Biodiversity and brewing attitude of non-Saccharomyces strains isolated from Uruguayan vineyards and other ecosystems

In recent years, interest in non-Saccharomyces yeasts for the innovation and development of different and alternative beer styles has been increasing, especially for the microbrewing industry. This work studied the biodiversity of non-Saccharomyces yeasts based on isolates from grapes of different Uruguayan vineyards, craft breweries and raw materials, with the aim of selecting autochthonous non-Saccharomyces yeasts with a brewing attitude. Brewing tests were performed on synthetic wort developed for this purpose, and the evolution of alcoholic fermentation was monitored by measuring glucose, maltose, maltotriose consumption, ethanol and glycerol production and final sensory analysis. A total of two hundred seventy-one yeast strains belonging to different genera were evaluated according to these parameters. After evaluating alcoholic fermentation performance, a native yeast strain belonging to the species Starmerella meliponinorum was selected due to its high maltotriose consumption and glycerol production, making it a very promising brewing yeast, especially for production of low carbohydrate beers.

An evaluation of a macroalgal bioassay tool for assessing the spatial extent of nutrient release from offshore fish farms

In this study we develop and evaluate a macroalgal bioassay tool for monitoring the spatial extent of dissolved wastes loaded from offshore fish farms into the marine coastal ecosystem. This tool is based on the analysis of the nitrogen stable isotope ratio (delta(15)N) in tissues of several benthic primary producers (macroalgae and Posidonia oceanica epiphytes) incubated, by means of incubation devices, in the water column at increasing distances (from 0 m to 1000 m) from the fish cages. The bioassays were performed in three fish farms situated in different geographical locations (the Canary Islands, Murcia and Catalonia) and we test: the suitability of the different macroalgae species used in relation with their resistance to incubation and their sensitivity to fish farm wastes and the most appropriate incubation depth (5 m or approximately 20 m) and incubation time (2, 4 or 6 days) to detect the spatial distribution of delta(15)N around fish farms. In general terms, the results showed a significant increment of delta(15)N values toward the fish cages with respect to the reference (initial) and control values for all the species of macroalgae tested except for the red algae Asparagopsis taxiformis from Canary Islands. The magnitude and shape of the reported spatial responses varied as a function of the experimental settings analyzed as well as a function of the nutrient regime characteristics of each coastal area. The spatial gradient was more consistent in the shallow part of the water column (5 m depth), than in the deeper part ( approximately 20 m) and was statistically significant after an incubation period of four days. These results confirm the effectiveness and reliability of the method proposed, enabling the spatial extent of nutrients derived from fish farms to be assessed in an effective and simple manner, suitable for use in monitoring programs around offshore fish farms.