Lactobacillus plantarum strain LB17.2b, isolated from traditional table olive fermentation has been shown to produce thermostable antibacterial proteins. At pH 6.5, the proteinaceous fraction obtained from culture supernatant was active against Enterococcus faecalis and against natural competitors of L. plantarum from olive fermentation brines. Bioactivity was quantified against Weissella paramesenteroides DSM20288 using the critical dilution method by a regression procedure. This bioactivity has been found to be growth-associated indicating a primary metabolite kinetics. Ultrafiltration studies with supernatants from different fermentation times have been carried out. A twofold increase in the activity of the retentate from the 30 kg. mol-1 cutoff membrane was observed, by comparison with the total activity applied to this membrane (culture supernatant). The addition of the filtrate to this retentate caused a marked drop in activity, most probably associated with the presence of an inhibitor. These studies also demonstrated the presence of another antibacterial proteinaceous compound showing a wider inhibitory spectrum and produced during culture stationary phase. In the presence of lactic acid (pH 3.7), these antimicrobial proteinaceous compounds have been found to inhibit Gram-negative human pathogens, probably by a synergistic effect. At the present time one bacteriocin-like compound was isolated, showing a molecular mass of approximately 50 kg. mol-1. The presence of another compound of different properties and with a molecular mass between 3 and 10 kg. mol-1 was also detected. antimicrobial activity / bacteriocin / lactic acid / Lactobacillus plantarum Résumé-Activité antimicrobienne de L. plantarum isolé d'une fermentation lactique traditionnelle d'olives de table. La souche de Lactobacillus plantarum LB17.2b, isolée à partir de la fermentation traditionnelle des olives de table, a montré la capacité à produire des protéines antimicrobiennes thermostables. À pH 6.5, la fraction protéique obtenue à partir du surnageant de la culture était active contre Enterococcus faecalis et contre les compétiteurs naturels de L. plantarum,

Grafting is the most used propagation method in viticulture and is the unique control strategy against Phylloxera. Nevertheless, its practice remains limited mainly due to inconsistent graft success and difficulties in predicting graft compatibility responses of proposed scion–rootstock combinations, slowing down the selection of elite rootstocks. Aiming to identify optimal phenotypic parameters related to graft (in)compatibility, we used four clones of two grapevine cultivars that show different compatibility behavior when grafted onto the same rootstock. Several physiological parameters, internal anatomy of the graft union, chlorophyll fluorescence, and pigment contents of homo- and heterografts were monitored in a nursery-grafting context. The measurements highlighted enhanced performance of the heterografts due to rooting difficulties of Vitis vinifera homografts. This suggests that in viticulture, homografts should only be used as compatibility controls regarding qualitative attributes. By observing the internal anatomy of the union, we found that grapevines might require longer times for graft healing than anticipated. While Affinity Coefficients were not informative to assess incompatibility, leaf chlorophyll concentration analysis proved to be a more sensitive indicator of stress than the analysis of chlorophyll fluorescence. Overall, we conclude that graft take correlated best with callus formation at the graft junction three weeks after grafting.

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In viticulture, grafting is used to propagate Phylloxera-susceptible European grapevines, thereby using resistant American rootstocks. Although scion–rootstock reciprocal signaling is essential for the formation of a proper vascular union and for coordinated growth, our knowledge of graft partner interactions is very limited. In order to elucidate the scale and the content of scion–rootstock metabolic interactions, we profiled the metabolome of eleven graft combination in leaves, stems, and phloem exudate from both above and below the graft union 5–6 months after grafting. We compared the metabolome of scions vs. rootstocks of homografts vs. heterografts and investigated the reciprocal effect of the rootstock on the scion metabolome. This approach revealed that (1) grafting has a minor impact on the metabolome of grafted grapevines when tissues and genotypes were compared, (2) heterografting affects rootstocks more than scions, (3) the presence of a heterologous grafting partner increases defense-related compounds in both scion and rootstocks in shorter and longer distances from the graft, and (4) leaves were revealed as the best tissue to search for grafting-related metabolic markers. These results will provide a valuable metabolomics resource for scion–rootstock interaction studies and will facilitate future efforts on the identification of metabolic markers for important agronomic traits in grafted grapevines.