Usefulness of a set of simple in vitro tests for the screening and identification of probiotic candidate strains for dairy use

In vitro Evaluation of Candidate Bacillus Strains Against erysipelothrix rhusiopathiae from Erysipelas Outbreaks in Layer Flocks

Erysipelas is a zoonotic disease, causing acute infections in swine, poultry, and a wide variety of animals, including humans. In layers, erysipelas is considered an emerging disease characterized by hepatomegaly, splenomegaly, septicemia, and acute death. It affects flocks between 43 and 73 wk old and can result in 50% overall mortality. Layer hens possibly affected by an erysipelas outbreak were sampled in this study. Organs at necropsy showed the typical erysipelas lesions; the presence of Erysipelothrix rhusiopathiae was confirmed by selective plating and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The antimicrobial effect of a set of 20 proprietary Bacillus direct-fed microbials (DFM), individual strains and in combinations, was analyzed against confirmed E. rhusiopathiae isolates, by agar-well diffusion assay. Nine of the Bacillus strains screened in this study were found effective at inhibiting the growth of all four E. rhusiopathiae isolates from erysipelas cases. The findings of this study highlight the potential of using the Bacillus DFMs in vivo to evaluate their efficacy as biocontrol alternatives to reduce the growth E. rhusiopathiae in poultry production.

Goat Cheese Produced with Sunflower (Helianthus annuus L.) Seed Extract and a Native Culture of Limosilactobacillus mucosae: Characterization and Probiotic Survival

The microbiological and biochemical properties of a goat cheese produced using Helianthus annuus (sunflower) seed extract as a coagulant and the potentially probiotic autochthonous culture Limosilactobacillus mucosae CNPC007 were examined in comparison to a control cheese devoid of the autochthonous culture. Throughout a 60-day storage period at 6 ± 1 °C, lactobacilli maintained a count of above 8 log CFU/g. Additionally, its viability in cheeses subjected to the in vitro gastrointestinal conditions demonstrated improvement over this period. Specifically, the recovery of lactobacilli above 6 log CFU/g was observed in 16.66% of the samples in the first day, increasing to 66.66% at both 30 and 60 days. While total coliforms were detected in both cheese trials, this sanitary parameter exhibited a decline in L. mucosae cheeses during storage, falling below the method threshold (<3 MPN/g) at 60 days. This observation suggests a potential biopreservative effect exerted by this microorganism, likely attributed to the higher acidity of L. mucosae cheeses at that point (1.80 g/100 g), which was twice that of the control trial (0.97 g/100 g). Furthermore, distinct relative proportions of >30 kDa, 30-20 kDa, and <20 kDa proteins during storage was verified for L. mucosae and control cheeses. Consequently, either the H. annuus seed extract or the L. mucosae CNPC007 autochthonous culture influenced the biochemical properties of the cheese, particularly in terms of proteolysis. Moreover, L. mucosae CNPC007 acidification property resulted in a biopreservative effect throughout the storage period, indicating the potential as a promising source of probiotics for this product.

Probiotic evaluation, adherence capability and safety assessment of Lactococcus lactis strain isolated from an important herb "Murraya koenigii"

Lactic acid bacteria (LAB) isolated from medicinal herb Murraya koenigii, commonly known as curry leaf, which promotes the growth and maintenance of gut microbiota, were studied for their probiotic potential. The key objective of this research was to isolate and evaluate probiotic characteristics, test adherence capabilities, and confirm their safety. Lactococcus lactis (MKL8), isolated from Murraya koenigii, was subjected to in vitro analysis to assess its resistance to the gastric environment, ability to adhere Caco-2 cells, anti-microbial activity, hydrophobicity, auto-aggregation, and safety profiling through MTT assay and hemolytic. MKL8 exhibited growth at 0.5% phenol concentrations (> 80%) and was able to survive in conditions with high bile concentrations (> 79%) and a relatively low pH (72%-91%). It shows high tolerance to high osmotic conditions (> 73%) and simulated gastric juice (> 72%). Additionally, MKL8 demonstrated strong hydrophobicity (85%), auto-aggregation (87.3%-91.7%), and adherence to Caco-2 cells. Moreover, it had an inhibitory effect against pathogens too. By performing the hemolytic and MTT assays, the non-toxicity of MKL8 isolate was examined, and it exhibited no harmful characteristics. Considering MKL8's resistance to gastrointestinal tract conditions, high surface hydrophobicity, non-toxicity, and ability to inhibit the tested pathogens, it can be concluded that MKL8 demonstrated promising probiotic properties and has potential for use in the food industry.

