Technological and safety characteristics of Staphylococcaceae isolated from Spanish traditional dry-cured sausages

Study on simulation effect of physical and chemical characteristics of sausage by sausage model system

Introduction

The incorporation of Staphylococcus xylosus in sausage production is hypothesized to affect various physicochemical properties and flavor profiles of sausages. This study aimed to evaluate the simulation of these features in a sausage model and establish its applicability for in vitro studies.

Methods

Both a control and an experimental model, inclusive of Staphylococcus xylosus, were assessed for changes in physicochemical indexes (pH and water activity, Aw) and the concentration of flavoring components (esters and aldehydes). Thiobarbituric acid reactive substances (TBARS) values were also measured to evaluate lipid oxidation.

Results

The introduction of Staphylococcus xylosus resulted in no significant changes in pH and Aw between the sausage and the model. However, there was a considerable increase in the content of volatile flavor compounds, specifically esters and aldehydes, in the experimental groups compared to the control. Additionally, the TBARS values in experimental groups were significantly lower than those in the control group at the end of the testing period.

Discussion

The findings indicate that Staphylococcus xylosus plays a critical role in enhancing the flavor profile of sausages through the increased synthesis of volatile compounds and inhibiting fat oxidation. The sausage model effectively simulated the physicochemical and flavor index responses, demonstrating its potential utility for further in vitro research on sausage fermentation and preservation techniques.

Interaction of the extracellular protease from Staphylococcus xylosus with meat proteins elucidated via spectroscopic and molecular docking

This study aimed to assess the effect of an external protease secreted by Staphylococcus (S.) xylosus on the hydrolysis and flavor properties of meat protein. The results indicated that the protease significantly increased the solubility of myofibrillar proteins (MPs) and sarcoplasmic proteins (SPs) in water (P < 0.05), and altered their surface hydrophobicity and secondary structure. The results of micromorphological and free amino acids analyses suggested that the protease degraded the large and insoluble meat protein aggregates into small molecular proteins with uniform distribution and amino acids, especially glycine, glutamic acid, leucine, and cysteine. Moreover, the protease-catalyzed hydrolysis promoted the formation of some volatile compounds in the MPs and SPs. Additionally, molecular docking analysis suggested that hydrogen bond and hydrophobic interaction promoted the formation of a S. xylosus protease/meat protein complex. These results provided a basis for the future application of S. xylosus protease in meat products.

Hydrolysis of Beef Sarcoplasmic Protein by Dry-Aged Beef-Isolated Penicillium oxalicum and Its Associated Metabolic Pathways

Yanbian cattle have a unique meat flavor, and high-grade meat is in short supply. Therefore, in this study, we aimed to improve the added value of Yanbian cattle low-fat meat and provide a theoretical reference for the subsequent development of an excellent starter. Rump meat from Yanbian cattle was dry-aged and then screened for protease-producing fungi. Three protease-producing fungi (Yarrowia hollandica (D4 and D11), Penicillium oxalicum (D5), and Meesziomyces ophidis (D20)) were isolated from 40 d dry-aged beef samples, and their ability to hydrolyze proteins was determined using bovine sarcoplasmic protein extract. SDS-PAGE showed that the ability of Penicillium oxalicum (D5) to degrade proteins was stronger than the other two fungi. In addition, the volatile component content of sarcoplasmic proteins in the D5 group was the highest (45.47%) and comprised the most species (26 types). Metabolic pathway analysis of the fermentation broth showed that phenylalanine, tyrosine, and tryptophan biosynthesis was the most closely related metabolic pathway in sarcoplasmic protein fermentation by Penicillium oxalicum (D5). Dry-aged beef-isolated Penicillium oxalicum serves as a potential starter culture for the fermentation of meat products.

