A cDNA clone of wheat oxalate oxidase (OxO) under the control of the constitutive CAMV 35S promotor was expressed in tomato plants by Agrobacterium -mediated transformation. Twenty-six transgenic tomato lines were obtained and analysed. PCR experiments confirmed the incorporation of the OxO gene in all tested tomato lines. The transgenic tomato plants expressed a 124-kDa protein showing OxO activity, and were able to convert different oxalic acid (OA) concentrations in vitro . In a detached leaf assay, most of the transgenic lines showed reduced disease symptoms compared with controls, following inoculation with Botrytis cinerea . In addition, leaves of the line T15 showed a marked reduction in symptoms compared with the control following inoculation with Sclerotinia sclerotiorum .

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Aims: To investigate the effect of anionic polysaccharides often used in beverage applications (xanthan and k-carrageenan) on the antimicrobial efficacy of the cationic surfactant lauric arginate (LAE) against typical spoilage yeasts. Methods and Results: The antimicrobial efficacy of LAE against Saccharomyces cerevisiae, Candida albicans and Zygosaccharomyces bailii in the absence and presence of anionic polysaccharides was assessed by microtitre and macrobroth dilution assays. Combining LAE with either xanthan or k-carrageenan caused a pronounced decrease in LAE's antimicrobial efficacy, with the minimal inhibitory and lethal concentrations (MIC and MLC) both increasing with increasing polysaccharide concentration. This reduction in antimicrobial efficacy was more pronounced for the addition of k-carrageenan. To determine the cause of loss of activity, physical properties of solutions were examined. Turbidity and sedimentation measurements indicated that complexes between LAE and anionic polysaccharides had been formed. Electrophoresis measurements showed that complexes had varying electrical charges and dimensions depending on solution composition. Conclusion: Results suggest that electrostatic interactions between LAE and anionic polysaccharides play a major role in complex formation and loss of antimicrobial activity. Significance and Impact of the Study: Results have important implications for the utilization of LAE as an antimicrobial agent in beverage and food products containing anionic polysaccharides.

Funding information German Ministry of Economics and Energy (via AiF) and the FEI

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