Recent and substantial yield losses of Styrian oil pumpkin (Cucurbita pepo L. subsp. pepo var. styriaca Greb.) are primarily caused by the ascomycetous fungus Didymella bryoniae but bacterial pathogens are frequently involved as well. The diversity of endophytic microbial communities from seeds (spermosphere), roots (endorhiza), flowers (anthosphere), and fruits (carposphere) of three different pumpkin cultivars was studied to develop a biocontrol strategy. A multiphasic approach combining molecular, microscopic, and cultivation techniques was applied to select a consortium of endophytes for biocontrol. Specific community structures for Pseudomonas and Bacillus, two important plant-associated genera, were found for each microenvironment by fingerprinting of 16S ribosomal RNA genes. All microenvironments were dominated by bacteria; fungi were less abundant. Of the 2,320 microbial isolates analyzed in dual culture assays, 165 (7%) were tested positively for in vitro antagonism against D. bryoniae. Out of these, 43 isolates inhibited the growth of bacterial pumpkin pathogens (Pectobacterium carotovorum, Pseudomonas viridiflava, Xanthomonas cucurbitae); here only bacteria were selected. Microenvironment-specific antagonists were found, and the spermosphere and anthosphere were revealed as underexplored reservoirs for antagonists. In the latter, a potential role of pollen grains as bacterial vectors between flowers was recognized. Six broad spectrum antagonists selected according to their activity, genotypic diversity, and occurrence were evaluated under greenhouse conditions. Disease severity on pumpkins of D. bryoniae was significantly reduced by Pseudomonas chlororaphis treatment and by a combined treatment of strains (Lysobacter gummosus, P. chlororaphis, Paenibacillus polymyxa, and Serratia plymuthica). This result provides a promising prospect to biologically control pumpkin diseases.

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The combination of a laccase-hydroxybenzotriazole (HBT) mediator system with/without cellobiose dehydrogenase (CDH) or an additional Fenton reaction step for the elimination and/or detoxification of phenolic compounds in dry olive mill residues (DOR) and liquid olive mill wastewaters (OMW) was evaluated. The laccase-HBT-CDH and laccase-HBT-CDH-Fenton system were the most effective, removing at least 69 and 72 % of phenolic compounds from a total of 698 and 683 mg in OMW and DOR, respectively, in 12 h. The efficient removal of phenolic compounds was also accompanied by [80 % reduction in biochemical oxygen demand and chemical oxygen demand in both DOR and OMW. Microbial community analysis using single-strand conformation polymorphism (SSCP) gels showed that biogas reactors supplemented with untreated and laccase-HBT-CDH-Fenton-treated DOR and OMW strongly inhibited growth of microorganisms. In contrast, the laccase-HBTand laccase-HBT-CDH-pretreated OMW and DOR were detoxified as evidenced by SSCP analysis, which also indicated a distinct sensitivity of the individual members of the anaerobic population toward the toxicants. Further, although the laccase-HBT-CDH-Fenton system was effective in bleaching and removing phenolic compounds in both OMW and DOR, it was not able to support methane production. However, laccase-HBT and laccase-HBT-CDH indeed supported biogas production. This study therefore shows that the laccase-HBT-CDH system has a potential for the detoxification of olive mill residues, which can be potentially used as substrates for downstream processes.