Isolation and Identification of Lactic Acid Bacteria from Cow Milk and Milk Products

Biofilm inhibition and antagonism of Klebsiella pneumoniae by probiotic lactic acid bacteria (LAB) isolated from raw cow milk

Lactic acid bacteria (LAB) with their potential health benefits are naturally prevalent in dairy and fermented food products. This probiotic microbiota can be an alternative biological tool for controlling other pathogenic bacteria. The study aimed to isolate lactic acid bacteria (LAB) from raw cow milk and evaluate their probiotic potential. Twelve gram-positive isolates showing tolerance to bile salt, acid, and low pH were identified by 16S rRNA sequencing, which revealed the isolates belong to the genera including Lactococcus, Enterococcus, Streptococcus, Bacillus, and Weissella. In case of probiotic potential, the isolates exhibited arrays of probiotic properties: autoaggregation (33.65-84.63 %), co-aggregation (8.17-83.22 %), cell surface hydrophobicity for both polar (13.37-90.24 %) and non-polar solvents (5.52-53.58 %) and able to form biofilm (75 % weak, 16.67 % moderate and 8.33 % strong). Statistical analysis revealed the correlation pattern between the probiotic properties and showed a significant strong positive correlation between cell surface hydrophobicity and aggregation. Additionally, three isolates L. lactis, W. confusa, and E. gallinarum that were sensitive to antibiotics, able to produce biofilm, and did not contain virulence genes were able to reduce the biofilm formation of pathogen K. pneumoniae (1.3-4 log) in the co-culture assay. These Findings suggest that LAB from the raw cow milk could serve as a natural biocontrol agent for preventing and controlling K. pneumoniae biofilm formation and pave the way for innovative intervention of LAB in food safety and clinical settings.

Antagonistic Effects of Lactic Acid Bacteria Isolated from Ethiopian Traditional Fermented Foods and Beverages Against Foodborne Pathogens

Lactic acid bacteria (LAB) found in Ethiopian traditional fermented foods and beverages have potential antagonistic effects against foodborne pathogens due to their capacity to produce various antimicrobial metabolites. This study evaluated the antagonistic activity of LAB isolated from Ethiopian traditional fermented foods and beverages against foodborne pathogens and characterized their antimicrobial substances. A total of 180 traditional fermented foods and beverages were collected, and the antagonistic activities of LAB were evaluated against selected foodborne pathogens. The effects of pH, temperature, enzymes, and food additives on the antagonistic effects of cell-free supernatant produced by LAB were investigated. LAB identification and characterization were conducted using an integrated phenotypic approach and MALDI TOF MS spectrum analysis, and data were analyzed using one-way ANOVA and Tukey post hoc analysis. A total of 956 LAB were isolated, of which seventeen (17 LAB) isolates of Pediococcus pentosaceus (Pc. pentosaceus (n = 7)), Pediococcus acidilactici (Pc. acidilactici (n = 2)), Enterococcus faecium (Ec. faecium (n = 6)), and Lactococcus lactis (Lc. lactis (n = 2)) were screened for antagonistic activity based on their ability to produce bacteriocins, probiotic activity, and preservative potential. Pc. pentosaceus JULABB16, Pc. pentosaceus JULABB01, and Ec. faecium JULABBr39 showed strong antagonistic activity against all pathogens, with mean inhibition zone diameters ranging from 23.50 to 35.50 mm. Lc. lactis, Pc. pentosaceus, Pc. acidilactici, and Ec. faecium produced bioactive metabolites that were sensitive to proteolytic enzymes and capable of withstanding high temperatures (80-100 °C) and acid concentrations (pH 2-10). The CFS produced by Lc. lactis, Pc. pentosaceus, Pc. acidilactici, and Ec. faecium showed the most impending antagonistic activity against all pathogens. The bioactive substances produced by LAB isolates had promising effects against food spoilage and pathogenic bacteria, making them potential natural food preservatives.

Antibiotic Resistance in Lactic Acid Bacteria from Dairy Products in Northern Italy

