Characterization and evaluation of lactic acid bacteria isolated from goat milk

Selection of starter lactic acid bacteria capable of forming biofilms on wooden vat prototypes for their future application in traditional Sicilian goat's milk cheese making

In this study, 327 presumptive lactic acid bacteria (LAB) were isolated from goats' milk acid curds produced at a Sicilian dairy farm with the aim to identify potential starter cultures for traditional cheeses. All isolates were first processed by randomly amplified polymorphic DNA (RAPD)-PCR analysis. This approach identified 63 distinct strains which were evaluated for their acidifying capacity. Only 15 strains specifically stood out for their acidification capacity and were identified through 16S rRNA gene sequencing as Lactococcus lactis (11 strains) Enterococcus faecalis (three strains), and Ligilactobacillus animalis (one strain). Notably, all 15 LAB isolates produced bacteriocin-like inhibitory substances and anti-biofilm compounds, against both planktonic and biofilm forms of Listeria monocytogenes, Salmonella Enteritidis, Escherichia coli, and Staphylococcus aureus, albeit at varying levels. Among these 15 LAB, En. faecalis RGM25 and Lc. lactis RGM55, susceptible to five antibiotics tested, were put in contact with wooden vat prototypes, because all equipment used in traditional cheese production in Sicily are made of wood. Scanning electron microscopy and bacterial plate counts of the wooden vat prototypes showed the development of biofilms at levels of approximately 6.0 log CFU/cm2. Overall, this study contributes to establishing a custom-made LAB starter cultures with bio-preservatives properties for Sicilian cheese productions.

Effect of ripening time on the content of bioactive peptides and fatty acids profile of Artisanal Coalho cheese

The present study aimed to investigate the influence of ripening on the physicochemical, microbiological aspects, and fatty acid profile of Artisanal Coalho Cheeses and to detect if there are peptides with bioactive potential in their composition. Artisanal Coalho Cheese samples were kindly provided by a dairy farm located in Brazil in the Rio Grande do Norte state. A completely randomized design was adopted, with four maturation periods (0, 30, 45, and 60 days). Physicochemical traits (pH, total solids, moisture, non-fat solids, fat in total solids, protein, ash, fatty acid profile) and microbiological characterization (Salmonella sp, Listeria monocytogenes, total and thermotolerant coliforms, Staphylococcus aureus) were analyzed on cheese samples. Additionally, assays were performed for antioxidant and antihypertensive bioactivity through ACE and antimicrobial inhibition of the peptides extracted from the samples. There was a linear increase in total solids and ash content and a decrease in moisture content with increasing maturation time. The matured cheese samples had a lower pH than fresh Artisanal Coalho Cheese. Twenty-seven fatty acids were identified in the cheeses: 15 saturated, 07 monounsaturated, and 05 polyunsaturated, with a linear reduction of essential fatty acids (n6 and n3) during maturation. The microbiological quality of the cheeses was satisfactory, with an absence of undesirable bacteria in 92% of the cheese samples. Water-soluble peptide fractions from all periods tested showed antioxidant and antihypertensive potential with ACE control, and the maturation process potentiated these capacities, with a decline in these activities observed at 60 days. The antimicrobial activity against Gram-positive and Gram-negative bacteria increased with maturation, reaching better results until 60 days. The maturation process on wooden planks in the periods of 30, 45, and 60 days allows the production of Artisanal Coalho Cheese of an innovative character, safe to consumers from the microbiological point of view, with differentiated physicochemical and functional characteristics and good quality of lipid fraction compared to fresh cheese, enabling the addition of value to the dairy chain.

Unveiling the Potential of Lactic Acid Bacteria from Serbian Goat Cheese

This study aimed to unleash the potential of indigenous lactic acid bacteria (LAB) originating from traditionally made Serbian goat cheese. Following the isolation and identification of the LAB, the safety aspects of the isolates were evaluated through tests for hemolytic activity and antibiotic sensitivity. The selected isolates were then tested for various technological properties, including growth in methylene blue, proteolytic activity, acidification, curd formation ability in both pure and enriched goat milk, diacetyl production, antagonistic potential against other LAB, and biofilm formation ability. The results indicated that Lactococcus spp., Lacticaseibacillus spp., and Lactiplantibacillus spp. did not exhibit α or β hemolysis, while enterococci displayed α hemolysis. A higher number of isolates demonstrated sensitivity to ampicillin, tetracycline, and streptomycin, while sensitivity to gentamicin and vancomycin was strain-dependent. Based on the evaluation of technological properties, Lacticaseibacillus paracasei M-1 and Lactiplantibacillus plantarum C7-7, C7-8, and C14-5 showed promising characteristics. Additionally, Lactococcus lactis subsp. lactis strains C0-14 and C21-8 emerged as promising candidates with notable technological properties. Notably, certain indigenous strains LAB exhibit promising technological properties and safety profiles. These characteristics make them suitable candidates for use as starter or adjunct cultures in goat's milk cheese production, potentially enhancing the quality and safety of the cheese as well as hygiene practices among small-scale dairy producers.

