Selection of autochthonous lactic acid bacteria from goat dairies and their addition to evaluate the inhibition of Salmonella typhi in artisanal cheese

Probiotic and functional potential of lactic acid bacteria isolated from pulque and evaluation of their safety for food applications

Pulque is a traditional Mexican non-distilled alcoholic beverage to which several beneficial functions are attributed, mainly associated with gastrointestinal health, which can be explained by the presence of probiotic bacteria in its microbiota. Therefore, the objective of this work was to evaluate the safety, probiotic activity, and functional characteristics of seven strains of lactic acid bacteria (LAB) isolated from pulque using the probiotic strain Lactobacillus acidophilus NCFM as control. The LAB isolates were identified by 16S rRNA sequencing and MALDI Biotyper® MS as belonging to three different Lactobacillaceae genera and species: Lactiplantibacillus plantarum, Levilactobacillus brevis and Lacticaseibacillus paracasei. Most strains showed resistance to gastric juice, intestinal juice and lysozyme (10 mg/L). In addition, all strains exhibited bile salt hydrolase (BSH) activity and antibacterial activity against the pathogenic strain Listeria monocytogenes. Additionally, cell surface characteristics of LAB were evaluated, with most strains showing good hydrophobicity, auto-aggregation, and co-aggregation towards enteropathogenic Escherichia coli and L. monocytogenes. In terms of safety, most of the strains were sensitive to the tested antibiotics and only the Lact. paracasei UTMB4 strain amplified a gene related to antibiotic resistance (mecA). The strains Lact. plantarum RVG2 and Lact. plantarum UTMB1 presented γ-hemolytic activity, and the presence of the virulence-related gene agg was identified only in UTMB1 strain. Regarding functional characterization, the tested bacteria showed good β-galactosidase activity, antioxidant activity and cholesterol reduction Based on principal component analysis (PCA) and heat mapping, and considering the strain Lact. acidophilus NCFM as the probiotic reference, the strains Lacticaseibacillus paracasei UTMB4, Lactiplantibacillus plantarum RVG4 and Levilactobacillus brevis UTMB2 were selected as the most promising probiotic strains. The results of this study highlighted the probiotic, functional and safety traits of LAB strains isolated from pulque thus supporting the health benefits attributed to this ancestral beverage.

The Impacts of Acidophilic Lactic Acid Bacteria on Food and Human Health: A Review of the Current Knowledge

The need to improve the safety/quality of food and the health of the hosts has resulted in increasing worldwide interest in acidophilic lactic acid bacteria (LAB) for the food, livestock as well as health industries. In addition to the use of acidophilic LAB with probiotic potential for food fermentation and preservation, their application in the natural disposal of acidic wastes polluting the environment is also being investigated. Considering this new benefit that has been assigned to probiotic microorganisms in recent years, the acceleration in efforts to identify new, efficient, promising probiotic acidophilic LAB is not surprising. One of these effots is to determine both the beneficial and harmful compounds synthesized by acidophilic LAB. Moreover, microorganisms are of concern due to their possible hemolytic, DNase, gelatinase and mucinolytic activities, and the presence of virulence/antibiotic genes. Hence, it is argued that acidophilic LAB should be evaluated for these parameters before their use in the health/food/livestock industry. However, this issue has not yet been fully discussed in the literature. Thus, this review pays attention to the less-known aspects of acidophilic LAB and the compounds they release, clarifying critical unanswered questions, and discussing their health benefits and safety.

Probiotic characteristics and whole-genome sequence analysis of Pediococcus acidilactici isolated from the feces of adult beagles

The beneficial effects of lactic acid bacteria are well known and recognized as functional foods that are health benefits for companion animals. This study, for the first time, reports the probiotic properties, safety, and whole-genome sequence of Pediococcus acidilactici GLP06 isolated from feces of beagles. In this study, candidate probiotic bacteria P. acidilactici GLP02 and GLP06 were morphologically characterized and tested for their antimicrobial capacity, tolerance to different conditions (low pH, bile salts, an artificial gastrointestinal model, and high temperature), antibiotic sensitivity, hemolytic activity, cell surface hydrophobicity, autoaggregation activity, and adhesion to Caco-2 cells. P. acidilactici GLP06 showed better probiotic potential. Therefore, P. acidilactici GLP06 was evaluated for in vivo safety in mice and whole-genome sequencing. The results showed, that the supplemented MG06 group (1010 cfu/mL), GLP06 was not only nontoxic to mice, but also promoted the development of the immune system, improved resistance to oxidative stress, and increased the diversity of intestinal microorganisms and the abundance of Lactobacillus. Whole-genome sequencing showed that P. acidilactici GLP06 was 2,014,515 bp and contained 1,976 coding sequences, accounting for 86.12% of the genome, with no drug resistance genes and eight CRISPR sequences. In conclusion, the newly isolated canine-derived P. acidilactici GLP06 had good probiotic potential, was nontoxic to mice and promoted the development of immune organs, improved the biodiversity of the intestinal flora, and had no risk of drug-resistant gene transfer, indicating that P. acidilactici GLP06 can be used as a potential probiotic for the prevention and treatment of gastrointestinal diseases in companion animals.