Background: The spread of antibiotic resistance genes (ARGs) from the food chain is a significant public health concern. Dairy products from raw milk containing lactic acid bacteria (LAB) resistant to antimicrobials may serve as vectors for the transfer of resistance to commensal or potentially pathogenic bacteria in the human gut. Detecting ARGs in dairy products and milk is, therefore, crucial and could aid in the development of strategies to mitigate resistance dissemination through the food chain. Objectives: This study aimed to determine the presence of ARGs and assess the antibiotic susceptibility of LAB strains isolated from dairy products made from raw milk. Methods: Fifty-four LAB strains were isolated from 41 dairy samples and were tested for antimicrobial susceptibility using broth microdilution to determine Minimal Inhibitory Concentration (MIC). Moreover, the presence of resistance genes related to tetracyclines, beta-lactams, quinolones, and erythromycin was examined using six multiplex PCR assays. Results: Lactobacillus spp. and Leuconostoc spp. strains exhibited a high level of resistance to vancomycin (93-100%). Low-level resistance (4.2-20%) was observed in Lactococcus spp. and Lactobacillus spp. strains against tetracycline. Additionally, Lactococcus spp. strains showed resistance to trimethoprim/sulfamethoxazole, erythromycin, and clindamycin. Twenty-two out of 54 LAB strains (40.7%) carried at least one antibiotic resistance gene, and five of these were multidrug-resistant. Genes associated with acquired resistance to tetracycline were commonly detected, with tetK being the most frequent determinant. Conclusions: This study demonstrated that LABs in dairy products can act as reservoirs for ARGs, potentially contributing to the horizontal transfer of resistance within microbial communities in food and consumers. These findings highlight the need for the ongoing surveillance of antibiotic resistance in LAB and the implementation of control measures to minimize the dissemination of resistance through dairy products.

Optimization of citrulline production from a Bacillus subtilis BH-01 isolated from raw buffalo milk

The main purpose of this study was to optimize the L-citrulline production process using Plackett-Burman and Box-Behnken designs. L-citrulline-producing bacterium BH-01 was isolated from raw buffalo milk. The isolate was tested for probiotic activities such as tolerance to simulated gastric and intestinal juices, antagonistic activity against six antibiotic-resistant bacteria, and temperature tolerance. L-citrulline production and arginine deiminase (ADI) activity were optimized using statistical designs. The bacterial isolate was molecularly identified as Bacillus subtilis strain AUMC B-498 (accession number PP574248.1). The strain exhibited resistance at pH 2.0 and bile salt 0.5% for a two-hour exposure period. It could inhibit the growth of Escherichia coli, Klebsiella pneumonia, Serratia sp., Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), and Streptococcus pneumoniae. From the results of statistical optimization, the Plackett-Burman design identified temperature, L-arginine, incubation period, and peptone as the most effective factors among the eight selected variables. Based on these, the Box-Behnken design was used to optimize the factors required to maximize citrulline production. The maximum L-citrulline was 632.5 µg/L, and ADI activity was 1.42 U/mL. Therefore, BH-01 isolated from Buffalo milk might be a promising candidate in food, biotechnological, and pharmaceutical applications due to its dual functionality for citrulline production and probiotic characteristics.

Screening of lactic acid bacteria from the milk of Sahiwal cows and characterization of their probiotic potential for preventing bovine mastitis

Antibiotic therapy has been the most popular line of treatment for the control of mastitis worldwide during the last few decades. Alternative and sustainable treatments must be developed because pathogens are becoming more resistant to antibiotics, leading to the development and spread of antimicrobial resistance (AMR). The aim of the current investigation was to isolate lactic acid bacteria (LAB) with probiotic potential that can inhibit mastitis-causing pathogens to prevent bovine mastitis. Milk samples were collected from Sahiwal cows, and a total of 150 bacteria were isolated, of which 76 were found to be catalase negative, and resistant to vancomycin. Twenty-three isolates displayed greater acid and bile tolerance, with > 90% survivability, and were molecularly characterized by 16S rRNA partial sequencing. The autoaggregation percentages for SML7 and SML41 were greater (p<0·05) 80.38±0.19% and 80.28±0.04%, respectively. SML10 (92.04±0.26 μmol/mL) had the highest (p<0.05) ferric-reducing antioxidant power (FRAP) activity, while SML20 (52.1±0.99%) had the highest 1,1 diphenyl 2 picrylhydrazyl (DPPH) scavenging activity. All the strains were nonhemolytic or nonmucinolytic. The highest antimicrobial activity was observed in several strains (SML41, SML63, SML76, and SML60) against common mastitis-causing pathogens, namely, E. coli ATCC25922, Staphylococcus aureus ATCC25923, Enterococcus faecalis NCDC114, Streptococcus agalactiae NCDC208, and Enterococcus faecium NCDC124. The coaggregation efficacy of SML20 with S. aureus was the highest (67.69±1.21%), while SML41 showed the highest (69.75±0.29%) coaggregation efficacy with E. faecalis NCDC114 and SML63 (68.078±0.26) with S. agalactiae NCDC208. Overall, seven distinct lactic acid bacterial clusters were identified by cluster analysis of the phylogenetic tree as follows: Enterococcus hirae (1), Limosilactobacillus reuteri (1), Pediococcus acidilactici (4), Weissella confusa (11), Lactobacillus helveticus (3), Limosilactobacillus balticus (2), and Lacticaseibacillus rhamnosus (1). The Lactobacillus helveticus SML41, Lactobacillus helveticus SML60, Weissella confusa SML61, Lacticaseibacillus rhamnosus SML63, Weissella confusa SML64, and Pediococcus acidilactici SML76 isolates were found to possess the most desirable characteristics of potential probiotics based on principal component analysis (PCA). Therefore, the strains chosen in the current investigation demonstrated techno-functional characteristics that rendered them appropriate for probiotic use to treat and prevent intramammary infections in dairy cattle in a sustainable manner.

