Biocontrol Ability and Action Mechanism of Starmerella bacillaris (Synonym Candida zemplinina) Isolated from Wine Musts against Gray Mold Disease Agent Botrytis cinerea on Grape and Their Effects on Alcoholic Fermentation

Gray mold is one of the most important diseases of grapevine in temperate climates. This plant pathogen affects plant growth and reduces wine quality. The use of yeasts as biocontrol agents to apply in the vineyard have been investigated in recent years as an alternative to agrochemicals. In this work, fermenting musts obtained from overripe grape berries, therefore more susceptible to infection by fungal pathogens such as Botrytis cinerea, were considered for the selection of yeasts carrying antifungal activity. Thirty-six isolates were identified as Starmerella bacillaris, a species recently proven to be of enological interest. Among them 14 different strains were studied and antifungal activity against B. cinerea was demonstrated, for the first time, to be present in S. bacillaris species. The production of volatile organic compounds (VOCs), tested in vitro, was found to be the main responsible of S. bacillaris antifungal effects. All the strains were able to reduce B. cinerea decay on wounded grape berries artificially inoculated with gray mold. The colonization level of wound was very high reaching, after 5 days, a concentration of 10(6) cells per ml of grape juice obtained after berry crushing. At this cell concentration S. bacillaris strains were used to ferment synthetic and natural musts. The sequential yeast inoculation, performed by adding S. cerevisiae 48 h after S. bacillaris, was needed to complete sugar consumption and determined a significant increase in glicerol content and a reduction of ethanol and acetic acid concentrations. The high wound colonization ability, found in this work, together with the propensity to colonize grape berry and the interesting enological traits possessed by the selected S. bacillaris strains allow the use of this yeast as biocontrol agent on vine and grape berries with possible positive effects on must fermentation, although the presence of S. cerevisiae is needed to complete the fermentation process. This work introduces new possibilities in wine yeast selection programs in order to identify innovative wine yeasts that are simultaneously antifungal agents in vineyards and alternative wine starters for grape must fermentation and open new perspective to a more integrated strategy for increasing wine quality

Characteristics of Compost Obtained from Winemaking Byproducts

A model procedure for the sustainable management of plant biomass related to wine production, namely vine branches from agricultural practices in the vineyard and marcs remaining after grapes crushing, was devised. An artificial humification process was set up that could respond to the needs of environmental sustainability and could be a safe way to be reintroduce in the vineyard part of the organic matter previously exported, thus contributing to recover or maintain vineyard soil fertility. Two different strategies for composting were tested, namely a static pile, made by branches and marcs, and a pile that was fed twice a year alternatively with vine branches and grape marcs. The experimentation lasted 710 days, during which environmental parameters, i.e. temperature and rainfalls were monitored. Growth dynamics of the principal functional groups of microorganism were followed. A characterization of the composted material was obtained by measuring several parameters among which, pH, carbon, nitrogen, sulfur and heavy metals content. The characteristics of the produced compost fulfill the requirements prescribed by the Italian legislation regarding the use of compost as soil amendment. Germination tests demonstrated the absence of phytotoxicity and conversely evidenced a stimulating activity towards root development

Comparative evaluation of cheese whey microbial composition from four Italian cheese factories by viable counts and 16S rRNA gene amplicon sequencing

The microbiota of cheese whey from four dairy companies located in the North-East of Italy was evaluated during winter and spring using both culture-dependent and culture-independent methods. Although no significant differences were observed (p > 0.05) for any of the six microbial categories analysed by plate counting among the dairy companies, significant differences at the family and genus level were revealed by linear discriminant analysis (LDA). In particular, variations in the abundance of the families Pseudomonadaceae and Enterobacteriaceae, as well as of the genus Acinetobacter were observed and positively correlated with plate count results (p < 0.05). The combined use of culture-dependent and culture-independent approaches gave a better description of the hygienic conditions and food safety aspects and could therefore be suggested as a useful integrated approach. \ua9 2020 Elsevier Lt

Whole-genome sequence of Starmerella bacillaris PAS13, a nonconventional enological yeast with antifungal activity

