
Cultural conditions
The specific environmental factors required for the growth of microorganisms.
161
Clumps or chains of cells
Aggregates of bacteria that can develop into a single colony, complicating colony counts.
162
Advantages of Viable Counts
Sensitive detection of a single cell and allows for positive identification of the organism counted.
163
Disadvantages of Viable Counts
Only living cells develop colonies counted, and cultural conditions may not support all organisms.
164
Filamentous bacteria growth determination
Only way to determine growth of filamentous bacteria.
165
Rapid and easy measurement
It is rapid and easy.
166
Time-consuming measurement
Time consuming; not very sensitive.
167
Culture quantity requirement
Needs several hundred millions of culture to collect a sufficient quantity.
168
Dry Weight Measurements
Dry at 100ºC for 6 to 24 hours.
169
Chemical Constituents Measurements
Direct chemical measurement: chemical component of the cells (e.g. total N, total protein, or total DNA content).
170
Determination of Cell Constituent
The total quantity of the cell constituent is directly related to the total microbial cell mass.
171
Total protein or nitrogen determination
Milliequivalent of the product/ml.
172
Bacterial cell products
Acid; Gases; ATP (Firefly luciferase catalyzes light-emitting reaction when ATP is present).
173
Synchronous culture
A bacterial culture in which all cells are at the same stage of the cell cycle at a given time.
174
Simultaneous bacterial division
The bacterial population divides almost simultaneously, allowing researchers to study specific phases of growth and cellular processes more precisely.
175
Synchronous growth pattern
Step-like growth pattern indicates that all cells of the population divide at about the same time.
176
Synchronization of bacterial population
By careful selection of cells that have just divided, a bacterial population can be synchronized in the bacterial cell division cycle.
177
Duration of synchrony
Synchrony can be maintained for only a few generations.
178
Hypothetical synchronous growth
A hypothetical situation in which the number of cells in a culture would increase in a stair-step pattern, dividing together at the same rate.
179
Nonsynchronous growth
A natural situation in which an actual culture has cells dividing at one rate and other cells dividing at a slightly slower rate.
180
Methods to Achieve Synchronous Culture
Selection by Induction (Physical or Chemical Triggers).
181
Temperature shifts
Sudden changes in temperature can synchronize cell division.
182
Nutrient starvation and replenishment
Depriving bacteria of an essential nutrient (e.g., nitrogen or phosphate) and then reintroducing it forces cells to restart synchronized growth.
183
Size-based selection
Young, newly divided cells are smaller; filtering or centrifuging bacteria can separate cells of similar size and age.
184
Chemical inhibitors
Certain chemicals (e.g., hydroxyurea) can temporarily block DNA replication, synchronizing cells when the inhibitor is removed.
185
Chemostat cultivation
A continuous culture system where nutrients are added at a controlled rate, ensuring cells grow synchronously.
186
Advantages of synchronous culture
Helps study cell cycle regulation and bacterial division.
187
Utility of synchronous culture
Useful in analyzing DNA replication, metabolism, and gene expression at specific growth phases.
188
Reproducibility in experiments
Allows better reproducibility in experiments related to antibiotic effects or metabolic studies.
189
Limitations of synchronous culture
Difficult to maintain perfect synchronization over multiple generations.
190
Stress from synchronization methods
Some synchronization methods may stress bacteria, affecting normal physiology.
191
Continuous Culture
A bacterial culture system in which fresh nutrients are constantly supplied, and waste products are removed, allowing bacteria to grow indefinitely in a steady-state condition.
192
Batch Culture
A culture where nutrients are depleted over time, unlike continuous culture which maintains bacterial growth at a desired phase.
193
Chemostat
A bioreactor where the growth rate is controlled by limiting a specific nutrient (e.g., glucose, nitrogen).
194
Dilution Rate
The rate of adding fresh medium that determines the bacterial growth rate in a chemostat.
195
Turbidostat
A system that maintains a constant cell density by continuously adjusting the medium flow based on optical density (turbidity).
196
Steady-State Growth
Cells remain in a constant physiological state.
197
Better Control
Researchers can control growth conditions such as pH, oxygen levels, and nutrient concentration.
198
Industrial & Biotechnological Applications
Uses in fermentation, enzyme production, and wastewater treatment.
199
Efficiency of Continuous Culture
More efficient than batch culture as it reduces downtime since the culture doesn't need frequent restarting.
200
Limitations of Continuous Culture
Requires precise control systems to maintain stability, risk of contamination over long periods, and genetic mutations can accumulate, altering bacterial behavior.
