Fermentation submerged

By combination of all data thus obtained the process may be controlled with sufficient precision by a process computer. The culture within the fermenter can be maintained over a considerable amount of time in the state of maximum productivity. 

Submerged fermentations are mostly operated in batch processes but can also be run continuously in certain cases (continuous fermentation). Batch fermentations may last up to 10 days. Following the fermentation the flavour raw material is extracted from the fermentation broth. In industrial fermentations typically cell counts of 10-30 g/1 are obtained. For a profitable cost/efficiency relation a product yield of 20-30 g/1 has to be achieved. Aerobe fermentations require oxygen transfer rates to the fermentation broth of about 100 mmol/1 per hour. Depending on the viscosity of the media 0.75-2.5 KW stirring power has to be applied for each m of fermentation broth. 

---

Gellan Gum. GeUan gum is the generic name for the extraceUular polysaccharide produced by the bacterium. Pseudomonas elodea (ATCC 31461). Proprietary to Kelco Division of Merck Co., Inc., geUan gum is manufactured in an aerobic, submerged fermentation (76). 

Fermentation. The commercial P-lactam antibiotics which act as starting material for all of the cephalosporins ate produced by submerged fermentation. The organisms used for the commercial production of the penicillins and cephalosporins ate mutants of PenicU/in chTysogenum and Cephalosporium acremonium respectively (3,153,154). Both ate tme fungi (eucaryotes). In contrast, the cephamycins ate produced by certain species of procaryotic Streptomyces including Streptomyces clavuligerus and Streptomyces lipmanii (21,103). 

The development of the submerged fermentation technique resulted in tremendous progress in the field of industrial enzymology. This technique was used in the early 1950s for the production of bacterial amylases for the textile industry. 

Generally, the fermentation proeess involves the addition of a speeifie eulture of mieroorganisms to a sterilized liquid substrate or broth in a tank (submerged fermentation), addition of air if aerobie, in a well-designed gas-liquid eontaetor. The fermentation proeess is then earried out to grow mieroorganisms and to produee the required ehemieals. Table 11-1 lists examples of the proeesses used by fermentation. 

To 17 C of a culture obtained by submerged fermentation as mentioned above, siliceous earth is added and the batch is filtered. The mixture of mycelium and the siliceous earth are agi-tatedforl hour with 2.5 Cof butanol. This treatment is repeated twice. Thebutanolic extracts are combined, washed with water, evaporated to dry ness (about 10 g) and boiled with acetone (80 ml). The residue (5.41 g of yellowish powder) is distamycin. 

Citric acid fermentation of cane-molasses is by submerged fermentation in a 21 biostat (B. Braun) stirred fermenter. A strain of Aspergillus niger is the most widely used for commercial production. A. niger is also highly recommended in the present study, which can obtained from the American Type Culture Collection, Rockville, Maryland, USA. Molasses... 

Citric acid fermentation of cane-molasses by submerged fermentation in 21 B. Braun stirred fermenter (working volume 21) is performed. A strain of A. niger ATCC 11414 is... 

Pretreatment of Substrate. Several different lignocelluloses were pretreated with NaOH. This pretreatment partially solubilizes the hemicelluloses and lignin and swells the cellulose so that the organism can utilize it for its growth and for production of a cellulase system in SSF. The treated lignocelluloses were not washed. The NaOH treatment is done with a minimum amount of water so that, after the addition of nutrient solution and inoculum, the moisture content is less than 80% wt/wt and there is no free water in the medium. More water was added to make suspensions of different lignocellulosic substrates of the desired concentration (1% or 5%) for liquid-state (submerged) fermentation (LSF). 

Pleurotus sajor-caju was selected in the present study for the utilization of polysaccharides from corn stalks for production of protein-rich mycelial biomass in submerged fermentation rather than for production of mushrooms (fruiting bodies). Production of mycelial biomass of various mushrooms including morels in submerged cultural conditions is another way to use them as food, food additives or mushroom flavor agents (8,9). 

The industrial production of penicillin by Pfizer in 1943 transformed the chemistry of natural products. Microbiology became its field and pharmaceutical research became its leading trend. The main driving force behind the research of the chemistry of natural products was and still remains to be human health care. Since the advent of antibiotics, many sources of natural chemicals, such as plants, fungi and bacteria, have been searched for antibacterials, anticancer products, immuno-suppressors and chemicals that affect the human psyche. This research was so successful that, even today, more than half of all pharmaceuticals are either natural products or derived from, or inspired by them. The market of antibiotics alone was ca. US 30 billion in 2005. The majority of antibiotics is produced by submerged fermentation of filamentous microorganisms such as soil prokaryotic actinomycetes and eukaryotic moulds, ascomycetes. 

Vecht-Lifshitz SE, Magdassi S, Braun S, Effect of addition of surface active agents on pellet formation in submerged fermentation of Streptomyces tendae, JDisp Sci... 

A summary of the factors which are known to influence ethanol production from glucose in a gas-solid fluidized bed fermenter, or which may have an influence based on observations with submerged fermentations, is shown in Figure 6.1. In anaerobic beds, the key factors are the fermentation temperature and ethanol inhibition, both of which have a dramatic effect on the specific rafe of ethanol production. Bed dehydration and its influence on yeast pellet moisture content is also important, since a failure of fermentation may occur if the pellets become too dry (Bauer, 1986). 

Aeration is of importance in the fermentation industries. In the manufacture of baker s yeast, penicillin, and other antibiotics, an adequate air supply is required for optimum yields in certain submerged fermentation processes. 

Fermentation. Dalbaheptides are produced by submerged fermentation and this topic has been reviewed. In a few cases addition of a biosynthetic precursor of the core aglycones such as tyrosine and p-hydroxyphenylglycine increased the yields. 

Cost-effective Enzymes. Submerged fermentation was the key to obtaining cost effective enzymes. As was the case for penicillin, success in submerged fermentation of microbes that produced the intracellular enzyme... 

---