Fermentation

Medium formulation is an essential stage in the design of fermentation process. Most fermentation media require liquid media, although some solid-substrate fermentations are also operated. Fermentation media must satisfy all the nutritional requirements of the microorganisms and fulfill the technical objectives of the process. There are several stages where media are required in a fermentation process; inoculum (starter culture), propagation steps, pilot-scale fermentations and the main production fermentations.

According to Cruger W and Cruger A (1990); on a large scale, the sources of nutrients should be selected to create a medium which should meet as many as many possible of the following criteria:

• It should produce the maximum yield of product or biomass per gm of substrate used.
• It should produce maximum concentration of product or biomass.
• It should permit the maximum rate of product formation.
• There should be the minimum yield of undesired products.
• It should be of a consistent quality and be readily available throughout the year.
• It should cause minimal problems during media preparation and sterilization.
• It should cause minimal problems in other aspects of the production process particularly aeration and agitation, extraction, purification and waste treatment.

The initial step in media for media formulation is the examination of the overall process on the stoichiometery for growth and product formation. The optimization of a medium should be carried out such that it meets as many as possible of the seven criteria. Different combinations and sequences of process conditions have to be investigated to determine growth conditions (Stanbury P. F and Whitaker A; 1995). Medium optimization can be carried by the classical method, in which one independent variable is changed while keeping all others at a certain level. An aerobic fermentation process may be represented as: Carbon and energy source + Nitrogen source + O2 + other requirements Biomass + products + CO2 + H2O + heat This primarily involves consideration of the input of the carbon and nitrogen sources, minerals and oxygen and their conversion to cell biomass, metabolic products.

Based on this information, it should be possible to calculate the minimum quantities of each element required to produce a certain quantity of biomass and metabolite According to Prasanthi V et al (2008); Chlorella vulgaris is a green, spherical, single celled fresh water microalga belongs to the phylum Chlorophyta. As per the study conducted so far it is found that green algae are the highest source of chlorophyll in the plant world and particularly, Chlorella one of the members of green algae is the richest source of chlorophyll which is widely used as a health food and feed supplement.

The aim of this work is to design different medium types to evaluate optimization combinations for maximum growth, morphology and pigment content of C. vulgaris. Effect of glucose Three different volumes of glucose from apple juice while other variables are kept constant. The volumes that were used are 5g/l, 15g/l and 30g/l. The highest chlorophyll production (12%) was obtained with a glucose concentration of 15g/l. Glucose is used as a carbon source which is required for all biosynthesis leading to reproduction, product formation and cell maintenance. It also serves as the energy source.

Carbon requirements may be determined from the biomass yield coefficient (Y), an index of the efficiency of conversion of a substrate into the cellular material: Ycarbon (g/g) = biomass produced  Glucose substrate utilized (g) An increase in glucose concentration of 30g/l resulted in the production of chlorophyll being at a constant this is because all the active sites of the microorganism are occupied and active carrying out biochemical reactions. At low glucose concentration of 5g/l very little biomass (chlorophyll) is obtained and also there is low growth rate.

Thus, glucose concentration significantly influences chlorophyll production and microbial growth of the microorganism. Constraints that can be generated include the fact that apple juice not only contains one type of sugar, glucose but also contains other sugars (fructose and sucrose) which the microorganism can either utilise for growth resulting in us not obtaining accurate optimization results and also the other sugars can inhibit the growth of the microorganism. Apple juice also contains soluble pectin these can be difficult to digest hence a reduction in biomass.

Effect of nitrogen from defatted soya Nitrogen being important constituent of the cell protein was needed for algal growth, either in combined or in molecular form. It is also a component of proteins nucleic acids some co-enzymes. Industrially important microorganisms can utilize both inorganic and organic nitrogen sources. Inorganic nitrogen may be supplied as ammonium salts, often ammonium sulphate and diammonium hydrogen phosphate, or ammonia; these can be used in place of defatted soya. Ammonia can also be used to adjust the pH of the fermentation.

As nitrogen deficiency develops the amount of chlorophyll in the cells decreases faster than the nitrogen content in C. vulgaris. Nitrogen is a limiting factor if continually increased it can inhibit the production of chlorophyll. Varying concentrations of nitrogen were used i. e 0. 3g/l, 0,6g/l and 2. 0g/l. At 0. 3g/l little chlorophyll is obtained this is due to the fact that nitrogen being a macronutrient it is required in high concentration. At 0. 6g/l high yields of chlorophyll are obtained and at 2. 0g/l nitrogen turns to be a limiting factor and can lead to culture toxicity.

Constraints can be generated when using Ammonia as a substitute for defatted soya this is due to the fact that ammonia leads to high pH which results in a precipitate formation in the medium but lower pH of the medium prevent the precipitation. Foaming in a microbiological process is due to media proteins that become attached to the air-broth interface where they denature to form stable foam. Non-treatment of foam may block air filters, resulting in loss of aseptic conditions. The foam production can be controlled by addition of chemical antifoam. Natural antifoams include plant oils (e. g. Soya, sunflower and rapeseed), hence defatted soya is used as a nitrogen source rather than ammonia. Also high concentrations of ammonium ions can be toxic to cells of the microbe. Effect of Mg2+ MgSO4 can be used as the source of magnesium. It promotes the maximum growth of the present alga and it is also incorporated as an enzyme co-factor component of chlorophyll. Three salt concentrations were used 0. 1g/l; 0. 5g/l and 1g/l. At low salt concentration of 0. 1g/l it results in a magnesium deficiency which interrupted cell division in Chlorella which results in abnormally large cell formation. Increase in salt concentration of 0. g/l and 1g/l of magnesium alone in the medium resulted in higher cell number, although increase in nitrogen alone did not make much difference that means cells need magnesium to synthesize chlorophyll. The process of multiplication requires a larger concentration of magnesium in the medium than does the production of cell material. Iron uptake is strictly required to optimize the process.

References

1. Crueger W and Crueger A. 1990. A Textbook of Industrial Microbiology. Oxford. Panima Publishing Corporation.
2. Stansbury P. F and Whitaker A . 1995. Principles of fermentation technology. New York. Pergamon Press.
3. Prasanthi V, Yugandhar M. N, Vuddaraju S. P, Nalla K. K, Raju C. A. I and Donthireddy S. R. R. Optimization of the fermentation media using statistical approach and artificial neural networks for the production of chlorophyll by Chlorella vulgaris. International Journal of Natural and Engineering Sciences. 2008. 2 (3): 51-56

Alexandra Mitchell Dr.

Lamont King GAFST 200 November 30, 2010 Sugar Cane Alley Jose understands at a young age that in order to escape the indentured life of working in a sugar cane plantation like his ancestors before him, he must do something different. In the classroom, Jose is a very bright student as seen through his peers and especially his professor who eventually helped Jose get into a prestigious school because of his academic excellence. He assures his grandmother who is his sole provider and family that one day she’ll no longer have to work tirelessly in the sugar cane plantation.Jose dreams of taking work in a more profitable and higher field then the plantation his community is chained to all being done by attaining a high education. Through the life of a plantation worker and the ones seen in Van Onselen’s article as a migration worker, slavery may have been abolished, but their freedom is severely limited. At the end of the film, the plantation workers were singing a song and one line of its lyrics clearly summed up what is needed to end the forced monetary economy many of the African Americans are trapped in, “Money and justice are what’s needed to end our suffering. In his article titled, “Social Control in the Compounds,” Van Onselen does a good job portraying the hard lives of the Chibaro people working in a nearby mine plantation.

These workers paralleled the lives of the ones working in the sugar cane plantation where they were both trapped and limited in their freedom. They were oppressed under the proletarian labor economy that made it difficult to move up in the labor field and many were financially indentured to their plantation living day-by-day and paycheck-to-paycheck.This system made it extremely hard for the African Americans to move around and find better work somewhere else. There was almost total control over the labor and the whole idea of this widespread control was to lengthen its cycle. There were laws passed, credits to pay off, and the inflation of food prices making it a widely controlled monopoly. One law called for labor contracts detailing what was needed of the workers and many were paid by tokens or coupons that proved useless outside the plantation which in turn lengthened the workers time spent at one location.Many Chibaro workers as cited in his article couldn’t even pay off simple life necessities such as groceries, which forced them to have credit further lengthening their stay at each plantation.

Many times the communities only had one grocery store, so for more control, the labor industry would inflate the prices making it nearly impossible for the people to be out of debt and even able to leave their workplace in search of more prominent work availabilities.For example, in the movie, a woman and her family couldn’t afford her groceries so she asked the clerk to put it on their tab which would need to be paid off making their stay permanent until they were free from debt. But this proved impossible to clear debt, because a worker’s paycheck given by the tightly controlled economy never amounted to what a family needed to get by. Mr. Mdeouze acts as a mentor and he opens Jose’s eyes to the corrupt society and how it in some ways mirrors the past.Although they are free from slavery, their freedom is limited by the labor-controlled economy making any further progress beyond the abolishment of slavery nearly impossible, “…we were free but our bellies were empty. ” Mr.

Mdeouze does although make one factor clear to Jose and that is the distinct value of education the power it has. The wise old man cited the life of a free African American man working on the sugar cane plantation perfectly when mentoring young Jose, “learning is second key that opens to our freedom. He is traditional in that he doesn’t believe that he’s a free man and reiterates that he won’t return to Africa until he’s dead and buried. Jose learns through Mr. Mdeouze that Africa has yet to return to it’s roots and white power is still perceived to be the dominant race in it’s every attempt to control all aspects of the African American life and still hold their power to utilize them for hard labor. Leopold is a young mulatto living amongst the plantation and is the son of the white landowner of the Sugar Cane plantation.When his father falls ills and is on his deathbed, he refuses to pass down his position to Leopold with the explanation of it being a white man’s job and not one of a Mulatto.

Leopold lived in his family’s nice home with his African mother then denying the African roots in him by his family’s societal stance. By not allowing Leopold to inherit the plantation as a legitimate landowner, this then denies also the white man roots in him.Therefore by being rejected by both sides of the race spectrum unsurprisingly lead to the demise of Leopold. He found himself hopeless in terms of his identity and in mounds of trouble as seen at the end of the movie. I believe Leopold’s fate was inevitable because he was rejected and out casted in his own community and no longer had an adequate place in society. The tightly controlled labor economy in the early twentieth century made African American’s freedom severely limited.There were all but few ways to escape this corruptly controlled monetary system, but one way was through attaining a higher education as learned by young Jose.

He quickly discovered that education can provide him with more work opportunities and a better life all together. In summary, as seen through the movie and read in the article by Van Onselen, there still seemed to remain obvious elements of slavery in the lives of plantation and mine African American workers even after slavery had been long abolished.

Agitators in fermenter play a major function in blending the medium. Agitation in fermenters improves heat and mass conveyance across the agitation armored combat vehicle. Mechanically moved fermenters are well-suited for usage with shear-sensitive agitations that require good O transportation and majority commixture than the conventional air lift fermenters.

Fermenter, in biotechnology is usually explained as a container where the host cells incorporating the recombinant Deoxyribonucleic acid are grown. In simple footings fermenter is an setup which maintains optimum conditions for the growing of micro-organisms which are used in big scale agitation in the production of enzymes and other chemicals. Basically the fermenter consists of a fomenter either bottom driven or top driven. The most normally used is the fermenter with a top-drive assembly because of its easiness of operation, orderly design, dependability, and hardiness.

Agitators in fermenter play a major function in blending the medium which is invariably aerated which means supplying efficient mass exchange in footings of gas stage and liquid stage ( blending ) by providing nutrition and taking away the metabolites. Mass transportation is enhanced by agitation from the headspace to the majority of the liquid ; it creates less anaerobiotic environment ( microaerophilic ) for agitation, farther decelerating down the agitation clip and upseting the ecological equilibrium.

The chief intent of agitation usually are intermixing of two mixable liquids, fade outing solids in liquids, scattering a gas in a liquid as all right bubbles, suspending of all right solid atoms in a liquid and to increase heat transportation between the fluid and a spiral or jacket in the vas wall. Agitators must able to make self-cleaning and must forestall monolithic subsiding.

Agitation provides practical benefits peculiarly in agitation vass with hapless heat-transfer characteristics. It improves heat and mass conveyance across the agitation armored combat vehicle. By bettering those agitation can cut down temperature heterogeneousness and destroy concentration gradients during agitation, supplying a more unvarying microenvironment for microbic growing. This has positive economic and merchandise quality-related benefits like cut downing the agitation clip, and better standardizing process public presentation and merchandise properties.

Most of the chemical and processing industries depend on effectual agitation and commixture of fluids for most operations. Generally agitation refers to coercing fluid by mechanical agencies to flux in a peculiar form like circulatory or other pattern inside a vas. Blending normally involves scattering two or more separate stages such as a fluid and a solid or two fluids with one another.

Agitation besides has disadvantages peculiarly in industrial agitation procedures. Agitation may interfere with the gel-formation procedure, a cardinal quality property in house yoghurt ( Kristo et al. , 2003 ; Lee and Lucey, 2004 ) and agitation during agitation would suppress the lactic acid formation involved in the procedure ( Driessen, 1998 ; Early, 2000 ) , accordingly widening the agitation clip and perchance changing the quality, there is a possibility of it favoring the incorporation of air into the system, interfering with the agitation kineticss, an anaerobiotic event.

Agitators have different parts and all the traveling parts can be made unapproachable by enveloping underneath the vas, therefore doing it a safer piece of setup. There are different sorts of fomenters with or without motor driven. With the motor belt goaded fomenter any spillage can be avoided by straight falling onto the motor since it is non sited straight below the fomenter shaft. Double mechanical seal in the fomenter is necessary to guarantee that the medium does non leak out at the shaft lodging. Depending upon blending demands the agitation shaft will be provided with two or three impellers, each with four or six blades. It is of import that the exterior coating of the fomenter should fit that specified for the vas. Bigger impeller diameters result in shorter blend clip and lower extremum shear. Though it has benefits it is besides necessary to see the higher cost, increased quiver and larger run-out and more robust design demands associated with larger diameter impellers and greater fluid forces. Orientation and size of fomenters varies with fermenters.

Scale-Up: In production conditions, either the fomenter revolutions per minute is varied or the impeller is changed to obtain similar blending clip. These impellers can run at much higher tip velocities since they convert a bigger fraction of their power input into unstable pumping instead than shear.

There are two chief occupations of fomenters in a cell civilization. First is to obtain the coveted O and C dioxide mass transportation by bring forthing adequate shears which can be characterized by gas mass transportation effectivity and the 2nd is to maintain the vessel well-blended to minimise fluctuations in temperature, pH and linear concentration. The cells inside should be exposed to higher mechanical force or thermic force and or emphasis. The peak shear rate must be kept low plenty to avoid cell harm or emphasis. Bigger the mass transportations is better, because cut downing the fraction of O in the sprinkle gas or flow of sprinkle gas lowers the operating cost and reduces cell harm in certain cell lines. Deluging occurs if the fomenter turns excessively easy for the gas rate and if the gas burden exceeds the implosion therapy point consequences in lower mass transportation. Doppler velocimetry is used to mensurate the shear produced by an fomenter utilizing a optical maser beam to scan the instantaneous speed at points throughout the vas.

The fomenter is preferred to be top mounted which makes it easy to take it during go oning operation and to avoid voidance of fermenter during care work on the fomenter. Airlift type and automatically stirred/ agitated fermenters are widely used in bioprocessing. Airlift fermenters are utile where there is necessity of soft agitation and low cost O transportation and in comparatively less syrupy fluids while the mechanical fomenter is works more expeditiously for higher-viscosity fluids. Normally used fermenter which utilizes mechanical agitation rules chiefly uses radial flow impellers during the agitation procedure.

Top-mounted fomenters are common in smaller vass where they are easier to seal, but do require longer shafts and larger diameter to command run-out and quiver while in big scale production underside mounted fomenters are by and large used where they need shorter shafts of 3m or less. The latter type is easy to manage since the shaft are of smaller diameter and they are cost effectual. It is easy to take the mechanical seal. Agitator must be mounted either on an angle or offset from the vas Centre line when the vas does non hold baffles. Baffled vass with centre top-mounted fomenters are more common.

General Chromium Steel Steel Fomenter With High Opposition to Corrosion

A mechanical fomenter is driven by an explosion-proof motor ( electric motor ) , it has a shaft and cogwheel coupled to a cogwheel box that drives the impeller shaft and may even hold immersed bearings if the shaft is really long. The impellers ( turbines ) transform mechanical power into unstable circulation or agitation. The aim of the properly designed mechanical agitation system are unvarying suspension of solids, appropriate application of shear, homogeneous fluid belongingss throughout the system and economical application of applied power. The rotating parts in a mechanical fomenter are capable to change by reversaling emphasiss that may ensue in metal weariness, failure of shafts, seals and fomenter blades particularly when the environment is temperature specific.

Experimental setup that consists of jacketed 50 milliliter reactor ( Parr, theoretical account 4843 ) with mechanical agitation.

Fermenter with Mechanical Agitation ( www.scielo.br/scielo.php? script=sci_arttext )

During the commixture procedure, the mechanical fomenter plants by turning the mechanical power into thermic energy where the energy ( temperature ) is introduced non-uniformly into the volume. This produces harmful effects to the life beings and agitations in the procedures, which exist merely in limited temperature scope. The commixture can be improved by increasing rates of aeration and mechanical agitation. However, the influence of aeration rate on blending clip was most outstanding merely under conditions of small or no mechanical agitation. The independent agitation reduces the demand for long flow channels besides maintains efficient blending irrespective of merchandise throughput or viscousness.

The fermenter design becomes more complex when mechanical agitation is applied for blending nevertheless it offers considerable advantages in footings of versatility and public presentation. Strong axial commixture is one of the less desirable characteristics of mechanical fomenter.

There are some major disadvantages in utilizing mechanical fomenters such as unsystematic commixture, where it shear fluid and impel it around the commixture vas. High-turbulent and dead zones are formed during blending which consequence in un-uniform nutrition supply to cells, due to mechanical force produced by sociable ‘s beater the microbic cells may decease. Overheating is formed on the terminals of sociable ‘s beater countries ( micro zones ) which are besides destructive for cells.

Mechanical fomenter has merely a motor ; it may hold a provender pump, nevertheless. Mechanical fomenters can non be made on plastic if necessary. Top-entering mechanical fomenters typically require a befuddled armored combat vehicle and it can non blend the armored combat vehicle when it ‘s less full. More dead musca volitanss are formed whilst utilizing a mechanical fomenter. Mechanical fomenter typically needs one impeller diameter of clearance near the armored combat vehicle to supply energy during solid suspension.

A mechanical fomenter by and large uses less energy for liquid blending in armored combat vehicles smaller than 3 thousand Defense Intelligence Agency, but during solids suspension, liquid blending and gas/liquid contacting in large-volume ( over 1,000 gal ) fermenters with mechanical agitation costs higher.

The additive liquid speed in the downcomer increased with the increasing velocity of the fomenter but was non sensitive to the aeration rate, except in the airlift manner of operation ( N=0 revolutions per minute ) . The fact that the liquid speed varied small with aeration rate in automatically agitated operation whereas at a changeless agitation speed the commixture clip declined with increasing rate of aeration suggests that under given conditions of mechanical commixture, the gas bubbles lifting through the fluid were an of import cause of blending. Bubbling frequence additions with increasing aeration rate and the bubbles lifting relation to the liquid carry in their aftermaths a certain sum of fluid. As celebrated earlier, the consequence of mechanical agitation on blending clip was pronounced merely at comparatively low aeration rates. At higher aeration speeds ( UGr?0.04 ms?1 ) , lifting bubbles seemed to the dominant cause of the commixture

Depending on the strength of the mechanical agitation, air sparging of the riser zone may or may non better the commixture public presentation. At sufficiently high aeration rates ( UGr?0.04 ms?1 ) , the usage of mechanical agitation during commixture has lesser importance.

