## 4 Discussion  
Fruits and vegetables are staples in human diets worldwide. In developed countries, there is a constantly increasing demand for these products, not to mention that social nutritional movements such as vegetarianism and veganism are gaining followers on a daily basis. From this perspective, the safety of fruits and vegetables is a public health issue of top priority. In the present study, we purchased fruits (apples, pears and peaches) and vegetables (tomatoes, red peppers, white cabbage, carrots and RTU salad) from local open markets and retail stores. Table 2 shows the pathogens and spoilage bacteria isolated from these products, including _E. coli_, _L. monocytogenes_ and _Salmonella_ spp. These findings underline the danger that fruits and vegetables can carry a load of pathogens, which, under certain conditions, may initiate an outbreak. Twelve of these strains were selected and used as target cell indicators of the production of bacterioxins from LAB and _Bifidobacterium_ strains. Contamination with such pathogens can easily occur during preharvest (soil, manure, irrigation water), harvest (handling) and postharvest (transportation, storage, etc.) treatments. Because these products, and particularly the fruits, are eaten raw, they have been described as causative agents of outbreaks [50; 51; 52; 53; 54]. Although practices such as washing and sanitation reduce the microbial load to some extent, they do not eliminate the dangerous pathogens, e.g., _E. coli_ O157:H7, _Salmonella_ spp. and _L. monocytogenes_[55; 54]. Furthermore, consumers expect and demand \"natural and mild\" means to preserve food safety from the industry--means that do not alter the sensorial characteristics of food and, of course, pose any health hazards to the consumer [52; 56]. Bacteriocins, or BLS in general, seem to be an ideal solution to satisfy these demands since they are safe for consumers, natural in their origin and, by exerting antimicrobial activity, can extend the shelf life of fruits and vegetables [57; 58]. Nature and natural products are excellent sources of BLS-producing bacteria. Our results revealed 101 strains of 16 species of LAB and Bifidobacteria (Table 1) isolated from oregano honeycombs, indicating an impressive biodiversity with the potential to harness BLS-producing microorganisms. This is a novel finding since there are no other reports in the literature concerning the microbiology of oregano honey. The wild types of _Lactobacillus_ are stable and adapted to a variety of environments. They survive by (a) the production of organic acids, mainly lactic acid, as byproducts of the fermentation of carbohydrates, (b) the production of substances with antibacterial activity such as hydrogen peroxide and (c) the production of BLS. In our study, and in order to analyze the antimicrobial effect of the LAB and _Bifidobacterium_ strains isolated from oregano honeycombs to pathogens and spoilage bacteria isolated from fruits and vegetables, the cell-free supernatant (CFS) fluid of the cultures underwent three different categories and treatments: it was left untreated (Category A), modified to pH 6 by the addition of NaOH to eliminate organic acids (Treatment B) and, finally, in addition to NaOH, catalase was added to eliminate hydrogen peroxide (Treatment C). Our results (Table 3) show that in 10 out of 14 pathogens and spoilage bacteria, the distribution of the antibacterial potency of LAB and _Bifidobacterium_ (expressed in millimeters of inhibition zones) was not affected by the different treatments of the CFS. This finding strongly suggests that, firstly, this antimicrobial activity was due to the BLS, and secondly, BLS' activity overshadows the antimicrobial effect of organic acids and hydrogen peroxide. For example, in the case of _E. coli_ strain No.