Leticia Andrea Fernandez

• Doctora en Ciencias Biológicas
• Universidad Nacional del Sur

Managed populations of honey bees (Apis mellifera Linnaeus; Hymenoptera: Apidae) are regularly exposed to infectious diseases. Good hive management including the occasional application of antibiotics can help mitigate infectious outbreaks, but new beekeeping tools and techniques that bolster immunity and help control disease transmission are welcom...

We evaluated the microbial composition of water kefir grains and beverage over the course of one year to determine whether the number and type of microorganisms changed over the time. Bacteria and yeast colonies with different morphologies were isolated from water kefir and their antimicrobial activity was evaluated against Paenibacillus larvae and...

The honeys from the Phytogeographic Provinces (PP) of the south of Buenos Aires province (Argentina) were characterised by the sugar composition and physicochemical parameters used for honey quality control. A large set (n=329) of traceable raw honey samples obtained from beekeepers were analysed and met the specifications of the national and/or in...

In this study, propolis extract (EPE) and oregano essential oil (OEO), both natural products with different bioactive compounds, were evaluated in vitro and in vivo against Sclerotinia sclerotiorum. This phytopathogen is important worldwide as it can contaminate seeds and infect seedlings of many species. Antifungal susceptibility assays on culture...

Bee pollen is the result of the agglutination of pollen grains collected from flowers and mixed with nectar and salivary secretions by honey bees. Bee pollen is a natural product exposed to environmental conditions and also provides a unique microhabitat for yeasts and bacterial communities. We analyzed 30 fresh bee pollen samples obtained from the...

Aims: This study aimed to evaluate in vitro individual and combined antifungal activity of propolis extract (PE) and oregano essential oil (OEO) against Penicillium allii, causal agent of blue mold disease. The chemical characterization of both products was also included. Methods and results: Chromatographic analysis of PE and OEO confirmed the...

Bee-pollen is a functional food sold for human and animal consumption but also is a favorable microhabitat for many spore-forming bacteria. Among them, Bacillus cereus can produce several toxins and other virulence factors, causing an emetic or diarrheal syndrome after ingestion. The study involved 36 bee-pollen samples obtained from different samp...

The antimicrobial activity of four concentrations of hydroalcoholic extracts from honeybee propolis and Scaptotrigona jujuyensis geopropolis was screened in vitro against five tomato pathogenic bacteria. The agar-well diffusion method was used and the tested bacteria were Clavibacter michiganensis subsp. michiganensis, Xanthomonas gardneri, Xanthom...

In order to evaluate if bee pollen properly processed could be conserved for more than 12 months without suffering alterations on its microbiological and chemical qualities, 48 dried bee pollen samples from Argentina were stored at room (23 ± 2 °C) and at refrigerated temperatures (4 °C) during two years. The microbiological (culturable heterotroph...

In order to evaluate if the different stages of bee pollen production could lead to changes in the microbiota, counts of filamentous fungi and yeast, culturable heterotrophic mesophilic bacteria, aerobic spore-forming bacteria, sulfite-reducing clostridia, enterobacteria, total and thermotolerant coliforms, and the study of human pathogenic bacteri...

Propolis is a viable alternative for chemical control of plant pathogens due to its antimicrobial properties. The present study was conducted to determine the sensorial, physical and chemical characteristics of four propolis from Argentina, and their respective hydroalcoholic extracts. In vitro antifungal activity of hydroalcoholic propolis extract...

Dekkera bruxellensis is one of the most important contaminant yeasts of alcoholic fermentation. The use of propolis, which can selectively target contaminating yeasts without affecting the starter one, Saccharomyces cerevisiae, could be a useful nonconventional strategy for controlling the growth of contaminant yeasts. The objective of this researc...

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...

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...

Phosphate-solubilizing bacteria (PSB) abundance and ribotypes were examined in the top soil (0–10 cm) of agricultural fields under no-till management sampled in two seasons, summer (February) and late winter (September), in 2010. No-till plots under sustainable agricultural practices (intense crop rotation) or under non-sustainable practices (soybe...

Seven phosphate-mobilizing pseudomonads were isolated, identified, and characterized in terms of their biofertilizer potential and root-colonizing properties. Pseudomonas protegens (ex-fluorescens) CHA0 was used for comparative purposes. Four isolates (LF-MB1, LF-P1, LF-P2, and LF-P3) clustered with members of the “Pseudomonas fluorescens complex,”...

Three bacterial strains capable of degrading atrazine were isolated from Manfredi soils (Argentine) using enrichment culture techniques. These soils were used to grow corn and were treated with atrazine for weed control during 3 years. The strains were nonmotile Gram-positive bacilli which formed cleared zones on atrazine solid medium, and the 16S...

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 an...

Honeys from Ventania system: microbiological quality evaluation at different points of honey-processing. One stage of honey production is extraction. Honey is a product with minimal types and levels of microorganisms; however it could be contaminated during its manipulation. The aim of this work was to evaluate the microbiological contamination of...

One stage of honey production is extraction. Honey is a product with minimal types and levels of microorganisms; however it could be contaminated during its manipulation. The aim of this work was to evaluate the microbiological contamination of honey at different processing points. Mould and yeast, total coliform number as well as the presence of S...

Two hundred and fifty strains, all of them representatives of native Bradyrhizobium sp., isolated from soils cultivated with soybean have been characterized by their denitrification activity. In addition, the denitrification potential of those soils was also measured by evaluating the most-probable-number (MPN) of denitrifying bacteria and the deni...

Transformation of organic phosphorus (Po) into soluble inorganic phosphorus (Pi) is called mineralization and is carried out by phosphatase enzymes. The present research focuses on the study of the phosphatase activity of five soils from the soybean area of the Northern Pampean region, by evaluating the phosphatase activity in soil samples and the...

Transformation of organic phosphorus (Po) into soluble inorganic phosphorus (Pi) is called mineralization and is carried out by phosphatase enzymes. The present research focuses on the study of the phosphatase activity of five soils from the soybean area of the Northern Pampean region, by evaluating the phosphatase activity in soil samples and the...

The efficiency of 13 phosphate-solubilizing bacteria (PSB; four Burkholderia sp., five Enterobacter sp., and four Bradyrhizobium sp.) was assessed in a soil plate assay by evaluating soil phosphorus (P) availability. A commercial argentine strain, Pseudomonas fluorescens, was used for comparing solubilizing activity. Burkholderia sp. PER2F, Enterob...

RESUMEN En el presente trabajo se estudia la habilidad fisiológica para solubilizar fosfato inorgánico de diferentes grupos bacterianos así como de cepas de Bradyrhizobium sp. aislados de suelos sojeros. Se recolectaron muestras de suelo y se determinó el número de la microflora total así como el total de bacterias, hongos y de solubilizadores. La...

The nodule-appearance period was studied by means of a plant infection technique using inoculants that had been stored at 5, 20 and 30°C during 16 and 31 days. In addition, two soybean inoculation methods were compared via experiments in the growth chamber: seed-applied inoculation and soil-applied inoculation. The aplication of a liquid inoculant...