Development of an S-layer gene-based PCR-DGGE assay for monitoring dominant Lactobacillus helveticus strains in natural whey starters of Grana Padano cheese.

Monitoring L. helveticus strain dynamics in natural whey starters is of great interest at the industrial level due to the key role that this bacterial population plays in Grana Padano cheese production. In this study, we aimed to develop a PCR-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) assay based on the slpH locus, in parallel with performing culture-dependent analysis of whey samples using optimized media to maximize the number of isolated strains. We designed new primers targeting the slpH locus to amplify a gene region that would be suitable for PCR-DGGE analysis and discriminating strains. Our results confirmed that the developed PCR-DGGE method was rapid and reliable for monitoring the L. helveticus population in whey starter cultures. All sequences of bands detected in the PCR-DGGE profiles from whey samples showed high similarity to S-layer genes of L. helveticus, and perfectly matched with the slpH locus sequences of dominant strains. Overall, our findings indicated that the target region of the slpH locus was sufficiently heterologous to discriminate L. helveticus strains, and that our PCR-DGGE analysis provided a more accurate picture of the population composition of whey starters compared to culture-dependent techniques that often fail to isolate the most abundant strains.

Bacterial diversity in typical Italian salami at different ripening stages as revealed by high-throughput sequencing of 16S rRNA amplicons.

The bacterial diversity involved in food fermentations is one of the most important factors shaping the final characteristics of traditional foods. Knowledge about this diversity can be greatly improved by the application of high-throughput sequencing technologies (HTS) coupled to the PCR amplification of the 16S rRNA subunit. Here we investigated the bacterial diversity in batches of Salame Piacentino PDO (Protected Designation of Origin), a dry fermented sausage that is typical of a regional area of Northern Italy. Salami samples from 6 different local factories were analysed at 0, 21, 49 and 63 days of ripening; raw meat at time 0 and casing samples at 21 days of ripening where also analysed, and the effect of starter addition was included in the experimental set-up. Culture-based microbiological analyses and PCR-DGGE were carried out in order to be compared with HTS results. A total of 722,196 high quality sequences were obtained after trimming, paired-reads assembly and quality screening of raw reads obtained by Illumina MiSeq sequencing of the two bacterial 16S hypervariable regions V3 and V4; manual curation of 16S database allowed a correct taxonomical classification at the species for 99.5% of these reads. Results confirmed the presence of main bacterial species involved in the fermentation of salami as assessed by PCR-DGGE, but with a greater extent of resolution and quantitative assessments that are not possible by the mere analyses of gel banding patterns. Thirty-two different Staphylococcus and 33 Lactobacillus species where identified in the salami from different producers, while the whole data set obtained accounted for 13 main families and 98 rare ones, 23 of which were present in at least 10% of the investigated samples, with casings being the major sources of the observed diversity. Multivariate analyses also showed that batches from 6 local producers tend to cluster altogether after 21 days of ripening, thus indicating that HTS has the potential for fine scale differentiation of local fermented foods.

Reuterin, Phenyllactic Acid, and Exopolysaccharides as Main Antifungal Molecules Produced by Lactic Acid Bacteria: A Scoping Review.

The primary goal of this scoping review is to collect, analyze, and critically describe information regarding the role of the main compounds (reuterin, phenyllactic acid, and exopolysaccharides) produced by LAB that possess antifungal properties and provide some suggestions for further research. The use of lactic acid bacteria (LAB) to mitigate spoilage and extend the shelf life of foodstuffs has a long history. Recently, there has been a growing interest in the unique properties of these additions to the foodstuffs in which they are applied. In recent studies regarding biopreservation, significant attention has been given to the role of these microorganisms and their metabolites. This fascinating recent discipline aims not only to replace traditional preservation systems, but also to improve the overall quality of the final product. The biologically active by-products produced by lactic acid bacteria are synthesized under certain conditions (time, temperature, aerobiosis, acidity, water activity, etc.), which can be enacted through one of the oldest approaches to food processing: fermentation (commonly used in the dairy and bakery sectors). This study also delves into the biosynthetic pathways through which they are synthesized, with a particular emphasis on what is known about the mechanisms of action against molds in relation to the type of food.

The distinctive effect of different insect powders as meat extenders in beef burgers subjected to cooking and in vitro gastrointestinal digestion.