Technological and Safety Characterization of Coagulase-Negative Staphylococci Isolated from Sardinian Fermented Sausage Made by Ovine Meat

Ripened sheep sausages are widely consumed in Italy, particularly in Sardinia. Despite their driving role in flavor and color development, coagulase-negative staphylococci in these products have been rarely investigated. A total of 70 CoNS cultures isolated from Sardinian sheep sausages were characterized by rep-PCR and M13-RAPD typing and identified by 16S rDNA sequencing. S. xylosus and S. equorum accounted for more than 70% of the total isolates, whilst S. pasteuri (8.5%), S. succinus (2.8%), and S. haemolyticus (2.8%) were less represented. The genes encoding the synthesis of putrescine, tyramine, cadaverine, and histamine were evaluated by PCR. None of the strains hosted genes for decarboxylases, except one S. pasteuri strain that was potentially a tyramine-producer. Antibiotic resistance was evaluated, along with nitrate reductase, lipolytic, and proteolytic activity, in a pool of selected cultures. Resistance to the primary antibiotics was rather widespread. S. xylosus, S. equorum, and S. pasteuri strains were all resistant to amoxicillin and kanamycin. S. equorum strains were sensitive to all tested antibiotics. S. xylosus strains were all resistant to penicillin B. Conversely, all S. pasteuri strains were resistant to both ampicillin and penicillin B, and four out of five strains exhibited tetracycline resistance. The high variability in the production of sheep sausages makes the search for adjunct cultures of crucial relevance. According to this perspective, the characterization of the autochthonous CSN population represents the first step to approach a starter selection.

Isolation, characterization, and fermentation potential of coagulase-negative Staphylococci with taste-enhancing properties from Chinese traditional bacon

No proprietary starter cultures for crafting Chinese bacon. This study aimed to isolate Coagulase-negative Staphylococci (CNS) from Chinese bacon, identify their species, and evaluate their ability to produce biogenic amines (BAs), peptides, free amino acids (FAAs), and degrade proteins. Twenty-one isolates were deficient in hemolysis, DNase, and coagulase activities, and exhibited low amino acid decarboxylase activity. Further characterization revealed 11 CNS species showing protease, lipase, or nitrate reductase activities. Specifically, S. cohnii WX-M8 was able to degrade both sarcoplasmic and myofibrillar proteins, while S. saprophyticus MY-A10 was found to only degrade myofibrillar proteins. Both were able to reduce the BAs and increase the content of peptides around day 3. The meat fermented by these two CNS contained FAAs that are more conducive to taste formation, such as Glu and Asp, and reduced the content of bitter FAAs. These findings will provide insights into the use of CNS for Chinese bacon.

Regulatory Effects of Ganoderma lucidum, Grifola frondosa, and American ginseng Extract Formulation on Gut Microbiota and Fecal Metabolomics in Mice

The bioactivities of Ganoderma lucidum, Grifola frondosa, and American ginseng have been extensively studied and documented. However, the effects of their complexes on the structural properties of intestinal microbiota and fecal metabolism remain unclear. Therefore, this paper aims to present a preliminary study to shed light on this aspect. In this study, an immunocompromised mouse model was induced using cyclophosphamide, and Ganoderma lucidum, Grifola frondosa, and American ginseng extract formulation (referred to as JGGA) were administered via gavage to investigate their modulatory effects on gut microbiota and fecal metabolism in mice. The effects of JGGA on immune enhancement were explored using serum test kits, hematoxylin-eosin staining, 16SrDNA high-throughput sequencing, and UHPLC-QE-MS metabolomics. The findings revealed potential mechanisms underlying the immune-enhancing effects of JGGA. Specifically, JGGA administration resulted in an improved body weight, thymic index, splenic index, carbon scavenging ability, hypersensitivity, and cellular inflammatory factor expression levels in mice. Further analysis demonstrated that JGGA reduced the abundance of Firmicutes, Proteobacteria, and Actinobacteria, while increasing the abundance of Bacteroidetes. Additionally, JGGA modulated the levels of 30 fecal metabolites. These results suggest that the immune enhancement observed with JGGA may be attributed to the targeted modulation of gut microbiota and fecal metabolism, thus promoting increased immunity in the body.