Technological Characterization of Lactic Acid Bacteria Strains for Potential Use in Cheese Manufacture

A total of 26 lactic acid bacteria isolates from both Italian and Brazilian cheeses were tested for their use in cheesemaking. Isolates were screened for salt tolerance, exopolysaccharide and diacetyl production, lipolytic, acidifying, and proteolytic activities. In addition, the aminopeptidase (Pep N and Pep X) activities, were evaluated. Most of the strains demonstrated salt tolerance to 6% of NaCl, while only two L. delbruekii (P14, P38), one L. rhamnosus (P50) and one L. plantarum (Q3C4) were able to grow in the presence of 10% (w/v) of NaCl. Except for 2 L. plantarum (Q1C6 and Q3C4), all strains showed low or medium acidifying activity and good proteolytic features. Furthermore, lipolytic activity was revealed in none of the strains, while the production of EPS and diacetyl was widespread and variable among the tested strains. Finally, regarding aminopeptidase activities, 1 L. delbrueckii (P10), 1 L. rhamnosus (P50), and 1 L. lactis (Q5C6) were considered as the better performing, showing high values of both Pep N and Pep X. Based on data presented here, the aforementioned strains could be suggested as promising adjunct cultures in cheesemaking.

Antistaphylococcaland antioxidant activities of bacteriocinogeniclactic acid bacteriaand essential oil in goat coalho cheese

AIMS

Bacteriocinogenic lactic acid bacteria (LAB) isolates and Croton heliotropiifoliusessential oil (EO) were used to inhibit Staphylococcus aureussubsp.aureusand enhance the antioxidant action in goat coalhocheese (GCC).

METHODS AND RESULTS

LAB isolates were selected for their inhibitory capacity against S. aureus subsp. aureus, safety, existence of bacteriocin-encoding genes, bacteriocinogenic activity, and its antistaphylococcal action. The staphylococcal inhibition capacity of C. heliotropiifolius EO was also verified.Three cheeses were prepared containing: S. aureussubsp.aureus (GCC SA),S. aureussubsp.aureus+ LAB (GCC SA+LAB), and S. aureussubsp. aureus+ EO (GCC SA+EO). Samples were analyzed on days 0, 7, 14 and 21. Based on the screening, three LAB isolates were selected and identified as Enterococcus faecium. In GCC, the smallest population of S. aureussubsp.aureuswas found until the 17th in the GCC SA+EO and from the 18th in the GCC SA+LAB. Total phenolic content (TPC) and antioxidant activity increased over time in GCCs.

CONCLUSIONS

Autochthonous bacteriocinogenic LAB and C. heliotropiifolius EO are natural resources of the Caatinga, an exclusively Brazilian biome that predominates in the Northeast of the country, with the potential to reduce the presence of S. aureus and increase the antioxidant activity in the GCC.

SIGNIFICANCE AND IMPACT OF THE STUDY

GCC is a product of cultural importance in northeastern Brazil. The process of obtaining the GCC is manual and there is a high frequency of S. aureus in the product. Resources of the Caatinga with biofunctional properties can be tested to reduce the risk of staphylococcal toxins, and contribute to the nutritional value of the GCC, maintaining regional characteristics and respecting the local cultural tradition. LAB and C. heliotropiifolius EO contribute to the incorporation of bioactive substances and microbiological quality, generating a value-added GCC with exclusive resources ofthe Caatinga.

Whole genome sequencing for the risk assessment of probiotic lactic acid bacteria

Probiotic bacteria exhibit beneficial effects on human and/or animal health, and have been widely used in foods and fermented products for decades. Most probiotics consist of lactic acid bacteria (LAB), which are used in the production of various food products but have also been shown to have the ability to prevent certain diseases. With the expansion of applications for probiotic LAB, there is an increasing concern with regard to safety, as cases with adverse effects, i.e., severe infections, transfer of antimicrobial resistance genes, etc., can occur. Currently, in vitro assays remain the primary way to assess the properties of LAB. However, such methodologies are not meeting the needs of strain risk assessment on a high-throughput scale, in the context of the evolving concept of food safety. Analyzing the complete genetic information, including potential virulence genes and other determinants with a negative impact on health, allows for assessing the safe use of the product, for which whole-genome sequencing (WGS) of individual LAB strains can be employed. Genomic data can also be used to understand subtle differences in the strain level important for beneficial effects, or protect patents. Here, we propose that WGS-based bioinformatics analyses are an ideal and cost-effective approach for the initial in silico microbial risk evaluation, while the technique may also increase our understanding of LAB strains for food safety and probiotic property evaluation.