Mealworm (MWP), migratory locust (LP), and house cricket (CP) are novel foods recently authorized by the European Commission. This work tested their powders as meat extenders at 5% inclusion in beef burgers. Insect powders were abundant in phenolics, recording the highest values in LP (1184.9 µg/g). The sensory analysis highlighted a higher visual and olfactory acceptability for MWP-burgers, followed by CP- and LP-burgers, whereas the texture of cooked burgers remained unaffected. Following pan-cooking, MWP-burgers and control exhibited comparable chemical profiles, while a significant down-accumulation of the heterocyclic amine 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline was observed in CP-burgers. In vitro gastrointestinal digestion highlighted metabolomic trends like control for MWP- and LP-burgers. In contrast, a reduced accumulation of lipids and increased content of dipeptides like glutaminylarginine (possibly acting as enzyme modulators) was observed for the CP-burgers.

Replacement of nitrates and nitrites in meat-derived foods through the utilization of coagulase-negative staphylococci: A review.

Nitrates and nitrites, which are synthetic additives, are traditionally used as curing agents in meat-based products. These synthetic additives are employed in the preparation of fermented meat foods to improve quality characteristics and microbiological safety, develop distinct flavours and red-colour stability, and counteract lipid oxidation. Nitrites also display significant bacteriostatic and bactericidal action against spoilage microorganisms and foodborne pathogens (such as Clostridium botulinum and Listeria monocytogenes). However, meat curing is currently under scrutiny because of its links to cardiovascular diseases and colorectal cancer. Based on the current literature, this review provides recent scientific evidence on the potential utilisation of coagulase-negative staphylococci (CNS) as nitrate and nitrite substitutes in meat-based foods. Indeed, CNS are reported to reproduce the characteristic red pigmentation and maintain the typical high-quality traits of cured-meats, thanks to their arginine degradation pathway, thus providing the nitrite-related desirable attributes in cured meat. The alternative strategy, still based on the NOS pathway, consisting of supplementing meat with arginine to release nitric oxide (NO) and obtain a meat characterised by the desired pinkish-red colour, is also reviewed. Exploiting NOS-positive CNS strains seems particularly challenging because of CNS technological adaptation and the oxygen dependency of the NOS reaction; however, this exploitation could represent a turning point in replacing nitrates and nitrites in meat foods.

Impact of axenic and mixed starter cultures on metabolomic and sensory profiles of ripened Italian salami.

In this work, the synergistic/antagonistic impact of glucose and mixed starter cultures, namely Latilactobacillus sakei, Pediococcus pentosaceus, and Staphylococcus xylosus, was evaluated in Italian salami in terms of metabolomics and sensory profiles. As expected, Salami manufactured with 0.5 % glucose exhibited a substantial pH drop, showing values close to 5 at 12 days of ripening. Metabolomics revealed 1841 metabolites, mainly belonging to amino acids, peptides, glycerolipids, and nucleic acids, showing a greater hierarchical role of glucose addition when compared with inoculated microbial starters. Distinct metabolomic fingerprints could be observed across treatments, mainly concerning glutamyl peptides like gamma-glutamyl-glutamate (related to the kokumi taste), biogenic amines (spermine), and lipid oxidation products (i.e., the oxylipin 13S-hydroperoxylinolenic acid). Such differences may drive the differences in sensory profiles recorded among treatments. These findings indicate the need to select ad-hoc starter cultures to improve the safety, quality, and sensory traits of salami.

The effect of common duckweed (Lemna minor L.) extract on the shelf-life of beef burgers stored in modified atmosphere packs: A metabolomics approach.

The impact of duckweed extracts (DEs) on the shelf-life of packaged beef burgers was evaluated through classical assays and untargeted metabolomics. Beef burgers were formulated with an antioxidants-free control (CON), 1 g/kg sodium ascorbate (ASC), and increasing levels of a DEs, namely 1 (DE1), 5 (DE5), and 10 (DE10) g/kg, packaged under modified atmosphere and stored at 4 °C for 19 days. The DEs, abundant in phytochemicals, determined no issues with the hygienic status of the product. DEs modulated the redox status, being ineffective in preserving linolenic acid from peroxidation. However, the oxidation marker 2-nonenoic acid was down-accumulated in the DE10 sample following 19 days of storage, recording a lower glutathione:glutathione disulfide ratio. The accumulation of adipate semialdehyde revealed the inefficiency of DEs in coping with protein oxidation, while DEs prevented the accumulation of biogenic amines. Therefore, this work suggests a potential pro-oxidant role of the formulated DEs.

Metabolomics and gene-metabolite networks reveal the potential of Leuconostoc and Weissella strains as starter cultures in the manufacturing of bread without baker's yeast.