Transforming the fermented fish landscape: Microbiota enable novel, safe, flavorful, and healthy products for modern consumers

Regular consumption of fish promotes sustainable health while reducing negative environmental impacts. Fermentation has long been used for preserving perishable foods, including fish. Fermented fish products are popular consumer foods of historical and cultural significance owing to their abundant essential nutrients and distinct flavor. This review discusses the recent scientific progress on fermented fish, especially the involved flavor formation processes, microbial metabolic activities, and interconnected biochemical pathways (e.g., enzymatic/non-enzymatic reactions associated with lipids, proteins, and their interactions). The multiple roles of fermentation in preservation of fish, development of desirable flavors, and production of health-promoting nutrients and bioactive substances are also discussed. Finally, prospects for further studies on fermented fish are proposed, including the need of monitoring microorganisms, along with the precise control of a fermentation process to transform the traditional fermented fish to novel, flavorful, healthy, and affordable products for modern consumers. Microbial-enabled innovative fermented fish products that consider both flavor and health benefits are expected to become a significant segment in global food markets. The integration of multi-omics technologies, biotechnology-based approaches (including synthetic biology and metabolic engineering) and sensory and consumer sciences, is crucial for technological innovations related to fermented fish. The findings of this review will provide guidance on future development of new or improved fermented fish products through regulating microbial metabolic processes and enzymatic activities.

Antibiotic Resistance/Susceptibility Profiles of Staphylococcus equorum Strains from Cheese, and Genome Analysis for Antibiotic Resistance Genes

In food, bacteria carrying antibiotic resistance genes could play a prominent role in the spread of resistance. Staphylococcus equorum populations can become large in a number of fermented foods, yet the antibiotic resistance properties of this species have been little studied. In this work, the resistance/susceptibility (R/S) profile of S. equorum strains (n = 30) from cheese to 16 antibiotics was determined by broth microdilution. The minimum inhibitory concentration (MIC) for all antibiotics was low in most strains, although higher MICs compatible with acquired genes were also noted. Genome analysis of 13 strains showed the S. equorum resistome to be composed of intrinsic mechanisms, acquired mutations, and acquired genes. As such, a plasmidic cat gene providing resistance to chloramphenicol was found in one strain; this was able to provide resistance to Staphylococcus aureus after electroporation. An msr(A) polymorphic gene was identified in five strains. The Mrs(A) variants were associated with variable resistance to erythromycin. However, the genetic data did not always correlate with the phenotype. As such, all strains harbored a polymorphic fosB/fosD gene, although only one acquired copy was associated with strong resistance to fosfomycin. Similarly, a plasmid-associated blaR1-blaZI operon encoding a penicillinase system was identified in five ampicillin- and penicillin G-susceptible strains. Identified genes not associated with phenotypic resistance further included mph(C) in two strains and norA in all strains. The antibiotic R/S status and gene content of S. equorum strains intended to be employed in food systems should be carefully determined.

Characterization of indigenous coagulase-negative staphylococci isolated from Chinese spontaneously fermented meat products

Technological, safety-related and volatile properties were analyzed in coagulase-negative staphylococci (CNS) isolates from Chinese spontaneously fermented meat products. A total of 107 CNS isolates were identified via 16 S rRNA sequencing, and the most recovered species were S. saprophyticus (53.3 %), S. edaphicus (12.1 %), and S. epidermidis (10.3 %). Among them, 58 CNS isolates belonging to 9 species were selected with higher activities of catalase, nitrate reductase, proteolysis, and lipolysis, as well as higher tolerance to stressful environmental conditions. Then, 7 CNS isolates belonging to 4 species were further selected based upon excellent technological characteristics, lack of hemolysis and antibiotic resistance, and a low production of biogenic amines. The volatile profiles of these 7 strains cultivated in pork broth was determined. S. casei No. 1 produced significant amounts of phenethyl alcohol, geraniol, and 3-methyl-butanol. S. xylosus No. 120 produced the highest amount of methyl ketones with the potential to provide dry-cured odor of fermented meats. The volatile profile was highly strain dependent. Several CNS identified in this study have the potential to be used as the starter cultures for fermented meat products.

