lecture3&4)

Fermentation
What is the fermentation?
Fermentation is a metabolic process, which converts carbohydrates to alcohols, organic acids or gases by the activity of enzymes of microbial origin. Microbes involved in fermentation process: Bacteria and Fungi.
The process of anaerobic respiration in the muscle cells of animals during exercise, which produce lactic acid, is also a type of fermentation. The technique of fermentation was very ancient in origin Egyptians and Sumerians had the knowledge of the technique of converting starchy grains to alcoholics
For a microbiologist, the word ‘fermentation’ means many processes such as:
1-A method of mass cultivation of microbes under aerobic or anaerobic conditions
2-Any biological process occurs in the absence of oxygen
3-Spoilage of food by microbial activity
4-Production of alcoholic beverages, organic acids, antibiotics or biopolymers
5-Partial oxidation of carbohydrates
In the biochemical sense the term fermentation, refer to a metabolic process in which organic compounds (particularly carbohydrates) are broken down to release energy without the involvement of a terminal electron acceptor such as oxygen.
The term fermentation can be also be applied to any industrial process that produce a material that is useful to human and if the process depends on the activity of one or more M.Os. This processes known as industrial fermentation, are usually carried out on large scale and in a vessels in which the organisms are normally grow on liquid media.
What is industrial fermentation? The intentional use of fermentation technology for the large-scale production of microbial biomass or metabolites is called industrial fermentation. Fermented products have immense use in food, medicine and other industries. Modern industrial fermentation units use genetically engineered microbes for the rapid production of desired metabolites.
A vast range of materials is produced by industrial fermentations and these includes:
1- Organic chemicals used as fuels, food additives (yeast extract from yeast cells produced as bio product of brewing industry), antibiotics and enzymes for use in the food and other industries. Vinegar is an example of a food additive produced by industrial fermentation.
2-Food produced on a large scale as a result of the activities of microorganisms. E.g. cheese, yoghurt and bread.
3-Production of alcoholic beverages.
Materials produced by industrial fermentation can be divided in to four groups:-
1 -Microbial biomass such as organisms produced on a large scale for the extraction of protein(single cell protein)that can be used as a part of the of the human diet.(Quorn is an example of a single cell protein produced by the fungus Fusarium graminearum m the mycoprotien purified from fungi is used as food and incorporated with a high dishes, Mushroom production another process that can be considered as industrial fermentations.
2-Microbial enzyme
3-Microbial metabolite:
A-Primary metabolite products: microorganisms produce it s during the log phase (trophophase) many essential materials very important in it is growth such as amino acids, nucleic acids, nucleotides, proteins, lipids, carbohydrates.
B-Secondary metabolite products: microorganisms produce it s during the stationary phase (idiophase) these substance have no relation with the growth processes these product used in pharmaceutical manufacturing industry.
4-Bioconversions: M.Os cells were used for modifying special compounds been added previously to the culture media, to other compounds close to it (from the chemical level) but its more valuable on the commercial level. The bioconversion include hydration, oxidation, hydroxylation…ets.
The bioconversion characterized from the ordinary chemical conversion by the specialization and that can work with in low temperature and with the absence with the heavy metals that cause pollution for example production of acetic acid from alcohol solutions it produce by oxidation of ethanol by Acetobacter.
Increasing the production of primary metabolites:
While the cell cannot produce large scale of primary metabolites because of cellular control; there is some way to increase the production:
1-Genetic modification: the purpose of this to get high productive strains
2-Modification of culture components: this can lead to change the permeability of cell membrane or to increase the production.
Control and regulation of secondary metabolites process:
The control over this process can be done by many way:
1-By controlling the chromosomes that determination the genetic information which responsible for production and creation the enzymes which taking a part in its production.
2-Controlling the energy quality represented by ATP, ADT, AMP
3-Controlling the culture material.
General features of secondary metabolites:
1-These materials have no relation to the growth processes especially the log phase, that is why it does not show up in idio phase or reproductive phase.
2- These materials are produced by the cells within stationary phase and sometimes produced by cells that are within very low growth rate cells.
3- Most of the secondary metabolites materials are either antibiotics or pharmacological materials or toxins extrinsic enzymes. some of these materials have no physiological action regarding the M.Os but it has a basic action in some of high specialized biological activity.
4- Most of the secondary metabolites materials are secreting out of the cells.
5- The secondary metabolites materials are produced in high quantity in compare with primary metabolites materials.
6-These materials are produced by a specials group of M.Os or plants
7-The creation paths that by it these materials produced are very limited and most of it have relation with the primary metabolites materials, it is coming from specific materials during the paths.
What is a fermenter?
The fermenter: is a tightly sealed reaction chamber in which a controlled reaction can take place. It keeps any contaminants (biotic and abiotic alike) from disturbing or even spoiling the enclosed reaction mechanism.
The heart of industrial fermentation is a ‘Fermenter Fermenter is type of bioreactor.
Fermenter: a system provided with controlled environmental conditions for the growth of microbes in liquid culture and production of specific metabolites.
A-It is a device in which the microbes are cultivated and motivated to form the desired products
B- It is containment system to provide the accurate environment for the optimum growth and metabolic activity of the microbes.
C- Fermenter prevents the entry and growth of contaminating microbes from outside.
D- Fermenter: containment system for the cultivation of prokaryotic cells (bacteria) and fungi
E- Bioreactor: containment system for the cultivation of mammalian or insect cells

Fermenter (fig 1)
What are the different types of fermentation process / methods?
There are three types of industrial fermentation processes based on the methods of fermentation and types of fermenters
1-Batch fermentation
2-Continuous fermentation
3-Fed-batch fermentation
1-Batch Fermentation:
1- Microorganism is inoculated into a fixed volume of medium
2- As the growth takes place, the nutrients are consumed and the product of growth accumulates in the fermenter
3-Product of growth may be of two types: (a) Biomass and (b). Metabolites
4-The nutrient environment in the fermenter is continuously changed
5-This change in the environment in the fermenter will enforce change in the metabolism of cells
6-This also results in the cessation of cell multiplication
7- Cessation of growth is due to the scarcity of nutrients and accumulation of metabolites
8-Once the microbes reached the stationary phase they start to accumulate the metabolites
9-Metabolites are extracted from the fermenter by downstream processes
10-After the fermentation is over, the residues are taken out from the fermentation tank, and the vessel is then cleaned and sterilized before next batch of fermentation
11-Thus in batch fermentation, the large scale production is done as separates ‘batches’
12-Microbes in the batch culture show the following pattern of growth with distinct phases


(1)Log phase: initial phase, no apparent growth of microbes, they adapt to the environmental conditions
(2)Transient acceleration: the inoculum begins to grow slowly.
. (3)Exponential phase: microbial growth proceeds at the maximum possible rate
(4)Deceleration phase: decline in the growth rate of microbes
(5)Stationary phase: no overall growth rate (death of the cells equals to the division of cells). Most of the secondary metabolites are produced in this phase
(6)Death phase: no growth at all, cells starts to die and the population size decreases. Usually the fermentation stops before the death phase.
The batch cultures characterized by it is contain limited quantity of nutrient materials the inoculate has been added at the beginning of the fermentation and under changeable circumstances like the concentration of the growth suppressing nutrient material and pH may change during the fermentation and the side products increase more as time pass, the air supply by shaking the culture with the vibratory.
(2). Continuous Fermentation: