Submerged culture

Refermented with aerobic yeast light (white) flor (Fino) sherries, Spanish man2anilla types, California (etc) submerged culture dry sherry. See... 

There are currently two medicinally valuable alkaloids of commercial import obtained from ergot. Commercial production involves generation parasiticaHy on rye in the field or production in culture because a commercially useful synthesis is unavailable. The common technique today (65) is to grow the fungus in submerged culture. Clavicepspaspali (Stevens and Hall) is said to be more productive than C. purpurea (Fries). In this way, ergotamine (100,... 

Submerged-Culture Generators. Adaptation of the surface-film growth procedure for producing antibiotics to an aerated submerged-culture process has been successful in making vinegar. A mechanical system keeps the bacteria in suspension in the Hquid in the tank, in intimate contact with fine bubbles of air. The excess heat must be removed and the foam, which accumulates at the top of the tank, must be destroyed. 

The most widely used submerged-culture oxidizer is the Brings acetator (50). It uses a bottom-driven hoUow rotor turning in a field of stationary vanes arranged in such a way that the air which is drawn in is intimately mixed with the Hquid throughout the whole bottom area of the tank (51,52). In the United States, continuous cavitator units are used widely for cider-vinegar production. 

A strain of thermophilic Acetobacter - 9. patented in Japan for oxidizing ethanol in a submerged culture oxidizer at temperatures as high as 37°C with considerable savings in cooling water. Another theimophilic strain oiyAcetobacter xn.2An.. 2cm.ed full activity at 35°C, and 45% of its maximum activity at 38°C. 

Submerged culture oxidizers can also be operated on a continuous basis. Continuous monitoring of ethanol and acetic acid concentrations, temperature, and aeration rates permit control of feed and withdrawal streams. Optimum production, however, is achieved by semicontinuous operation because the composition of vinegar desired in the withdrawal stream is so low in ethanol that vigorous bacterial growth is impeded. Bacterial... 

A fermentation such as that of Pseudomonas dentrificans typicaby requires 3—6 days. A submerged culture is employed with glucose, comsteep Hquor and/or yeast extract, and a cobalt source (nitrate or chloride). Other minerals may be required for optimal growth. pH control at 6—7 is usuaby required and is achieved by ammonium or calcium salts. Under most conditions, adequate 5,6-dimethylben2imida2ole is produced in the fermentation. However, in some circumstances, supplementation maybe required. 

The carbohydrate (again often molasses, 15 - 25%) and added nutrients are pH-adjusted to below 4.0 and, for Otis process, have to be sterilised. It is necessary to add potassium hexacyanoferrate but greater care is required in this process compared to surface culture. The A. niger seems to be more sensitive to and more easily inhibited by hexacyanoferrate in submerged culture. It is essential however to lower the ferrous and manganese concentrations, probably below 200 and 5 pg l1 respectively, to optimise the performance of A. niger. 

The submerged culture process continues to increase in terms of the percentage of dtric acid produced compared to that produced by the surface culture method. Tower bioreactors are preferred over stirred reactors because they cost less, there is less risk of contamination and they are less limited by size. 

The first culture technique, reported in 1927, to be attempted commercially was a surface-culture, shallow-pan technique, though this method has not been used for many years. Relatively soon after this, in 1933, production using a submerged culture technique was reported and this method has been in use continuously since then. Various significant developments have been made, notably the addition of caldum carbonate to neutralise the adds produced in order to increase yields (1937) and the use of sodium hydroxide for neutralisation (1952). 

Despite these advantages, deep (submerged) cultures were still deemed to be the most viable route to satisfying the market demand for penicillin. It was estimated that a surface culture equivalent to 2 hectares would be required to produce the same amount of penicillin as a deep culture equivalent to 5 x 104 litres. The desire to switch to deep cultures was thus driven by commercial consideration. 

The mold isolated by Alexander Fleming in early 1940s was Penicillium notatum, who noted that this species killed his culture of Staphylococcus aureus. The production of penicillin is now done by a better penicillin-producing mould species, Penicillium chryso-genum. Development of submerged culture techniques enhanced the cultivation of the mould in large-scale operation by using a sterile air supply. 

A batch process is customary for producing antibiotics. Submerged culture is used to propagate fungus with suitable carbohydrate resources. This assumption is based on simplicity in calculations and the normal use of penicillin in die pharmaceutical industry. Assume we... 

In the production of antibiotics, sufficient growth of fungi in submerged cultures has created potential sources of biomass as SCP and as flavour additives to replace mushrooms the biomass contains 50-65% protein.1,5 Production of mushroom from lignocellulosic waste seems to be a suitable and economical process since the raw material is inexpensive and available in most countries. 

The perceived sensitivity of plant cells to the hydrodynamic stress associated with aeration and agitation conditions is typically attributed to the physical characteristics of the suspended cells, namely their size, the presence of a cell wall, the existence of a large vacuole, and their tendency to aggregate. Table 1 illustrates some of the differences between plant cells and other biological systems. Chalmers [19] attributed shear sensitivity in mammalian cultures at least in part to the fact that these cells occur naturally as part of a tissue, surrounded by other cells. The same is true for plant cells. The more robust microbial systems, on the other hand, exist in nature as single organisms or mycelial structures, very close to the forms they assume in submerged culture. 

A.6A Production of Cultures in Various Modes 5.4.6.4.1 Submerged Cultures... 

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