Interaction between protease from Staphylococcus epidermidis and pork myofibrillar protein: Flavor and molecular simulation

This study investigated the influence of a protease from Staphylococcus (S.) epidermidis on the hydrolysis and flavor development in pork myofibrillar protein (MP). The surface hydrophobicity, fluorescence, Fourier transform infrared spectra, and atomic force microscopy analysis indicated that hydrolysis significantly changed surface hydrophobicity and secondary structure of MP (p < 0.05), and improved the stability of MP in water. The contents of free amino acid from MP, especially glutamic and alanine, significantly increased (p < 0.05), and the production of volatile compound such as aldehydes, alcohols and acid were promoted under the action of protease. MP treated with S. epidermidis protease is non-cytotoxic to the HEK-293 cells. Molecular docking analysis suggested that the interaction between the protease and actin was spontaneous and mainly involved hydrogen bonding forces. In summary, this study provides a theoretical basis for the future application of S. epidermidis protease in fermented meat products.

Purification and Characterization of the Protease from Staphylococcus xylosus A2 Isolated from Harbin Dry Sausages

The protease generated from Staphylococcus (S.) xylosus A2, which was isolated from Harbin dry sausages, was purified and characterized. The molecular weight of the purified protease was approximately 21.5 kDa, and its relative activity reached the highest at pH 6.0 and 50 °C. At pH 4.0−8.0 and temperatures of 20−50 °C, the protease was stable. Its activity was significantly improved by Ca2+ and Zn2+ ions (p < 0.05). The Michaelis constant and maximum velocity of the protease were 2.94 mg/mL and 19.45 U/mL·min, respectively. The thermodynamic parameters analysis suggested that the protease showed better catalytic properties at 40 °C. Moreover, the protease could hydrolyze meat proteins, and obtained hydrolysate is non-cytotoxic to the HEK-293 cells. These findings provide a theoretical basis for understanding the enzymatic characterization of S. xylosus A2 protease and its future application in fermented meat products.

Technological and Safety Characterization of Kocuria rhizophila Isolates From Traditional Ethnic Dry-Cured Ham of Nuodeng, Southwest China

Nuodeng ham is known for its unique processing techniques and flavor. In the present study, proteolytic microorganisms from cured artisanal Nuodeng ham were investigated in order to identify and select potential starter cultures for its faster and safer fermentation. Eight isolates, accounting for 57% of proteolytic microorganisms, were found to be related to Kocuria rhizophila. Relevant properties of K. rhizophila as potential starter culture were evaluated in vitro for the first time. Intra-species diversities were found in phylogenetic and physiological properties of K. rhizophila isolates. Nevertheless, desirable attributes, such as halo-tolerance, nitrate reductase and protease activity, as well as the absence of antimicrobial resistance and amino acid decarboxylase activity, were observed in selected isolates. Moreover, genome analysis of isolates K24 and K45 confirmed their lack of typical genes for virulence, antimicrobial resistance and amino acid decarboxylase. K. rhizophila may thus represent a novel starter candidate of coagulase-negative cocci group and contribute to color and flavor development of fermented meats.

The relationship between flavor formation, lipid metabolism, and microorganisms in fermented fish products

Traditional fermented fish products are favored due to their unique flavors. The fermentation process of fish is accompanied by the formation of flavor substances through a complex metabolic reaction of microorganisms, especially lipolysis and lipid oxidation. However, it is difficult to precisely control the reaction of microorganisms during the fermentation process in modern industrial production, and fermented fish products have lost their traditional characteristic flavors. The purpose of this review is to summarize the different kinds of fermented fish, core microorganisms in it, and flavor formation mechanisms, providing guidance for industrial cultural starters. Future research on the flavor formation mechanism is necessary to confirm the relationship between flavor formation, lipid metabolism, and microorganisms to ensure stable flavor and safety, and to elucidate the mechanism directly toward industrial application.

