Selection of a New Highly Resistant Strain for Malolactic Fermentation under Difficult Conditions

Malolactic fermentation (MLF) is a biological process that contributes to wine quality, but it is frequently affectedby various vinification conditions. Resistance to four wine-limiting factors was studied with respect to 10 Oenococcusoeni strains in order to select a suitable strain for performing reliable MLF in difficult wines. Resistance to lowfermentation temperature, high SO2 and/or ethanol concentration, and low pH were assayed in laboratory tests. Apool of the most resistant strains was used in a set of laboratory MLFs. At the end of fermentation, the dominantstrains were identified by RAPD-PCR. The PN4 strain was found to be dominant in the majority of cases and underthe most detrimental wine conditions, and it was therefore chosen as the single-strain inoculum for the subsequentMLF trials. The effectiveness of the PN4 strain was confirmed in a series of MLFs carried out in three differentcountries under experimental and industrial conditions. It accomplished MLF in wines with up to 15.8% ethanol,pH as low as 3.0, 60 mg/L of free SO2, and in fermentation temperatures below 17ºC. Our findings indicate that theO. oeni PN4 strain could be an effective starter, guaranteeing regular and reliable MLF fermentation

Modulation of wine sensory profile by lactic bacterial activity in a global warming scenario by different malolactic fermentation strategies

Aim. Incoming global warming imposing strategies to adapt wine chemical profile at an unknown scenario. In this sense malolactic fermentation (MLF), the biological deacidification of wines, must become a conscious choice to optimize the content in organic acids and the sensory profile of the wine. The authors present different works to understand how modulate the oenological activity of strains of Oenococcus oeni. The effect of different strategies of bacterial inoculum and correction of acidity were considered. Method. Simultaneous fermentation is an alternative strategy for managing MLF, which involves the inoculation of lactic bacteria into the grape must, instead into the wine at the end of alcoholic fermentation as traditionally practiced in winemaking. This approach has been tested in southern red wines with a high ethanol potential, withe aromatic wines, and sparkling-base wines. Furthermore, on a population of strains of O. oeni was verified the effect of the correction of grape must/wine acidity by different organic acids, in terms of MLF kinetics, cell viability and diacetyl production. Results. In the last years the focus of the selection of bacterial strains for malolactic fermentation was re-oriented from the mere ability to accomplish malic acid degradation, to the adaptability at different winemaking protocols. In this sense, simultaneous inoculum of bacteria and yeast in grape must seems to achieve different goals. In southern, high ethanol and low acidity wines bacteria results more active respect to tests performed by traditional post-alcoholic inoculum, accomplishing MLF without spoilage effects, such as volatile acidity increase. In the case of tests performed in winemaking if aromatic or sparkling base wines the simultaneous inoculum results in a higher varietal character. Tartaric, malic, and citric acid were tested to correct the low acidity of grape must/wine before MLF. Malic acid over the 2.5 g/L affected evolution of MLF, while citric acid stimulates bacterial activity and diacetyl production. The addition of tartaric acid results counterproductive at the higher value. Bacterial activity in grape must is more efficient than in wine in terms of rate and completeness of MLF. Conclusion. The acidic profile of wine is one of the key aspects in a global warming scenario, for longevity and organoleptic quality. This work offers useful information to modulate the activity of lactic acid bacteri

Drought avoidance adaptive traits in seed germination and seedling growth of Citrullus amarus landraces

Abstract Citrullus lanatus cultivation is affected by drought stress. Citrullus species that grow wild and domesticated in arid areas, are considered potential useful donors of drought tolerance traits. Here, we evaluated the response of seed germination, seedling establishment and growth to different water availabilities in eleven landraces of C. amarus, from most of their cultivation range and in one C. lanatus commercial cultivar ('Sugar Baby'). 'Sugar Baby' germinated to lower water potential better than all C. amarus landraces, while seedling establishment was much higher in C. amarus than in C. lanatus. Finally, seedling growth of C. amarus landraces and the C. lanatus cultivar followed different patterns depending on water availability, showing enhanced biomass growth under wet conditions and no changes between dry and wet growing treatments, respectively. The different water use strategies in seed germination and seedling growth found in the two crops highlight drought avoidance strategies linked to the species growing environment in C. amarus, not present in the C. lanatus cultivar. The high seedling establishment, the plastic responses to water availabilities and the strong root system, indicate that genetic resources of C. amarus may have important applications in breeding programmes and in the selection of water-use efficient rootstock lines