Characterization and Assessment of Native Lactic Acid Bacteria from Broiler Intestines for Potential Probiotic Properties

Probiotics are the most promising alternative to antibiotics for improving animal production and controlling pathogenic infections, while strains derived from natural hosts are considered highly desirable due to their good adaptation to the gastrointestinal tract. The aim of this study was to screen Lactobacillus with broad-spectrum antibacterial activity from broilers fed an antibiotic-free diet and evaluate their potential as poultry probiotics. A total of 44 lactic acid bacteria (LAB) strains were isolated from the intestines of healthy broilers, among which 3 strains exhibited outstanding antimicrobial activity and were subsequently identified through 16S rRNA sequencing as Enterococcus faecium L8, Lactiplantibacillus plantarum L10, and Limosilactobacillus reuteri H11. These three isolates demonstrated potent bacteriostatic activity against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella cholerae, with inhibition zones ranging from 15.67 ± 1.53 to 21.33 ± 0.58 mm. The selected LAB strains exhibited high tolerance to acid and bile salts, with L. reuteri H11 displaying the highest survival rate (ranging from 34.68% to 110.28%) after exposure to 0.3% (w/v) bile salts for 6 h or a low pH environment (pH 2, 2.5, and 3) for 3 h. Notably, L. reuteri H11 outperformed other strains in terms of hydrophobicity (84.31%), auto-aggregation (53.12%), and co-aggregation with E. coli ATCC 25922 (36.81%) and S. aureus ATCC 6538 (40.20%). In addition, the three LAB isolates were either fully or moderately susceptible to the tested antibiotics, except for strain L8, which resisted gentamycin and vancomycin. Consequently, these three LAB strains, especially L. reuteri H11, isolated from the intestines of broiler chickens, represent promising probiotic candidates that can be employed as feed additives to enhance production performance and control poultry pathogens.

Isolation, characterization of Weissella confusa and Lactococcus lactis from different milk sources and determination of probiotic features

This study aimed to investigate the probiotic properties of Lactic Acid Bacteria (LAB) isolates derived from various milk sources. These isolates identified based on their morphological characteristics and 16S rRNA gene sequencing. Four strains of Lactococcus lactis and two strains of Weissella confusa were identified with over 96% 16S rRNA gene similarity according to the NCBI-BLAST results. The survival of the isolates was determined in low pH, pepsin, bile salts, and pancreatin, and their adhesion ability was assessed by in vitro cell adhesion assay, hydrophobicity, auto- and co-aggregation, and safety criteria were determined by hemolytic, gelatinase activities, and DNAse production ability tests. The results showed that the LAB isolates had different levels of resistance to various stress factors. L. lactis subsp. cremoris MH31 showed the highest resistance to bile salt, while the highest pH resistance was observed in L. lactis MH31 at pH 3.0. All the isolates survived in pepsin exposure at pH 3.0 for 3 h. The auto-aggregation test results showed that all strains exhibited auto-aggregation ranging from 84.9 to 91.4%. Co-aggregation percentage ranged from 19 - 54% and 17 - 57% against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213, respectively. The hydrophobicity capacity of the LAB isolated ranged from 35-61%. These isolates showed different adhesion abilities to Caco-2 cells (81.5% to 92.6%). None of the isolates exhibited DNase, gelatinase and hemolytic activity (γ-hemolysis). All results indicate that these LAB strains have the potential to be used as probiotics.

Pathogenic Biofilm Removal Potential of Wild-Type Lacticaseibacillus rhamnosus Strains

The emergence of antimicrobial resistance remains one of the greatest public health concerns. Biofilm formation has been postulated as a mechanism of microbial pathogens to resist antimicrobial agents. Lactic Acid Bacteria (LAB) and their metabolites have been proposed to combat bacterial biofilms due to their antimicrobial activity. In this vein, the aim of the present study was to investigate the biofilm removal potential of cell-free supernatants (CFSs) of five wild-type Lacticaseibacillus rhamnosus strains, isolated from Greek natural products, in comparison to the commercially available L. rhamnosus GG strain, against biofilms formed by common foodborne pathogens (Salmonella Enteritidis, Salmonella Typhimurium, Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus). The biofilm removal activity of LAB was assessed on a two-day-old mature biofilm using a microtiter plate-based procedure. Both non-neutralized and neutralized CFSs removed biofilms in a concentration-dependent manner. The biofilm removal activity of the non-neutralized CFSs was significantly higher compared to the neutralized CFSs, as expected, with ranges of 60-89% and 30-80%, respectively. The biofilm removal efficiency of L. rhamnosus OLXAL-3 was significantly higher among the wild-type L. rhamnosus strains tested (20-100% v/v). In conclusion, our results suggest the great potential of the application of wild-type L. rhamnosus strain' CFSs as effective natural agents against pathogenic bacterial biofilms.

An Overview of the Occurrence of Bioactive Peptides in Different Types of Cheeses

The search for improvements in quality of life has increasingly involved changes in the diet, especially the consumption of foods which, in addition to having good nutritional value, are characterized by offering health benefits. Among the molecules that trigger several beneficial responses are peptides, which are specific fragments of proteins known to produce positive effects on the human body. This review aimed to discuss the bioactive potential of peptides from cheeses. Studies show that the protein composition of some cheese varieties exhibits a potential for the release of bioactive peptides. The production of these peptides can be promoted by some technological procedures that affect the milk structure and constituents. The cheese maturation process stands out for producing bioactive peptides due to the action of enzymes produced by lactic acid bacteria. Thus, in addition to being proteins with high biological value due to their excellent amino acid profile, peptides from some types of cheeses are endowed with functional properties such as anti-hypertensive, antimicrobial, antioxidant, anticarcinogenic, opioid, and zinc-binding activities.

