A . V EY R AT , M . C. MI R AL LE S AN D G . PE RE Z -M AR T IN EZ . 1999. A random amplified polymorphic DNA (RAPD) assay coupled to a fast and reproducible cell lysis method from Lactobacillus colonies were developed to type lactobacilli of different strains and species, with the aim of precisely enumerating each of the different Lactobacillus strains inoculated in a nutrient-rich environment, such as sausage meat batter. Colonization assays were carried out in an aseptic meat fermentation system for up to 14 d and the inoculated strains were challenged with mixtures of wild lactobacilli. The proportion of inoculated strains remaining at different times was compared with the total number of lactobacilli grown on MRS agar by RAPD. The colonization rate of the different strains tested was very different. The RAPD-fast lysis method developed is simple and, with a low cost per assay, could also be applied to other food fermentations.

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FGA (furfurylamine; 1,2,3,4 tetra-O -acetyl-β -d -glucose; adipic acid monoethyl ester), a chemical mixture of three analogues of plant growth regulators that increases the protection of tomato plants against phytopathogens, was demonstrated to have direct antimicrobial activity. It reduced the growth in vitro of the filamentous fungi Alternaria solani and Botrytis cinerea , and the oomycetes Phytophthora capsici and Phytophthora citrophthora (ED 50 0·18 -0·26% w/v, depending on species). The components of this mixture were also active against these phytopathogens, but sensitivity to the compounds was different for each pathogen. Adipic acid monoethyl ester (E) showed the highest and widest range of activity. Experiments on B. cinerea and A. solani indicated that this compound prevented spore germination in addition to mycelial growth and at high concentrations (0·5% w/v), inhibiting both the yeast Saccharomyces cerevisiae and the bacterium Escherichia coli . This ester retarded A. solani infection of tomato leaves, providing evidence for its efficacy in a biological context and its potential use in plant disease prevention.