R. Fritz

Antimicrobial activity of some Argentinean wild plant essential oils against Paenibacillus larvae larvae, causal agent of American foulbrood (AFB)

Summary Five essential oils from Argentinan wild plants were tested in vitro for antimicrobial activity against different strains of Paenibacillus larvae larvae, causal agent of American foulbrood in honey bees, Apis mellifera L. The species selected from which to extract the essential oils were aguaribay (Schinus molle var. areira L), Andean thyme (Acantholippia seriphioides A. Gray), peperine (Mintosthachys mollis H.B.K. Gris), camomile (Tagetes minuta L.) and pennyroyal (Lippia turbinata Griseb.). Oils were extracted from different parts of the plants by steam distillation. Minimal inhibitory concentration (MIC) and minimal bactericide concentration (MBC) were evaluated on Mueller-Hinton broth and on MYPGP agar respectively, by the tube dilution method. MIC and MBC minimum and maximum values obtained were 200–250 mgL−1 and 200–300 mgL−1 for Andean thyme and 800–1000 mgL−1 and 850–1100 mgL−1 for pennyroyal, respectively. The other oils had intermediate MIC and MBC values between the formers mentioned. Highly significant differences between MIC and MBC values for the essential oils tested were found. Tukeys mean separation test indicated that Andean thyme (A. seriphioides) essential oil was different from the other four essential oils at α<0.01. Andean thyme proved to be the most effective in vitro essential oil against P. larvae larvae. Therefore, it may be a promising natural alternative to traditional antibiotics, meriting further studies on its field applicability for AFB control.

Antimicrobial activity of Pimpinella anisum and Foeniculum vulgare essential oils against Paenibacillus larvae.

Abstract The essential oil obtained by hydrodistillation from the fruits of Pimpinella anisum L. (green anise) and Foeniculum vulgare Miller (fennel) were analyzed by GC and GC/MS and physicochemical properties. The oils of P. anisum and F. vulgare were found to be especially rich in (E)-anethole, 96.3% and 92.7%, respectively. The MICs were determined by the tube dilution method against Paenibacillus larvae. The oils showed MICs values were 300 µg/mL and 250 μg/mL for P. anisum and F. vulgare, respectively. Both oils presented great similarity in physiochemical properties values and antimicrobial activity.

Bioactivity of Rosmarinus officinalis essential oils against Apis mellifera, Varroa destructor and Paenibacillus larvae related to the drying treatment of the plant material

In this study, chemical composition, physicochemical properties and bioactivity of two essential oils of Rosmarinus officinalis extracted from plant material with different drying treatments against Apis mellifera, Varroa destructor and Paenibacillus larvae were assessed. The lethal concentration 50 (LC50) for mites and bees was estimated using a complete exposure method test. The broth microdilution method was followed in order to determine the minimum inhibitory concentrations (MICs) of the essential oils against P. larvae. Physicochemical properties were similar in both the essential oils, but the percentage of components showed certain differences according to their drying treatment. β-Myrcene and 1,8-cineole were the main constituents in the oils. The LC50 for complete exposure method at 24, 48 and 72 h was minor for mites exposed to R. officinalis essential oil dried in oven conditions. MIC values were 700–800 µg mL−1 and 1200 µg mL−1 for R. officinalis dried in air and oven conditions, respectively. The results reported in this research show that oil toxicity against V. destructor and P. larvae differed depending on the drying treatment of the plant material before the distillation of essential oil.

Typical Microorganisms in Cold Marinated Anchovies (Engraulis anchoita) Filled with Corn Oil and Spices

Abstract The aim of this work was to study the influence of microbiological load of spices in the microflora of anchovy marinades. Microorganisms were not detected in anchovy at the end of the marinating stage, previous to packaging the marinated fillet. In the spices used, the microorganisms found were Lactobacillus paracasei paracasei 1, Bacillus mycoides, and Monilia spp. in black pepper; L. cellobiosus and B. mycoides in bay leaves; L. acidophilus and B. mycoides in paprika; and L. acidophilus, B. mycoides and Micrococcus varians in milled red pep per. After three months of storage of marinated anchovy at 4°C and 18°C only L. paracasei paracasei 1, L. acidophilus 1, M. varias and B. mycoides were found. Several of these bacteria were from spices and were considered typical of marinades, since the homeostatic mechanisms were adaptable in the medium.

In vitro antibacterial and antiparasitic effect of citrus fruit essential oils on the honey bee pathogen Paenibacillus larvae and the parasitic mite Varroa destructor.

Sandra Rosa Fuselli, Matías Maggi, Susana Beatriz García de la Rosa, Judith Principal, Martín Javier Eguaras and Rosalía Fritz Universidad Nacional de Mar del Plata (UNMdP), Facultad de Ciencias Exactas y Naturales, Mar del Plata, Argentina. Comisión de Investigaciones Científicas (CIC), La Plata, Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina. Estación de Apicultura, Decanato de Ciencias Veterinarias, Universidad Centroccidental “Lisandro Alvarado” (UCLA), Tarabana, Estado Lara, Venezuela.