Probiotic characterization of Bacillus species strains isolated from an artisanal fermented milk product Dahi

Dahi, an artisanal fermented milk product, widely consumed in Pakistan, is microbiologically diverse, and many bacterial communities await investigation. The current study is first to present probiotic assessment of Bacillus species strains isolated from dahi. Based on 49 identified strains assessed, only 6 strains, i.e., Bacillus licheniformis QAUBL19, QAUBL1901, and QAUBL1902; Bacillus mycoides QAUBM19 and QAUBM1901; and Bacillus subtilis QAUBSS1 were having prominent persistence in the simulated gastrointestinal fluids, being non-hemolytic, with no DNase activity. Probiotic characteristics, cholesterol-assimilating, and carbohydrate-fermenting capabilities were assessed for all the strains. These six strains each showed variant cholesterol assimilating abilities. B. licheniformis QAUBL19 retaining most desired probiotic traits presented both notable cholesterol assimilating and bile salt hydrolase activities. It can be used as a probiotic of choice with hypocholesterolemia ability. B. subtilis QAUBSS1 showed wide carbohydrate fermentation ability and strongest antibacterial potential. It is likely to be considered a probiotic for living beings and starter culture for fermentation of food/feed.

Pediococcus acidilactici isolated from traditional cheese as a potential probiotic with cytotoxic activity against doxorubicin-resistant MCF-7 cells

The considerable flexibility of cancerous cells to escape from chemical and biological drugs makes it clear that much is to be done to control and eliminate such cells. Probiotic bacteria, in this regard, have shown promising performance. In this study, we isolated and characterized lactic acid bacteria from traditional cheese. Then we evaluated their activity against doxorubicin-resistant MCF-7 cells (MCF-7/DOX) through MTT assay, Annexin V/PI protocol, real-time PCR, and western blotting. Among the isolates, one strain with more than 97% similarity with Pediococcus acidilactici showed considerable probiotics properties. Low pH, high bile salts, and NaCl could not significantly affect this strain while it was susceptible to antibiotics. Also, it had a potent antibacterial activity. Besides, the cell-free supernatant of this strain (CFS) significantly reduced the viability of MCF-7 and MCF-7/DOX cancerous cells (to about 10% and 25%, respectively), while it was safe for normal cells. Also, we found that CFS could regulate the Bax/Bcl-2 at mRNA and protein levels to induce apoptosis in drug-resistant cells. We determined 75% early apoptosis, 10% late apoptosis, and 15% necrosis in the cells treated with the CFS. These findings can accelerate the development of probiotics as promising alternative treatments to overcome drug-resistant cancers.

Characterization and selection of probiotic lactic acid bacteria from different dietary sources for development of functional foods

INTRODUCTION

Dietary sources have an abundance of bacteria, mainly lactic acid bacteria (LABs), which have long been regarded as probiotics in humans and animals. Lactic acid bacteria (LAB) have been used as probiotic agents due to their ability to produce a variety of beneficial compounds for cultivars and their status as safe microorganisms.

METHODS

In this current study, the lactic acid bacteria (LAB) were isolated from several dietary sources such as curd, pickle, milk, and wheat dough. The principal focus of this study was to determine the survivability of these microorganisms in the gastrointestinal tract and to use promising strains to create probiotic drinks with numerous health benefits. The isolates were identified using a combination of morphological, biochemical, molecular and sugar fermentation patterns, like phenotypic characteristics, sugar fermentation, MR-VP reaction, catalase test, urease test, oxidase test, H2S production, NH3 production synthesis from arginine, citrate utilization, indole test, and 16s rRNA sequencing.

RESULTS

Two (CM1 and OS1) of the 60 isolates obtained showed the best probiotic results and were identified as Lactobacillus acidophilus CM1 and Lactobacillus delbrueckii OS1. These organism sequences were submitted to Gen bank with accession numbers OP811266.1 and OP824643.1, respectively. The acid tolerance test results indicated that most strains could survive significantly in an acidic environment with pH levels of 2 and 3. Similarly, the salt tolerance test results showed that both Lactobacillus acidophilus CM1 and Lactobacillus delbrueckii OS1 could survive at 4 and 6% NaCl levels significantly. The isolates also showed their ability to ferment sugars such as lactose xylose, glucose, sucrose, and fructose.

DISCUSSION

In conclusion, the study showed that the bacteria isolated from different food sources were indeed probiotic lactic acid bacteria and had probiotic properties. These isolates hold potential for future research in the formulation of millet-based probiotic beverages. However, further studies are required to confirm their effectiveness and safety in improving human health. This research provides a foundation for developing functional foods and drinks that can positively affect human health by incorporating probiotic microorganism.

