Genetic relatedness of Staphylococcus aureus isolates within food outbreaks by single nucleotide polymorphisms

Investigation of bacterial food outbreaks by whole genome sequencing can rely on the inspection of the genetic relatedness between isolates through the application of single nucleotide polymorphism (SNP) thresholds. However, there is no consensus for Staphylococcus aureus in the context of food outbreaks. In this study, we propose a SNP cut-off by taking into account the mutation rate and the evolution time of this pathogen in food. Through in vitro microevolution, we determined the mutation rate of three S. aureus strains grown under mimicked food stressing conditions. From the mutation rate, we set a cut-off of 28 SNPs considering 30 days as evolution time based on the average shelf-life of foods contaminated by S. aureus and the timeline for identifying this pathogen in outbreaks. The SNP threshold was applied to retrospectively study ten staphylococcal food outbreaks to assess whether isolates from food and/or of human origin from the same outbreak were epidemiologically related. To interpret SNP distances, phylogenetic tree topologies and bootstraps were integrated and showed that isolates differing by up to 28 SNPs were monophyletic. Our suggested cut-off can be used in outbreak management to identify closely related S. aureus strains.

Effect of seasonality on physico-chemical and microbiological properties of nicastrese milk and artisanal cheese

Nicastrese is an indigenous Italian goat breed reared in the Calabria region under semi-extensive practices. From January to June, the milk yield of 400 multiparous Nicastrese goats was evaluated. In addition, tank milk and ripened cheese samples were subjected to physico-chemical and microbiological analyses with the aim to assess the effect of the seasonality on quality parameters. The volatile organic compounds profile of the ripened Nicastrese cheese samples was evaluated. Results showed that the seasonality had a significant effect on milk fat, lactose, urea, citric acid contents and acidity. Microbiological analysis of tank milk samples revealed variability among the different microbial groups investigated except for Escherichia coli. In addition, faecal coliforms and Listeria spp. were never detected. Regarding 60 days ripened cheese samples, almost all microbial groups showed a significant decrease during the analysed period, with the exception of Enterobacteria. It is interesting to note that Escherichia coli and Listeria spp. were not detected in any cheese sample investigated, confirming the cheese safety. Overall, volatile organic compounds, detected on cheese samples, decreased trough the investigated period and this behavior could be related to the feeding quality and to the milk's goat nutritional components.

Goat Dairy Product Assortment in Different Sales Channels in Northwestern Italy

An analysis of goat dairy-based product assortment was carried out in the metropolitan area of Turin (Northwestern Italy), considering three different sales channels: large-scale retail chains, retail stores, and direct sales in farmers' markets (FMs). The survey results show a widespread presence of goat products in the Turin market. In each type of selected distribution channel, characterized by its own peculiarities, products differed both in terms of reference numbers and assortment; they were better in large-scale retail distribution, both in terms of quality and typicality, whereas specialized retail and direct sales were better equipped. Furthermore, given the importance of the sector at the regional level, we also focused, through the analysis of product origin, on the fact that local provenience increases from large-scale distribution to fully regional farmers' markets. The mean price was different, being lower in direct sales at FMs, and medium to high and high at retail sales, as they are considered high quality niche products. The offer is correlated and in agreement with consumer targets (modern, ethical, and traditional), finding the "ideal" product in the different types offered, however, even if the results underline the potential of this sector, the fragmentation of the goat sector in Piedmont still represents a limit to expansion, and to the positioning of products in the market.

Screening Method to Evaluate Amino Acid-Decarboxylase Activity of Bacteria Present in Spanish Artisanal Ripened Cheeses

A qualitative microplate screening method, using both low nitrogen (LND) and low glucose (LGD) decarboxylase broths, was used to evaluate the biogenic amine (BA) forming capacity of bacteria present in two types of Spanish ripened cheeses, some of them treated by high hydrostatic pressure. BA formation in decarboxylase broths was later confirmed by High Performance Liquid Chromatography (HPLC). An optimal cut off between 10⁻25 mg/L with a sensitivity of 84% and a specificity of 92% was obtained when detecting putrescine (PU), tyramine (TY) and cadaverine (CA) formation capability, although these broths showed less capacity detecting histamine forming bacteria. TY forming bacteria were the most frequent among the isolated BA forming strains showing a strong production capability (exceeding 100 mg/L), followed by CA and PU formers. Lactococcus, Lactobacillus, Enterococcus and Leuconostoc groups were found as the main TY producers, and some strains were also able to produce diamines at a level above 100 mg/L, and probably ruled the BA formation during ripening. Enterobacteriaceae and Staphylococcus spp., as well as some Bacillus spp. were also identified among the BA forming bacteria isolated.