Probing the microbial diversity and probiotic candidates from Pakistani foods: isolation, characterization, and functional profiling

Probiotics represent beneficial living microorganisms that confer physiological, nutritional, and functional advantages to human health, holding significant potential for development of functional foods. This research aimed to isolate, identify, and characterize potential probiotic bacterial strains sourced from fermented and non-fermented foods from Pakistan. A total of 341 bacterial strains were isolated from diverse food samples (81) collected from various regions of Pakistan. Strains were identified using 16S rRNA gene sequencing and phylogenetic analysis. The identified strains belonged to genera Bacillus, Staphylococcus, Microbacterium, Shigella, Micrococcus, Enterococcus, Sporosarcina, Paenibacillus, Limosilactobacillus, Kosakonia, Dietzia, Leclercia, Lacticaseibacillus, Levilactobacillus, Kluyvera, Providencia, Enterobacter, Neisseria, Streptococcus, Acinetobacter, Corynebacterium, Pantoea, Mammaliicoccus, Pseudomonas, Burkholderia, and Alkalihalobacillus. Selected strains were chosen for probiotic assessment, employing existing literature as a guideline. Among these selections, six strains exhibited hemolytic activity, and seven strains displayed resistance to multiple antibiotics, prompting their exclusion from subsequent evaluations. The remaining strains demonstrated auto-aggregation capacities spanning 3.39-79.7%, and displayed coaggregation capabilities with reported food-borne pathogens. Furthermore, nine strains exhibited antimicrobial properties against food-borne pathogens. The assessment encompassed diverse characteristics such as cell surface hydrophobicity, survival rates under varying conditions, cholesterol reduction ability, casein digestion capability, and antioxidant activity. Phylogenomic analysis, digital-DNA DNA hybridization (digi-DDH), and average nucleotide identity (ANI) calculations unveiled novel species potentially belonging to the genera Sporosarcina and Dietzia. Based on these findings, we advocate for the consideration of Staphylococcus cohnii subsp. cohnii NCCP-2414, Lacticaseibacillus rhamnosus NCCP-2569 and Levilactobacillus brevis NCCP-2574 as prime probiotic candidates with the potential for integration into formulation of functional foods.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-023-03903-6.

β-Glucosidase activity and antimicrobial properties of potentially probiotic autochthonous lactic cultures

Background

The demand for lactic acid bacteria products, especially probiotics, has increased. Bacteria that increase polyphenol bioavailability and act as bio preservatives are sought after. This study aims to identify autochthonous lactic acid cultures from EMBRAPA that demonstrate β-glucosidase activity and inhibitory effect on microbial sanitary indicators.

Methods

Cell-free extracts were obtained by sonicating every 5 s for 40 min. The extracts were mixed with cellobiose and incubated at 50 °C. The reaction was stopped by immersing the tubes in boiling water. The GOD-POD reagent was added for spectrophotometer readings. Antimicrobial activity was tested against reference strains using the agar well diffusion method. Lactic cultures in MRS broth were added to 0.9 cm wells and incubated. The diameter of the inhibition zones was measured to determine the extension of inhibition.

Results

Only L. rhamnosus EM1107 displayed extracellular β-glucosidase activity, while all autochthonous strains except L. plantarum CNPC020 demonstrated intracellular activity for this enzyme. L. plantarum CNPC003 had the highest values. On the other hand, L. plantarum CNPC020, similarly to L. mucosae CNPC007, exhibited notable inhibition against sanitary indicators. These two strains significantly differed from the other five autochthonous cultures regarding S. enterica serovar Typhimurium ATCC 14028 inhibition (P < 0.05). However, they did not differ from at least one positive control in terms of inhibition against S. aureus ATCC 25923 and E. coli ATCC 25922 (P > 0.05). Therefore, it is advisable to consider these cultures separately for different technological purposes, such as phenolics metabolism or bio preservative activity. This will facilitate appropriate selection based on each specific property required for the intended product development.

Lactic acid bacteria with a strong antioxidant function isolated from "Jiangshui," pickles, and feces

Excessive free radicals and iron death lead to oxidative damage, which is one of the main causes of aging and diseases. In this field of antioxidation, developing new, safe, and efficient antioxidants is the main research focus. Lactic acid bacteria (LAB) are natural antioxidants with good antioxidant activity and can regulate gastrointestinal microecological balance and immunity. In this study, 15 LAB strains from fermented foods ("Jiangshui" and pickles) or feces were evaluated in terms of their antioxidant attributes. Strains with strong antioxidant capacity were preliminarily screened by the following tests: 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl radical, superoxide anion radical scavenging capacity; ferrous ion chelating assay; hydrogen peroxide tolerance capacity. Then, the adhesion of the screened strains to the intestinal tract was examined using hydrophobic and auto-aggregation tests. The safety of the strains was analyzed based on their minimum inhibitory concentration and hemolysis, and 16S rRNA was used for molecular biological identification. Antimicrobial activity tests showed them probiotic function. The cell-free supernatant of selected strains were used to explore the protective effect against oxidative damage cells. The scavenging rate of DPPH, hydroxyl radicals, and ferrous ion-chelating of 15 strains ranged from 28.81-82.75%, 6.54-68.52%, and 9.46-17.92%, respectively, the scavenging superoxide anion scavenging activity all exceeded 10%. According to all the antioxidant-related tests, strains possessing high antioxidant activities J2-4, J2-5, J2-9, YP-1, and W-4 were screened, these five strains demonstrated tolerance to 2 mM hydrogen peroxide. J2-4, J2-5, and J2-9 were Lactobacillus fermentans and γ-hemolytic (non-hemolytic). YP-1 and W-4 were Lactobacillus paracasei and α-hemolytic (grass-green hemolytic). Although L. paracasei has been proven as a safe probiotic without hemolytic characteristics, the hemolytic characteristics of YP-1 and W-4 should be further studied. Due to the weak hydrophobicity and antimicrobial activity of J2-4, finally, we selected J2-5, J2-9 for cell experiment, J2-5 and J2-9 showed an excellent ability that resistant to oxidative damage by increasing SOD, CAT, T-AOC activity of 293T cells. Therefore, J2-5, and J2-9 strains from fermented foods "Jiangshui" could be used as potential antioxidants for functional food, health care, and skincare.