Spatial and Temporal Persistence of Fluorescent Lactiplantibacillus plantarum RS-09 in Intestinal Tract

The beneficial effects of the probiotic strain Lactiplantibacillus plantarum (formerly Lactobacillus plantarum) are based on its adherence and colonization ability in the gut. However, little is known about the migration and long-term gut colonization of the strain. This study evaluated the gut colonization modes of Lactiplantibacillus plantarum RS-09 to identify the strain with long-term gut colonization potential. We established CFDA/SE-labeled RS-09 to study the temporal and spatial distribution of RS-09 in the intestine as well as to analyze its persistence in different parts of the intestine by flow cytometry. This study has shown that the RS-09 strain maintains strong adhesion abilities under acid (pH 2.5) and base (pH 8.5) conditions. In addition, CFDA/SE can be used as an indicator for the labeling of L. plantarum RS-09 in the intestinal tract in vivo. We established a growth kinetics model of RS-09 to elucidate its persistence in the intestine. In vivo persistence experiments showed that the persistence rate of RS-09 was the highest in the cecum (69.5%) and the lowest in the duodenum (12.8%) at 96 h. After 20 days, RS-09 was predominantly localized in the cecum and colon steadily. These studies provide new insights into the long-term persistence of L. plantarum in the gastrointestinal tract. The CFDA/SE label system may be used to study the in vivo colonization dynamics of other probiotic strains.

The Reduction of Salt in Different Cheese Categories: Recent Advances and Future Challenges

Public awareness about excessive sodium intake and nutrition claims related to salt content entail the need for food industries to carefully reconsider the composition and processing of high sodium foods. Although in some products the reformulation with alternative ingredients is commonly practiced, in cheese the reduction of salt is still a challenging task, as sodium chloride exerts multiple and fundamental functions. Salt favors the drainage of the residual whey, enhances the taste and the aroma profile, regulates the texture, the final pH, the water activity, and affects the microbial growth. Ultimately, salt content modulates the activity of starter and non-starter lactic acid bacteria (NSLAB) during cheese manufacturing and ripening, influencing the shelf-life. Any modification of the salting procedure, either by reducing the level of sodium chloride content or by replacing it with other salting agents, may affect the delicate equilibrium within the above-mentioned parameters, leading to changes in cheese quality. The decrease of Na content may be differently approached according to cheese type and technology (e.g., soft, semi-hard, hard, and mold-ripened cheeses). Accordingly, targeted strategies could be put in place to maintain the overall quality and safety of different cheeses categories.

Probiotic activity traits in vitro and production of antimicrobial peptides by Lactobacillaceae isolates from pulque using Lactobacillus acidophilus NCFM as control

The objective of this work was to determine in vitro probiotic activity traits of 11 lactic acid bacteria (LAB) strains isolated from pulque obtained from three different locations in the Mexican states of Oaxaca and Puebla using the probiotic strain Lactobacillus acidophilus NCFM as a positive control, and to detect their production of antimicrobial peptides, including bacteriocins and peptidoglycan hydrolases (PGH). The LAB isolates were identified by sequencing of their 16S rRNA as belonging to four different genera of the Lactobacillaceae family: Lactiplantibacillus, Levilactobacillus, Lacticaseibacillus and Liquorilactobacillus, corresponding to the species plantarum, brevis, paracasei and ghanensis, respectively. Most of the strains showed resistance to high acidity (pH 2) and bile salts (0.5%), with survival rates up to 87 and 92%, respectively. In addition, most of the strains presented good antimicrobial activity against the foodborne pathogens Listeria monocytogenes, ECEC and Salmonella Typhi. The strain Liquorilactobacillus ghanensis RVG6, newly reported in pulque, presented an outstanding overall performance on the probiotic activity tests. In terms of their probiotic activity traits assessed in this work, the strains compared positively with the control L. acidophilus NCFM, which is a very-well documented probiotic strain. For the antimicrobial peptide studies, four strains presented bacteriocin-like mediated antibiosis and six had significant PGH activity, with two strains presenting outstanding overall antimicrobial peptide production: Lacticaseibacillus paracasei RVG3 and Levilactobacillus brevis UTMB2. The probiotic performance of the isolates was mainly dependent on strain specificity. The results obtained in this work can foster the revalorization of pulque as a functional natural product.