Air lift agitation utilizes compressed air to continuously recycle slurry. Consisting of simple piping, air lift agitation requires no traveling parts and negligible care. The consequence is homogenous slurry. Mechanical impeller will shear certain cells that are less delicate. For the ground the mechanical fomenter, which causes unwanted emphasis and perturbation is removed from the medium. About 70 % of consumed power is used for get the better ofing the defying force ( in a medium ) with mechanical fomenters. In this connexion mechanical power is automatically turned into thermic energy and therefore consequences in excess harmful warming of the civilization. Therefore this excess warming must be removed from the fermenters.

In Airlift Fermenters the civilizations are both aerated and agitated by air bubbles introduced at the underside of vass. The vas has an inner bill of exchange tubing through which the air bubbles and the aerated medium rise since aerated medium is lighter than not aerated one which consequences in commixture of the civilization every bit good as aeration.

The air bubbles lift to the top of the medium and the air passes out through an mercantile establishment. The cells and the medium that lift out of the bill of exchange tubing move down outside the tubing and are recirculated. O2 supply is rather efficient but scaling up nowadayss certain jobs. These sorts of fermenters are now used for production of monoclonal antibodies. The contents are pneumatically agitated by a watercourse of air and or sometimes by gas. In add-on to agitation, this watercourse besides has the of import map of interceding exchange between the gas stage and the medium ; O is normally transferred to the liquid, and in some instances metabolic merchandises are removed through exchange with the gas stage.

Air lift fermenters eliminate the possible grinding jobs encountered in agitated fermenters. Due to take down shear force the extents of cell desorption from atom surfaces would be less as compared to agitated systems while utilizing solid substrates. Air lift fermenters are energy efficient and easy to run, and require merely tight air for aeration and agitation and extinguish the demand of mechanical agitation. Oxygen transportation efficiency is higher than mechanical agitated fermenter.

Lab or pilot workss can non easy air trial because it requires long bubble opposition clip with minimal wall retarding force. The short vass where mechanical agitation is required for good agitation public presentation compared to air agitated fermenters. If the vas has chilling spirals the commixture is good from top to bottom. Air agitated fermenters exist in industry today for a broad scope of merchandises.

Air-Lift Stirred Without Mechanical Seal

The chief advantages in utilizing air lift fermenters are improved asepsis because of no top or bottom come ining agitation shaft, building of really big fermenter is possible because the design is non limited by motor size, shaft length and its weight, infrigidation demands are reduced 20 to 35 % because of no mechanical agitation, cheaper fermenter design. No care of motors, gear boxes, bearings or seals. The air agitated fermenter is a feasible blending power unit like a variable velocity thrust with no motor and drive noise. Air compressors can be steam driven to cut down power cost and go on to run during power outages in big workss with minimum power coevals for controls.

Air-lift fermenter exhibit lower rates of O mass transportation and commixture compared to agitated bioreactors and therefore their usage for industrial production of enzymes could ensue in O lack of the agitation broth and unequal majority commixture. On the other manus, compared to other fermenters, air-lift fermenters have a simpler design, have a lower capital and operating costs and exhibit a lower shear environment. For the latter ground, air-lift fermenters have been used successfully in agitation of shear sensitive micro-organism in high viscousness.

The chief disadvantages are because of weak blending they do non ever suit for civilizations with active critical maps. They do n’t hold intensive nutrition supply and do n’t take away the metabolites intensively. Sudden alteration of force per unit area will do the air bubbles drifting to the surface and in bend devastate sensitive cells. It besides produces abundant foaming. The application of chemical froth ledgeman makes quality of concluding merchandise worse and the procedure more expensive. These disadvantages are connected with hurt of cells and micro-organisms during the procedure of the medium commixture, deficient strength of mass exchange, formation of high-turbulent and dead zones, high power ingestion, low features when they works with syrupy fluids.

This is a table demoing the chief advantages and disadvantages of air lift and mechanical fomenters in fermenters:

• Mechanical
• Air lift