Recebido em 10/2/09; aceito em 24/6/09; publicado na web em 13/11/09The essential oils of seven Myrtaceae species were investigated for its chemical composition and antibacterial activity. The volatile oils were characterized by a high content of monoterpenoids of which 1,8-cineole (88.0, 65.0 and 77.0% for Melaleuca hypericifolia, Callistemon viminalis and Callistemon citrinus respectively), terpinen-4-ol (47.0 and 49.8% for Melaleuca thymifolia and Callistemon polandii respectively) and α-pinene (54.5% for Kunzea ericoides) were the major components. The oil from M. linariifolia was characterized by a high concentration of methyleugenol (87.2%). The oil from Melaleuca thymifolia was the most active, exhibiting high antimicrobial activity against all tested bacteria.

-Aspergilli are common contaminants of food and feed and a major source of mycotoxins. In this study, 87 Aspergillus strains were isolated from beans from 14 different cities in Brazil and identified to the species level based on partial calmodulin and β-tubulin sequence data. All green spored isolates belonged to section Flavi and were identified as A. flavus (n=39) or A. pseudocaelatus (n=1). All black spored isolates belonged to section Nigri and were identified as A. niger (n=24) or A. luchuensis (n=10), while the yellow spored strains were identified as A. westerdijkiae (n=7), A. ostianus (n=3), A. ochraceus (n=1) or A. wentii (n=2). The toxigenic potential of these Aspergillus strains from beans was studied by the prospection of genes in three of the major mycotoxin clusters: aflatoxin (seven genes checked), ochratoxin A (four genes) and fumonisin (ten genes and two intergenic regions). Genes involved in the biosynthesis of aflatoxin were only detected in A. flavus isolates: 17/39 A. flavus isolates proved to contain all the aflatoxin genes tested, the others missed one or more genes. The full complement of fumonisin biosynthesis genes was identified in all A. niger isolates. Finally, no genes for ochratoxin A were detected in any of the isolates. Our work suggests that aflatoxin production by some A. flavus strains and fumonisin production by A. niger isolates form the largest mycotoxin risks in Brazilian beans.

-The association of the fungus Stenocarpella maydis with corn seed may cause a reduction of seed germination and vigor of the emerged seedlings. This work was carried out in order to evaluate the effects of S. maydis on corn seed quality as well as on its early development. To evaluate such effects, seeds of cultivars RB9308YG (C1) and RB9108 (C2) were inoculated by the osmotic conditioner technique with two S. maydis isolates for 24(P1), 48(P2), 72(P3) and 96 hours (P4). Plants were grown in a room chamber at 20 °C and 25 °C and daily assessed until 28 days after emergence. Seed germination, incidence of S maydis, electrical conductivity, speed of emergence index (SEI), initial and final seedling population and dry weight of emerged plants, were assessed. The longer the exposition times of the seeds to the fungal colony, the more severe negative effects of the pathogens on seed vigor were observed. S. maydis caused reduced seed vigor in the speed of seedling emergence in the final stand and early development of corn seedlings.