Probiotic Potential and Wide-spectrum Antimicrobial Activity of Lactic Acid Bacteria Isolated from Infant Feces

In this study, we aimed to characterize lactic acid bacteria strains derived from infants' feces, to evaluate the probiotic potential and explore the wide-spectrum antimicrobial activity. Of 800 isolates, 20 inhibited the growth of enterotoxigenic Escherichia coli K88 and Salmonella enterica ATCC 13076. On the basis of 16S rRNA sequence analysis, the 20 isolates were assigned to Lactobacillus casei (7), Lactobacillus paracasei (2), Lactobacillus plantarum (4), Lactobacillus rhamnosus (2), Enterococcus avium (3), Enterococcus faecium (1), and Enterococcus lactis (1) species. In addition, 12 strains with high antimicrobial activity were investigated for the presence of probiotic properties such as physiological-biochemical characteristics, antimicrobial susceptibility, hemolytic activity, hydrophobicity, and aggregation activity. Wide-spectrum antimicrobial activity analysis revealed that approximately all tested strains inhibited the ten pathogens, and four strains (ZX221, ZX633, ZX3131, and ZX3875) had good probiotic properties and survived after being exposed to simulated gastrointestinal tract conditions. Moreover, we investigated the influence of pH on the wide-spectrum antimicrobial activity and found that four strains inhibited most pathogens at pH 4.5 and pH 5, whereas only ZX633 had an inhibitory effect on Bacillus subtilis ATCC 6633 and Micrococcus luteus ATCC 4698 at pH 5.5. Overall, Lact. casei ZX633 had wide-spectrum antimicrobial activity and could be considered a potential probiotic.

Probiotic Properties of Lactobacilli and Their Ability to Inhibit the Adhesion of Enteropathogenic Bacteria to Caco-2 and HT-29 Cells

We evaluated the probiotic properties of lactic acid bacteria using resistance, safety, and functional assays. A preliminary subtractive screening of nineteen strains was performed based on their survival in simulated gastric and intestinal juice, and cell surface characteristics (hydrophobicity and auto-aggregation). Five strains were selected for further characterization, which included the assessment of their co-aggregation to pathogens, phenol tolerance, antimicrobial activity, and safety. Moreover, their adhesion to Caco-2 and HT-29 cells and the ability to inhibit pathogenic bacteria adhesion were evaluated. All strains had high (≥ 80.0%) survival rates in gastric and intestinal juices. Among them, Lactobacillus brevis CCMA 1284, L. plantarum CCMA 0743, and L. plantarum CCMA 0359 exhibited higher hydrophobicity (95.33, 96.06, and 80.02%, respectively), while L. paracasei CCMA 0504 and L. paracasei CCMA 0505 had the highest auto-aggregation values (45.36 and 52.66%, respectively). However, these last two strains were positive for the DNAse test, which is a safety concern. The CCMA 0359 and CCMA 1284 strains did not show antimicrobial activity, while the CCMA 0505 strain had a higher percentage of adhesion (4.75%) to Caco-2 cells. In the simulated competition and exclusion assays, the CCMA 0743 strain was able to reduce Salmonella adhesion to both cells (Caco-2 and HT-29), but only the CCMA 0743 and CCMA 0505 strains inhibited Escherichia coli adhesion to HT-29 cells in the competition assay. According to the results of these evaluated attributes, this strain showed to be an excellent candidate for probiotic use.

Probiotic potential of Enterococcus hirae in goat milk and its survival in canine gastrointestinal conditions simulated in vitro

In canine nutrition, the use of goat nutraceutical dairy products is an innovative proposal. Therefore, the objective of this study was to prepare fermented goat milk with probiotic potential in dogs in an in vitro model. A total of 40 lactic acid bacteria (LAB) species were grown, of which 30 were CAP isolates originally from goat milk and 10 were CAN isolates originally from fecal material of newborn dogs. The isolates were selected based on resistance to the simulated canine gastrointestinal condition and acidifying ability. After this preliminary screening, the analyses were performed regarding β-galactosidase and exopolysaccharide formation, diacetyl production, adhesion proteins Mub and mapa, hydrophobicity, DPPH assay, virulence and antibiotic resistance. With these evaluations, four LAB isolates were identified using sequencing of the 16S rRNA gene. These were identified as Enterococcus hirae and were used to produce fermented goat milk. For statistical analysis, the data were analyzed using the Scott-Knott test and also submitted to analysis of variance and the Tukey test (P < 0.05). In the evaluation of goat milk fermented with E. hirae and control, over the 36-day storage period there was a reduction in pH and an increase in acidity, and higher levels of LAB were observed in goat milk fermented with E. hirae. Therefore, both these E. hirae isolates and the fermented goat milk produced showed satisfactory results in vitro, demonstrating probiotic efficiency and food safety for dogs.

Biodegradation of chlorpyrifos by a Weissella confusa strain and evaluation of some probiotic traits

Pesticides play an important role in agriculture; however, their excessive use causes several problems such as pollution of ecosystems and risks to human health. The presence of microorganisms able to degrade these pollutants can reduce their negative effect. The objective of this study was to test the capacity of Weissella confusa Lb.Con to tolerate or to degrade the chlorpyrifos pesticide. The results showed the capacity of the strain to tolerate a concentration of 200 μg/ml of chlorpyrifos. The strain Lb.Con has a remarkable capacity to grow in glucose-free MRS medium which contains different concentrations of chlorpyrifos. HPLC analysis showed that this strain was able to remove about 25% of chlorpyrifos. The evaluation of some probiotic properties showed that the strain Lb.Con had a remarkable resistance to the gastrointestinal conditions and a good antibacterial activity towards the pathogenic bacteria. The probiotic potential was evaluated to verify the possible use of W. confusa Lb.Con to detoxify harmful chlorpyrifos contained in food.