Identification and characterization of the causative agents of Focal Ulcerative Dermatitis in commercial laying hens

Focal Ulcerative Dermatitis (FUDS) is an emerging dermatological disease that affects cage-free laying flocks, it is characterized by the development of a lesion on the dorsum of the birds; FUDS is sporadic in nature and can result in a drop in egg production and up to 50% of cumulative mortality. A total of two cage-free flocks (flock 1: no history of FUDS; flock 2: birds affected with FUDS) from a commercial laying hen operation in the mid-west U.S. were sampled in this study. The microbial composition of skin, cloacal, cecal, and ileal samples from each bird was characterized through next generation sequencing (NGS). Results identified Staphylococcus aureus and Staphylococcus agnetis as the potential causative agents of FUDS, being the most predominant in FUDS positive birds. These results were confirmed by plating, with both staphylococci as the only pathogens isolated from lesions of FUDS positive birds. A total of 68 confirmed Staphylococcus isolates from skin and environmental samples were further analyzed by whole genome sequencing (WGS) for the presence of antimicrobial resistance (AMR) genes and virulence factors that could have contributed to the development of FUDS. Forty-four-point one-two percent of the isolates had between one and four acquired AMR genes encoding for macrolides, lincosamides, spectrogramines, and beta-lactams resistance. Six classes of virulence factors associated with adherence, enzyme, immune evasion, secretion system, toxin, and iron uptake were identified. The antimicrobial effect of 4 proprietary Bacillus Direct Fed Microbial (DFM) combinations was evaluated against the Staphylococcus aureus and Staphylococcus agnetis isolates, by agar well-diffusion (AWD) assay and competitive exclusion (CE) on broth culture. Through this antimicrobial screening, a particular two-strain combination of Bacillus pumilus was identified as the most effective inhibitor of both staphylococci. A customized Bacillus pumilus product is being used at different farms with history of FUDS resulting in the successful inhibition of both Staphylococcus aureus and Staphylococcus agnetis, decreasing FUDS mortalities, and improving harvestable eggs.

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).

Optimization of bioprocess of Schleiferilactobacillus harbinensis Ca12 and its viability in frozen Brazilian berries (Açai, Euterpe oleracea Mart.)

Amazonian palm berries (açaí, Euterpe oleracea Mart.) are fruits with high nutritional value and antioxidant activity and have aroused the interest of consumers, popularizing fruit pulps enriched with probiotics. Amazonian palm berries (açaí, Euterpe oleracea Mart.) are fruits with high nutritional potential, providing a source of carbohydrates, fibers, proteins, lipids, vitamins, and minerals. Furthermore, açai provides several health benefits, including antioxidant activity. Nutritionally enhanced foods have aroused the interest of consumers, popularizing fruit pulps enriched with probiotics. Probiotics are dietary supplements consisting of live, beneficial microorganisms in the host which improve the intestinal microbiota. The objective of this study was to isolate, identify, and characterize the probiotic potential of an isolated Schleiferilactobacillus harbinensis strain (dubbed Ca12) and provide an optimized bioprocess for its production, using the complete factorial and central rotational compound design to supplement the frozen açai pulp. The isolated strain S. harbinensis Ca12 presented adequate resistance to gastric juice and bile salts, microbial activity against different Candida strains, self-aggregation and coaggregation properties, high adhesion in HT-29 cells, and 35% inhibition of Salmonella in HT-29 cells. When optimized, the cellular biomass production of the S. harbinensis Ca12 strain was approximately 600% higher than the unsupplemented whey, with a production of 3.6 × 1010 CFU mL^-1. The S. harbinensis Ca12 strain's viability in the creamy and traditional frozen açai pulp was shown to be stable for up to 6 months at 20 °C. The impact of this study involved for the first time the S. harbinensis Ca12 described in the Brazilian cocoa pulp with activity against Candida albicans of clinical importance, creating the potential of a new functional food with important benefits to human health as prevention for candidiasis.

Biopreservation and probiotic potential of a large set of lactic acid bacteria isolated from Brazilian artisanal cheeses: From screening to in product approach