A 100-Year Review: Advances in goat milk research

In the century of research chronicled between 1917 and 2017, dairy goats have gone from simply serving as surrogates to cows to serving as transgenic carriers of human enzymes. Goat milk has been an important part of human nutrition for millennia, in part because of the greater similarity of goat milk to human milk, softer curd formation, higher proportion of small milk fat globules, and different allergenic properties compared with cow milk; however, key nutritional deficiencies limit its suitability for infants. Great attention has been given not only to protein differences between goat and cow milk, but also to fat and enzyme differences, and their effect on the physical and sensory properties of goat milk and milk products. Physiological differences between the species necessitate different techniques for analysis of somatic cell counts, which are naturally higher in goat milk. The high value of goat milk throughout the world has generated a need for a variety of techniques to detect adulteration of goat milk products with cow milk. Advances in all of these areas have been largely documented in the Journal of Dairy Science (JDS), and this review summarizes such advances.

Rapid detection of Lactococcuslactis isolates producing the lantibiotics nisin, lacticin 481 and lacticin 3147 using MALDI-TOF MS

The aim of the study was to evaluate the potential use of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) for fast and reliable detection of strains producing the lantibiotics nisin, lacticin 481 and lacticin 3147 in a large collection of lactococci. A total of one hundred lactococcal isolates from traditional ewe's and goat's raw milk cheeses were identified to the species level as Lactococcuslactis by MALDI-TOF MS based on comparison with lactococcal entries in the BioTyper database. Mass spectra in the range 2000-4000Da of the identified isolates were compared to reference spectra of three lactococcal strains producing lacticin 481 (IFPL 330), lacticin 3147 (IFPL 105) and nisin (IFPL 503). Only eight isolates had mass spectra with peaks that could be unequivocally identified as lacticin 481 (2900.47Da) or nisin (3330.31Da). None of the assayed isolates matched the mass spectra corresponding to the two-peptide lacticin 3147 (2847.97 and 3306.29Da). The results obtained by MALDI-TOF MS were genetically validated by amplification of the corresponding structural gene coding for lacticin 481, nisin and lacticin 3147. MALDI-TOF MS can be used as a fast and reliable technique to screen a large number of lactococcal isolates for the ability to produce the lantibiotics nisin, lacticin 481 and lacticin 3147.

Lactobacillus plantarum IFPL935 favors the initial metabolism of red wine polyphenols when added to a colonic microbiota

This work aimed to unravel the role of Lactobacillus plantarum IFPL935 strain in the colonic metabolism of a polyphenolic red wine extract, when added to a complex human colonic microbiota from the dynamic simulator of the human intestinal microbial ecosystem (SHIME). The concentration of microbial-derived phenolic metabolites and microbial community changes along with fermentative and proteolytic activities were monitored. The results showed that L. plantarum IFPL935 significantly increased the concentration of the initial microbial ring-fission catabolite of catechins and procyanidins, diphenylpropanol, and, similarly, 4-hydroxy-5-(3'-hydroxyphenyl)valeric acid production. Overall, the addition of L. plantarum IFPL935 did not have an impact on the total concentration of phenolic metabolites, except for batches inoculated with colonic microbiota from the effluent compartment (EC), where the figures were significantly higher when L. plantarum IFPL935 was added (24 h). In summary, the data highlighted that L. plantarum IFPL935 may have an impact on the bioavailability of these dietary polyphenols. Some of the microbial-derived metabolites may play a key role in the protective effects that have been linked to a polyphenol-rich diet.

Influence of autochthonous adjunct cultures on ripening parameters of Argentinean goat's milk cheeses

BACKGROUND

Argentinean semi-hard goat's cheeses manufactured with and without the addition of autochthonous adjunct cultures of Lactobacillus plantarum ETC17, Lactobacillus rhamnosus ETC14 and Enterococcus faecium ETC3 were analysed to evaluate the effect of these strains on ripening parameters.