Microbial Interactions within the Cheese Ecosystem and Their Application to Improve Quality and Safety

The cheese microbiota comprises a consortium of prokaryotic, eukaryotic and viral populations, among which lactic acid bacteria (LAB) are majority components with a prominent role during manufacturing and ripening. The assortment, numbers and proportions of LAB and other microbial biotypes making up the microbiota of cheese are affected by a range of biotic and abiotic factors. Cooperative and competitive interactions between distinct members of the microbiota may occur, with rheological, organoleptic and safety implications for ripened cheese. However, the mechanistic details of these interactions, and their functional consequences, are largely unknown. Acquiring such knowledge is important if we are to predict when fermentations will be successful and understand the causes of technological failures. The experimental use of "synthetic" microbial communities might help throw light on the dynamics of different cheese microbiota components and the interplay between them. Although synthetic communities cannot reproduce entirely the natural microbial diversity in cheese, they could help reveal basic principles governing the interactions between microbial types and perhaps allow multi-species microbial communities to be developed as functional starters. By occupying the whole ecosystem taxonomically and functionally, microbiota-based cultures might be expected to be more resilient and efficient than conventional starters in the development of unique sensorial properties.

Use of Starter Cultures in Foods from Animal Origin to Improve Their Safety

Starter cultures can be defined as preparations with a large number of cells that include a single type or a mixture of two or more microorganisms that are added to foods in order to take advantage of the compounds or products derived from their metabolism or enzymatic activity. In foods from animal origin, starter cultures are widely used in the dairy industry for cheese, yogurt and other fermented dairy products, in the meat industry, mainly for sausage manufacture, and in the fishery industry for fermented fish products. Usually, microorganisms selected as starter culture are isolated from the native microbiota of traditional products since they are well adapted to the environmental conditions of food processing and are responsible to confer specific appearance, texture, aroma and flavour characteristics. The main function of starter cultures used in food from animal origin, mainly represented by lactic acid bacteria, consists in the rapid production of lactic acid, which causes a reduction in pH, inhibiting the growth of pathogenic and spoilage microorganisms, increasing the shelf-life of fermented foods. Also, production of other metabolites (e.g., lactic acid, acetic acid, propionic acid, benzoic acid, hydrogen peroxide or bacteriocins) improves the safety of foods. Since starter cultures have become the predominant microbiota, it allows food processors to control the fermentation processes, excluding the undesirable flora and decreasing hygienic and manufacturing risks due to deficiencies of microbial origin. Also, stater cultures play an important role in the chemical safety of fermented foods by reduction of biogenic amine and polycyclic aromatic hydrocarbons contents. The present review discusses how starter cultures contribute to improve the microbiological and chemical safety in products of animal origin, namely meat, dairy and fishery products.

Adjunct Culture of Non-Starter Lactic Acid Bacteria for the Production of Provola Dei Nebrodi PDO Cheese: In Vitro Screening and Pilot-Scale Cheese-Making

The present study aimed at selecting non-starter lactic acid bacteria strains, with desirable technological and enzymatic activities, suitable as adjunct culture for the Provola dei Nebrodi cheese production. One hundred and twenty-one lactic acid bacteria, isolated from traditional Provola dei Nebrodi cheese samples, were genetically identified by Rep-PCR genomic fingerprinting, using the (GTG)₅-primer, and by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS). Twenty-seven strains, included in the qualified presumption of safety (QPS) list, were tested for technological and proteinase/peptidase activities. Results showed that technological features and flavour formation abilities were strain-dependent. Among the selected strains, Lacticaseibacillus paracasei PN 76 and Limosilactobacillus fermentum PN 101 were used as adjunct culture in pilot-scale cheese-making trials. Data revealed that adjunct cultures positively affected the flavour development of cheese, starting from 30 days of ripening, contributing to the formation of key flavour compounds. The volatile organic compound profiles of experimental cheeses was significantly different from those generated in the controls, suggesting that the selected adjunct strains were able to accelerate the flavour development, contributing to a unique profile of Provola dei Nebrodi cheese.