Revealing the nutritious treasures: an extensive investigation of health benefits of cultured dairy foods

Cultured milk products including yogurt, buttermilk, and lassi have made their way into South Asian cuisine for hundreds of years and are extraordinarily beneficial to human health. With a study background on lactic acid bacteria (LAB), these products are scientifically proved to aid in strengthening the immune system, for their anti-mutagenic effects, suitability for those who are lactose intolerant, and for protection against cancer, osteoporosis, and gut disorders. As of now, no scientific attention has been given to the microbial diversity of cultured milk products despite its prominent production and importance in the culture. New emerging approaches for studying the genetic composition and metabolic features of microbial communities, such as metagenomics and metabolomics, will open up important sources of knowledge and be a significant tool for informing conservation. These products are highly valued worldwide in the management of cardiometabolic diseases (CMDs), which encompass hypertension, type 2 diabetes, and obesity. The aim of this article will therefore advocate for the health benefits as well as cultural importance of cultured milk products. Indian fermented milk products, along with their historical development, cultural, and research aspects, thereby, highlighting the potential of this kind of product in promoting global health through functional food application, with a focus on recent advancements in their therapeutic potential and applications.

The Prophylactic Protection of Salmonella Typhimurium Infection by Lentilactobacillus buchneri GX0328-6 in Mice

Salmonellosis is a disease caused by non-typhoid Salmonella, and although some lactic acid bacteria strains have been shown previously to relieve Salmonellosis symptoms, little has been studied about the preventive mechanism of Lentilactobacillus buchneri (L. buchneri) against Salmonella infection in vivo. Therefore, the L. buchneri was fed to C57BL/6 mice for 10 days to build a protective system of mice to study its prevention and possible mechanisms. The results showed that L. buchneri GX0328-6 alleviated symptoms caused by Salmonella typhimurium infection among C57BL/6 mice, including low survival rate, weight loss, increase in immune organ index and hepatosplenomegaly, and modulated serum immunoglobulin levels and intrinsic immunity. Importantly, the L. buchneri GX0328-6 enhanced the mucosal barrier of the mouse jejunum by upregulating the expression of tight junction proteins such as ZO-1, occludins, and claudins-4 and improved absorptive capacity by increasing the length of mouse jejunal villus and the ratio of villus length to crypt depth and decreasing the crypt depth. L. buchneri GX0328-6 reduced the intestinal proliferation and invasion of Salmonella typhimurium by modulating the expression of antimicrobial peptides in the intestinal tract of mice, and reduced intestinal inflammation and systemic spread in mice by downregulating the expression of IL-6 and promoting the expression of IL-10. Furthermore, L. buchneri GX0328-6 increased the relative abundance of beneficial bacteria colonies and decreased the relative abundance of harmful bacteria in the cecum microflora by modulating the microflora in the cecum contents.

Bifidobacterium favimelis sp. nov., isolated from black comb honey

A strain of the bacterial genus Bifidobacterium, IMAU50987T, that was isolated from black comb honey from Lianghe County, Dehong Autonomous Prefecture, Yunnan Province, China, could not be accurately identified as a known species using 16S rRNA gene sequencing. In this study, the taxonomic status of strain IMAU50987T was evaluated using whole-genome sequencing combined with phenotypic analyses. Strain IMAU50987T was Gram-positive, non-motile and non-spore-forming. Comparative of 16S rRNA gene sequence similarity analysis indicated that strain IMAU50987T could be attributed to the genus Bifidobacterium and most closely related to the B. mellis Bin7NT (98.5% identity). Comparative sequence analysis of eight housekeeping genes (pyrG, thrS, glnA1, recA, tuf, dnaB, rpoC and xfp) showed that strain IMAU50987T was different from closely related species. Phylogenomic analysis based on the 88 single-copy genes in the phylogenetic tree showed that strain IMAU50987T belonged to the B. asteroides group. The highest average nucleotide identity value for strain IMAU50987T was 77.0% in comparison with B. choladohabitans B14384H11T and B. apis F753-1T. However, the highest digital DNA-DNA hybridization value was 23.1% compared with B. apis F753-1T and B. xylocopae XV2T; the highest average amino acid identity value was 73.2% compared with B. polysaccharolyticum W8117T. These values are below the accepted threshold for novel species boundaries. The draft genome size of strain IMAU50987T was 1.9 Mb, and the DNA G+C content was 63.5%. The major cellular fatty acids of strain IMAU50987T were C16 : 0, C18 : 1  ω9c and Sum in Feature 7 (C19 : 1  ω7c/C19 : 1  ω6c). The cell-wall peptidoglycan was of the A3α l-Lys-Gly type. Based on data from this study, a novel species, Bifidobacterium favimelis sp. nov., is proposed with the type strain IMAU50987T (= GDMCC 1.4189T = JCM 36315T).