Starmerella bacillaris is a fermentative yeast commonly found in vineyards. Here, we present the draft genome sequence of S. bacillaris PAS13, a nonconventional enological yeast with a potential role as a biocontrol agent. This gene sequence will provide insights into the genetic basis of yeast activity against gray mold disease (Botrytis cinerea)

Aspects of Plant-Microbe Interactionsin Heavy Metal Polluted Soil

The role of soil microbiota, specifically rhizospheric microorganisms, in the development of phytoremediation techniques has to be elucidated in order to speed up the process and to optimize the rate of mobilization/absorption of pollutants. To meet such a purpose, several heavy metal resistant bacterial strains were isolated from a contaminated soil and from the rhizosphere of some spontaneous plants grown therein, such as Brassica sp., Trifolium repens, Trifolium pratense and Chenopodium album. Colonization of the rhizosphere is known to be helpful for bacteria, but their presence is also supposed to be functional to the plants, especially if in connection with their ability to produce Plant Growth Promoting (PGP) compounds (e.g. indole-acetic acid) or to protect the plant from pathogens. Therefore, in such an adverse environment, plants and bacteria surely take advantage by cooperating. Several bacterial isolates were tested and found to be capable of producing PGP compounds. Among them, a highly heavy metal resistant strain (Br-10) was isolated from the roots of a spontaneous plant belonging to the Brassicaceae family, whose members are known to accumulate heavy metals, and identified by phenotypic tests and 16S rDNA analysis as Serratia plymuthica. To evaluate its putative biocontrol activity, a screening of its antagonistic properties against various soil phytopathogens was also undertaken. Among the pathogenic fungi tested, a strain of Phytophtora megasperma f. sp. glycinea was found to be sensitive. Preliminary investigations of Br-10 resistance mechanisms, performed through hybridization studies on genomic DNA, suggested for S. plymuthica strain Br-10 the existence of a resistance mechanism different from that codified by the well-known czc gene cluster of Alcaligenes eutrophus that encodes for cadmium, zinc and cobalt resistance through an efflux system. By the use of Inductively Coupled Plasma analysis Cd was found to be preferentially adsorbed or accumulated rather than being forced out of the cell or not imported at all. Growth kinetics studies revealed that increasing Cd levels do not seem to affect cell growth up to the stationary phase, while having a clear impact on cell viability during the stationary phase

Study on nitrogen demand and fermentation performance of autochthonous wine yeasts selected from vineyards of important Italian winemaking regions

In this study the fermentative activities of 10 wine yeasts in synthetic must supplied with three different nitrogen concentration were compared. The yeast strains tested were mine autochthonous yeasts and a commercial starter, used as control. The autochthonous strains belong to collection of 569 isolates obtained from the vineyards (by means of single grape bunch fermentation) of two important DOC areas of the Veneto Region: \u201cProsecco di Conegliano-Valdobbiadene\u201d and \u201cPiave\u201d. Concerning these strains the main genetic and physiological aspects were deeply investigated and correlated with fermentation performances In this work 5 strains isolated from Prosecco vineyard and 4 from Raboso Piave were chosen on the basis of their interesting technological traits

Increasing vineyard biodiversity by indigenous Saccharomyces cerevisiae strains spreading: yeast persistence and effect on spontaneous grape must fermentations

Background: Recent studies indicate that S. cerevisiae strain biodiversity in vineyard is highly variable and seems to be influenced not only by grapevine varieties but also by pesticide treatments. High biodiversity level is necessary to guarantee spontaneous fermentation that recently have been re-evaluated both for positively influencing sensorial characteristics of wine and for supporting a more \u201cnatural\u201d management of wine-making process. Objectives: The aim of this work was to increase yeast biodiversity by spraying five indigenous S. cerevisiae strains on grape vineyards and to evaluate their persistence and colonizing ability. Methods: From a collection of vineyard yeasts isolated in the area of \u201cProsecco di Conegliano-Valdobbiadene\u201d DOCG five strains were chosen and sprayed on two vineyard of the same wine-making region: one was cultivated using conventional practices and the other grown under organic farming methods. Bark and leaf samples were collected and added to synthetic must. After fermentation yeasts were isolated and mtDNA analysis was performed to identify the inoculated strains. Conclusions: The presence of the introduced strains was monitored 10 days and 2 months after yeast culture spray. Results on strain ability to colonize grapevine bark are also reported