Lactic Acid Bacteria (LAB) could provide a valid alternative to S. cerevisiae as a starter culture for bakery products, avoiding yeast-related health problems while contributing to the technological and functional properties of bread. In this work, we evaluate the role of certain LABs (Leuconostoc citreum SB6, Weissella cibaria UC4051, Weissella confusa UC4051, and the commercial starter cultures Weissella cibaria, and Leuconostoc mesenteroides) in producing functional compounds (pro-technological, health-promoting, and postbiotic-like molecules). For this purpose, we analysed the genotypic and phenotypic features of strains, and we investigated dough fermentation from microbiological and metabolomics approaches. Results evidenced a clear discrimination between the metabolic activity of baker's yeast and LAB. The most discriminant metabolites derived from proteolysis and lipolysis, such as peptides, amino acids, and fatty acyls. Furthermore, we elucidated the different metabolism of these strains by building gene-metabolite interaction networks that pairwise compared the LAB strains of the same genus. While most of the networks showed a characteristic nucleotide metabolism, only the commercial W. cibaria exhibited an interaction network composed of amino acids and their related genes. In conclusion, our findings reveal that LAB strains under investigation, and particularly the commercial W. cibaria, can enhance the functional properties of bread.

Incidence of Tetracycline and Erythromycin Resistance in Meat-Associated Bacteria: Impact of Different Livestock Management Strategies.

The extensive use of antibiotics as growth promoters, or their continued abusive misuse to cure or prevent the onset of bacterial infections as occurs in the intensive farming, may have played a pivotal role in the spread of reservoirs of antibiotic resistance (AR) among food-associated bacteria including pathogens representing risks to human health. The present study compares the incidence of tetracycline and erythromycin resistances in lactic acid bacteria (LAB) and coagulase negative staphylococci (CNS) from fermented products manufacturing using meat from intensive animal husbandry (industrialized manufacturing Italian salami) and from extensive farms (artisanal sausages facilities pork and llama Argentinean sausages). A higher incidence of tetracycline resistance (TET-R) compared to erythromycin resistance (ERY-R) was observed among the 205 isolates. Unlike CNS strains, the LAB showed a significant correlation between the TET-R and the ERY-R phenotypes. Genotypic assessment shows a high correlation with tetK and tetM for the TET-R strains and with ermB and ermC for the ERY-R strains. Multiple correspondence analyses have highlighted the association between AR phenotypes and CNS species isolated from Italian salami, while the susceptible phenotypes were associated with the LAB species from Argentinean sausages. Since antibiotic resistance in meat-associated bacteria is a very complex phenomenon, the assessment of bacterial resistance in different environmental contexts with diverse farming practices and food production technologies will help in monitoring the factors influencing AR emergence and spread in animal production.

Strategies for Nitrite Replacement in Fermented Sausages and Effect of High Pressure Processing against Salmonella spp. and Listeria innocua.

The development of nitrite-free meat products is a current industrial concern. Many efforts have been attempted to replace the nitrite effect in cured meats colour formation and pathogens control. Our previous work evidenced that lactic acid and a cold ripening were the best hurdle technologies for nitrite-free fermented sausages from metabolomics. In the first part of this work, we investigated the effect of lactic acid compared with both two alternative additives (glucono-D-lactone and a mix of sodium di-acetate/sodium lactate) and with low-nitrite sausages, all of them following either cold or traditional ripening. For this purpose, microbiological analysis, pH, water activity (aw), and a sensory study were performed. All nitrite-free sausages (cold or traditional ripened) showed quality and safety traits similar to low-nitrite traditionally ripened ones used as control. In addition, sensory study revealed that sausages with lactic acid were the most preferred cold ripened samples, supporting that this is an optimal strategy for the production of nitrite-free sausages. We selected this product for further studies. Indeed, in the second part, we evaluated the impact of ripening, and other hurdle technologies as High Pressure Processing (HPP) and under-vacuum storage against Listeria innocua and Salmonella spp. by a challenge test. Maximal declines were obtained for ripening along with HPP (i.e., 4.74 and 3.83 log CFU/g for L. innocua and Salmonella spp., respectively), suggesting that HPP might guarantee nitrite-free sausages safety. Although the quality of raw materials remains essential, these hurdle strategies largely contributed to nitrite-free sausages safety, offering a promising tool for the meat industry.

Changes in the chemical and sensory profile of ripened Italian salami following the addition of different microbial starters.