Screening of Wild Lactic Acid Bacteria from Algerian Traditional Cheeses and Goat Butter to Develop a New Probiotic Starter Culture

Twenty-five lactic acid bacterial (LAB) strains have been isolated from traditional goat butter and three types of cheese (dry Klila, frech Klila, and Bouhezza) and evaluated for technological abilities, probiotic properties, and potentials as starter cultures. The twenty-five LAB strains comprised eight strains belonging to Lactobacillus, four strains belonging to Lactococcus, eleven strains belonging to Enterococcus, and two strains belonging to Leuconostoc. A non-hierarchical cluster analysis was performed in order to select the performing strains. After carrying out the preliminary phenotypic characterizations and the probiotic potential, three strains designated as BM10, B15, and C30 belonging to the genus Lactobacillus and Enterococcus with good tolerance to acidity were selected. The strains showed a significant resistance to 0.5% bile salts and 0.4% phenol. Hemolytic activity was not detected; in addition, good hydrophobicity and autoaggregation was obtained. A significant antimicrobial activity was exhibited by all selected strains against Listeria innocua. Genotypic identification by 16S rRNA allowed the identification of B15, BM10, and C30 as Lactobacillus plantarum, Lactobacillus casei, and Enterococcus durans, respectively. The results of the current study suggest that the strains isolated from Algerian fermented dairy products have high potential as probiotic starter cultures in the goat butter and cheese industry.

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.

An Insight into Goat Cheese: The Tales of Artisanal and Industrial Gidotyri Microbiota

The purpose of this study was to determine for the first time the microbiota in artisanal-type and industrial-type Gidotyri cheeses and investigate the influence of the cheese-making practices on their composition using culture-independent techniques. The microbiota present in artisanal with commercial starters (Artisanal_CS, n = 15), artisanal with in-house starters (Artisanal_IHS, n = 10) and industrial (Ind., n = 9) Gidotyri cheese samples were analyzed using a targeted metagenomic approach (16S rRNA gene). The Ind. Gidotyri cheese microbiota were less complex, dominated by the Streptococcaceae family (91%) that was more abundant compared to the artisanal Gidotyri cheeses (p < 0.05). Artisanal cheeses were more diverse compositionally with specific bacterial species being prevalent to each subtype. Particularly, Loigolactobacillus coryniformis (OTU 175), Secundilactobacillus malefermentans (OTU 48), and Streptococcus parauberis (OTU 50) were more prevalent in Artisanal_IHS cheeses compared to Artisanal_CS (p ≤ 0.001) and Ind. (p < 0.01) Gidotyri cheeses. Carnobacterium maltaromaticum (OTU 23) and Enterobacter hormaechei subsp. hoffmannii (OTU 268) were more prevalent in Artisanal_CS cheeses compared to Artisanal_IHS cheeses (p < 0.05) and Ind. cheeses (p < 0.05). Hafnia alvei (OTU 13) and Acinetobacter colistiniresistens (OTU 111) tended to be more prevalent in Artisanal_CS compared to the other two cheese groups (p < 0.10). In conclusion, higher microbial diversity was observed in the artisanal-type Gidotyri cheeses, with possible bacterial markers specific to each subtype identified with potential application to traceability of the manufacturing processes’ authenticity and cheese quality.

Postbiotics: From emerging concept to application

The microbiome innovation has resulted in an umbrella term, postbiotics, which refers to non-viable microbial cells, metabolic byproducts and their microbial components released after lysis. Postbiotics, modulate immune response, gene expression, inhibit pathogen binding, maintain intestinal barriers, help in controlling carcinogenesis and pathogen infections. Postbiotics have antimicrobial, antioxidant, and immunomodulatory properties with favorable physiological, immunological, neuro-hormonal, regulatory and metabolic reactions. Consumption of postbiotics relieves symptoms of various diseases and viral infections such as SARS-CoV-2. Postbiotics can act as alternatives for pre-probiotic specially in immunosuppressed patients, children and premature neonates. Postbiotics are used to preserve and enhance nutritional properties of food, elimination of biofilms and skin conditioning in cosmetics. Postbiotics have numerous advantages over live bacteria with no risk of bacterial translocation from the gut to blood, acquisition of antibiotic resistance genes. The process of extraction, standardization, transport, and storage of postbiotic is more natural. Bioengineering techniques such as fermentation technology, high pressure etc., may be used for the synthesis of different postbiotics. Safety assessment and quality assurance of postbiotic is important as they may induce stomach discomfort, sepsis and/or toxic shock. Postbiotics are still in their infancy compared to pre- and pro- biotics but future research in this field may contribute to improved physiological functions and host health. The current review comprehensively summarizes new frontiers of research in postbiotics.

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.

Leuconostoc mesenteroides LVBH107 Antibacterial Activity against Porphyromonas gingivalis and Anti-Inflammatory Activity against P. gingivalis Lipopolysaccharide-Stimulated RAW 264.7 Cells

