A semi-industrial process (800-l fermentor) for lycopene production by mated fermentation of Blakeslea trispora plus (+) and minus (-) strains has been developed. The culture medium was designed at the flask scale, using a program based on a genetic algorithm; and a fermentation process by means of this medium was developed. Fermentation involves separate vegetative phases for (+) and (-) strains and inoculation of the production medium with a mix of both together. Feeding with imidazole or pyridine, molecules known to inhibit lycopene cyclase enzymatic activity, enhanced lycopene accumulation. Different raw materials and physical parameters, including dissolved oxygen, stirring speed, air flow rate, temperature, and pH, were checked in the fermentor to get maximum lycopene production. Typical data for the fermentation process are presented and discussed. This technology can be easily scaled-up to an industrial application for the production of this carotenoid nowadays widely in demand.

The content of a-aminoadipyl-cysteinyl-valine, the first intermediate of the penicillin biosynthetic pathway, decreased when Penicillium chrysogenum was grown in a high concentration of glucose. Glucose repressed the incorporation of [14C]valine into a-aminoadipyl-cysteinyl-[14C]valine in vivo. The pool of a-aminoadipic acid increased sevenfold in control (lactose-grown) penicillin-producing cultures, coinciding with the phase of rapid penicillin biosynthesis, but this increase was very small in glucose-grown cultures. Glucose stimulated homocitrate synthase and saccharopine dehydrogenase activities in vivo and increased the incorporation of lysine into proteins. These results suggest that glucose stimulates the flux through the lysine biosynthetic pathway, thus preventing at-aminoadipic acid accumulation. The repression of a-aminoadipyl-cysteinyl-valine synthesis by glucose was not reversed by the addition of oa-aminoadipic acid, cysteine, or valine. Glucose also repressed isopenicillin N synthase, which converts a-aminoadipyl-cysteinyl-valine into isopenicillin N, but did not affect penicillin acyltransferase, the last enzyme of the penicillin biosynthetic pathway.Glucose exerts a negative control on the biosynthesis of penicillin in Penicillium chrysogenum (17,22) similar in many aspects to carbon catabolite regulation of the biosynthesis of cephalosporins in Acremonium chrysogenum (3,24) and cephamycins in Streptomyces clavuligerus (1,23) and Streptomyces lactamdurans (6). Glucose (28 to 140 mM) produces a concentration-dependent repression of the incorporation of ['4C]valine into penicillin but does not have an inhibitory effect on such incorporation by enzymes formed before glucose addition (22). The total activity of the penicillin-synthesizing enzymes in P. chrysogenum is repressed by glucose (22). Derepression of penicillin biosynthesis occurs after depletion of glucose. However, the overall biosynthetic activity of the pathway in vivo is determined by the availability of precursors of the L-a-aminoadipyl-Lcysteinyl-D-valine (ACV) tripeptide and by the activities of the (at least) three enzymes involved in penicillin biosynthesis.The first well-established intermediate in the penicillin biosynthetic pathway, ACV (2, 11), appears to be formed by a sequential condensation of the three precursor amino acids (8) (Fig. 1). ACV is then cyclized to form isopenicillin N by the action of isopenicillin N synthase, an enzyme that has been purified to near homogeneity from extracts of P. chrysogenum (19,21). In the last step of penicillin biosynthesis, the a-aminoadipyl side chain of isopenicillin N is exchanged for phenylacetic acid, which is previously activated in the form of phenylacetyl coenzyme A (CoA) (20; B. Spencer and C. Maung, Biochem. J. 118:29p-30p, 1970).The recent development of reliable assay methods to quantify the tripeptide ACV (11) and to measure the activities of isopenicillin N synthase (21) and penicillin acyltransferase (E.

The addition of glucose to batch cultures of Penicillium chrysogenun: AS-P-78 reduced the biosynthesis of penicillin. This regulatory effect was also observed in penicillin biosynthesis by nitrogen-limited resting cells when cultures were previously grown in high concentrations of glucose. The effect of glucose was concentration-dependent in the range of 28-j140 mm. Incorporation of L-[U-"C]valine into penicillin in nitrogen-limited resting cultures was reduced by 70% when cells were grown on 140 mm glucose, as compared with that grown on lactose. It was not affected when the sugar was added to the resting cell system, in which penicillin biosynthesis took place without growth. Fructose, galactose and sucrose exerted the regulatory effect to the same extent as glucose (64 to 70%). Lactose did not exert suppression of penicillin biosynthesis.Penicillin-synthesizing activity in control cultures with lactose reached a peak at 24 hours of incubation and decreased slowly thereafter, as studied with resting cell cultures in which further protein synthesis was blocked with cycloheximide.Glucose repressed the formation of penicillin-synthesizing enzymes, but had no effect on the activity of these enzymes. These results suggest that glucose represses but does not inhibit penicillin biosynthesis.

We cloned the carB and carRA genes involved in ␤-carotene biosynthesis from overproducing and wild-type strains of Blakeslea trispora. The carB gene has a length of 1,955 bp, including two introns of 141 and 68 bp, and encodes a protein of 66.4 kDa with phytoene dehydrogenase activity. The carRA gene contains 1,894 bp, with a single intron of 70 bp, and encodes a protein of 69.6 kDa with separate domains for lycopene cyclase and phytoene synthase. The estimated transcript sizes for carB and carRA were 1.8 and 1.9 kb, respectively. CarB from the ␤-carotene-overproducing strain B. trispora F-744 had an S528R mutation and a TAG instead of a TAA stop codon. The overproducing strain also had a P143S mutation in CarRA. Both B. trispora genes could complement mutations in orthologous genes in Mucor circinelloides and could be used to construct transformed strains of M. circinelloides that produced higher levels of ␤-carotene than did the nontransformed parent. The results show that these genes are conserved across the zygomycetes and that the B. trispora carB and carRA genes are functional and potentially useable to increase carotenoid production.

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