Articles scientifiques

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02 janvier 2006

Microbiology of maple sap and biofilm formation in maple sap collection system

Auteur : Luc Lagacé.

Cet article est disponible seulement en anglais. Vous pouvez obtenir l'article auprès de l'Hokkaido University Press. L'article est  tiré de : M. Terazawa (ed) Tree sap III, Proceedings of the 3rd international symposium on sap utilization (ISSU) in Bifuka 2005, Hokkaido University Press, Sapporo, Japan.

Maple sap is the sweet exudate collected from maple trees during the spring season to produce maple syrup. It is a rich medium composed mainly of organic compounds and minerals that can support the growth of many species of microorganisms. These microorganisms are bacteria, yeasts and moulds that can develop in the taphole of maple trees as well as in the sap collection system in the form of a biofilm. The biofilm can be thought of as a reservoir of microorganisms that will continuously inoculate the sap and consequently modify its chemical composition. Microbial growth in maple sap as been known for a long time to be detrimental for maple syrup quality with regards to its colour, texture and taste. The microbial community of maple sap and biofilm was recently studied using molecular tools such as the amplified ribosomal DNA restriction analysis (ARDRA) and scanning electron microscopy. These methods have permitted the observation of the biofilm formation on the interior surface of tubing of the sap collection system and the characterization of maple sap microbiota by the identification of many species of bacteria in which, Pseudomonas species occupied an important place. A review of the results obtained with these techniques will therefore be presented here along with a comprehensive discussion on the relevant impact of these findings.

03 janvier 2005

Compartimentage chez l’érable à sucre

Le compartimentage de l'érable à sucre.

01 avril 2004

Identification of the Bacterial Community of Maple Sap by Using Amplified Ribosomal DNA (rDNA) Restriction Analysis and rDNA Sequencing

Auteurs : L. Lagacé, M. Pitre, M. Jacques et D. Roy.

Cet article est disponible seulement en anglais (Applied and Environmental Microbiology, April 2004, vol. 70, no. 4, 2052-2060). Le numéro de référence (Digital Object Identifier (DOI)) est le : 10.1128/AEM.70.4.2052-2060.2004 .

The bacterial community of maple sap was characterized by analysis of samples obtained at the taphole of maple trees for the 2001 and 2002 seasons. Among the 190 bacterial isolates, 32 groups were formed according to the similarity of the banding patterns obtained by amplified ribosomal DNA restriction analysis (ARDRA). A subset of representative isolates for each ARDRA group was identified by 16S rRNA gene fragment sequencing. Results showed a wide variety of organisms, with 22 different genera encountered. Pseudomonas and Ralstonia, of the {gamma}- and ß-Proteobacteria, respectively, were the most frequently encountered genera. Gram-positive bacteria were also observed, and Staphylococcus, Plantibacter, and Bacillus were the most highly represented genera. The sampling period corresponding to 50% of the cumulative sap flow percentage presented the greatest bacterial diversity according to its Shannon diversity index value (1.1). {gamma}-Proteobacteria were found to be dominant almost from the beginning of the season to the end. These results are providing interesting insights on maple sap microflora that will be useful for further investigation related to microbial contamination and quality of maple products and also for guiding new strategies on taphole contamination control.

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