Isolation and Genetic Identification of Endophytic Lactic Acid Bacteria From the Amazonian Açai Fruits: Probiotics Features of Selected Strains and Their Potential to Inhibit Pathogens

The açai palm (Euterpe oleracea) is native to the Amazon basin, a humid tropical forest. High levels of total mesophilic bacteria with high diversity have been consistently reported in açai fruits. As local consumers have few digestive problems, the results of the present study reveal the lactic acid bacteria (LAB) recovered from açai fruits with characteristics that suggest they are possible candidates for probiotics and antagonistic potential against pathogens for the first time. Açai fruits were sampled from five different locations in the Eastern Amazonia floodplains. Sixty-six isolates were recovered from fruits and tested for some probiotic characteristics following FAO/WHO guidelines. Approximately 65% of the isolates showed no catalase or oxidase activity, Gram-positive staining or cocci and bacilli cell morphology. Furthermore, 48% of the isolates demonstrated preliminary characteristics that suggest safety for use, as they presented no coagulase enzyme activity or gamma-hemolysis. These strains were identified as belonging to the genera Lactiplantibacillus and Pediococcus, and 32 strains also presented resistance to vancomycin, ciprofloxacin and streptomycin. In addition, 28 isolates showed a survival rate, expressed as log cycle reduction, higher than 0.9 under gastric conditions (pH 2). All strains tested positive in bile salts deconjugation tests and showed a survival rate higher than 0.8 in the presence of this salt. Regarding antimicrobial activity against pathogens, all strains were able to inhibit Salmonella Typhimurium (ATCC^® 14028^TM) and 97% were capable of inhibiting Escherichia coli (ATCC^® 25922^TM). Concerning the results of in vitro antagonistic assays, three isolates (B125, B135, and Z183 strains) were selected for antagonistic tests using açai juice contaminated with these two pathogens. All tested LAB strains were able to inhibit pathogen growth in açai juice. In summary, açai fruits are a potential source of LAB isolates to be investigated as probiotics.

Bacterial Succession through the Artisanal Process and Seasonal Effects Defining Bacterial Communities of Raw-Milk Adobera Cheese Revealed by High Throughput DNA Sequencing

The bacterial community of the artisanal Adobera cheese from Los Altos de Jalisco was described through high-throughput sequencing of 16S rRNA gene libraries. Samples were collected in two different seasons (dry and rainy) during four key steps of the manufacturing process (raw milk, fresh curd, matured curd, and cheese). Bacterial diversity was higher in early steps in comparison with the final elaboration stages. Firmicutes and Proteobacteria were the most abundant phyla, strongly represented by the Streptococcaceae, Enterobacteriaceae and Lactobacillaceae families, and core bacteria genera such as Streptococcus spp., Lactococcus spp., and Lactobacillus spp. Undesirable bacteria, including Pseudomonas spp. and Acinetobacter spp., were also detected in raw milk but almost undetectable at the end of the cheese manufacturing process, and seemed to be displaced by lactic-acid bacteria-related genera. Seasonal effects were observed on the community structure but did not define the core microbiota composition. Predictive metabolism was related to membrane transport, and amino-acid, lipid, and carbohydrate metabolism pathways. Our results contribute to deduce the role of bacteria involved in Adobera cheese manufacturing in terms of the metabolism involved, cheese microbial safety, and how undesirable bacterial populations could be regulated by process standardization as a potential tool to improve safety.

Lactic Acid Bacteria Adjunct Cultures Exert a Mitigation Effect against Spoilage Microbiota in Fresh Cheese

Lactic acid bacteria (LAB) have a strong mitigation potential as adjunct cultures to inhibit undesirable bacteria in fermented foods. In fresh cheese with low salt concentration, spoilage and pathogenic bacteria can affect the shelf life with smear on the surface and packaging blowing. In this work, we studied the spoilage microbiota of an Italian fresh cheese to find tailor-made protective cultures for its shelf life improvement. On 14-tested LAB, three of them, namely Lacticaseibacillus rhamnosus LRH05, Latilactobacillus sakei LSK04, and Carnobacterium maltaromaticum CNB06 were the most effective in inhibiting Gram-negative bacteria. These cultures were assessed by the cultivation-dependent and DNA metabarcoding approach using in vitro experiments and industrial trials. Soft cheese with and without adjunct cultures were prepared and stored at 8 and 14 °C until the end of the shelf life in modified atmosphere packaging. Data demonstrated that the use of adjunct cultures reduce and/or modulate the growth of spoilage microbiota at both temperatures. Particularly, during industrial experiments, C. maltaromaticum CNB06 and Lcb. rhamnosus RH05 lowered psychrotrophic bacteria of almost 3 Log CFU/g in a 5-week stored cheese. On the contrary, Llb. sakei LSK04 was able to colonize the cheese but it was not a good candidate for its inhibition capacity. The combined approach applied in this work allowed to evaluate the protective potential of LAB strains against Gram-negative communities.

