ChE 4109 - Growth Kinetics (Batch)

Growth

It is the most essential response to physicochemical environment.

Growth

For cells, it is the replication and cell size.

Unstructured-Distributed Model

It is a model for cellular growth kinetics in which cells are represented by a single component, which is uniformly distributed throughout the culture.

Structured-Distributed Model

It is a model for cellular growth kinetics in which multiple cell components, uniformly distributed throughout the culture interact with each other.

Unstructured-Segregated Model

It is a model for cellular growth kinetics in which cells are represented by a single component, but form a heterogeneous mixture.

Structured-Segregated Model

It is a model for cellular growth kinetics in which cells are composed of multiple components and form a heterogeneous mixture.

Unstructured-Distributed Model

For this model, only one component in the medium is rate limiting.

Autocatalytic Reaction

The type of reaction for microbial growth.

True

TRUE OR FALSE:

Quantifying cell concentration is critical for the determination of cell growth kinetics and for the design and analysis of bioreactors.

Direct Method

This method for quantification of cell concentration is not feasible due to the presence of suspended solids or interfering compounds

Hemocytometer

It is a direct cell number counting on a calibrated grid (cells/grid square) using microscope counting stain of live and dead cells.

Hemocytometer

For this cell number concentration counting method particle-free suspension is needed and usually for non-aggregated cells.

Plate Counts Method

In this cell number concentration counting method, culture samples are diluted and spread on agar surface and incubated

Plate Counts Method

In this cell number concentration counting method, it is more suited for bacteria & yeasts where colonies are counted and used as number of colony forming units (CFU)

Particle Counter

In this cell number concentration counting method, based on high electrical resistance of cells in an electrolyte solution sucked up into a vacuum chamber with one electrode.

Particle Counter

In this cell number concentration counting method, electrical potential is applied across the electrodes and measured resistance (pulses) is directly related to cell concentration

Nephelometer

In this cell number concentration counting method, cells scatter light & the scattered light intensity is measured using a phototube.

Nephelometer

In this cell number concentration counting method, intensity of scattered light is directly proportional to cell concentration and best for dilute cell suspensions.

Packed Cell Volume

In this quantification of cell mass concentration, fermentation broth is centrifuged in a graduated tube and volume of cells are measured.

Spectrometer

In this quantification of cell mass concentration, absorption of light by suspended cells in culture media and particle-free suspension is needed.

Spectrometer

In this quantification of cell mass concentration, extent of light transmission is a function of cell density and thickness of the chamber.

Spectrometer

It is a fast, inexpensive and simple method of counting cell mass concentration where in optical density is measured.

Product Formation

In this quantification of cell mass concentration, products of cell metabolism such as ethanol and lactic acid can be related to microbial growth.

Product Formation

In this quantification of cell mass concentration, viscosity of broth correlated with extent of microbial growth.

Batch Culture

It is when cells grown in liquid nutrient medium (constant volume) and take up dissolved nutrients and convert into biomass.

Lag Phase

It occurs immediately after inoculation & is the period of adaptation and change in cell number is zero.

Lag Phase

During this phase, cells reorganize their molecular constituents when put into new medium and cell mass may increase, but not cell number density.

5 to 10%

The inoculum size should be what percent of the growth medium by volume?

Diauxic Growth

It is defined by multiple lag phases in the middle of growth cycle.

Diauxic Growth

It is due to cells adapting to the second carbon source when the first substrate is exhausted.

Exponential Phase

It is post adaptive phase and progressive doubling of cell number, thus also called as logarithmic phase.

Exponential Phase

During this phase, cells multiply rapidly, cell mass & cell density increase exponentially with time.

Balanced Growth

The term for which all cell components grow at the same rate.

Exponential Phase

In this phase, the nutrient concentrations are large, hence growth rate is independent of nutrient concentration.

Deceleration Phase

It follows exponential phase where in growth decelerates due to depletion of essential nutrients or accumulation of toxins.

Deceleration Phase

This will results to unbalanced growth where cell composition & size will change.

Stationary Phase

This phase starts when net growth rate is zero and cell mass concentration is constant, but viable cells decrease.

Stationary Phase

During this phase, cells are metabolically active & produce secondary metabolites due to metabolite deregulation

Endogenous Metabolism

Cell catabolizes cellular reserves for new building blocks and for energy-producing monomers.

Maintenance Energy

Cells spend this energy to maintain energized membrane, transport of nutrients, motility, and repair damage.

Growth Termination

It is due to exhaustion of nutrients & accumulation of toxins and inhibitory product formation.

Death Phase

It is due to nutrient depletion and/or toxin accumulation.

Death Phase

During the early stage of this phase, re-establishment of the culture is possible.

Narrow Distribution

In this type of distribution, cell death occurs simultaneously.

Broad Distribution

In this type of distribution, fraction of the population survives & can be used to re-establish the culture.

Stoichiometric Parameter

This parameter is used to define growth kinetics better.

Yield Coefficients

It can be defined based on the amount of consumption of another material.

Maintenance Coefficient

It is used to describe the specific rate of substrate uptake for cellular maintenance.

1. Growth-associated

2. Non-growth-associated

3. Mixed-growth-associated

Types of microbial products

Growth-associated Product

It is produced along with microbial growth and the specific rate of product formation is proportional to the specific rate of growth.

Growth-associated Product

An example of this product formation is ethanol production by anaerobic fermentation of glucose by yeast.

Non-growth-associated Product

It is produced at the end of log phase and at the start of stationary phase.

Non-growth-associated Product

The specific rate of product formation is constant and secondary metabolites are formed when growth rate is zero.

Non-growth-associated Product

An example of this product formation are antibiotics.

Mixed-growth-associated Product

This takes place during slow growth phase and stationary phase

Mixed-growth-associated Product

An example of this product formation are lactic acid fermentation and xanthan gum.