Use Of Bacteria In Nutrition

Question 1

What are the main factors that control growth of the microorganism

Answer 1

Availability of carbon, nitrogen and any specific nutrients required
- Substrate pH
- Incubation temperature
- Moisture content
- Redox potential
- Stage of growth of micro-organism
- Presence of other competing micro-organism

Question 2

What are the main advantages of fermentation

Answer 2

Use of mild pH and temperature to maintain and/or improve nutritional and sensory quality
- Produce flavour and texture that cannot be achieved otherwise
- Low energy consumption due to mild operation procedures
- Generally simple technology

Question 3

What is a batch culture

Answer 3

Batch culture is a closed system where all nutrients are supplied at the start, and nothing (except gases, pH agents, or antifoam) is added or removed during the process.
• The culture proceeds through typical growth phases: lag, log, stationary, and decline, as nutrients are gradually depleted and waste accumulates.
• Once nutrients are exhausted or the desired product is reached, the process stops, and the culture is harvested.

Question 4

What is a continuous culture

Answer 4

Continuous culture is an open system where fresh nutrients are continuously added, and culture broth (containing cells and products) is simultaneously removed at the same rate, keeping the culture volume constant.
• This setup maintains the cells in a steady state, typically in the exponential (log) growth phase, allowing for consistent product yield over extended periods.
• Continuous cultures can last for days or weeks, and are used for processes that benefit from constant conditions and high productivity

(Used more in industry as does not require stopping and cleaning but takes a long time)

Question 5

What are the two main methods of fermentation

Answer 5

Batch culture and continuous culture

Question 6

What are homofermentative microorganisms

Answer 6

Produce a single byproduct

Question 7

What are Heterofermentative micro-organisms

Answer 7

Produce more than one byproduct

Question 8

What are the most important commercial fermentations

Answer 8

Lactic acid and ethanol

Question 9

What do many fermentations involve

Answer 9

complex mixtures of micro-organisms or sequences ofmicroorganisms

Question 10

What are microorganisms described by in lactic acid fermentations

Answer 10

Acid tolerance i.e. Lactobacillus casei (1.5 - 2%)
- Lactobacillus bulgaricus (2.5 - 3%)

Question 11

Why is a starter culture added in lactic acid fermentation

Answer 11

• to generate large numbers of the desired culture rapidly
• To reduce fermentation time
• To inhibit growth of pathogens and spoilage bacteria

Question 12

What is pickling

Answer 12

Pickling includes the use of lactic acid fermentation and the use of salt (16%)

Question 12

How are buttery products produced

Answer 12

Production of “buttery” aroma of milk products by fermentation of citrate in milk by micro-organisms to aldehydes, ketones and organic acids

Question 13

How is beer wort used to produce alcoholic drinks

Answer 13

Use of hop extracts and dextrose syrups to increase product uniformity
- Higher temperature shorter-time boiling to reduce energy consumption
- Varlation in the composition of the wort, strain of yeast, fermentation time and conditions results in a wide range of beers
- Substrates are from barley, millet, sorghum, maize

Question 14

What is pickling

Answer 14

Pickling includes the use of lactic acid fermentation and the use of salt (16%)

Question 15

How is wine must used to produce alcoholic drinks

Answer 15

Sugars from the must are fermented to produce 6-14% ethanol
- Lactic acid bacteria produce acidity to improve flavour and
aroma

Question 16

What are bacteria cell factories

Answer 16

living organisms that produce medically or commercially useful biomolecules (antibiotics, enzymes, drugs, hormones etc.)

Question 17

What is the advantage of biotechnology/ bacterial cellular factories

Answer 17

Main advantage is that cells do the hard work…
- Bacterial cultures grow quickly and easily, input materials often cheap and environmentally friendly…
- …whereas chemical synthesis can be difficult, laborious and involve expensive and toxic reagents

Question 18

How are antibiotics produced by bacteria

Answer 18

Secondary metabolites produced naturally by bacteria

Question 19

Which vitamin is only produced by certain bacteria and archaea

Answer 19

Vitamin B12

Question 20

What plays a role in the synthesis in B vitamins

Answer 20

Microbiome

Question 21

What are the two types of control of transcription initiation

Answer 21

Positive and negative control

Question 22

What is positive control of transcription

Answer 22

positive control - increases transcription when activators bind DNA

Question 23

What is negative control of transcription

Answer 23

negative control - reduces transcription when repressors bind to DNA regulatory regions called operators

Question 24

How to bacteria respond to changes in their environment

Answer 24

Gene expression

Question 25

What are operons

Answer 25

Genes involved in the same metabolic pathway

Question 26

When are operons induced

Answer 26

Some operons are induced when the metabolic pathway is needed.

Question 27

When are operons repressed

Answer 27

Some operons are repressed when the metabolic pathway is no longer needed.

Question 28

What does the lac operon contain

Answer 28

• The lac operon contains genes for the use of lactose as an energy source.

Question 29

What are the regulatory regions of the lac operon

Answer 29

Regulatory regions of the operon include the CAP binding site, promoter, and the operator.

Question 30

What does the coding region of the lac operon contain

Answer 30

The coding region contains genes for 3 enzymes: - B-galactosidase, permease, and transacetylase

Question 31

What is the lac operon negatively regulated by

Answer 31

Repressor protein

Question 32

How does the the repressor protein work to negatively regulate the lac operon

Answer 32

lac repressor binds to the operator to block transcription

Question 33

What happens to the lac operon in the presence of lactose

Answer 33

in the presence of lactose, an inducer molecule binds to the repressor protein –repressor can no longer bind to operator –transcription proceeds Compounds of interest are able to be produced

Question 34

What is the preferred substrate of bacteria

Answer 34

In the presence of both glucose and lactose, bacterial cells prefer to use glucose.

Question 35

What does glucose prevent

Answer 35

Induction of the lac operon

Question 36

How does glucose prevent induction of the lac operon

Answer 36

binding of CAP - CAMP complex to the CAP binding site is required for induction of the lac operon - high glucose levels cause low CAMP levels - high glucose → low CAMP → no induction

Question 37

What is genetic modification of bacteria/ recombinant protein production

Answer 37

recombinant DNA technologies that enable proteins to be be made in large quantities by bacterial fermentation

Question 38

What if you want to express a mammalian or mutant protein?/ describe recombinant DNA technology

Answer 38

-Firstly we clone the gene of interest into an expression vector, then transform into E. coli Transform -Generates a microbial "factory" for the gene of interest -E. coli "factories" are grown by large scale fermentation • Expression of the gene of interest is induced • Cells are lysed and the expressed protein is purified for research, commercial or medical use

Question 39

What are the advantages of recombinant therapeutics

Answer 39

Huge range of actual and potential applications • Well understood theoretical and practical path to commercialization • Small scale, high value products (therapeutics) and high volume, low cost commodities (enzymes)

Question 40

What is synthetic biology and bioengineering

Answer 40

Synthetic biology is the design and construction of new biological parts, devices, and systems, and the re-design of existing, natural biological systems for useful purposes. • Wide ranging definition - multidisciplinary field • Often uses concepts from engineering

Question 41

What is the advantages of synthetic biology

Answer 41

Synthetic biology takes produces designer organisms: - Engineering complex metabolic pathways to make new compounds - Allows biological solutions to world problems!