Although methionine can supply sulphur to CPC biosynthetic pathway, this is not the sole mechanism of its stimulatory effect, since norleucine, a non-sulphur analogue also has similar effect.
Methionine also induces four of the enzymes of CPC biosynthesis at the level of transcription (Martin and Demian, 2002). Beet molasses, a by-product of beet sugar industry, contains sucrose which support slower growth than glucose but a higher rate of specific productivity (Vicik ., 1990). In addition, it contains trace elements such as, potassium, sodium, calcium, zinc, iron and copper (El-Abyad ., 1992) that may act as macro or micro nutrient for the fungal strain. Corn steep liquor, a by-product of corn wet milling, was used by many investigators as a medium component for CPC production (Jurgens ., 2002; Seidel ., 2002).
Biosynthesis of cephalosporin C.
A thorough literature review was performed and it was noticed that though a number of highly productive strains and a number of different strategies have been used for better yield, not much attention has been given in the constituents of synthetic medium used for its biosynthesis.
Studies on the cephalosporin C biosynthesis by fermentation
In the range of the examined levels of variables, it is apparent from that, KH2PO4, corn steep liquor, soya oil, L-methionine, beet molasses and urea showed positive main effects. Soya oil, beet molasses and corn steep liquor were the most significant variable that increased CPC production. On the other hand, ZnSO4, NH4SO4, Na2SO4, CuSO4 and MgSO4 showed negative main effects with different values. Consequently, these constituents were excluded from the fermentation medium as they stand for additional concentrations over the optimal range. A simplified medium of the following composition (g L-1) was expected to be close to optimal levels: soya oil, 80; beet molasses, 120; corn steep liquor, 220. Soya oil contains different s such as cysteine, isoleucine, leucine, lysine, methionine, phenyl alanine, threonine, tyrosine and valine (El-Refai ., 1986; Martin and Demian, 2002). The biosynthesis of CPC begins by the condensation of three s, L-aminoadipic acid, L-cysteine and L-valine, to form the tripeptide δ-(L-aminoadipyl)-L-cysteinyl-D-valine (LLD-ACV) by the ACV synthetase enzyme (Martin and Demian, 2002). Methionine has long been known as the major stimulant of the formation of arthrospores which is correlated with CPC production (Martin and Demian, 2002).
Cephalosporin-C transaminase - Wikipedia
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