RESULTS

Gross composition was similar among cheeses. Microbiological analysis indicated that lactic acid bacteria added to cheeses reached high levels. None of the strains assayed affected the primary proteolysis. Overall, E. faecium had a clearer effect on the peptide and lipolysis profiles of cheeses. Analysis of the volatile fraction of cheeses indicated that the levels of several compounds involved in the overall flavour of goat's cheeses were affected by the presence of E. faecium. This could explain the differences detected in the global perception of cheeses made with this strain compared with control cheeses.

CONCLUSION

The present work represents a first contribution to knowledge of the ripening process of Argentinean goat's cheeses made with the addition of autochthonous adjunct cultures. The results suggest that E. faecium ETC3 showed a significant effect during ripening, which was reflected both in the profiles of proteolysis, lipolysis and volatile compounds and in the global sensory perception of cheeses.

Influence of lamb rennet paste on the lipolytic and sensory profile of Murcia al Vino cheese

The influence of lamb rennet paste (71.1% chymosin, 177 international milk-clotting units/mL, 4.57U/g of lipase activity) during the ripening of Murcia al Vino goat cheese was studied. The aim of this study was to improve the knowledge of the effect of lamb rennet paste on the lipolytic patterns in this type of cheese by reference to the evolution of total and free fatty acids. A sensory analysis was carried out to compare cheeses made with commercial and paste rennet. The rennet paste showed higher lipolytic activity, enhancing the production of short-chain free fatty acids. In addition, the cheese produced with lamb rennet paste had a slightly more bitter and piquant taste, making it an attractive commercial alternative that can be used to develop new varieties of goat cheese.

Expression in Lactococcus lactis of functional genes related to amino acid catabolism and cheese aroma formation is influenced by branched chain amino acids

Formation of cheese aroma compounds by Lactococcus lactis from amino acid catabolism depends on a complex network of reactions, which involve enzymes such as aminotransferases, dehydrogenases, lyases, and decarboxylases, among others. Based on the ability of some L. lactis strains to grow with low requirements of amino acids, we have studied in L. lactis IFPL730 the effect of the branched chain amino acid (BCAA) content on the expression of functional genes related to amino acid catabolism and aroma compound formation (araT, bcaT, kivD, ytjE and panE). L. lactis IFPL730 growth rate decreased under leucine, valine or isoleucine starvation but the strain reached similar viable counts at the stationary phase in all culture conditions studied. The level of expression of some genes encoding enzymes involved in amino acid catabolism changed significantly (P<0.05) when those conditions were compared. Specially, α-ketoisovalerate decarboxylase (kivD), BCAA-specific aminotransferase (bcaT) and C-S lyase (yjtE) gene expressions increased markedly by both isoleucine and valine starvation. In addition to gene expression, formation of volatile compounds was determined in all growth conditions. The results showed that BCAA starvation conditions caused a significant increase (P<0.05) in the formation of metabolic end products related to cheese aroma, such as 3-methylbutanal and 3-methylbutanol.

Effect of flavan-3-ols on the adhesion of potential probiotic lactobacilli to intestinal cells

The effect of dietary flavan-3-ols on the adhesion of potential probiotic lactobacilli strains to intestinal cells was unraveled. The inhibitory activity of these compounds on intestinal cells was highlighted. The cytotoxic effect was shown to depend on both the compound's chemical structure (galloylation and polymerization) and degree of differentiation of intestinal cells. The effect of flavan-3-ols on bacteria adhesion differed greatly between compounds, strains, and intestinal cells. All flavan-3-ols inhibited significantly Lactobacillus acidophilus LA-5 and Lactobacillus plantarum IFPL379 adhesion except epigallocatechin gallate, which enhanced L. acidophilus LA-5 adhesion to Caco-2. Procyanidins B1 and B2 increased remarkably the adhesion of Lactobacillus casei LC115 to HT-29 cells, whereas epigallocatechin increased L. casei LC115 adhesion to Caco-2. These data showed the potential of flavan-3-ols to alter gut microecology by modifying adhesion of lactobacilli strains to intestinal cells.