The increasing interest in products with functional properties has encouraged the search for new lactic acid bacteria (LAB) present in natural sources, as traditional fermented foods. In this study, a large set of wild LAB isolates (n = 220) from Brazilian artisanal cheeses (BAC) were assessed for their probiotic and biopreservation potential. First, the rational selection was performed. From the tested isolates, 92 (41.8 %) were resistant to low pH (2 and 3). These isolates were submitted to bile salt (0.4 % Oxgall powder) resistance, and 22 were selected and submitted to adhesion assays. The autoaggregation values ranged from 68.5-99% and were considered moderate to high (20-70 %). Hydrophobicity values varied significantly between LAB (5.0-64.3%), and seven isolates presented values higher than 40 %. All selected LAB (n=22) were capable of adhering to Caco-2 (> 70 %) cells, and none isolate displayed any tested gene for biogenic amine production. Most isolates (18/22) showed less than 1 log CFU reduction after passage through the simulated gastrointestinal tract (GIT) conditions. A total of twenty isolates satisfied key in vitro criteria to be considered as probiotics. A hierarchical cluster analysis (HCA) was performed, and two clusters were observed, showing high variability between Lactobacillus plantarum isolates regarding adhesion properties and survival to GIT stress and one influence of the source of isolation on these properties. After screening, the antimicrobial activity of Lb. plantarum (1QB77) was tested in microcheeses in which survival of two relevant pathogenic bacteria (Staphylococcus aureus and Listeria monocytogenes) was monitored along ripening and after a simulated GIT passage, concomitantly. L. plantarum (1QB77) has shown the ability to reach high counts (∼ 9 log CFU/g) at the end of ripening. This isolate was also able to reduce counts of S. aureus and L. monocytogenes in microcheeses in approx. 2.3 and 2.5 log CFU/g, respectively, until the 21st day of ripening; and about 3.2 and 3.5 log CFU/g after simulated GIT passage. Overall, the assessment of the probiotic properties of a large set of LAB was fundamental for gaining insights on the technological, functional, and potential regional traits of wild LAB isolates that can be used to develop starter cultures for tailored applications.

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.

Characterization and evaluation of lactic acid bacteria from indigenous raw milk for potential probiotic properties

Raw milk contains wide microbial diversity, composed mainly of lactic acid bacteria (LAB), which are used as probiotics in both human and animal husbandry. We isolated, characterized, and evaluated LAB from indigenous Bangladeshi raw milk to assess probiotic potential, including antagonistic activity (against Escherichia coli O157: H7, Enterococcus faecalis, Salmonella Typhimurium, Salmonella Enteritidis, and Listeria monocytogenes), survivability in simulated gastric juice, tolerance to phenol and bile salts, adhesion to ileum epithelial cells, auto- and co-aggregation, hydrophobicity, α-glucosidase inhibitory activity, and antibiotic susceptibility tests. The 4 most promising LAB strains showed probiotic potential and were identified as Lactobacillus casei, Lactobacillus plantarum (which produced plantaricin EF), Lactobacillus fermentum, and Lactobacillus paracasei. These strains inhibited all pathogens tested at various degrees, and competitively excluded pathogens with viable counts of 3.0 to 6.0 log cfu/mL. Bacteriocin, organic acids, and low-molecular-weight substances were mainly responsible for antimicrobial activity by the LAB strains. All 4 LAB strains were resistant to oxacillin and 3 were resistant to vancomycin and streptomycin, with multiple antibiotic resistance indices >0.2. After further in vivo evaluation, these LAB strains could be considered probiotic candidates with application in the food industry.

Isolation, characterization, and assessment of lactic acid bacteria toward their selection as poultry probiotics

BACKGROUND

Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host, are now accepted as suitable alternatives to antibiotics in the control of animal infections and improving animal production. Lactic acid bacteria (LAB) with remarkable functional properties have been evaluated in different studies as possible probiotic candidates. The purpose of this study was to isolate, characterize and assess the potentials of LAB from poultry gastrointestinal tract as potential poultry probiotics.

RESULTS

Potential LAB probiotics were isolated from broilers, characterized and evaluated for probiotic properties including antagonistic activity (against Escherichia coli, E. coli O157: H7, Enterococcus faecalis, Salmonella Typhimurium, S. Enteritidis and Listeria monocytogenes), survivability in simulated gastric juice, tolerance to phenol and bile salts, adhesion to ileum epithelial cells, auto and co-aggregation, hydrophobicity, α-glucosidase inhibitory activity, and antibiotic susceptibility tests. Most promising LAB strains with excellent probiotic potentials were identified by API 50 CHL and 16S rRNA sequencing as Lactobacillus reuteri I2, Pediococcus acidilactici I5, P. acidilactici I8, P. acidilactici c3, P. pentosaceus I13, and Enterococcus faecium c14. They inhibited all the pathogens tested with zones of inhibition ranging from 12.5 ± 0.71 to 20 ± 0 mm, and competitively excluded (P < 0.05) the pathogens examined while adhering to ileum epithelial cells with viable counts of 3.0 to 6.0 Log CFU/ml. The selected LAB strains also showed significant (P < 0.005) auto and co-aggregation abilities with α-glucosidase inhibitory activity ranging from 12.5 to 92.0%. The antibiotic susceptibility test showed 100.00% resistance of the LAB strains to oxacillin, with multiple antibiotic resistance indices above 0.5.

CONCLUSION

The selected LAB strains are ideal probiotic candidates which can be applied in the field for the improvement of poultry performance and control of pathogens in poultry, hence curtailing further transmission to humans.

