Luigi Ciampi

Isolation and partial purification of a metabolite from a mutant strain of Bacillus sp. with antibiotic activity against plant pathogenic agents

EJB Electronic Journal of Biotechnology ISSN: 0717-3458 Vol.5 No.1, Issue of April 15, 2002© 2002 by Universidad Catolica de Valparaiso -- Chile Received November 15, 2001 / Accepted April 3, 2002

Effects of a bacteriocin-like inhibitory substance from Carnobacterium piscicola against human and salmon isolates of Listeria monocytogenes.

The aim of this study was to characterize the antagonism of a bacteriocin-like inhibitory substance (BLIS) produced by Carnobacterium piscicola L103 against Listeria monocytogenes strains isolated from salmon and human samples. The inhibitory effect of the BLIS was evaluated in Tryptic soy agar (TSA) during different growth phases of L. monocytogenes at 5 degrees C, using the well diffusion method. Also, the type of inhibition, either bacteriostatic or bactericidal of the BLIS in Tryptic soy broth (TSB), was studied and the development of resistant cells investigated. Results showed an antagonistic effect of the BLIS on all the strains of L. monocytogenes. Four selected strains presented a higher sensitivity to the BLIS in the exponential growth phase and were more resistant in the stationary phase. In TSB, the inhibitory substance showed a partially bactericidal effect on L. monocytogenes. After inactivation of the BLIS with a protease, however, a regrowth of L. monocytogenes was found. The isolate most affected by the action of the BLIS was one of salmon origin. From the 86 isolated colonies that grew in the presence of the BLIS, 93% showed total resistance and 7% partial resistance, which was maintained through five consecutive culture cycles in the absence of the BLIS.

Bacteriocin like substance production by Carnobacterium piscicola in a continuous system with three culture broths. Study of antagonism against Listeria monocytogenes on vacuum packaged salmon

Tres meios de cultura foram avaliados quanto a producao de substâncias semelhantes a bacteriocinas (SSB) por Carnobacterium piscicola L 103, utilizando um sistema continuo de cultura. A eficacia da substância antagonista contra Listeria monocytogenes foi testada em salmao embalado a vacuo. As SSB foram produzidas em bioreator de 1.0 L, em cultura continua e em cultura estacionaria, utilizando D-MRS, mod. D-MRS e APT como meios de cultivo. Files de salmao foram inoculados com SSB (200 AU mL-1 e 800 AU mL-1) e L. monocytogenes (8.0 x 101 ufc cm-2) e mantidos a 4oC. O crescimento de L. monocytogenes foi verificado a cada 5 dias, durante 15 dias. C. piscicola L 103 antigiu a fase estacionaria depois de 12 h de incubacao em cultivo em batelada, sendo a atividade SSB de 800 AU mL-1 nos meios D-MRS e mod. D-MRS e de 400 AU mL-1 no caldo APT. Durante a cultura continua, a atividade SSB aumentou ate 6400 AU mL-1 nos dois tipos de caldo MRS, ao passo que no caldo APT esta atividade diminuiu a 50 AU mL-1, indicando uma clara vantagem de uso dos dois primeiros meios de cultura e do sistema de crescimento continuo. SSB mostrou efeito bacteriostatico sobre L. monocytogenes quando inoculada em salmao, com contagens de 6,0 x 103 ufc cm-2 apos 15 dias. Nao foram encontradas diferencas significantes entre as duas atividades utilizadas. No ensaio controle, sem SSB, a contagem de L. monocytogenes aumentou ate 1,0 x 106 ufc cm-2 apos 15 dias de estocagem.

Potato germplasm collecting expedition to the Guaitecas and Chonos Archipelagos, Chile, 1990

SummaryA joint Chilean, Italian, and United States potato (Solanum tuberosum) germplasm collecting expedition was conducted in the Guaitecas and Chonos Archipelagos, south of Chiloé Island, between March 4 – March 21, 1990. The expedition resulted in 30 collections ofSolanum tuberosum and 1 collection ofFragaria chiloensis L. Twenty-three of the potato collections were along the salt-water-swept shores of the islands. These beach populations, unlike the indigenous landraces in southern Chile, are self-perpetuating populations and provide useful new germplasm for researchers interested in the origin of cultivated potatoes and in the origin ofSolanum tuberosum in Chile.

Nematicidal activity of leaves of common shrub and tree species from Southern Chile against Meloidogyne hapla.

L. Bohm, N. Arismendi, and L. Ciampi. 2009. Nematicidal activity of leaves of common shrub and tree species from Southern Chile against Meloidogyne hapla. Cien. Inv. Agr. 36 (2): 249-258. The biological control of the root-knot nematode, Meloidogyne hapla, was evaluated through the addition of organic amendments of dry and chopped leaves of Buddleja globosa, Drymis winteri, Eucalyptus globulus, Gevuina avellana, Laurelia sempervirens, Luma apiculata, Maytenus boaria and Ugni molinae to the soil substratum. The assays were carried out in pots seeded with lettuce plants (cv. Reina de Mayo). All pots were inoculated with 2000 eggs and juveniles of M. hapla, and then maintained under greenhouse conditions for 45 days. Control pots without foliage additions were also seeded with lettuce. The results show that the addition of dry leaves of L. sempervirens, G. avellana, M. boaria, D. winteri, and B. globosa signifi cantly reduced root-knot nematode development in soil in which lettuce plants were grown. On the other hand, while all of the treatments signifi cantly affected the development of eggs and juveniles of M. hapla, the best inhibitory effect was found with dry leaves of U. molinae, D. winteri and L. sempervirens. For all plant species, an increase in the concentration of dry leaves incorporated into the substratum resulted in better control of nematode population.

Patología Vegetal Micológica

Este texto esta dedicado a este grupo particular de agentes infecciosos. En sus páginas se abarcan diversos temas que son de interés para los que se interesan en temas de sanidad vegetal. Se presentan numerosas fi chas que ilustran aspectos de síntomas y signos, temas de epidemiología y muchas fotografías en colores. Además, se han incluido esquemas de los signos microscópicos de casi todas las especies que se tratan.

Determinación de Especies de Erwinia (grupo carotovora) como Agentes Causales de Pudrición Blanda en Cala (Zantedeschia spp.)

A B S T R A C T During the 2002 growing season a research was conducted in order to establish the causal agents responsible for “soft rot” in stems and tubers of calla (Zantedeschia spp.) in greenhouse productions in Southern Chile. In order to compare with local bacterial isolates, “soft rot” was induced in potato (Solanum tuberosum L.) tubers from commercial productions near the city of Valdivia. To establish differences in virulence, potato isolates were inoculated on calla tissues and viceversa. 33 isolates were determined to belong to the genus Erwinia (carotovora group) (E.c.) accordingly to the following characteristics: Gram (-), oxidase (-), potato rot (+). Complementary and more specific tests included, sensitivity to erythromycin, utilization of palatinose, reducing substances from sucrose, acid production from α-methyl glucoside and growth at 37oC. Finally, it was possible to identify two isolates of E.c. subsp. atroseptica and 21 E.c. subsps. carotovora isolated from calla plants tubers. There was no evidence of the phytopathogenic species E. chrysanthemi among the isolates studied, an indication that this bacterial pathogens is absent in Chile. This is the first report indicating that isolates of Erwinia carotovora subsp. atroseptica are affecting a new crop in Chile, such as calla. The cross inoculations performed demonstrated that virulence is more aggressive with isolates obtained from calla tissues. Chances that the isolates obtained from calla came from abroad are very high, and may interfere with local crops such as potato.