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1% per month at-30 °C
E. Venkata Naga Raju*1 and G. Divakar 2
The sulfonate esters 6 and 7 were stable to diazonium coupling conditions in acidic aqueous methanol to afford 8 and 9. Subsequent acid-catalyzed condensation of 8 with N-ethyl-7-hydroxy-tetrahydroquinoline yielded the desired TFMB-protected sulfonated oxazine 23. However, the standard oxazine dye-formation conditions of HCl in hot aqueous ethanol led to substantial deprotection of AcOTFMB, presumably because carboxylic esters are labile to these conditions. Gratifyingly, dye formation in hot acetic acid readily afforded the desired oxazine dye 24 with the AcOTFMB sulfonate ester intact ().
Increased yields of fibrinolytic proteases were reported by several workers who used different sugars such as maltose 43, 44, mannitol 44, glucose 74, 78 and fructose 68, 77.
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Carbon source: Studies have also indicated a reduction in fibrinolytic protease production due to catabolic repression by glucose 43, 44, 74, 78. On the other hand the low yields of fibrinolytic protease production with the lowering of pH brought about by the rapid growth of the organism66, 70, 79, 80, 81. In commercial practice, high carbohydrate concentrations repressed fibrinolytic protease production. Therefore, carbohydrate was added either continuously or in aliquots throughout the fermentation to supplement the exhausted component and keep the volume limited and thereby reduce the power requirements 66.
Metal ion requirement: Divalent metal ions such as calcium, cobalt, copper, boron, iron, magnesium, manganese, and molybdenum are required in the fermentation medium for optimum production of fibrinolytic proteases. However, the requirement for specific metal ions depends on the source of enzyme. The use of MgSo4, AgNO3, CaCl2, MnCl2 at a concentration of 0.1-0.5mM or NaN3 at a concentration of 0.1- 0.5mM resulted in an increase in fibrinolytic protease activity in Bacillus subtilis, β-hemolytic 71, 73, 79, Oidiodendron flavum 82, Schizophyllum commune 83, 84, Pseudomonas aeruginosa 43, Bacillus lichniformis B4 44, Rhizomucor miehei 78, Ganoderma lucidum VK 12 85, Escherichia coli 86, Candida guilliermondii 66, Bacillus cereus GD55 77.
(i) Improvement in the yields of fibrinolytic proteases; and
pH and temperature: The important characteristic of most microorganisms is their strong dependence on the extracellular pH for cell growth and enzyme production. The culture pH also strongly affects many enzymatic processes and transport of various components across the cell membrane 87. The optimum pH 5-8 reported for maximum fibrinolytic protease production by Bacillus subtilis, β-hemolytic 71, 73, 79, Oidiodendron flavum 82, Schizophyllum commune 83, 84, Pseudomonas aeruginosa 43, Bacillus lichniformis B4 44, Rhizomucor miehei 78, Ganoderma lucidum VK 12 85, Escherichia coli 86, Candida guilliermondii 66, Bacillus cereus GD55 77. In view of a close relationship between fibrinolytic protease synthesis and the utilization of nitrogenous compounds, pH variations during fermentation may indicate kinetic information about the fibrinolytic protease production, such as the start and end of the fibrinolytic protease production period.
Apart from serving as a nitrogen source, rice chaff, sessamum oil cake and sunflower oil cake also provide several micronutrients, vitamins, and growth-promoting factors. Suitable nitrogen sources as substitutes for rice chaff, sessamum oil cake and sunflower oil are still being evaluated. Peptone (1%) and yeast extract (1–2%) also serve as excellent nitrogen sources 44, 68. Addition of certain amino compounds was shown to be effective in the production of extracellular fibrinolytic proteases by Bacillus lichniformis B4 local isolate 44. However, aspartate appeared to have inhibitory effects on both protease and fibrinolytic protease production 77.
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(i) Variations in the aeration rate;
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(ii) Variations in the agitation speed of the bioreactor; or
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On the contrary, several reports have demonstrated the use of organic nitrogen sources leading to higher fibrinolytic protease production than the inorganic nitrogen sources 43, 44, 72, 73. Tingwei and Rueilan74 recorded maximum enzyme yields using a combination of 3% soybean meal. Rice chaff, Sessamum oil cake and Sunflower Oil Cake were found to be a cheap and suitable source of nitrogen by some workers 66, 68, 75, 76.
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Temperature is another critical parameter that has to be controlled and varied from organism to organism. The mechanism of temperature control of enzyme production is not well understood 88. The optimum temperatures 30°C-40°C reported for maximum fibrinolytic protease production by Bacillus subtilis 67, 90, β-hemolytic 71, 73, 79, Oidiodendron flavum 82, Schizophyllum commune 83, 84, Pseudomonas aeruginosa 43, Bacillus lichniformis B4 44, Rhizomucor miehei 78, Ganoderma lucidum VK 1285, Escherichia coli86, Candida guilliermondii66, Bacillus cereus72, 77, Cordyceps militaris 80, Penicillium chrysogenum SGAD 12 75, Bacillus sphaericus 89.
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Aeration and agitation: During fermentation, the aeration rate indirectly indicates the dissolved oxygen level in the fermentation broth. Different dissolved oxygen profiles can be obtained by:
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Enzyme synthesis was found to be repressed by rapidly metabolizable nitrogen sources such as amino acids or ammonium ion concentrations in the medium 22, 24. However, one report indicated no repression in the fibrinolytic protease activity with the use of ammonium salts 43. An increase in fibrinolytic protease production by the addition of ammonium sulphate was also observed by Amrita Raja and Nancy Khess 43. Similarly, sodium nitrate was found to be stimulatory for fibrinolytic protease production 43. Substitution of silver nitrate in the basal medium with sodium nitrate increased enzyme production even more 71.
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