Probiotics, active microorganisms benefiting human health, currently serve as nutritional supplements and clinical treatments. Periodontitis, a chronic infectious oral disease caused by Porphyromonas gingivalis (P. gingivalis), activates the host immune response to release numerous proinflammatory cytokines. Here, we aimed to clarify Leuconostoc mesenterica (L. mesenteroides) LVBH107 probiotic effects based on the inhibition of P.gingivalis activities while also evaluating the effectiveness of an in vitro P.gingivalis lipopolysaccharide-stimulated RAW 264.7 cell-based inflammation mode. L. mesenteroides LVBH107 survived at acid, bile salts, lysozyme, and hydrogen peroxide conditions, auto-aggregated and co-aggregated with P. gingivalis, exhibited strong hydrophobicity and electrostatic action, and strongly adhered to gingival epithelial and HT-29 cells (thus exhibiting oral tissue adherence and colonization abilities). Moreover, L.mesenteroides LVBH107 exhibited sensitivity to antibiotics erythromycin, doxycycline, minocycline, ampicillin, and others (thus indicating it lacked antibiotic resistance plasmids), effectively inhibited P.gingivalis biofilm formation and inflammation (in vitro inflammation model), reduced the secretion of pro-inflammatory cytokines (TNF-α, IL-6 and IL-1β) and inflammatory mediators (NO and PGE₂), and decreased the expression levels of inflammation related genes. Thus, L.mesenterica LVBH107 holds promise as a probiotic that can inhibit P.gingivalis biofilm formation and exert anti-inflammatory activity to maintain oral health.

Potential utilization of dairy industries by-products and wastes through microbial processes: A critical review

The dairy industry generates excessive amounts of waste and by-products while it gives a wide range of dairy products. Alternative biotechnological uses of these wastes need to be determined to aerobic and anaerobic treatment systems due to their high chemical oxygen demand (COD) levels and rich nutrient (lactose, protein and fat) contents. This work presents a critical review on the fermentation-engineering aspects based on defining the effective use of dairy effluents in the production of various microbial products such as biofuel, enzyme, organic acid, polymer, biomass production, etc. In addition to microbial processes, techno-economic analyses to the integration of some microbial products into the biorefinery and feasibility of the related processes have been presented. Overall, the inclusion of dairy wastes into the designed microbial processes seems also promising for commercial approaches. Especially the digestion of dairy wastes with cow manure and/or different substrates will provide a positive net present value (NPV) and a payback period (PBP) less than 10 years to the plant in terms of biogas production.

Incidence of virulence determinants and antibiotic resistance in lactic acid bacteria isolated from food products

Background: Lactic acid bacteria (LAB) confer beneficial health effects in humans. However, the safety of these bacteria and their potential to spread resistance in the environment must be evaluated. Materials & methods: Fifty-three LAB were isolated from different food samples and assessed for the prevalence of virulence determinants and antibiotic resistance profile. Results: Multiple resistance was reported for Lactobacillus brevis MIM04, having revealed phenotypic resistance to vancomycin (MIC >128 μg/ml), ampicillin, cefotaxime, oxacillin and gentamicin. Virulence traits (cylA, gelE, esp and agg) were detected using specific primers. Enterococcus faecium CHE32, Lactobacillus plantarum CHE37 and E. faecium MLK68 lack virulence genes, possess antimicrobial activity and survive in low pH and bile salt conditions. Conclusion: Isolated LAB revealed probiotic properties.

Characterization and Evaluation of the Probiotic Potential In Vitro and In Situ of Lacticaseibacillus paracasei Isolated from Tenate Cheese

ABSTRACT

The objectives of this investigation were (i) to isolate bacteria from various foods (dairy products, fruits, and vegetables) and evaluate their probiotic potential and (ii) to select, identify, and characterize the bacterial strain(s) with the highest probiotic potential. From 14 food samples, 117 bacterial strains were isolated; however, only 42 (T1 to T42) had the correct characteristics (gram positive, coccoid, and bacilliform) and were catalase and oxidase negative to be considered presumptive lactic acid bacteria (LAB). The antagonistic activity of the 42 strains was evaluated against Escherichia coli (O157:H7E09), Listeria monocytogenes (ATCC 19115), Staphylococcus aureus (ATCC 25923), and Salmonella enterica serotype Typhimurium (ATCC 14028). The nine strains with the highest antagonistic activity were recovered from the following foods: pulque (T1), sprouted beans (T26), Ranchero cheese (T30, T31, T32, T33, T35, and T36), and Tenate cheese (T40). The inhibition zones on culture and sensitivity plates were 17.0 ± 1.2 to 19.3 ± 2.8 mm in diameter. Based on the antagonistic activity against pathogenic bacteria and resistance to low pH and bile salts, strain T40 had the highest probiotic potential. A 16S rRNA technique was used to identify strain T40 as Lacticaseibacillus paracasei (renamed from Lactobacillus paracasei in April 2020). This strain had no resistance to ampicillin, gentamicin, erythromycin, and tetracycline. The antagonistic activity was evaluated in situ (fresh cheese) against pathogenic bacteria, supporting the probiotic potential of L. paracasei. Isolates of this LAB recovered from Tenate cheese had characteristics of a probiotic microorganism with high potential for use in food technology.