Liquid baits with Oenococcus oeni increase captures of Drosophila suzukii

The spotted-wing drosophila (SWD), Drosophila suzukii Matsumura (Diptera: Drosophilidae), native to Eastern Asia, is an invasive alien species in Europe and the Americas, where it is a severe pest of horticultural crops, including soft fruits and wine grapes. The conventional approach to controlling infestations of SWD involves the use of insecticides, but the frequency of application for population management is undesirable. Consequently, alternative strategies are urgently needed. Effective and improved trapping is important as an early risk detection tool. This study aimed to improve Droskidrink® (DD), a commercially available attractant for SWD. We focused on the chemical and behavioral effects of adding the bacterium Oenococcus oeni (Garvie) to DD and used a new trap design to enhance the effects of attractive lures. We demonstrate that microbial volatile compounds produced by O. oeni are responsible for the increase in the attractiveness of the bait and could be later utilized for the development of a better trapping system. Our results showed that the attractiveness of DD was increased up to two-fold by the addition of commercially available O. oeni when combined with an innovative trap design. The new trap-bait combination increased the number of male and especially female catches at low population densitie

Microbiological and chemical monitoring of Marsala base wine obtained by spontaneous fermentation during large-scale production

The present work was undertaken to evaluate the effect of the natural winemaking on the microbial and chemical composition of Marsala base wine. To this purpose, a large-scale vinification process of Grillo grape cultivar was monitored from harvesting to the final product. Total yeasts (TY) showed a rapid increase after must pressing and reached values almost superimposable to those registered during the conventional winemakings. Lactic acid bacteria (LAB) were registered at the highest levels simultaneously to yeast growth at the beginning of the process. Saccharomyces cerevisiae was the species found at the highest concentrations in all samples analysed. Several strains (n= 16) was registered at high levels during the alcoholic fermentation and/or aging of wine; only two of them were detected on the grape surface. Lactobacillus plantarum was the LAB species most frequently isolated during the entire vinification process. Ethanol content was approximately 14% (v/v) at the end of vinification. The value of pH did not greatly vary during the process and the volatile acidity (VA) was detected at low concentrations during the entire transformation. The concentration of malic acid rapidly decreased during the AF; on the other hand, lactic acid showed an irregular trend during the entire process. trans-caffeil tartaric acid was the most abundant hydroxycinnamoyl tartaric acid and volatile organic compounds (VOC) were mainly represented by isoamylic alcohol and isobutanol

Notulae to the Italian alien vascular flora: 3

In this contribution, new data concerning the Italian distribution of alien vascular flora are presented. It includes new records, exclusions, confirmations, and status changes for Italy or for Italian administrative regions for taxa in the genera Acer, Amaranthus, Araujia, Aubrieta, Avena, Bidens, Calycanthus, Celtis, Elaeagnus, Eragrostis, Euonymus, Fallopia, Ficus, Hedera, Lantana, Ligustrum, Ludwigia, Morus, Oenothera, Opuntia, Oxalis, Parkinsonia, Paspalum, Paulownia, Platycladus, Pleuropterus, Rumex, Salvia, Senecio, Setaria, Syagrus, Tradescantia, Trifolium and Yucca. Furthermore, a new combination in the genus Vicia is proposed

Notulae to the Italian native vascular flora: 3.

In this contribution new data concerning the distribution of native vascular flora in Italy are presented. It includes new records, exclusions, and confirmations to the Italian administrative regions for taxa in the genera Asplenium, Bolboschoenus, Botrychium, Chamaerops, Crocus, Galeopsis, Grafia, Helosciadium, Hieracium, Juniperus, Leucanthemum, Lolium, Medicago, Phalaris, Piptatherum, Potamogeton, Salicornia, Salvia, Seseli, Silene, Spiraea, Torilis and Vicia. Rhaponticoides calabrica is proposed as synonym novum of R. centaurium. Furthermore, new combinations in the genera Galatella and Lactuca are proposed