The essential oils from Thymus capitatus (L.) Hoffmgg. et Link, Ocimum basilicum (L.), Myrtus communis (M.) and Laurus nobilis (L.) have been characterized and tested against two bacteria (Lactobacillus plantarum and Escherichia coli) and a fungus (Geotrichum candidum), using a submerged broth culture method. The results obtained showed that T. capitatus and O. basilicum were the greatest inhibitors of all the strains tested, and that Escherichia coli was more inhibited than Lactobacillus plantarum by all the essential oils tested.

A new tyrosinase-encoding gene (2,204 bp) and the corresponding cDNA (1,857 nucleotides) from the white-rot fungus Pycnoporus sanguineus BRFM49 were cloned. This gene consisted of seven exons and six introns and encoded a predicted protein of 68 kDa, exceeding the mature tyrosinase by 23 kDa. P. sanguineus tyrosinase cDNA was over-expressed in Aspergillus niger, a particularly suitable fungus for heterologous expression of proteins of biotechnological interest, under the control of the glyceraldehyde-3-phosphate-dehydrogenase promoter as strong and constitutive promoter. The glucoamylase preprosequence of A. niger was used to target the secretion. This construction enabled the production of recombinant tyrosinase in the extracellular medium of A. niger. The identity of the purified recombinant protein was confirmed by N-terminal amino acid sequencing. The maturation process was shown to be effective in A. niger, and the recombinant enzyme was fully active, with a molecular mass of 45 kDa. The best transformant obtained, A. niger D15#26-e, produced extracellular tyrosinase activities of 534 and 1,668 U l(-1) for monophenolase and diphenolase, respectively, which corresponded to a protein yield of ca. 20 mg l(-1).

An oil obtained from the dried leaves of Lavandula stoechas L. in 0.77% yield was analyzed by capillaryGC and GC/MS. Fenchone (68.2%) and camphor (11.2%) were the main components of the 28 identified molecules. This oil has been tested for antimicrobial activity against six bacteria, and two fungi. The results showed that this oil was active against all of the tested strains; Staphylococcus aureus was the more sensitive strain.

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