In this work, Italian salami were produced using microbial starters (Pediococcus pentosaceus, Lactobacillus sakei, and Staphylococcus xylosus) and compared to a control sample (without starter). Metabolomics in combination with microbiological and sensory analyses were used to investigate the overall quality. Samples were analyzed immediately after stuffing, following 7, 30, and 45 days of ripening. Each microbial starter imposed distinctive metabolomic signatures at the end of ripening. The accumulated discriminant compounds were mainly related to lipid oxidation (including hydroxy- and epoxy derivatives of fatty acids) following the inoculation with L. sakei. However, the inoculation with P. pentosaceus resulted in the accumulation of γ-glutamyl peptides, compounds driving a kokumi-related taste. Noteworthy, our findings supported the involvement of the chemical compounds profiled in the definition of final taste and aroma. This information paves the way towards the definition of more objective and tailored starters-related flavours enhancement approaches in the sector of cured meat.

Exploring Coagulase-Negative Staphylococci Diversity from Artisanal Llama Sausages: Assessment of Technological and Safety Traits.

Llama sausage is still produced following artisanal procedures, with the autochthonous microbiota being mainly responsible for the fermentation process. In this work, the taxonomical identification and technological-safety criteria of coagulase-negative staphylococci (CNS) isolated from two different productions of llama sausages (P: pilot and A: artisanal) were investigated. Staphylococcus (S) equorum and S. saprophyticus were the species most frequently found in P production, followed by S. succinis and S. warneri; a wider species variability was observed in A factory being S. equorum, S. capitis, S. xylosus, S. pasteuri, S. epidermidis and S. saprophyticus as the main identified species. The technological characterization of 28 CNS strains showed their ability to hydrolyze gelatin and tributyrin together with a relevant nitrate reductase activity. Phenotypic and genotypic approaches were conducted to investigate the main safety traits. Llama's CNS strains exhibited weak decarboxylase and hemolytic activity and low biofilm production; additionally, no enterotoxin genes were detected. Correlation analysis between phenotypic and genotypic data showed low values for the biofilm parameters, while high correlation was observed for oxacillin, ampicillin, tetracycline and aminoglycosides resistance and their genetic determinants. Data obtained may contribute to broaden knowledge about the autochthonous strains of this poorly studied fermented product, thus helping to select an appropriate combination of potential starter cultures to improve llama sausage safety and quality.

Genome-Assisted Characterization of Lactobacillus fermentum, Weissella cibaria, and Weissella confusa Strains Isolated from Sorghum as Starters for Sourdough Fermentation.

Sourdough fermentation of bakery products is a well-established and widespread technique to confer an added value to the resulting food. In recent decades, gluten-free raw materials have gained more attention due to the diffusion of food disorders such as coeliac disease, but, at the same time, they present difficult manipulation and scarce technological properties because of the absence of gluten. For this reason, the present work was aimed at selecting starter cultures for sourdough application that are isolated from fermentation of sorghum flour. Three isolates of Lactobacillus fermentum, Weissella cibaria, and Weissella confusa were selected for the following properties: exopolysaccharide synthesis, acidification, CO2 production, and amylase activity. The investigated phenotypic characteristics were confirmed by genomic analyses, which also highlighted other potentially beneficial features for use in bakery products employment. These strains, together with bakery yeast, were used for bread preparation using sorghum and wheat flour and after 24 h of fermentation the resulting dough was analyzed to assess the improvement of its characteristics. The presence of lactic acid bacteria (LAB) had a great impact on the final dough, and the best preparation, from a rheological point of view, resulted in one made of sorghum and wheat flour with added LAB and bakery yeast, whose resulting characteristics were similar to all wheat flour doughs. The results of this study suggest a potential application of the selected starters in sorghum composite bread and should be validated with data from large-scale pilot tests conducted in industrial bakeries.

Impact of cooking and fermentation by lactic acid bacteria on phenolic profile of quinoa and buckwheat seeds.