Capability of Lactobacillus plantarum IFPL935 to catabolize flavan-3-ol compounds and complex phenolic extracts

Lactobacillus plantarum IFPL935 was incubated with individual monomeric flavan-3-ols and dimeric A- and B-type procyanidins to identify new metabolites and to determine the effect of compound structural features on bacterial growth and catabolism. Complex extracts rich in A-type proanthocyanidins and phenolic acids from cranberry were also tested. The results showed that L. plantarum IFPL935 exhibited higher resistance to nongalloylated monomeric flavan-3-ols, A-type dimeric procyanidins, and cranberry extract than to (-)-epicatechin-3-O-gallate and B-type dimeric procyanidins. Despite these findings, the strain was capable of rapidly degrading (-)-epicatechin-3-O-gallate, but not A- or B-type dimeric procyanidins. However, it was able to produce large changes in the phenolic profile of the cranberry extract mainly due to the catabolism of hydroxycinnamic and hydroxybenzoic acids. Of most relevance was the fact that L. plantarum IFPL935 cleaved the heterocyclic ring of monomeric flavan-3-ols, giving rise to 1-(3',4'-dihydroxyphenyl)-3-(2″,4″,6″-trihydroxyphenyl)propan-2-ol, activity exhibited by only a few human intestinal bacteria.

Volatile sulphur compounds-forming abilities of lactic acid bacteria: C-S lyase activities

Volatile sulphur compounds (VSCs) are of prime importance in the overall aroma of cheese and make a significant contribution to their typical flavours. Thus, the control of VSCs formation offers considerable potential for industrial applications. Here, lactic acid bacteria (LAB) from different ecological origins were screened for their abilities to produce VSCs from L-methionine. From the data presented, VSC-forming abilities were shown to be strain-specific and were correlated with the C-S lyase enzymatic activities determined using different approaches. High VSCs formation were detected for those strains that were also shown to possess high thiol-producing abilities (determined either by agar plate or spectrophotometry assays). Moreover, differences in C-S lyase activities were shown to correspond with the enzymatic potential of the strains as determined by in situ gel visualization. Therefore, the assessment of the C-S lyase enzymatic potential, by means of either of these techniques, could be used as a valuable approach for the selection of LAB strains with high VSC-producing abilities thus, representing an effective way to enhance cheese sulphur aroma compounds synthesis. In this regard, this study highlights the flavour forming potential of the Streptococcus thermophilus STY-31, that therefore could be used as a starter culture in cheese manufacture. Furthermore, although C-S lyases are involved in both biosynthetic and catabolic pathways, an association between methionine and cysteine auxotrophy of the selected strains and their VSCs-producing abilities could not be found.

Chemical and instrumental approaches to cheese analysis

Overcoming the complexity of cheese matrix to reliably analyze cheese composition, flavor, and ripening changes has been a challenge. Several sample isolation or fractionation methods, chemical and enzymatic assays, and instrumental methods have been developed over the decades. While some of the methods are well established standard methods, some still need to be researched and improved. This chapter reviews the chemical and instrumental methods available to determine cheese composition and monitor biochemical events (e.g., glycolysis, lipolysis, and proteolysis) during cheese ripening that lead to the formation of cheese flavor. Chemical and enzymatic methods available for analysis of cheese composition (fat, protein, lactose, salt, nitrogen content, moisture, etc.) are presented. Electrophoretic, chromatographic, and spectroscopic techniques are also reviewed in the light of their application to monitor cheese ripening and flavor compounds. Novel instrumental methods based on Fourier-transform infrared spectroscopy that are currently being researched and applied to cheese analysis are introduced.

Characterization of lactococci and lactobacilli isolated from semihard goats' cheese

Several strains ofLactococcus lactissubsp.lactis, Lactobacillus caseiandLactobacillus plantarumisolated from traditional goats' cheese have been studied for titratable acidity, proteolysis in milk and enzymic activities. Aminopeptidasc activities were measured with whole cells and cells permeabilized with Triton X-100. Caseinolytic activity was investigated using electrophoresis in polyacrylamide gel with sodium dodecyl sulphate.Lc. lactissubsp.lactishad a level of proteolytic activity in skim milk greater than that ofLb. casei, while this activity inLb. plantarumwas very low. Alanine aminopeptidase activity was almost non-existent for all strains tested, while lysine aminopeptidase activity appeared to be of fundamentally intracellular origin. Leucine aminopeptidase activity was also greater in cells that had been permeabilized than in whole cells forLb. caseiandLb. plantarum. Lc. lactissubsp.lactisleucine aminopeptidase activity was greater in whole cells. No significant hydrolysis of casein was found withLb. caseiI FPL 725 andLb. plantarumIFPL 722 permeabilized with Triton X-100 after 24 h incubation with whole bovine casein.

