This study evaluated the probiotic properties (stability at different pH values and bile salt concentration, auto-aggregation and co-aggregation, survival in the presence of antibiotics and commercial drugs, study of β-galactosidase production, evaluation of the presence of genes encoding MapA and Mub adhesion proteins and EF-Tu elongation factor, and the presence of genes encoding virulence factor) of four LAB strains (Lactobacillus casei SJRP35, Leuconostoc citreum SJRP44, Lactobacillus delbrueckii subsp. bulgaricus SJRP57 and Leuconostoc mesenteroides subsp. mesenteroides SJRP58) which produced antimicrobial substances (antimicrobial peptides). The strains survived the simulated GIT modeled in MRS broth, whole and skim milk. In addition, auto-aggregation and the cell surface hydrophobicity of all strains were high, and various degrees of co-aggregation were observed with indicator strains. All strains presented low resistance to several antibiotics and survived in the presence of commercial drugs. Only the strain SJRP44 did not produce the β-galactosidase enzyme. Moreover, the strain SJRP57 did not show the presence of any genes encoding virulence factors; however, the strain SJRP35 presented vancomycin resistance and adhesion of collagen genes, the strain SJRP44 harbored the ornithine decarboxylase gene and the strain SJRP58 generated positive results for aggregation substance and histidine decarboxylase genes. In conclusion, the strain SJRP57 was considered the best candidate as probiotic cultures for further in vivo studies and functional food products development.

The probiotic potential of Leuconostoc mesenteroides subsp. mesenteroides SJRP55, isolated from water buffalo mozzarella cheese was evaluated. The microorganism presented resistance to stressful conditions that simulated the gastrointestinal tract, and to the best of our knowledge, Leuconostoc mesenteroides subsp. mesenteroides SJRP55 was the first of this species with the ability to deconjugate bile salts. Tolerance to NaCl was temperature dependent, as well the results obtained by aggregation capacity. The strain presented good adhesion properties, β-galactosidase activity, viability in fermented milk during storage, inactive against Streptococcus thermophilus and sensitive to most of the tested antibiotics. Some analgesic medications inhibited the growth of the strain. Leuconostoc mesenteroides subsp. mesenteroides SJRP55 exhibited in vitro probiotic potential, and it can be better characterized through future in vivo tests. This bacterium presents higher functional properties compared to other studied strains, and therefore, it is a potential candidate for the application as a probiotic strain, which could be used by industries in the manufacture of functional milk-based products.

Leuconostoc mesenteroides is a lactic acid bacterium (LAB) that has been isolated from differentsources. Some of its strains are able to produce bacteriocins, and most of them belong to class IIa and shows anti-Listeria activity. Additionally, Lc. mesenteroides specie can be a probiotic candidate; promising studies have shown the potential of this specie to survive and grow under various stress conditions present in the gastrointestinal tract (GIT). On the other hand, this microorganism can cause spoilage in some types of food matrices and scarce reports have shown the pathogenic potential of this specie. In this review, we focus on an overview of Lc. mesenteroides bacteriocins-producing strains and its probiotic potential, in contrast with Lc. mesenteroides the spoilage and pathogenic cases reported in the literature. IntroductionLeuconostoc genus belongs to Firmicutes phylum, which includes Gram positive, heterofermentative (fermenting glucose to D-lactic acid, ethanol/acetic acid, and CO 2 from phosphoketolase pathway) microorganisms, and presents coccoid or rod-like shape. These bacteria are usually presented in pairs or short chains, nonmotile, nonspore forming, catalase negative, anaerobic facultative, mesophilic and do not produce ammonia from arginine. They display complex nutritional requirements, including different amino acids. Furthermore, they exhibit absence of H 2 S formation, growth in presence of 7% NaCl and low guanine-cytosine (GC) content on the DNA molecule (31-49%). These microorganisms have mesophilic characteristics with optimal growth between 20 and 30 °C . Species belonging to genus Leuconostoc (Lc. argentinum, Lc. carnosum, Lc. citreum, Lc. fallax, Lc. ficulneum, Lc. fructosum, Lc. gasicomitatum,Lc. gelidum, Lc. inhae, Lc. kimchii, Lc. lactis, Lc.mesenteroides, Lc.pseudomesenteroides) can be found mainly in vegetables, cereals, silage, fruits, wine, fish, meat and dairy products. (1-9) A significant review published by Hemme and FoucaudScheunemann (3) presents an overview about Leuconostoc species, their habitat, taxonomy, metabolism and genetics, their implications in health and safety, and their potential use in dairy technology and functional foods.Despite the recent studies that show many benefits attributed to LAB, only a few reports about probiotic potential and bacteriocin applications using Lc. mesenteroides species have been found in the literature. Moreover, Leuconostoc spp. has a promising future for application in dairy foods as bacteriocinogenic and/or probiotic microorganism through enhancement of Downloaded by [University of Otago] at 04:40 14 March 2015A c c e p t e d M a n u s c r i p t 3 physicochemical characteristics of these products, mainly due to the production of organic acids, CO 2 and volatile compounds, which contribute to the flavor and texture of butter, cream and cheeses. In this paper, we review the potential of Lc. mesenteroides for application as a probiotic and bacteriocin-producing culture, in contrast with its relationship to spoilage process an...