In this work, quinoa and buckwheat cooked seeds were fermented by two autochthonous strains of lactic acid bacteria isolated from the corresponding seeds, namely Lactobacillus paracasei A1 2.6 and Pediococcus pentosaceus GS·B, with lactic acid chemically acidified seeds as control. The impact of cooking and fermentation on the comprehensive phenolic profile of quinoa and buckwheat seeds was evaluated through untargeted ultra-high-pressure liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF-MS). Samples were analyzed also for in vitro antioxidant capacity (as FRAP and ORAC assays) and total phenolic content (TPC). The in vitro spectrophotometric assays highlighted that the microbial fermentation was more efficient in increasing (p < .05) the TPC and in vitro antioxidant potential in quinoa cooked seeds. However, an increase (p < .05) in TPC and ORAC radical scavenging was observed in both pseudocereals after the different cooking processes (i.e., boiling or toasting). The untargeted phenolic profiling depicted the comprehensive phenolic composition in these matrices. Raw seeds of both pseudocereals possessed a similar phenolic content (4.4 g kg-1 equivalents; considering free and bound fractions). Besides, the metabolomics-based approach showed that all treatments (i.e., cooking and fermentation) induced the release of specific classes, namely phenolic acids and tyrosols. The PLS-DA multivariate approach identified in flavonoids the best markers allowing to discriminate the different treatments considered (i.e., cooking, chemical acidification and microbial fermentation). These findings support the use of cooking and microbial fermentation to ensure the health-promoting properties of non-wheat grains, such as buckwheat and quinoa.

Impact of cystic fibrosis disease on archaea and bacteria composition of gut microbiota.

Cystic fibrosis is often associated with intestinal inflammation due to several factors, including altered gut microbiota composition. In this study, we analyzed the fecal microbiota among patients with cystic fibrosis of 10-22 years of age, and compared the findings with age-matched healthy subjects. The participating patients included 14 homozygotes and 14 heterozygotes with the delF508 mutation, and 2 heterozygotes presenting non-delF508 mutations. We used PCR-DGGE and qPCR to analyze the presence of bacteria, archaea and sulfate-reducing bacteria. Overall, our findings confirmed disruption of the cystic fibrosis gut microbiota. Principal component analysis of the qPCR data revealed no differences between homozygotes and heterozygotes, while both groups were distinct from healthy subjects who showed higher biodiversity. Archaea were under the detection limit in all homozygotes subjects, whereas methanogens were detected in 62% of both cystic fibrosis heterozygotes and healthy subjects. Our qPCR results revealed a low frequency of sulfate-reducing bacteria in the homozygote (13%) and heterozygote (13%) patients with cystic fibrosis compared with healthy subjects (87.5%). This is a pioneer study showing that patients with cystic fibrosis exhibit significant reduction of H2-consuming microorganisms, which could increase hydrogen accumulation in the colon and the expulsion of this gas through non-microbial routes.

Microbial ecology involved in the ripening of naturally fermented llama meat sausages. A focus on lactobacilli diversity.

Llama represents for the Andean regions a valid alternative to bovine and pork meat and thanks to the high proteins and low fat content; it can constitute a good product for the novel food market. In this study, culture-dependent and independent methods were applied to investigate the microbial ecology of naturally fermented llama sausages produced in Northwest Argentina. Two different production technologies of llama sausage were investigated: a pilot-plant scale (P) and an artisanal one (A). Results obtained by High-Throughput Sequencing (HTS) of 16S rRNA amplicons showed that the production technologies influenced the development of microbial communities with a different composition throughout the entire fermentation process. Both sequencing and microbiological counts demonstrated that Lactic Acid Bacteria (LAB) contributed largely to the dominant microbiota. When a total of 230 isolates were approached by RAPD-PCR, presumptive LAB strains from P production exhibited an initial variability in RAPD fingerprints switching to a single profile at the final of ripening, while A production revealed a more heterogeneous RAPD pattern during the whole fermentation process. The constant presence of Lactobacillus sakei along the fermentation in both productions was revealed by HTS and confirmed by species-specific PCR from isolated strains. The technological characterization of Lb. sakei isolates evidenced their ability to grow at 15°C, pH4.5 and 5% NaCl (95%). Most strains hydrolyzed myofibrillar and sarcoplasmic proteins. Bacteriocins encoding genes and antimicrobial resistance were found in 35% and 42.5% of the strains, respectively. An appropriate choice of a combination of autochthonous strains in a starter formulation is fundamental to improve and standardize llama sausages safety and quality.

Microbial analyses of traditional Italian salami reveal microorganisms transfer from the natural casing to the meat matrix.