Stability of microbial communities in goat milk during a lactation year: Molecular approaches

The microbial communities in milks from one herd were evaluated during 1-year of lactation, using molecular methods to evaluate their stability and the effect of breeding conditions on their composition. The diversity of microbial communities was measured using two approaches: molecular identification by 16S and 18S rDNA sequencing of isolates from counting media (two milks), and direct identification using 16S rDNA from clone libraries (six milks). The stability of these communities was evaluated by counting on selective media and by Single Strand Conformation Polymorphism (SSCP) analysis of variable region V3 of the 16S rRNA gene and variable region V4 of the 18S rRNA gene. One hundred and eighteen milk samples taken throughout the year were analyzed. Wide diversity among bacteria and yeasts in the milk was revealed. In addition to species commonly encountered in milk, such as Lactococcus lactis, Lactococcus garvieae, Enterococcus faecalis, Lactobacillus casei, Leuconostoc mesenteroides, Staphylococcus epidermidis, Staphylococcus simulans, Staphylococcus caprae, Staphylococcus equorum, Micrococcus sp., Kocuria sp., Pantoea agglomerans and Pseudomonas putida, sequences were affiliated to other species only described in cheeses, such as Corynebacterium variabile, Arthrobacter sp., Brachybacterium paraconglomeratum, Clostridium sp. and Rothia sp. Several halophilic species atypical in milk were found, belonging to Jeotgalicoccus psychrophilus, Salinicoccus sp., Dietza maris, Exiguobacterium, Ornithinicoccus sp. and Hahella chejuensis. The yeast community was composed of Debaryomyces hansenii, Kluyveromyces lactis, Trichosporon beigelii, Rhodotorula glutinis, Rhodotorula minuta, Candida pararugosa, Candida intermedia, Candida inconspicua, Cryptococcus curvatus and Cryptococcus magnus. The analyses of microbial counts and microbial SSCP profiles both distinguished four groups of milks corresponding to four periods defined by season and feeding regime. The microbial community was stable within each period. Milks from winter were characterized by Lactococcus and Pseudomonas, those from summer by P. agglomerans and Klebsiella and those from autumn by Chryseobacterium indologenes, Acinetobacter baumanii, Staphylococcus, Corynebacteria and yeasts. However, the composition of the community can vary according to factors other than feeding. This study opens new investigation fields in the field of raw milk microbial ecology.

Compositional, microbiological, biochemical, volatile profile and sensory characterization of four Italian semi-hard goats' cheeses

Four semi-hard Italian goats' milk cheeses, Flor di Capra (FC), Caprino di Cavalese (CC), Caprino di Valsassina (CV) and Capritilla (C), were compared for compositional, microbiological, biochemical, volatile profile and sensory characteristics. Mean values for the gross composition in part differed between cheeses. At the end of ripening, cheeses contained 7·98−8·51 log10 cfu/g of non-starter lactic acid bacteria. Lactobacillus paracasei, Lb. casei and Lb. plantarum were dominant in almost all cheeses. As shown by the Principal Component Analysis of RP-FPLC data for the pH 4·6-soluble fractions and by the determination of free amino acids, secondary proteolysis of CC and CV mainly differed from the other two cheeses. A total of 72 volatile components were identified by steam distillation-extraction followed by gas chromatography-mass spectrometry. Free fatty acids and esters qualitatively and quantitatively differentiated the profile of CV and CC, respectively. The lowest concentrations of volatile components characterized FC. Descriptive sensory analysis using 17 flavour attributes was carried out by a trained panel. Different flavour attributes distinguished the four goats' cheeses and relationships were found with volatile components, biochemical characteristics and technology.

