Production of bioactive compounds by different fungal species

Production of cholesterol-lowering drugs Nowadays in Hungary and all over the world there is an increasing demand on cholesterol-lowering drugs. Highest risk factor of atherosclerosis and especially coronary occlusion is the high cholesterol level of the plasma. In the recent two decades the 3-hydroxy-3-methylglutaryl coenzyme A reductase (EC.1.1.1.34) as the rate limiting key enzyme of the cholesterol biosynthesis in the organism was extensively examined. Mevinolin and other related compounds (compactin, pravastatin, simvastatin) are the competitive inhibitors of the HMG-CoA reductase enzyme. Our investigations were focussed on finding microorganisms, which would produce HMG-CoA reductase enzyme inhibitors. During screening, covering about 20,000 fungus strains two microorganisms were selected, one of them an Aspergillusspecies was able to biosynthesize mevinolin and another strain belongs to thePenicilliumgenus was able to produce compactin. In the course of our experiments new, economic microbial processes were developed for both cholesterol-lowering agents

Generation of Useful Insertionally Blocked Sterol Degradation Pathway Mutants of Fast-Growing Mycobacteria and Cloning, Characterization, and Expression of the Terminal Oxygenase of the 3-Ketosteroid 9α-Hydroxylase in Mycobacterium smegmatis mc(2)155

Integration of the pCG79 temperature-sensitive plasmid carrying Tn611 was used to generate libraries of mutants with blocked sterol-transforming ability of the sterol-utilizing strains Mycobacterium smegmatis mc(2)155 and Mycobacterium phlei M51-Ept. Of the 10,000 insertional mutants screened from each library, 4 strains with altered activity of the sterol-degrading enzymes were identified. A blocked 4-androstene-3,17-dione-producing M. phlei mutant transformed sitosterol to 23,24-dinorcholane derivatives that are useful starting materials for corticosteroid syntheses. A recombinant plasmid, pFJ92, was constructed from the genomic DNA of one of the insertional mutants of M. smegmatis, 10A12, which was blocked in 3-ketosteroid 9α-hydroxylation and carrying the transposon insertion and flanking DNA sequences, and used to isolate a chromosomal fragment encoding the 9α-hydroxylase. The open reading frame encodes the 383-amino-acid terminal oxygenase of 3-ketosteroid 9α-hydroxylase in M. smegmatis mc(2)155 and has domains typically conserved in class IA terminal oxygenases. Escherichia coli containing the gene could hydroxylate the steroid ring at the 9α position