In this study the bacterial biodiversity, during the maturation process of traditional sausages (Salame Mantovano), produced with two different kinds of casing (hog middle or "Crespone" and hog bung or "Gentile"), was investigated by means of culture-dependent and -independent methods. In order to assess the natural variability linked to the type of casing used in production, the ingredients, as well as ripening conditions, were identical in both productions. The aim of the study was to understand the contribution of casing microflora during sausage ripening by identifying the dominant species and strains. The bacterial ecology of casings and salami at different ripening stages, as determined by plating, revealed higher staphylococci and enterococci counts for Gentile casing and for the entire ripening period of the salami studied. After molecular identification of 219 Lactobacilli and 225 cocci gram positive catalase positive (GPCP) isolates, the species most frequently isolated were Lactobacillus sakei, Lactobacillus curvatus, Staphylococcus xylosus, and Staphylococcus saprophyticus. Some L. sakei and S. saprophyticus strains, coming from casing, were also found in the salami at different times of ripening. A richer biodiversity was only detected at the beginning of maturation. We also report the first detection, by PCR-DGGE method, of Arcobacter marinus and Brochothrix thermosphacta species in casings and Kokuria salsicia in fresh sausage. Results suggesting that casing can be an important source of bacteria during natural fermentation when starter cultures are not used.

Archaeal microbiota population in piglet feces shifts in response to weaning: Methanobrevibacter smithii is replaced with Methanobrevibacter boviskoreani.

Methanogens commonly inhabit swine intestine. We analyzed the gut archaeal population by extracting DNA from the feces of nine piglets. We performed PCR to target the V6-V8 region of the 16S rRNA gene. Subsequent denaturing gradient gel electrophoresis (DGGE) revealed the presence of Methanobrevibacter boviskoreani, which has not previously been identified in pigs. We confirmed these data with a PCR-DGGE analysis of the mcrA gene, and subsequent sequencing. At 63 days old, the only band in fecal samples corresponded to M. boviskoreani. The DGGE analysis also showed that Methanobrevibacter smithii, which was abundant at 28 days, was dramatically reduced at 42 days, and it completely disappeared at 63 days. To confirm these data, we quantified M. smithii and the total archaeal population by quantitative PCR (qPCR); moreover, we designed a new set of species-specific primers based on the 16S rRNA gene of M. boviskoreani. The qPCR results confirmed the reduction in M. smithii over time and a simultaneous increase in M. boviskoreani. At 63 days, the total numbers of archaea and M. boviskoreani genomes were comparable, which suggested that M. boviskoreani represented the dominant archaea. This work showed that the archaeal population shifted during weaning, and M. boviskoreani replaced M. smithii.

High-throughput assessment of bacterial ecology in hog, cow and ovine casings used in sausages production.

Natural casings derived from different intestine portions have been used for centuries in the production of fresh and dry-fermented sausages. Here we analysed by means of culture-dependent methods and Illumina high-throughput sequencing of 16S rRNA amplicons the bacterial ecology of hog, cow and ovine casings at different stages of their preparation for sausages production. Several strains of Staphylococcus, Lactobacillus, Bifidobacterium, Vagococcus and Clostridium were counted, isolated and characterised at phylogenetic level. High-throughput sequencing analyses revealed a high bacterial diversity, which differed strongly between casings of different animal species. The technological processes involved in the preparation for casing had also a strong impact on the casings bacterial ecology, with a significant reduction of undesired microorganisms, and an increase in the proportion of lactobacilli and staphylococci. Natural casings were demonstrated to be complex ecological environments, whose role as microbiological inoculants in the production of sausages should not be underestimated.

Surface microbiota analysis of Taleggio, Gorgonzola, Casera, Scimudin and Formaggio di Fossa Italian cheeses.

The composition of the bacterial consortia of the smear Italian cheeses and their role on quality and safety is still poorly understood. The objective of this study was to identify and characterize the bacterial communities present on the surface of five traditional Italian cheeses, Casera Valtellina, Scimudin, Formaggio di Fossa, Gorgonzola and Taleggio. DGGE analysis performed using total DNA obtained from cheese surfaces enabled us to identify the dominant bacterial populations. Bands showing different intensity and identified as Staphylococcus, Micrococcus, Psychrobacter, Enterococcus and Brevibacterium species were detected on the surface of cheeses. The cluster analysis showed that Gorgonzola, Taleggio and Formaggio di Fossa cheeses present high similarity in their surface bacterial composition while major differences in the DGGE profiles were observed in Scimudin and Casera. The molecular taxonomical identification among the Gram positive isolates, reveals the presence of the following bacterial genera: Staphylococcus, Micrococcus, Macrococcus, Enterococcus, Lactobacillus, Carnobacterium, Leuconostoc, Brevibacterium, Corynebacterium, Brochothrix, Bacillus. The combination of culture dependent and independent techniques allowed us to obtain information about the bacterial species covering the surface of five different traditional Italian cheeses.