Piacentinu Ennese PDO Cheese as Reservoir of Promising Probiotic Bacteria

Piacentinu Ennese is a protected designation of origin (PDO) cheese produced in the surrounding area of Enna (Sicily, Italy), using raw ewe's milk without the addition of any starter cultures. In the present study, the Lactobacillus population of Piacentinu Ennese PDO cheese was in vitro screened in order to select promising probiotic strains to be further used in humans. One hundred and sixty-nine lactic acid bacteria (LAB) were isolated from 90 days ripened cheeses and identified by Rep-PCR genomic fingerprinting, using the (GTG)5-primer, and by MALDI-TOF MS. One hundred and thirteen (113) isolates belonging to QPS-list species were characterized for both safety and functional properties. All tested isolates were considered safe because none showed either gelatinase, DNase, mucinase, or hemolytic activity. Tolerance to lysozyme, bile salts, and acidic conditions, along with ability to survive under simulated gastrointestinal digestion, were observed. In addition, based on antimicrobial activity against pathogens, cell surface characteristics, Caco-2 adhesion abilities, and anti-inflammatory potential, it was possible to confirm the strain-dependent functional aptitude, suggesting that Piacentinu Ennese PDO cheese may be considered a precious source of probiotic candidates.

A Systematic Approach to Identify and Characterize the Effectiveness and Safety of Novel Probiotic Strains to Control Foodborne Pathogens

A total of 44 lactic acid bacteria (LAB) strains originally isolated from cattle feces and different food sources were screened for their potential probiotic features. The antimicrobial activity of all isolates was tested by well-diffusion assay and competitive exclusion on broth against Salmonella Montevideo, Escherichia coli O157:H7 and Listeria monocytogenes strain N1-002. Thirty-eight LAB strains showed antagonistic effect against at least one of the pathogens tested in this study. Improved inhibitory effect was observed against L. monocytogenes with zones of inhibition up to 24 mm when LAB overnight cultures were used, and up to 21 mm when cell-free filtrates were used. For E. coli O157:H7 and Salmonella maximum inhibitions of 12 and 11.5 mm were observed, respectively. On broth, 43 strains reduced L. monocytogenes up to 9.06 log₁₀ CFU/ml, 41 reduced E. coli O157:H7 up to 0.84 log₁₀ CFU/ml, and 32 reduced Salmonella up to 0.94 log₁₀ CFU/ml 24 h after co-inoculation. Twenty-eight LAB isolates that exhibited the highest inhibitory effect among pathogens were further analyzed to determine their antimicrobial resistance profile, adhesion potential, and cytotoxicity to Caco-2 cells. All LAB strains tested were susceptible to ampicillin, linezolid, and penicillin. Twenty-six were able to adhere to Caco-2 cells, five were classified as highly adhesive with > 40 bacterial cells/Caco-2 cells. Low cytotoxicity percentages were observed for the candidate LAB strains with values ranging from -5 to 8%. Genotypic identification by whole genome sequencing confirmed all as members of the LAB group; Enterococcus was the genus most frequently isolated with 21 isolates, followed by Pediococcus with 4, and Lactobacillus with 3. In this study, a systematic approach was used for the improved identification of novel LAB strains able to exert antagonistic effect against important foodborne pathogens. Our findings suggest that the selected panel of LAB probiotic strains can be used as biocontrol cultures to inhibit and/or reduce the growth of L. monocytogenes, Salmonella, and E. coli O157:H7 in different matrices, and environments.

Cocoa Pulp as Alternative Food Matrix for Probiotic Delivery

BACKGROUND

For screening probiotic strains with viability and stability in non-dairy foods for health benefits, we revised all patents relating to probiotics in food.

OBJECTIVE

Screening of potential probiotics from Brazilian Minas artisanal cheese and verify their survival in frozen Brazilian cocoa pulp.

METHODS

Isolation and identification of the strains. The potential probiotic characterization involved gastric juice and bile resistance, antibiotic and antimicrobial activity, hydrophobicity, autoaggregation, coaggregation and adhesion assay in HT-29 cells. Organoleptic, viability and stability of probiotic strain in frozen cocoa pulp were evaluated.

RESULTS

Fourteen strains of Lactobacillus plantarum (9), Weissella paramesenteroides (3), Lactobacillus fermentum (1), and Leuconostoc mesenteroides (1) were obtained. Most of the strains were resistant to simulated gastric acidity and bile salts. Almost all strains were sensitive to the antibiotics tested, except to ciprofloxacin and vancomycin. About 47% of the strains are potential producers of bacteriocins. High hydrophobicity was observed for four strains. Autoaggregation ranged from 8.3-72.6% and the coaggregation capacity from 5.2-60.2%. All of the assessed strains presented more than 90% of adhesion to HT-29 intestinal cells. The percentage of Salmonella inhibition in HT-29 cells ranged from 4.7-31.1%. No changes in color, aroma, and pH were observed in cocoa pulps after storage at -20 °C for 90 days.

CONCLUSION

Wild strains of acid lactic bacteria from cheese proved to be viable and stable in frozen Brazilian cocoa pulp. This work showed a promising application of L. plantarum isolated strains to be used with frozen cocoa pulp matrix in probiotics food industry.

