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Although several strains of B. subtilis with antifungal activity have been isolated worldwide, to date there are no published reports regarding the isolation of a native B. subtilis strain from strawberry plants in Mexico. A native bacterium (Bacillus subtilis 21) demonstrated in vitro antagonistic activity against different plant pathogenic fungi. Under greenhouse conditions, it was shown that plants infected with Rhizoctonia solani and Fusarium verticillioides and treated with B. subtilis 21 produced augment in the number of leaves per plant and an increment in the length of healthy leaves in comparison with untreated plants. In addition, B. subtilis 21 showed activity against pathogenic bacteria. Secreted proteins by B. subtilis 21 were studied, detecting the presence of proteases and bacteriocin-like inhibitor substances that could be implicated in its antagonistic activity. Chitinases and zwittermicin production could not be detected. Then, B. subtilis 21 could potentially be used to control phytopathogenic fungi that infect strawberry plants.

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30 31 Large amounts of peptides are naturally generated in foods through the proteolysis 32 phenomena taking place during processing. Such proteolysis is carried out either by 33 endogenous enzymes in ripened foods or by the combined action of endogenous and 34 microbial enzymes when fermented. Food proteins can also be isolated and hydrolysed 35 by peptidases to produce hydrolysates. Endo-peptidases act first followed by the 36 successive action of exo-peptidases (mainly, tri-and di-peptidylpeptidases, 37 aminopeptidases and carboxypeptidases). The generated peptides may be further 38 hydrolysed through the gastrointestinal digestion resulting in a pool of peptides with 39 different sequences and lengths, some of them with relevant bioactivity. However, these 40 peptides should be absorbed intact through the intestinal barrier and reach the blood 41 stream to exert their physiological action. This manuscript is reporting the enzymatic 42 routes and strategies followed for the generation of bioactive peptides.

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