Biochemical properties of extracellular protease from Staphylococcus carnosus RT6 isolated from Harbin dry sausages, and its hydrolysis of meat proteins

The characteristics of the extracellular protease, produced by Staphylococcus carnosus RT6 isolated from Harbin dry sausages, and its hydrolysis of meat proteins were investigated. The protease was purified by ammonium sulfate, ion exchange, and gel filtration chromatography to obtain a 20.0 kDa extracellular protease. The protease reached maximal activity at pH 9.0 and 50 °C and was stable at pH 7.0 to 11.0 and 20 to 40 °C. Its protease activity was easily inhibited in the presence of Zn²⁺ , Fe²⁺ , and Fe³⁺ . The enzymatic characterization of the protease revealed a V_max 49.50 U/ml·min, K_m 8.19 mg/ml, and the half-life = 28.06 min, ΔH^* _d  = 114.11 kJ/mol, ΔG^* _d  = 89.24 kJ/mol, and ΔS^* _d  = 77.00 J/mol·K at 50 °C. In addition, the protease hydrolyzed meat protein into small particles and produced soluble peptides. This study provides a basis for understanding the biochemical characteristics of the S. carnosus RT6 protease and its future application for fermented meat products.

Biochemical Changes during the Manufacture of Galician Chorizo Sausage as Affected by the Addition of Autochthonous Starter Cultures

In this work, the effect of the use of two autochthonous starter cultures (Lactobacillus sakei LS131 + Staphylococcus equorum SA25 (EQU), or L. sakei LS131 + Staphylococcus saprophyticus SB12 (SAP)) on the physicochemical, microbiological, proteolytic and lipolytic changes taking place during the manufacture of Galician chorizo, a traditional Spanish sausage, was studied. Three different batches (control (CNT), EQU and SAP) were manufactured in triplicate and analysed during the manufacturing process (samples were taken and analysed at 0, 2, 5, 9, 14, 21 and 30 days of ripening) for proximate composition, pH, aw, colour parameters, nitrogen fractions, free amino acids, biogenic amines, fat parameters and free fatty acids. The use of either of these two starter cultures slightly but significantly reduced the pH values during the fermentation and increased the percentage of transformation to nitrosyl-heme pigments as well as the a* and b* values in the final products. The two starters significantly decreased the Enterobacteriaceae counts in the final product, but without this microbial group completely disappearing. Both starter cultures significantly increased the α-amino acidic nitrogen and the total basic volatile nitrogen fractions during manufacturing, also increasing the free amino acid content and reducing the total biogenic amine content by approximately 20%. The SAP starter enhanced the lipolytic processes, increasing the free fatty acid content. Due to their performances, these two starter cultures seem to be suitable for increasing the quality and safety of the Galician chorizo sausage.

Evaluation of the Biogenic Amines and Microbial Contribution in Traditional Chinese Sausages

Biogenic amines (BAs) in sausages represent a health risk for consumers, and thus investigating the BAs accumulation mechanism is important to control the BAs. In this study, the BAs profiles of 16 typical Chinese sausage samples were evaluated, and 8 kinds of common BAs were detected from different samples. As a whole, the BAs contents of the majority of Chinese sausage samples were within the safe dosage range, except that the total BAs and histamine concentrations of sample HBBD were above the toxic dosage levels. Furthermore, the bacterial and fungal communities of the Chinese sausage samples were investigated by high-throughput sequencing analysis, and Staphylococcus, Bacillus, Lactococcus, Lactobacillus, Debaryomyces, and Aspergillus were identified as the predominant genera. Accordingly, 13 representative strains were selected from the dominant genera, and their BAs formation and degradation properties were evaluated. Finally, the results of fermented meats model experiment indicated that the Staphylococcus isolates including Staphylococcus pasteuri Sp, Staphylococcus epidermidis Se, Staphylococcus carnosus Sc1, Staphylococcus carnosus Sc2, and Staphylococcus simulans Ss could significantly reduce BAs, possessing the potential as the starter cultures to control the BAs in fermented meat products. The present study not only helped to explain the BAs accumulation mechanism in Chinese sausage, but also developed the candidates for potential BAs control in fermented meat products.

