Leticia A. Fernández

Denitrification Activity in Soils for Sustainable Agriculture

Denitrification is a microbial process in the nitrogen cycle in which oxidized nitrogen compounds are used as alternative electron acceptors for energy production. Denitrifying bacteria occur in practically every sort of environmental niche: soil, water, and sediment. Denitrification decreases the leaching of nitrate to ground and surface waters and is the main biological process responsible for the return of fixed nitrogen to the atmosphere. On the other hand, it contributes to the greenhouse effects, to the destruction of the ozone layer, and is a loss of nitrogen otherwise available for the growth of plants. A short overview of denitrification activity in soils leading to a sustainable agriculture is given. The genus Bradyrhizobium and its relevance in the process of denitrification are described.

Microbiological quality of honey from the Pampas Region (Argentina) throughout the extraction process

The microbiological quality of honey obtained from different processing points and the environmental quality within honey houses were assessed in the Pampas Region (Argentina). Mold and yeast (MY), culturable heterotrophic mesophilic bacteria (CHMB), the number of spore-forming bacteria as well as the presence of Shigella spp., Salmonella spp. and fecal coliforms were evaluated in 163 samples. These samples were taken from eight honey houses. Results showed that 89 samples had ≤10CFU of MY/g honey, 69 ranged from 10 to 50CFU/g and two reached 65.5CFU/g. Eighty one percent of the samples showed ≤30CFU of CHMB/g honey and only seven samples had between 50 and 54.25CFU/g. Thirty six honey samples were obtained from drums: in 25 samples (69.4%) CHMB counts were less than ≤30CFU/g of honey; in 20 samples (55.5%) the values of MY were between 10 and 50CFU/g honey and total coliforms were only detected in 20 samples. Fecal coliforms, spores of clostridia as well as Salmonella spp. and Shigella spp were not detected and less than 50 spores of Bacillus spp. per g were observed in the honey from drums. Therefore, the microbiological honey quality within the honey houses did not show any sanitary risks. Our results were reported to honey house owners to help them understand the need to reinforce proper honey handling and sanitation practices.

Antifungal activity in vitro of propolis solutions from Argentina against two plant pathogenic fungi: Didymella bryoniae and Rhizotocnia solani

Antifungal activity in vitro of propolis solutions from Argentina against two plant pathogenic fungi: Didymella bryoniae and Rhizotocnia solani Liliana Gallez, Mirta Kiehr, Leticia Fernández, Rolf Delhey and Débora Stikar. Laboratorio de Estudios Apícolas Departamento de Agronomía Universidad Nacional del Sur, San Andrés s/n Altos del Palihue, Bahía Blanca 8000, Buenos Aires, Argentina. Departamento de Agronomía Universidad Nacional del Sur, San Andrés s/n Altos del Palihue, Bahía Blanca 8000, Buenos Aires, Argentina.