Pilot scale fermentations with grape pomace from two different wineries were investigated during the 24 weeks of the ensiling period, along with laboratory scale experiments in which the environmental temperatures were held constant at 20, 25, 30 and 35 °C. During this period, yeast and lactic acid bacteria (LAB) counts were made, after which the identity of both groups of organisms was studied, as were the major microbial metabolites present. Major microbial and chemical alterations occurred during the first 3 weeks of ensilage, leaving a more stable product differing significantly from the initial substrate. The results obtained indicated that after initial growth, yeast and LAB populations undergo progressive inactivation at environmental temperatures above 20 °C, although LAB seem to adjust better to this specific, post‐fermentation environment. Homofermentative species of Lactobacillus were the dominant LAB. The initial yeast flora of non‐Saccharomyces species was replaced by a typical wine yeast flora, i.e. predominantly Saccharomyces cerevisiae. At the chemical level, major alterations were due to an alcoholic fermentation and a malolactic conversion within the first 3 weeks.

The kinetics of cell inactivation in the presence of ethanol at 20, 22.5% and 25% (v/v), was measured by progressive sampling and viable counting, and used as an inference of the ethanol resistance status of five non-Saccharomyces strains and one strain of Saccharomyces cerevisiae. The capacity of standard inocula of the same strains to establish growth at increasing initial ethanol concentrations was employed as a comparison. The effect of various different pre-culture conditions on the ethanol resistance of the 6 strains was analysed by the cell inactivation method and by the cell growth method. Exposing cells to 25% (v/v) ethanol for 4 min enabled the differentiation of the yeasts in terms of their resistance to ethanol. The results suggest that the two methods are generally concordant and that the cell inactivation method can, thus, be used to infer ethanol resistance of yeast strains.

The kinetics of cell inactivation in the presence of ethanol at 20, 22.5% and 25% (v/v), was measured by progressive sampling and viable counting, and used as an inference of the ethanol resistance status of five non-Saccharomyces strains and one strain of Saccharomyces cerevisiae. The capacity of standard inocula of the same strains to establish growth at increasing initial ethanol concentrations was employed as a comparison. The effect of various different pre-culture conditions on the ethanol resistance of the 6 strains was analysed by the cell inactivation method and by the cell growth method. Exposing cells to 25% (v/v) ethanol for 4 min enabled the differentiation of the yeasts in terms of their resistance to ethanol. The results suggest that the two methods are generally concordant and that the cell inactivation method can, thus, be used to infer ethanol resistance of yeast strains.

No abstract

Objectives: The significance of microorganisms in root canals with regard to the aetiology of periapical infection and the need for crucial bacteria control during treatment are undeniable. In this study, we re-port and discuss a review of the literature on Microbiological Root Canal Sampling (MRS). The procedure is analyzed in detail, discussing its powers, limitations and the influence of sample collection procedures on the incidence of true and false positive results. Data sources: MEDLINE/PUBMED, B-On and library files of Oporto University were accessed. Selection: Papers were selected using the keywords: “root ca¬nal sampling”; “apical periodontitis”; “endodontic pathogens”; “root canal infection”; “Culture”; “molecular biology”. The references were selected under inclusion criteria such as English language, accessibility, rel¬evance to the theme and scientific rigor. Conclusions: This review illustrated the absolute need to adhere to strict methodology procedures if valid samples are to be obtained. A combination of Culture and molecular identification approaches have confirmed the polymicrobial nature of endodontic infections with a pre¬dominance of anaerobic bacteria. Nucleic acid-based techniques provide significant additional information particularly regarding the not-yet-cultivable species of the microbial community, but greatly increase the budget of the procedure. Thus, assessment of the endodontic microflora, in the context of a polymicro¬bial biofilm ecosystem, and its relevance to endodontic treatments must rely in the complementariness of Culture and Metagenomics approaches as they are neither mutually exclusive nor competitive, but strongly complementary.