HIGHLIGHTS

Characterization of Lactic Bacteria Isolated from Raw Milk and Their Antibacterial Activity against Bacteria as the Cause of Clinical Bovine Mastitis

The objectives of this study were the selection of lactic acid bacteria (LAB) isolated from raw milk and studying their technological properties and antibacterial activities against bacteria as the cause of cattle mastitis. Biochemical and molecular identification using 16S–23S rRNA gene spacer analysis and 16S rRNA gene sequencing highlighted the presence of three species: Lactiplantibacillus plantarum, Lactococcus lactis, and Levilactobacillus brevis. The enzymatic characterization followed by the determination of technofunctional properties showed that LAB strains did not exhibit any hemolytic effect and were able to produce protease and lipase enzymes. Isolates showed very high antagonistic activity against Gram-positive and Gram-negative bacteria by producing H2O2, bacteriocin(s), and organic acid(s). APIZYM micromethod demonstrated that all selected strains are capable of producing valine arylamidase, cystine arylamidase, N-acetyl-β-glucosaminidase, and ᾳ-mannosidase. The antibiotic susceptibility assay showed that all selected strains were sensible to the majority of tested antibiotics. Based on these results, it can be concluded that the technological properties of the selected LAB allow considering their industrial use in order to formulate bioactive functional foods or drug(s).

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.

Screening Lactobacillus strains from artisanal Turkish goatskin casing Tulum cheeses produced by nomads via molecular and in vitro probiotic characteristics

BACKGROUND

Eleven Lactobacillus (L.) strains were newly isolated from traditional Turkish Tulum cheeses and were characterized regarding their potential probiotic characteristics (bile and acid tolerance, gastric and pancreatic juice tolerance, lysozyme tolerance, adhesion ability), virulence determinants (hemolytic activity, antibiotic resistance, biogenic amine production), and functional properties (antibacterial activity, β-galactosidase activity, production of exopolysaccharides, cholesterol removal).

RESULTS

These isolates were identified as L. brevis, L. plantarum, L. paracasei, L. coryniformis, L. rhamnosus and L. helveticus by 16S rRNA sequencing. With regard to safety aspects, none of the tested Lactobacillus isolates showed hemolytic activity or biogenic amine production. All the Lactobacillus isolates except isolate 24 were found to be sensitive or intermediate sensitive to penicillin, which is a frequently used antibiotic. Nine Lactobacillus isolates showed antibacterial activity against Staphylococcus aureus ATCC 25923, while only isolates 15 and 449 exhibited inhibitory activity against Listeria monocytogenes ATCC 7644. All isolated strains survived, even in the presence of 10.00 g L^-1 bile after 48 h, and exhibited good survival at pH 3, but only two isolates survived at pH 2. Among the strains, isolate 15 exhibited satisfactory auto-aggregative, cell-surface hydrophobicity features, cholesterol-lowering activity and good acid tolerance. Isolate 15 also showed the strongest bile and simulated pancreatic juice resistance and moderate lysozyme tolerance.

CONCLUSION

These outcomes suggest that isolate 15, identified as a L. plantarum strain from Tulum cheese, may be a promising probiotic candidate and could be suitable for use in several fermented foods. © 2020 Society of Chemical Industry.

Current Trends of Enterococci in Dairy Products: A Comprehensive Review of Their Multiple Roles

As a genus that has evolved for resistance against adverse environmental factors and that readily exchanges genetic elements, enterococci are well adapted to the cheese environment and may reach high numbers in artisanal cheeses. Their metabolites impact cheese flavor, texture, and rheological properties, thus contributing to the development of its typical sensorial properties. Due to their antimicrobial activity, enterococci modulate the cheese microbiota, stimulate autolysis of other lactic acid bacteria (LAB), control pathogens and deterioration microorganisms, and may offer beneficial effects to the health of their hosts. They could in principle be employed as adjunct/protective/probiotic cultures; however, due to their propensity to acquire genetic determinants of virulence and antibiotic resistance, together with the opportunistic character of some of its members, this genus does not possess Qualified Presumption of Safety (QPS) status. It is, however, noteworthy that some putative virulence factors described in foodborne enterococci may simply reflect adaptation to the food environment and to the human host as commensal. Further research is needed to help distinguish friend from foe among enterococci, eventually enabling exploitation of the beneficial aspects of specific cheese-associated strains. This review aims at discussing both beneficial and deleterious roles played by enterococci in artisanal cheeses, while highlighting the need for further research on such a remarkably hardy genus.

Impact of NSLAB on Kazakh cheese flavor

Xinjiang is a multiethnic region of China. Traditionally, most ethnic minorities are known to produce and consume cheese. Nomadic people have been reported to use lactic acid bacteria (LAB) for decades to produce fermented dairy products as part of a balanced diet. Non-starter LAB (NSLAB) contribute to different degrees of ripening, depending on the cheese variety. In the present study, we screened three types of NSLAB with good proteolysis and autolytic abilities from traditional Kazakh cheese: Pediococcus acidilactici R3-5, Staphylococcus epidermidis R4-2, and Lactobacillus rhamnosus R9-6. A control (no NSLAB) was also included, resulting in four distinct types of cheese samples. We used gas chromatography-mass spectrometry and the electronic nose system to identify volatile compounds and analyze the effect of NSLAB on cheese flavor at the ripening stage. The physicochemical indicators changed significantly during the ripening of Kazakh cheese. Compared with the control, the protein content, free fatty acid content, pH, flavor compounds, and odor profiles of the test cheeses were significantly different. The major chemical differences among cheeses were the synthesis of some key volatile components (ethyl caprylate, ethyl caprate, myristyl carbonate, capric acid, caprylic acid, nonanal, and benzyl alcohol). NSLAB can be used as an adjunct starter to make Kazakh cheese and the use of NSLAB affected the cheese flavor quality positively.