Nonconventional starter cultures of coagulase-negative staphylococci to produce animal-derived fermented foods, a SWOT analysis

Coagulase-negative staphylococci (CNS) are ubiquitous micro-organisms that are commonly present on animal skin and animal-derived foods. They are members of the beneficial microbial consortia of several fermented food products where they contribute to quality. Currently, only a few CNS species are included in commercial starter cultures, although many other ones with promising properties have been isolated from diverse food ecosystems. In the present study, a Strengths-Weaknesses-Opportunities-Threats (SWOT) analysis of the potential use of unconventional CNS starter cultures for the fermentation of animal-derived foods is carried out. An overview of both their desirable and worrisome metabolic traits is given. In general, the application of innovative CNS-based starter cultures offers opportunities to modulate flavour, improve the safety and health aspects and develop novel colour development strategies for clean label products. Yet, their implementation is often not straightforward as nontrivial obstacles or threats are encountered, which relate to technological, food safety and legal concerns. As most of the desirable and undesirable characteristics of CNS species are strain dependent, a case-by-case evaluation is needed when evaluating specific strains for their potential use as novel starter cultures.

The narrowing down of inoculated communities of coagulase-negative staphylococci in fermented meat models is modulated by temperature and pH

Coagulase-negative staphylococci (CNS) are involved in colour and flavour formation of fermented meats. Their communities are established either spontaneously, as in some artisan-type products, or using a starter culture. The latter usually consists of Staphylococcus carnosus and/or Staphylococcus xylosus strains, although strains from other CNS species also have potential for application. However, it is not entirely clear how the fitness of alternative starter cultures within a fermented meat matrix compares to conventional ones and how this may be affected by processing conditions. Therefore, the aim of this study was to assess the influence of two key processing conditions, namely temperature and acidity, on the competitiveness of a cocktail of five different strains of CNS belonging to species that are potentially important for meat fermentation (Staphylococcus xylosus 2S7-2, S. carnosus 833, Staphylococcus epidermidis ATCC 12228, Staphylococcus equorum DFL-S19, and Staphylococcus saprophyticus FPS1). To this end, fermented meat models consisting of cured meat batters with initial pH values of 5.3, 5.5, or 5.7 were inoculated with these strains, stuffed in containers, and incubated at 23, 30, or 37 °C. Both the pH level and the temperature influenced the composition of the CNS communities, giving a competitive advantage to the best adapted species. Staphylococcus xylosus preferred low temperature and mild acidity, whereas an elevated temperature selected for S. epidermidis and a low pH for S. carnosus. Under the conditions tested, S. saprophyticus and S. equorum were outcompeted by the three other CNS species. Hence, CNS communities in fermented meats are not only established based on the initial presence of specific species in the meat batter but also by their subsequent adaptation to the processing conditions during fermentation, potentially overruling the use of starter cultures.

Technological aspects of horse meat products - A review

Horse meat and its products can be considered as a food with a high nutritional value. However, due to cases of economically motivated food adulteration by the intentional addition of horse meat beef products in recent years, horse meat has become a controversial issue. Consumer confidence in meat products and the meat industry has diminished, although consumers consider the differences between the food content and the label as the major issue rather than the safety and nutritional characteristics of horse meat. The elaboration of meat products from horse meat (e.g. "cecina", dry-cured loin, salami, bressaola and pâté) is also an interesting alternative to other traditional meat products such as dry-cured pork hams, pork sausages and liver pâtés. In this review, the technological aspects, safety and storage stability of meat products elaborated from horse meat will be addressed by highlighting the nutritional and sensory aspects of these meat products. We aim to improve the existing knowledge about horse meat in the view of recent scandals.

