21th Lecture: 9/12/14

Topic: Microbial Metabolism and Nutritional

Notes:
1) Aerobic respiration is the production of ATP from glucose and oxygen. Oxygen acts as the final acceptor of electron. The theoretical maximum number of ATP generated per glucose in prokaryotes is 38 and in eukaryotes in 36 to 39.

C₆H₁₂O₆ + 6O_{2  yields} 6CO₂ + 6H₂O + energy (ATP)

• Glycolysis
• Transition reactions
• Citric acid cycle
• Electron transport chain and chemiosmosis

2) Anaerobic respiration is the production of ATP from glucose but in the absence of oxygen. The final electron acceptor is inorganic molecules such as nitrate, sulfate. Lactic acid produced will converted back into energy. The number of ATP produced is 36 ATPs or lesser.

3) Fermentation happened when the cells cannot respire and unable to recycle reduced electron carriers. Organic molecules are their electrons acceptor. There are two types of fermentation:

    a) Lactic acid fermentation -  (human and lactic acid bacteria)

Glucose oxidized to pyruvate. 2 molecules of pyruvate are reduced by 2 molecules of NADH to 2 molecules of lactic acid. Homolactic organisms only produce lactic acid.

    b) Alcohol fermentation - (yeast and some bacteria)

Glucose oxidized to pyruvate. 2 molecules of pyruvate converted into 2 molecules of acetylaldehyde and 2 molecules of carbon dioxide. Acetylaldehyde is reduced by NADH to produce ethanol. Heterolactic organisms use the pentose phosphate to produce lactic acid and ethanol.

4) Different types of bacteria produce different alcohol and products. For example, Saccharomyces produce ethyl alcohol and carbon dioxide. Clotridium produces Butyric acid, butyl alcohol, acetone, isopropyl alcohol, carbon dioxide and hydrogen.

5) Photosynthesis is the process in which light energy is trapped and converted to chemical energy.

6CO₂ + 6H₂O in the presence of light and chlorophyll yields C₆H₁₂O₆ + 6O₂

"Carbon dioxide is reduced to produce glucose and water is oxidised to produce oxygen.

6) Carbon fixation is a process convert carbon dioxide into organic form. It is a light-independent reaction and the most common pathway for carbon fixation is Calvin cycle.

7) ATP, NADH and precursor molecules metabolites formed will then used to synthesize subunits. The end products for carbohydrate catabolism is carbohydrate, the end products for protein catabolism is amino acid and the end products for lipid catabolism is glycerol and fatty acid.

8) Source of energy: Light (photo-) or inorganic or organic compounds (chemo-)
    Source of carbon: Carbon dioxide (auto-) or organic molecules (hetero-)
    Source of electron: Reduced inorganic molecules (litho-) such as H2O, H2, H2S, S, iron, N or organic molecules ( organo-)

9) 

Name	Energy source	Carbon source	Electron source
Photolithoautotroph	Light	Carbon dioxide	Reduced inorganic molecules
Photoorganoautotroph	Light	Carbon dioxide	Organic molecules
Photolithoheterotroph	Light	Organic molecules	Reduced inorganic molecules
Photoorganoheterotroph	Light	Organic molecules	Organic molecules
Chemolithoautotroph	Inorganic or organic molecules	Carbon dioxide	Reduced inorganic molecules
Chemoorganoautotroph	Inorganic or organic molecules	Carbon dioxide	Organic molecules
Chemolithoheterotroph	Inorganic or organic molecules	Organic molecules	Reduced inorganic molecules
Chemoorganoheterotroph	Inorganic or organic molecules	Organic molecules	Organic molecules

10) Mixotrophic organisms can alter metabolic pattern in response to environmental changes. For example:
Purple nonsulfur bacteria can undergo photoorganoheterotroph  in the absence of oxygen and undergo chemoorganoheterotrophs in the presence of oxygen.

Activities: No other activity except for teaching...^^

My own explorace:

1) Why the number of ATP produced have a range from 36 to 38?
It is because 2 ATP produced in glycolysis are used in transporting pyruvate and NADH2 into mitochondria. It is an active transport.

2) Why baby or older people cannot take too much probiotic?
The excessive probiotic will be hyperactivated and produce too much of enzyme and waste products. These are harmful to baby and older people.

3) Gas chromatography can use to determine the alcohol produced by different bacteria.

4) What is biofuel？
Biofuel is fuel that contains energy that are produced from living organisms. Alcohol will produced by the actions of microorganisms and enzymes through the fermentation of sugars or cellulose. The fermentation of sugars derived from wheat, corn, sugar cane and oil palm.

5) What are the function of precursor metabolites?
Precursor metabolites are intermediate molecules that can be either oxidize to generate ATP or marcomolecular subunits such as amino acid, lipids. Examples of precursor metabolites: pyruvate, ribose-5-phosphate, acetyl Co-A

6) Why archaea can resist to heat, cold, acid?
Archaea have membrane composed of glycerol-ether lipids which make them more resistant because ether are more chemically resistant than ester bonds. Besides that, in most archaea cell wall forms S-layer which is a rigid array of protein molecules that cover the outside of the cell and provides both chemical and physical protein. Acetylalosaminuronic acid in achaea also makes them stronger than bacteria. 

Reflection:
Yakult Factory visit
Yakult is a probiotics cultured milk and the bacteria strain inside this cultured milk is known as Lactobacillus casei Shirota strain. Shirota strain dicovered by Dr. Minoru Shirota in 1930 and introduced to the market in 1935. "Yakult" is an international word which means sour-milk. The requirements for probiotic have three: 1）They can live in intestines. 2）They reach intestines alive. 3) They have beneficial effect. The beneficial effects of Shirota strain are increase the number of good bacteria in the intestines and suppressed the number of harmful bacteria. They help in bowel movement and digestion.

The root of Yakult business is based on Shirota-ism:
a) Preventive medicine
b) A healthy intestine leads to a long life
c) A healthy life for all with affordable price

The process in making Yakult:
1) Shirota strain will be cultured in seed tank. The mother bacteria is imported from Japan and the sugar are inported from Australia. Milk powder, water, sugar and glucose are mixed to make sweet milky solution. The milky solution then mix with live Shirota stain in culture tank and leave for fermentation until it reach a ideal concentraion.
2) The plastic bottles are produced by moulding machine. The plastic bottles are then wrapped with bottles labels and stick the straw on the bottles.
3) The labelled empty bottles will then filled by yakult and capped with foil lid.
4) The 5 bottles-pack Yakult will also be loaded in a crate. All the crate will store in cold room at 5 degree celcius. Yakult stored in cold room are now ready for delivery.

From this factory visit, I have learnt a new bacteria strain. Shirota strain acts as probiotics in our body and Yakult even included in patient meal in hospital.  Before visit Yakult factory, I do not know that Yakult is that good. From few experiments they showed to us, Yakult is proven to be a good healthy probiotic cultured milk. We can consume 1 to 2 bottles of Yakult per day. It is a waste of money and bacteria strain to consume more than 2 bottles of Yakult per day but it is not harmful to our body.