Screening Potential Probiotic Characteristics of Lactobacillus brevis Strains In Vitro and Intervention Effect on Type I Diabetes In Vivo

Diabetes has become the third most serious threat to human health, after cancer and cardiovascular disease. Notably, Lactobacillus brevis is the most common species of LAB that produces γ-aminobutyric acid (GABA). The aim of this study is to clarify the effect of time, strain types, antibiotic concentrations, different levels of pH, and intestinal juices in aerobic or anaerobic conditions and the effect of interactions between these factors on the potential properties of KLDS 1.0727 and KLDS 1.0373, furthermore, antagonistic activity against foodborne pathogens. Moreover, another aim is to study the capability of KLDS 1.0727 and KLDS 1.0373 strains as gad gene carriers to express GABA that reduce the risk of type 1 diabetes in C57BL/6 mice as diabetic models. The obtained results exhibited the surprising tolerance of Lactobacillus brevis strains in vitro digestion models mimicking the conditions of the gastrointestinal tract, further, large antagonistic activity against foodborne pathogeneses. In vivo results displayed the significant effect on glucose level reduction, blood plasma, and histological assays of mice organs. As recommended, the use of Lactobacillus brevis strains should be widely shared in the market as a natural source of GABA in pharmaceutical and food applications.

Fermented Dessert with Whey, Ingredients from the Peel of Jabuticaba (Myrciaria cauliflora) and an Indigenous Culture of Lactobacillus plantarum: Composition, Microbial Viability, Antioxidant Capacity and Sensory Features

The use of agro-industrial wastes in combination with indigenous lactic acid bacteria is an interesting option to confer functional potential to food products. The microbial viability, chemical composition, antioxidant capacity, texture and sensory acceptability of a fermented dairy dessert containing the indigenous culture Lactobacillus plantarum CNPC003, whey and ingredients obtained from the jabuticaba (Myrciaria cauliflora) peel were compared with formulations without lactobacilli (control) or containing a commercial probiotic culture (Lactobacillus rhamnosus LR32). L. plantarum presented viability higher than 7 log CFU g-1 in the dessert, as did the commercial probiotic, for 21 days at 4 ± 1 °C. Total phenolic contents (45⁻60 mg gallic acid equivalents, GAE, 100 g-1) were comparable to those of other studies evaluating dairy products containing plant sources. The formulations were low in fat, presenting as acceptable for overall consumption, with attractive color and appreciable texture. Considering the total antioxidant capacity, 200⁻250 g of dessert would be necessary to capture 1 g of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The dessert with Lactobacillus plantarum CNPC003 is seen as a viable alternative for the use of whey and jabuticaba peel, as well as a potential functional food due to the concentration of lactobacilli reached, besides the presence of antioxidant phenolic compounds.

Beneficial and Safety Properties of a Corynebacterium vitaeruminis Strain Isolated from the Cow Rumen

Corynebacterium vitaeruminis MRU4 was isolated from the cow rumen and was differentiated from other isolates by rep-PCR and RAPD and identified by 16S rRNA sequencing. This strain presented higher survival rates for low pH and bile salts treatments, and it was able to survive and multiply in simulated gastric and intestinal environments. C. vitaeruminis MRU4 had a 53.2% auto-aggregation rate, 42.4% co-aggregation rate with Listeria monocytogenes Scott A, 41.6% co-aggregation rate with Enterococcus faecalis ATCC 19443, 10.0% co-aggregation rate with Lactobacillus sakei ATCC 15521, and 98.2% cell surface hydrophobicity rate. PCR analysis showed the presence of EFTu and map genes. The strain possessed positive results for deconjugation of bile salts (taurocholic acid, taurodeoxycholic acid, glycocholic acid, and glycodeoxycholic acid) and positive results for β-galactosidase activity and lactose assimilation activity (glucose of 8.15 ± 0.01 CFU/ml and lactose of 9.24 ± 0.02 CFU/ml). No virulence was observed by phenotypical tests. C. vitaeruminis MRU4 was resistant to oxacillin, gentamicin, erythromycin, clindamycin, sulfa/trimethoprim, and rifampicin by the disc diffusion method and showed resistance just for vancomycin by the Etest® strips test. The strain was negative for 50 tested virulence and resistance genes based on performed PCR. Based on our knowledge, this is the first report regarding the beneficial potential of one C. vitaeruminis strain.

In Vitro Evaluation of Beneficial Properties of Bacteriocinogenic Lactobacillus plantarum ST8Sh

Lactobacillus plantarum ST8Sh, isolated from Bulgarian salami "shpek" and previously characterized as bacteriocin producer, was evaluated for its beneficial properties. Based on the PCR analysis, Lb. plantarum ST8Sh was shown to host a gene related to the production of adhesion proteins such as Mab, Mub, EF, and PrgB. Genetic and physiological tests suggest Lb. plantarum ST8Sh to represent a potential probiotic candidate, including survival in the presence of low levels of pH and high levels of ox bile, production of β-galactosidase, bile salt deconjugation, high level of hydrophobicity, functional auto- and co-aggregation properties, and adhesion to cell lines. Application of semi-purified bacteriocin produced by Lb. plantarum ST8Sh in combination with ciprofloxacin presented synergistic effect on inhibition of Listeria monocytogenes Scott A. Based on observed properties, Lb. plantarum ST8Sh can be considered as a potential probiotic candidate with additional bacteriocinogenic properties.