Genomic insights into the virulence and salt tolerance of Staphylococcus equorum

To shed light on the genetic background behind the virulence and salt tolerance of Staphylococcus equorum, we performed comparative genome analysis of six S. equorum strains. Data on four previously published genome sequences were obtained from the NCBI database, while those on strain KM1031 displaying resistance to multiple antibiotics and strain C2014 causing haemolysis were determined in this study. Examination of the pan-genome of five of the six S. equorum strains showed that the conserved core genome retained the genes for general physiological processes and survival of the species. In this comparative genomic analysis, the factors that distinguish the strains from each other, including acquired genomic factors in mobile elements, were identified. Additionally, the high salt tolerance of strains enabling growth at a NaCl concentration of 25% (w/v) was attributed to the genes encoding potassium voltage-gated channels. Among the six strains, KS1039 does not possess any of the functional virulence determinants expressed in the other strains.

Recent advances in cured raw ham manufacture

Cured raw hams are a valuable and popular group of meat products. The consumption and international trade have increased during the last years, therefore new technologies to accelerate the production process and to increase product quality and safety are needed. In the current review, an overview of European protected cured raw hams is presented. Furthermore, traditional methods for cured raw ham production together with recent advantages in the techniques for pretreatment (trimming, blade tenderization, and freeze-thawing), curing/salting (tumbling, vacuum impregnation, pulsed pressure, ultrasound, pulsed electric fields, simultaneous thawing/salting), drying/ripening (Quick-Dry-Slice-process, oil drop application, high temperature short time process) and postprocessing (vacuum and modified atmosphere packaging, high hydrostatic pressure, high pressure carbon dioxide, high pressure carbon dioxide with ultrasound) are described. Moreover, application techniques and effects of protective cultures and starter cultures, such as molds, yeasts, coagulase-negative staphylococci and lactic acid bacteria, on cured raw ham quality and safety are reviewed.

Safety and technological characterization of coagulase-negative staphylococci isolates from traditional Korean fermented soybean foods for starter development

To select starters for the production of meju and doenjang, traditional Korean fermented soybean foods, we assessed the safety and technological properties of their predominant isolates, Staphylococcus saprophyticus, Staphylococcus succinus and Staphylococcus xylosus. Phenotypic antibiotic resistance, hemolysis and biofilm formation were strain-specific. None of the S. succinus isolates exhibited antibiotic resistance or hemolytic activities. Thirty-three selected strains, identified through safety assessments of 81 coagulase-negative staphylococci (CNS) isolates, produced cadaverine, putrescine, and tyramine, but not histamine in the laboratory setting. The production of these three biogenic amines may, however, be insignificant considering the high levels of tyramine produced by the control, Enterococcus faecalis. The 33 CNS strains could grow on tryptic soy agar containing 21% NaCl (w/v), exhibited acid producing activity at 15% NaCl, and expressed strain-specific protease and lipase activities. S. succinus 14BME1, the selected starter candidate, produced significant amounts of benzeneacetic acid, 2,3-butanediol, trimethylpyrazine, and tetramethylpyrazine through soybean fermentation.

Characterization and Technological Features of Autochthonous Coagulase-Negative Staphylococci as Potential Starters for Portuguese Dry Fermented Sausages

The manufacture of dry fermented sausages is an important part of the meat industry in Southern European countries. These products are usually produced in small shops from a mixture of pork, fat, salt, and condiments and are stuffed into natural casings. Meat sausages are slowly cured through spontaneous fermentation by autochthonous microbiota present in the raw materials or introduced during manufacturing. The aim of this work was to evaluate the technological and safety features of coagulase-negative staphylococci (CNS) isolated from Portuguese dry fermented meat sausages in order to select autochthonous starters. Isolates (n = 104) obtained from 2 small manufacturers were identified as Staphylococcus xylosus, Staphylococcus equorum, Staphylococcus saprophyticus, and Staphylococcus carnosus. Genomically diverse isolates (n = 82) were selected for further analysis to determine the ability to produce enzymes (for example, nitrate-reductases, proteases, lipases) and antibiotic susceptibility. Autochthonous CNS producing a wide range of enzymes and showing low antibioresistance were selected as potential starters for future use in the production of dry fermented meat sausages.