Brazilian artisanal cheeses are rich and diverse sources of nonstarter lactic acid bacteria regarding technological, biopreservative, and safety properties-Insights through multivariate analysis

In this study a total of 220 isolates of lactic acid bacteria (LAB) recovered from 10 types of Brazilian artisanal cheeses marketed in 4 main regions of Brazil were evaluated regarding their safety and ability to produce diacetyl (a precursor of aromatic compounds), exopolysaccharides (EPS; from different sugar sources), and antagonistic activity against Listeria monocytogenes and Staphylococcus aureus. The results indicated that 131 isolates (59.6%) were classified as strong (40.5%) and moderate (19.1%) diacetyl producers; 28 isolates (12.7%) stood out due to their remarkable production of EPS from different sugars, including sucrose (3.2%), fructose (2.3%), lactose (2.3%), and glucose (6%). Furthermore, 94.1% and 95.9% of isolates presented antagonistic activity against S. aureus and L. monocytogenes, respectively, even though only 27 isolates (12.3%) exhibited positive results in the bacteriocin production test. None of the isolates tested presented hemolytic activity, and 117 were classified as safe, due to their intrinsic resistance to a maximum of 4 different antibiotics. The data obtained for assessment of antibiogram profile and technological potential (moderate and high production of diacetyl, EPS, and bacteriocins) were submitted to a multiple correspondence analysis to correlate them with the cheese of isolation. Regarding the antimicrobial profile of LAB strains, it was possible to verify an association between isolates from Minas artisanal cheeses from Araxá and resistance to tetracycline; Minas artisanal cheeses from Serro and resistance to erythromycin; Coalho and Minas artisanal cheese from Cerrado and resistance to penicillin; and isolates from Serrano and Colonial cheeses with clindamycin and ceftazidime resistance. Although the susceptibility of strains to these antibiotics was considered high (71.8-80.5%), these data may be related to the horizontal transfer of genes in the production chain of these cheeses. Results of multiple correspondence analysis also showed that isolates with antagonistic activity were mostly isolated from Manteiga, Colonial, and Coalho cheeses. The isolates with high or moderate EPS-producer ability from sucrose, glucose, and fructose were mainly associated with Minas artisanal cheeses from Cerrado. In contrast, isolates with high or moderate EPS-producer ability from lactose were isolated from Serrano, Minas artisanal cheeses from Canastra, and Campo das Vertentes microregions. Finally, isolates from Minas artisanal cheeses (from Araxá microregion), Coalho, and Caipira cheeses were associated with moderate/high diacetyl production. To the best of the authors' knowledge, this study provides, for the first time, data indicating that the dominant technological, biopreservative, and safety properties of LAB isolates can be correlated with the type of Brazilian artisanal cheeses, which denotes its singularity. This knowledge is of utmost relevance for the development of starter or adjunct cultures with tailored properties.

Suitability of the Nisin Z-producer Lactococcus lactis subsp. lactis CBM 21 to be Used as an Adjunct Culture for Squacquerone Cheese Production

This research investigated the technological and safety effects of the nisin Z producer Lactococcus lactis subsp. lactis CBM 21, tested as an adjunct culture for the making of Squacquerone cheese in a pilot-scale plant. The biocontrol agent remained at a high level throughout the cheese refrigerated storage, without having a negative influence on the viability of the conventional Streptococcus thermophilus starter. The inclusion of CBM 21 in Squacquerone cheesemaking proved to be more effective compared to the traditional one, to reduce total coliforms and Pseudomonas spp. Moreover, the novel/innovative adjunct culture tested did not negatively modify the proteolytic patterns of Squacquerone cheese, but it gave rise to products with specific volatile and texture profiles. The cheese produced with CBM 21 was more appreciated by the panelists with respect to the traditional one.

Biodiversity and Multifunctional Features of Lactic Acid Bacteria Isolated From Table Olive Biofilms

In the present study, a total of 554 lactic acid bacteria (LAB) isolates were obtained from the olive surface of Manzanilla, Gordal, and Aloreña cultivars processed as green Spanish-style or directly brined (natural) olives. The isolates obtained from industrial processes were genotyped by rep-PCR with primer GTG₅, collecting a total of 79 different genotypes. The α-biodiversity indexes showed that the LAB diversity was higher in the biofilms on the fruits which followed the Spanish-style process than in those just brined. Sixteen genotypes had a frequency higher >1% and were identified, by multiplex PCR recA gene and 16S gene sequencing, as belonging to Lactobacillus pentosus (n = 13) and Lactobacillus plantarum (n = 3) species. A multivariate analysis based on a dataset with 89,744 cells, including technological (resistance to salt and pH, production of lactic acid, auto and co-aggregation with yeast species, β-glucosidase and esterase activities), and potential probiotic characteristics (survival to gastric and pancreatic digestions, resistance to antibiotics, inhibition of pathogens, presence of bsh genes, cholesterol removal, hemolytic, α-glucosidase, β-galactosidase, and phytase activities) showed that the 16 genotypes could be grouped into 3 great phenotypes. Thus, the genotype biodiversity in table olive biofilms was limited but, at phenotype level, it was even lower since L. pentosus predominated clearly (80.15% isolates). L. pentosus Lp13 was the genotype with the most promising characteristics for its use as a multifunctional starter, with this strain being and ubiquitous microorganism present in both natural and lye-treated olive fermentations.