Evaluation of indigenous lactic acid bacteria of raw mare milk from pastoral areas in Xinjiang, China, for potential use in probiotic fermented dairy products

In the present study 114 lactic acid bacteria strains, isolated from raw mare milks from pastoral areas for ethnic minorities in northwest China, were screened for probiotic traits, and their characteristics were compared with those of Lactobacillus rhamnosus GG, a commercial strain. Among the 114 strains identified, the most common species was Pediococcus pentosaceus (n = 52), followed by Leuconostoc lactis (n = 35), Lactobacillus helveticus (n = 7), Lactobacillus plantarum (n = 6), Lactobacillus kefiri (n = 5), Lactobacillus curvatus (n = 4), Lactobacillus paracasei (n = 3), and Lactococcus garvieae (n = 3). Based on acid and bile salt tolerance, 15 strains were further selected. All selected strains were subjected to a series of in vitro tests to assess their technological properties, including cell surface hydrophobicity (13.6-56.2%), autoaggregation ability (9.26-38.30%), coaggregation ability, and heat and lysozyme survival rates (84.74-94.01% and 80.52-99.37%, respectively). In vitro antagonism showed that Lb. plantarum (M5-19, M8-60, M8-59) exhibited the most strong inhibitory activity against 7 tested pathogens. Moreover, antibiotic resistance and hemolytic activity were investigated for safety assessment. No strain exhibited hemolytic activity, and most of the strains were sensitive to a series of 14 antibiotics of clinical importance. Ultimately, the principal component analysis of all data obtained above showed that 2 Lb. plantarum strains (M8-59, M8-60) and Lb. paracasei M1-36 exhibited the best potential for their inclusion as adjunct functional cultures in local fermented dairy products.

Probiotic potential and anticancer properties of Pediococcus sp. isolated from traditional dairy products

Herein, 18 lactic acid bacteria isolated from 30 samples of traditional dairy products were identified, and their probiotic potential was evaluated. According to the results, almost all strains showed the probiotic properties sufficiently, though M1 had better characterise. 16S rRNA gene sequencing revealed that this strain belongs to the Pediococcus sp. (<95 % similarity). This strain had substantial antipathogenic activity and did not show any worrying antibiotic resistance. Also, the strain was resistant to high concentrations of bile salt (1 %), NaCl (6.5 %), and low pH (2). Furthermore, it was revealed that cell-free supernatant (CFS), heat-killed cells and live cells derived from M1 significantly decreased the viability of MCF-7 cells so that the CFS resulted in 85 % cell death. Flow cytometry and western blot analysis determined that this compound induced apoptosis in the cancerous cells through increasing the BAX protein expression and decreasing the Bcl-2 protein expression.

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.

Probiotic Properties of a Lactobacillus fermentum Isolated from New-born Faeces

Lactic acid bacteria (LAB) have been demonstrated to have roles in many applications, ranging from lowering of cholesterol to immunological development. In this study, Lactobacillus fermentum was isolated from a new-born's faeces and its genotypic and probiotic characterizations were performed. Our results showed that the survival rate of isolated Lactobacillus fermentum was 39.39% at pH 2 and 81.34% in the stimulated gastric juice at pH 3. It also digested bile salts. Its surface hydrophobicity was found to be 57.59% in n-hexane. These findings indicated that the isolate can be a good probiotic candidate.

Antagonistic activity of strains of lactic acid bacteria isolated from Carpathian cheese

A promising area for improving probiotics is the search for new sources of strains and the development of complex preparations which would include different types of bacterial cultures that complement each other. Sources of selection may be traditional dairy products, in particular, cheeses made from raw milk. Wild strains can be endowed with antibacterial properties. The antagonistic action of lactic acid bacteria (LAB) has long attracted the attention of researchers and scientists. The aim of the study was to investigate the antagonistic activity against pathogenic and opportunistic microorganisms of LAB strains isolated from traditional Carpathian cheese. Three samples of cheese were selected for the research – one sample of brynza and budz (brynza before salting), made in the highlands of the Carpathians, and one sample of budz, made in the foothills. LAB were identified using classic microbiological and modern molecular genetic methods (RAPD-PCR, RFLP-PCR, 16S rRNA gene sequencing). The objects of our studies were five strains of LAB: Lactococcus lactis IMAU32258, L. garvieae JB2826472, Enterococcus durans FMA8, E. faecium L3-23, E. faecium IMAU9421. Technological parameters such as acid-forming activity of milk fermentation, resistance to high concentrations of NaCl and temperature optimums of cultivation were taken as the main criteria for assessing the suitability of LAB for inclusion in fermentation preparations. Antagonistic activity was determined by agar diffusion (agar well method) and optic density of test cultures using a Multiscan FC microplate reader (Thermo scientifiс, USA) at the wave of 620 nm. There were four reference strains of pathogenic and opportunistic microorganisms were test cultures: Listeria monocytogenes PCM 2191, Staphylococcus aureus PCM 458, Escherichia coli PCM 2208, Salmonella typhimurium PCM 2182. Strains of the test cultures were received from the collection of microorganisms of the Institute of Biology and Biotechnology the (University of Rzeszów, Poland). According to the ability of LAB strains to form lactic acid, L. lactis IMAU32258 was the best acid-forming agent with an acid-forming energy of 94 °T. E. faecium was characterized by moderate levels of active and titratable acidity. Less pronounced acid-forming ability was determined for the species E. durans and L. garvieae. Cultures of the genus E. faecium, L. garvieae and E. durans were the most resistant to high concentrations of NaCl (6.5%). Regarding temperature optimums, we found that strains of E. faecium and E. durans species grew both at temperatures of 10, 15 and 45 °C, whereas no growth of L. lactis IMAU32258 and L. garvieae JB282647 2 was observed at 45 °C. Among the studied bacteria, the strains of E. durans FMA8 and E. faecium L3-23 were characterized by the highest antagonistic activity in producing the largest zones of growth inhibition and optic density of pathogenic and opportunistic microorganisms. The strain L. garvieae JB282647 2 exhibited the lowest level of antagonistic activity against pathogenic and opportunistic microorganisms.

