Search

The use of malolactic starter cultures, often offer no guarantee of microbiological success due to the chemical and physical factors (pH, ethanol, SO2, nutrient availability) that occur during the winemaking process. This study was born with the aim of improving the performance of the lactic acid bacteria used as a starter culture in the de-acidification of wines. Two commercial strains of Oenococcus oeni, were used. Was evaluated the effect of exogenous l-proline added during the bacterial growth, on the improvement of their survival in the presence of different ethanol concentrations and their ability to degrade l-malic acid in synthetic wine with the presence of 12% (v/v) and 13% (v/v) of ethanol. The results showed that l-proline improve ethanol tolerance and so the malolactic performances of O. oeni. This work represents an important strategy to ensure good vitality and improve the performance of the malolactic starter.

In industrial winery, the use of mixed starter cultures composed of Saccharomyces and non-Saccharomyces yeasts is an approach of growing importance for winemakers to enhance the sensory and complexity of the wine without compromising the quality. In this work, the oenological properties and enzymatic activities of 196 non-Saccharomyces yeasts, belonging to Hanseniaspora guilliermondii and Hanseniaspora uvarum species, were investigated. This screening has allowed the selection of the best non-Saccharomyces yeast strain and the use of vinification for white grape of Campania Vitis vinifera cv Fiano, in an industrial scale. The experimental fermentations were performed in four different batches: batch A (H. guilliermondii BF1 and S. cerevisiae 404 in sequential inoculum); batch B only inoculum of S. cerevisiae 404; batch C without inoculation (spontaneous fermentation); batch D with the inoculum of H. guilliermondii BF1 strain. The results of chemical and sensorial analyses have showed that the best wine comes from batch A. In conclusion, the use of H. guilliermondii BF1 with good oenological properties and a strong β-glucosidase activity allowed to improve the sensorial complexity of the wine. Selected non-Saccharomyces yeast could be applied profitably to winemaking to enhance the quality of the wine using new fermentation technologies, and could be used in industrial winery.

Knowledge of the composition of the gut microbiota in freshwater fish living in their natural habitat has taxonomic and ecological importance. Few reports have been produced on the composition of the gut microbiota and on the presence of LAB in the intestines of freshwater fish that inhabit river environments. In this study, we investigated the LAB community that was present in the gastrointestinal tract (GIT) of Mediterranean trout (Salmo macrostigma) that colonized the Biferno and Volturno rivers of the Molise region (Italy). The partial 16S rRNA gene sequences of these strains were determined for the species-level taxonomic placement. The phylogenetic analysis revealed that the isolated LABs belonged to seven genera (Carnobacterium, Enterococcus, Lactobacillus, Lactiplantibacillus, Vagococcus, Lactococcus, and Weissella). The study of the enzymatic activities showed that these LABs could contribute to the breakdown of polysaccharides, proteins, and lipids. In future studies, a greater understanding of how the LABs act against pathogens and trigger the fish immune response may provide practical means to engineer the indigenous fish microbiome and enhance disease control and fish health.

Paenibacillus larvae is the causative agent of American foulbrood (AFB), a severe bacterial disease that affects larvae of honeybees. The present study evaluated, in vitro, antimicrobial activity of sixty-one Lactiplantibacillus plantarum strains, against P. larvae ATCC 9545. Five strains (P8, P25, P86, P95 and P100) that showed the greatest antagonism against P. larvae ATCC 9545 were selected for further physiological and biochemical characterizations. In particular, the hydrophobicity, auto-aggregation, exopolysaccharides production, osmotic tolerance, enzymatic activity and carbohydrate assimilation patterns were evaluated. The five L. plantarum selected strains showed suitable physical and biochemical properties for their use as probiotics in the honeybee diet. The selection and availability of new selected bacteria with good functional characteristics and with antagonistic activity against P. larvae opens up interesting perspectives for new biocontrol strategies of diseases such as AFB.

The use of malolactic starter cultures, often offer no guarantee of microbiological success due to the chemical and physical factors (pH, ethanol, SO(2), nutrient availability) that occur during the winemaking process. This study was born with the aim of improving the performance of the lactic acid bacteria used as a starter culture in the de-acidification of wines. Two commercial strains of Oenococcus oeni, were used. Was evaluated the effect of exogenous l-proline added during the bacterial growth, on the improvement of their survival in the presence of different ethanol concentrations and their ability to degrade l-malic acid in synthetic wine with the presence of 12% (v/v) and 13% (v/v) of ethanol. The results showed that l-proline improve ethanol tolerance and so the malolactic performances of O. oeni. This work represents an important strategy to ensure good vitality and improve the performance of the malolactic starter.