Evaluation of antimicrobial activity and probiotic properties of wild-strain Pichia kudriavzevii isolated from frozen idli batter

The present research was undertaken to study the probiotic characteristics of Pichia kudriavzevii isolated from frozen idli batter. Polymerase chain reaction amplification with 18S rRNA primers confirmed Pichia kudriavzevii, a xylose-utilizing probiotic strain. It was resistant to physiological concentrations of bile salts, pepsin and pancreatic enzyme. It also showed efficient auto-aggregation as well as co-aggregation ability with four commercial probiotic yeasts and exhibited good hydrophobicity in xylene and toluene. The strain inhibited the growth of 13 enteropathogens and showed a commensal relationship with four commercial probiotic yeast and bacteria. Moreover, it was resistant to 30 antibiotics with different modes of action. The yeast exhibited thermotolerance up to 95 °C for 2 h. The cell-free supernatants were also found to be heat stable, indicating the presence of thermostable secondary metabolites. Hence it could be exploited as starter culture, co-culture or probiotic in the preparation of fermented products or incorporated in heatable foods as well. Copyright © 2016 John Wiley & Sons, Ltd.

Composition of lactic acid bacteria during spontaneous curly kale (Brassica oleracea var. sabellica) fermentation

The present work is the first report on spontaneous fermentation of curly kale and characteristics of autochthonous lactic acid bacteria (LAB). Our results indicate that curly kale fermentation is the new possibility of the technological use of this vegetable. Bacteria representing ten different species were isolated from three phases of curly kale fermentation and identified by MALDI-TOF mass spectrometry and 16S rRNA gene sequencing. Among them, four species were identified as Lactobacillus spp. (Lb. plantarum 332, Lb. paraplantarum G2114, Lb. brevis R413, Lb. curvatus 154), two as Weissella spp. (W. hellenica 152, W. cibaria G44), two as Pediococcus spp. (P. pentosaceus 45AN, P. acidilactici 2211), one as Leuconostoc mesenteroides 153, and one as Lactococcus lactis 37BN. The functional properties of isolates, i.e. acid, NaCl and bile salt tolerance, enzyme activities, adhesion to hydrocarbons, and antibiotic resistance, were examined. Among the tested strains, Lb. plantarum 332, Lb. paraplantarum G2114, P. pentosaceus 2211, and Lb. brevis R413 exhibited the best hydrophobicity value and high tolerance to bile salts, NaCl, and low pH.

Catalytic Interactions and Molecular Docking of Bile Salt Hydrolase (BSH) from L. plantarum RYPR1 and Its Prebiotic Utilization

Prebiotics are the non-digestible carbohydrate, which passes through the small intestine into unmetabolized form, reaches the large intestine and undergoes fermentation by the colonic bacteria thus; prebiotics stimulate the growth of probiotic bacteria. Further, bile salt hydrolase (BSH) is an enzyme that catalyses the deconjugation of bile salt, so it has enormous potential toward utilizing such capability of Lactobacillus plantarum RYPR1 toward detoxifying through BSH enzyme activity. In the present study, six isolates of Lactobacillus were evaluated for the co-aggregation assay and the isolate Lactobacillus plantarum RYPR1 was further selected for studies of prebiotic utilization, catalytic interactions and molecular docking. The prebiotic utilization ability was assessed by using commercially available prebiotics lactulose, inulin, xylitol, raffinose, and oligofructose P95. The results obtained revealed that RYPR1 is able to utilize these probiotics, maximum with lactulose by showing an increase in viable cell count (7.33 ± 0.02 to 8.18 ± 0.08). In addition, the molecular docking of BSH from Lactobacillus plantarum RYPR1 was performed which revealed the binding energy -4.42 and 7.03 KJ/mol. This proves a considerably good interactions among BSH and its substrates like Taurocholic acid (-4.42 KJ/mol) and Glycocholic acid (-7.03 KJ/mol). These results from this study establishes that Lactobacillus plantarum RYPR1 possesses good probiotic effects so it could be used for such applications. Further, molecular dynamics simulations were used to analyze the dynamic stability of the of modeled protein to stabilize it for further protein ligand docking and it was observed that residues Asn12, Ile8, and Leu6 were interacting among BSH and its substrates, i.e., Taurocholic acid and Lys88 and Asp126 were interacting with Glycocholic acid. These residues were interacting when the docking was carried out with stabilized BSH protein structure, thus, these residues may have a vital role in stabilizing the binding of the ligands with the protein.

Probiotic Properties of Lactobacillus plantarum RYPR1 from an Indigenous Fermented Beverage Raabadi

Present study documents the potential probiotic Lactobacillus isolated from indigenous fermented beverage Raabadi, consumed during summers in Haryana and Rajasthan regions of India. A total of five Raabadi samples were collected aseptically and 54 isolates were purified using MRS medium. All the isolates were assessed for tolerance to low pH and bile salts. It was observed that out of 54 only 24 isolates could survive the simulated gastric conditions. These isolates were further evaluated in vitro for cell surface hydrophobicity, cell surface hydrophobicity, hypocholesteramic activity, anti-oxidative potential, BSH activity, antagonistic activity, and antibiotic resistance profile. In addition, the confirmation of phenol resistance was also done. On the basis of results obtained, the survival rate of isolates was noted and six isolates were finally selected for further studies. Among them Lactobacillus plantarum RYPR1 and RYPC7 showed good survival at pH 2 which shows good acid tolerance. Moreover, L. plantarum RYPR1 showed the highest hydrophobicity (79.13%) and represented the deconjugation of bile salts, which help in their adhesion to epithelial cells and colonization. Furthermore, RYPR1 also exhibited highest cholesterol reduction (59%) and subsequent analysis of results revealed that the above mentioned isolates further exhibit a good hypocholesterolemic effect and could be possibly used to prevent hypercholesterolemia. The present study divulges that L. plantarum RYPR1 has an excellent probiotic potential.