Inhibitory Effect of Lactobacillus plantarum FL75 and Leuconostoc mesenteroides FL14 against Foodborne Pathogens in Artificially Contaminated Fermented Tomato Juices

Tomatoes and tomato based-foods contain beneficial microorganisms and various organic acids that have important nutritional values for human. The objective of this study was to access the physiochemical properties of fermented tomatoes juices and to evaluate the competitiveness of lactic acid bacteria (LAB) against Listeria monocytogenes, Listeria innocua, and Salmonella spp., in artificially contaminated tomato juice. Microbial counting (LAB, fungi Salmonella spp., and Listeria spp.) was performed after fermentation and weekly during storage. Different organic acids (Lactic, succinic, and acetic) and ethanol were also monitored using HPLC method. Color parameters were also determined. The results showed an increase of lactic and acetic acid content, during fermentation and storage of juices inoculated with Lactobacillus plantarum and Leuconostoc mesenteroides at 25°C. Besides, citric acid and ethanol revealed higher content at the end of storage compared to that registered at 4°C. The pH from tomatoes juices decreased from an initial value of 4.5 to below 3.2. Alongside, foodborne pathogen population was significantly suppressed in tomatoes juices when the samples were coinoculated with LAB strains. Moreover, the inhibition of Salmonella species was faster compared to that of Listeria. After four weeks of storage at 4°C, Lb. plantarum and Lc. mesenteroides showed high survival rate, while pathogenic bacteria, yeasts, and molds cell numbers decreased drastically in all the contaminated vials. This work highlights the efficiency of Lb. plantarum and Lc. mesenteroides as potential starters for developing nutritious and safe fermented tomato juice products.

Evaluation of probiotic potential and anti-hyperglycemic properties of a novel Lactobacillus strain isolated from water kefir grains

A total of eight strains of lactic acid bacteria were isolated from water kefir grains and assessed for their in vitro α-glucosidase inhibitory activity. Lactobacillus mali K8 demonstrated significantly higher inhibition as compared to the other strains, thus was selected for in vitro probiotic potential characterization, antibiotic resistance, hemolytic activity and adaptation to pumpkin fruit puree. L. mali K8 demonstrated tolerance to pH 2.5 and resisted the damaging effects of bile salts, pepsin and pancreatin, comparable to that of Lactobacillus rhamnosus GG ATCC 53103 (reference strain). Lack of hemolytic activity and susceptibility to the five standard antibiotics indicated the safety of the K8 strain. This strain showed singular properties to be used as starters in the pumpkin fruit puree fermentation. These preliminary in vitro tests indicated the safety and functionality of the K8 strain and its potential as a probiotic candidate.

Lactic Acid Bacteria as Biological Control of Staphylococcus aureus in Coalho Goat Cheese

The aim of this study is to investigate the bacterial population in coalho goat cheese produced in the semi-arid northeast region of Brazil, to analyse the antibiotic resistance profiles of the identified pathogenic bacteria, to detect the staphylococcal enterotoxin genes and to evaluate the addition of autochthonous lactic acid bacteria (LAB) with technofunctional properties for the control of Staphylococcus aureus growth. In the analysed samples, strains of Escherichia coli (N=11), Salmonella spp. (N=18), Listeria spp. (N=6) and S. aureus (N=9) were classified as multidrug resistant (MDR). The most commonly isolated pathogen from the studied coalho goat cheese was S. aureus. Its isolates were positive for the genes encoding enterotoxins A (sea), B (seb), C (sec) and D (sed). The autochthonous LAB with the potential to inhibit S. aureus were identified as Enterococcus faecium. These strains were selected for in vitro tests of protective, safety, technological and functional properties. In the coalho goat cheese food matrix, these selected autochthonous LAB were able to reduce the enterotoxigenic MDR S. aureus load by approx. 3 log units.

Enzymes and Dairy Products

The use of enzymes in food production, including dairy products, is below expected due the high costs associated with their production and purification. Microbial enzymes have great potential for industrial applications since they can be produced via large-scale fermentation and they are easily expressed by cloning in well-known cultivated microorganisms. The combination of different procedures such as over-expression techniques and the use of low costs induction sources has resulted in the production of enzymes to be used in high added-value dairy products. The addition of glucose oxidase to probiotic yogurts has been indicated as an alternative to the maintenance of probiotic functionality. Bile salt hydrolase contributes to prevention of hypercholesterolemia which is interesting to produce new functional dairy products. This chapter discusses enzyme sources and their relevance in dairy products, the production of enzymes using cloning and super-expression techniques, as well as enzymes related to functional dairy products.