Alternatives for Improving Physical, Chemical, and Sensory Characteristics of Goat Cheeses: The Use of Arid-Land Forages in the Diet

To establish the effect of an alternative diet on the quality of Majorero cheese, the basic physicochemical parameters, fatty acid profile, and sensory characteristics were studied. Two groups of 20 Majorero goats were fed 2 different diets: a forage diet (DF), which had a high ratio of long fiber to concentrates (65:35), and a concentrate diet (DC), with a low ratio of long fiber to concentrates (35:65). The DF dietary fiber was supplied by native forages adapted to arid land. A total of 42 Majorero goat cheeses were used for this study: 21 in the DF group and 21 in the DC group. Seven cheeses from each group were tested after 2, 15, and 60 d of ripening. The milk produced by goats fed the DF diet had a higher fat concentration. No significant differences were observed in the milk fatty acid profile. The diet affected the chemical composition of the cheese in pH and fat content, and fat was significantly higher in cheeses made from DF milk than those from DC milk. Dietary characteristics had important effects on the medium-chain fatty acid composition (C6 to C14) of the cheese fat, giving DF cheeses the specific goat's milk flavor that is sought after for this type of cheese. The fatty acid composition (%) differed substantially among different ripening times. The DF cheeses were more appreciated by the panelists, as they had a greater variety of odors and flavors than the DC cheeses. The DF hard cheeses were described as having vegetable and fruity tones as well as tones of hay and dried fruit.

Discrepancies between the phenotypic and genotypic characterization of Lactococcus lactis cheese isolates

AIMS

The use of randomly amplified polymorphic DNA (RAPD)-PCR fingerprinting and plasmid profiles to determine at the strain level, the similarity of Lactococcus lactis isolates obtained during sampling of traditional cheeses and to verify its correspondence to the selected phenotypic characteristics.

METHODS AND RESULTS

A total of 45 L. lactis isolates were genotypically analysed by RAPD-PCR fingerprinting and plasmid patterns. Phenotypic traits used to compare strains were proteolytic, acidifying, aminotransferase (aromatic and branched chain aminotransferase) and alpha-ketoisovalerate decarboxylase (Kivd) activities. The results show that 23 isolates could be grouped in clusters that exhibited 100% identity in both their RAPD and plasmid patterns, indicating the probable isolation of dominant strains during the cheese sampling process. However, there were phenotypic differences between isolates within the same cluster that included the loss of relevant technological properties such as proteinase activity and acidifying capacity or high variation in their amino acid converting enzyme activities. Likewise, the analysis of a specific attribute, Kivd activity, indicated that 7 of 15 isolates showed no detectable activity despite the presence of the encoding (kivd) gene.

CONCLUSION

Phenotypic differences found between genotypically similar strains of L. lactis strains could be linked to differences in enzymatic expression.

SIGNIFICANCE AND IMPACT OF THE STUDY

Phenotypic analysis of L. lactis isolates should be considered when selecting strains with new cheese flavour forming capabilities.

The role and application of enterococci in food and health

The genus Enterococcus is the most controversial group of lactic acid bacteria. Studies on the microbiota of many traditional cheeses in the Mediterranean countries have indicated that enterococci play an important role in the ripening of these cheeses, probably through proteolysis, lipolysis, and citrate breakdown, hence contributing to their typical taste and flavour. Enterococci are also present in other fermented foods, such as sausages and olives. However, their role in these products has not been fully elucidated. Furthermore, the production of bacteriocins by enterococci is well documented. Moreover, enterococci are nowadays used as probiotics. At the same time, however, enterococci have been associated with a number of human infections. Several virulence factors have been described and the number of vancomycin-resistant enterococci is increasing. The controversial nature of enterococci has prompted an enormous increase in scientific papers and reviews in recent years, where researchers have been divided into two groups, namely pro and contra enterococci. To the authors' impression, the negative traits have been focused on very extensively. The aim of the present review is to give a balanced overview of both beneficial and virulence features of this divisive group of microorganisms, because it is only acquaintance with both sides that may allow their safe exploitation as starter cultures or co-cultures.

Phenotypic and genotypic characterization of lactobacilli isolated from Spanish goat cheeses

Lactic acid bacteria from 18 Spanish goat cheeses produced by seven dairies were isolated to evaluate the genetic diversity of this bacterial community. 136 representative isolates were characterized by phenotyping and Randomly Amplified Polymorphic DNA (RAPD-PCR) analysis. Ten species were identified with predominance of Lactobacillus paracasei subsp. paracasei. The presence of L. curvatus, L. pentosus, L. cellobiosus and L. rhamnosus has not hitherto been reported in Spanish goat cheeses. A high degree of genetic diversity was found for L. paracasei subsp. paracasei, L. curvatus and L. plantarum. Some of the identified strains displayed strong acidifying and proteolytic capacities.