Safety Assessment and Preliminary In Vitro Evaluation of Probiotic Potential of Lactococcus lactis Strains Naturally Present in Raw and Fermented Milk

The present study was conducted to find the potential of Lactococcus lactis strains naturally present in raw and fermented milk as probiotics and to evaluate their safety and some technological characteristics. There are numerous studies that evaluated probiotic properties of lactococci, nevertheless, limited studies on the probiotic potential of lactococci isolated from raw milk or dairy products were performed. Strains isolation from raw milk or dairy products and their characterization is important when selection of starter strains for the production of functional dairy foods is performed. Depending on aroma production and acidifying activity, 33 L. lactis strains were selected out of 169 and evaluated for safety, technological and probiotic properties. These strains were screened for antibiotic sensitivity, enzymatic activity, hemolytic and gelatinase activities. The strains were also assessed for resistance to bile salts and acid, growth in bile acids and cholesterol, cell surface hydrophobicity. Based on the obtained results, two strains with the best probiotic potential were selected. These two L. lactis strains, with 51% and 67% survival at low pH and more than 80% resistance to various bile salt concentrations, proved their resistance in vitro to gastric conditions. Also these strains proved to be good acidifiers (the pH of milk was reduced by at least 1 unit in 6 h at 30-37 °C) and can be used in the development of functional dairy foods as starter cultures.

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.

Fermented Seeds ("Zgougou") from Aleppo Pine as a Novel Source of Potentially Probiotic Lactic Acid Bacteria

Microorganisms inhabiting fermented foods represent the main link between the consumption of this food and human health. Although some fermented food is a reservoir of potentially probiotic microorganisms, several foods are still unexplored. This study aimed at characterizing the probiotic potential of lactic acid bacteria isolated from zgougou, a fermented matrix consisting of a watery mixture of Aleppo pine's seeds. In vitro methods were used to characterize the safety, survival ability in typical conditions of the gastrointestinal tract, and adherence capacity to surfaces, antimicrobial, and antioxidant activities. Strains belonged to the Lactobacillus plantarum group and Enterococcus faecalis showed no DNase, hemolytic, and gelatinase activities. In addition, their susceptibility to most of the tested antibiotics, satisfied some of the safety prerequisites for their potential use as probiotics. All the strains tolerated low pH, gastrointestinal enzymes, and bile salts. They displayed a good antibacterial activity and antibiofilm formation against 10 reference bacterial pathogens, especially when used as a cell-free supernatant. Furthermore, the lactic acid bacteria (LAB) strains inhibited the growth of Aspergillus flavus and Aspergillus carbonarius. Finally, they had good antioxidant activity, although depending on the strain. Overall, the results of this work highlight that zgougou represents an important reservoir of potentially probiotic LAB. Obviously, future studies should be addressed to confirm the health benefits of the LAB strains.

Safety and probiotic functionality of isolated goat milk lactic acid bacteria

Purpose

Lactic acid bacteria (LAB) are traditionally employed in the food industry. LAB strains from goat milk may also present probiotic potential, and it is fundamental to study the safety and functionality aspects which are desirable for their use in food. The objective of this study was to verify the probiotic potential of lactic bacteria isolated from goat milk.

Methods

The presence of safety-related virulence factors (hemolytic activity, gelatinase production, coagulase, and sensitivity to antibiotics) as well as functionality (exopolysaccharide (EPS) production, proteolytic activity, autoaggregation, gas production, survival in the gastrointestinal tract, and antimicrobial activity against bacteria that impair oral health) were determined.

Result

The selected LAB strains are safe against the evaluated parameters and have characteristics of possible probiotic candidates. Especially L. plantarum (DF60Mi) and Lactococcus lactis (DF04Mi) have potential to be added to foods because they have better resistance to simulated gastrointestinal conditions. In addition, they are isolated with already proven antimicrobial activity against Listeria monocytogenes, an important food-borne pathogen. DF60Mi was able to produce EPS (exopolysaccharides). LS2 and DF4Mi strains, both Lactococcus lactis subsp. lactis, demonstrated antimicrobial activity against S. mutans ATCC 25175, a recurrent microorganism in oral pathologies, mainly caries.

Conclusion

This study provides subsidies for future exploration of the potentialities of these LAB strains for both the development of new functional foods and for application in oral health.