Assessment of Characteristics and Functional Properties of Lactobacillus Species Isolated from Kimchi for Dairy Use

The objective of this study was to identify lactic acid bacteria (LAB) isolated from kimchi and to evaluate its characteristics and functional properties for application in fermented dairy products as a probiotic or commercial starter culture. Eight stains isolated from kimchi were selected through an investigation of phenotypic characteristics. Two strains (DK211 and DK303) were identified as Lactobacillus plantarum, another two (DK207 and DK215) as Lactobacillus paracasei, and one (DK301) as Lactobacillus sakei. The remaining three strains were identified as species of Weissella. All selected Lactobacillus strains had acid and bile tolerance, even though there was wide variation in the ability of each strain. DK303 showed a remarkably higher proteolytic activity. There were no significant differences in β-galactosidase activity among the tested strains, except that DK301 showed no activity. Auto-aggregation varied between 82.1 and 90.0%, and hydrophobicity values ranged from 0.5 to 51.6%.The strongest auto-aggregation and hydrophobicity were observed in DK211. All selected strains showed better 1,1-diphenyl-2-picrylhydrzyl (DPPH) scavenging activity than commercial strains. DK211, DK215, DK301, and DK303 had effective inhibitory activity against all pathogens tested except E. coli. When selected strains were used for yogurt preparation as a single starter culture, the time required to reach target titratable acidity (0.9) was 11-12 h. The yogurt fermented with DK211 had favorable panelists ratings for most sensory attributes, which were comparable with yogurt fermented with a commercial strain. The results suggest that strains isolated from kimchi could be potential probiotic and starter cultures for use in yogurt manufacturing.

Probiotic attributes of Lactobacillus fermentum isolated from human feces and dairy products

The objective of this study was to characterize native Lactobacillus fermentum isolates for their probiotic attributes. Accordingly, 12 L. fermentum isolates selected from indigenous fermented dairy products and infant fecal samples were evaluated for their probiotic properties by in vitro and PCR methods. The cultures exhibited high tolerance to acid and bile as well as survival in simulated transit fluids (above 70 %). Cell surface hydrophobicity was in the range of 0.55-57.69 % for xylene and 0.45-77.12 % for hexadecane, whereas auto-aggregation ranged between 9 and 62 %. Isolates exhibited efficient binding to mucin and fibronectin, bile salt hydrolase activity, cholesterol assimilation (49-76 %), and radical scavenging activity (37-77 %). The isolates demonstrated antibacterial activity against Listeria monocytogenes Scott A and Micrococcus luteus ATCC 9341. Molecular fingerprinting and identification of the isolates were achieved by PCR with GTG5 as well as 16S rRNA, phenylalanyl-tRNA synthetase alpha subunit (pheS), and RNA polymerase alpha subunit (rpoA) genes. This revealed the genomic diversity of the isolates from the two sources. Gene-specific amplification of probiotic marker genes was attained by PCR-based methods, and resultant products were sequenced. Multiple sequence alignment of the probiotic marker genes using bioinformatics revealed similarity to completely sequenced genomes of L. fermentum CECT 5716 and IFO 3956 with a few variations in mucin-binding protein gene sequences. Isolates designated as L. fermentum MCC 2759 and L. fermentum MCC 2760 showed the best probiotic attributes with high survival in simulated gastrointestinal fluids, in vitro adhesion, cholesterol reduction, and high antioxidative potential. Thus, these cultures could be potential probiotic candidates for application as functional foods.

Comparison of Microbiological and Probiotic Characteristics of Lactobacilli Isolates from Dairy Food Products and Animal Rumen Contents

Lactobacilli are employed in probiotic food preparations and as feed additives in poultry and livestock, due to health benefits associated with their consumption. The objective of this study was to evaluate and compare the probiotic potential of ten lactobacilli strains isolated from commercial dairy food products and animal rumen contents in New Zealand. Genetic identification of the isolates revealed that all belonged to the genus Lactobacillus, specifically the species L.reuteri, L. rhamnosus and L.plantarum. All isolates did not show any haemolytic behaviour. Isolates of dairy origin showed better tolerance to low pH stress. On the other hand, rumen isolates exhibited a higher tolerance to presence of bile salts. All isolates exhibited resistance to aminoglycoside antibiotics, however most were sensitive to ampicillin. Isolates of rumen origin demonstrated a higher inhibitory effect on Listeria monocytogenes, Enterobacter aerogenes and Salmonella menston. Bacterial adherence of all isolates increased with a decrease in pH. This screening study on lactobacilli isolates has assessed and identified potential probiotic candidates for further evaluation.