Enhanced biochemical, microbial, and ultrastructural attributes of reduced-fat labneh through innovative microalgae integration

Reduced-fat labneh, while offering health benefits, often presents a challenge due to its diminished nutritional profile compared to full-fat varieties. Microalgae, such as Spirulina platensis and Chlorella vulgaris, are increasingly explored for their potential to fortify foods with essential nutrients. This study innovatively investigates the use of these microalgae to enhance the quality of reduced-fat labneh. The effect of incorporating different concentrations of both microalgae was investigated at different concentrations (0.25, 0.5, and 1%) on nutritional profile (including total solids, fat, protein, carbohydrates, essential amino acids, unsaturated fatty acids, pigments, and phenolic compounds), antioxidant activity, texture, sensory attributes, and viability of the starter culture. The findings revealed that 0.25 and 0.5% concentrations of both microalgae positively influenced the sensory characteristics of the labneh and significantly enhanced its nutritional profile. However, a 1% concentration negatively impacted sensory qualities. Chlorella vulgaris enrichment resulted in higher pH values but compromised texture attributes. Importantly, both microalgae varieties enhanced the viability of the starter culture during 21 days of refrigerated storage. The scanning electron microscope images provide visual evidence of the microstructural changes in labneh with varying concentrations of microalgae and over different storage periods. This research establishes the optimal concentrations for individual microalgae enrichment in reduced-fat labneh, offering valuable insights into their potential to improve both nutritional and sensory aspects. However, it's important to mention that while both microalgae have similar effects, they might differ in their specific impacts due to their unique nutritional profiles and physical properties. Therefore, further investigations could explore optimizing a microalgae mixture and its potential application in functional food development.

Susceptibility of Foodborne Pathogens to Milk-Origin Lactic Acid Bacteria Supernatants: A Comprehensive Meta-Regression Study

This systematic review and meta-analysis compile the in vitro antimicrobial efficacy of lactic acid bacteria (LAB) supernatants against three common pathogenic bacteria found in dairy products: Salmonella spp., L. monocytogenes, and Staphylococcus aureus. After screening and analysis of full papers, identified by searches in PubMed, Scopus, and Web of Science databases, thirty-nine studies were regarded as relevant, and a total of 510 observations were recorded. The effects of moderators on inhibition diameters were assessed by adjusting three pathogen-specific meta-regression models. Results showed that, in general terms, strains from the Enterococcus genus displayed the highest inhibition values against L. monocytogenes (15.90 ± 2.138 mm), whereas Lacticaseibacillus strains were more effective against S. aureus (11.89 ± 0.573 mm). The well diffusion test outperformed the spot and disk diffusion tests, and more acidic LAB supernatants resulted in higher measurements of inhibition diameters (p < 0.001). Meta-regression models incorporating LAB genus, pathogen concentration, and incubation time explained 33.8%, 52.3%, and 19.8% of the total variance in inhibition diameters for L. monocytogenes, Salmonella spp., and S. aureus, respectively. None of the three models showed evidence of publication bias. This meta-regression study demonstrated that LAB strains present in dairy products possess a variable capacity to inhibit any of the three foodborne pathogens. Overall, L. monocytogenes was found to exhibit greater susceptibility than Salmonella spp. and S. aureus; thus, the antilisterial capacity of the selected LAB strains could be exploited in developing biocontrol strategies for cheese-making.

An in vitro evaluation of the effect of antimicrobial treatment on bovine mammary microbiota

Antimicrobial-resistant bacteria have been an increasing problem in human medicine and animal husbandry since the introduction of antimicrobials on the market in the 1940s. Over the last decades, efforts to reduce antimicrobial usage in animal husbandry have been shown to limit the development of resistant bacteria. Despite this, antimicrobial-resistant bacteria are still commonly detected and isolated worldwide. In this study, we investigated the presence of antimicrobial-resistant bacteria in bovine milk samples using a multiple approach based on culturing and amplicon sequencing. We first enriched milk samples obtained aseptically from bovine udders in the presence of two antimicrobials commonly used to treat mastitis and then described the resistant microbiota by amplicon sequencing and isolate characterization. Our results show that several commensal species and mastitis pathogens harbor antimicrobial resistance and dominate the enriched microbiota in milk in presence of antimicrobial agents. The use of the two different antimicrobials selected for different bacterial taxa and affected the overall microbial composition. These results provide new information on how different antimicrobials can shape the microbiota which is able to survive and reestablish in the udder and point to the fact that antimicrobial resistance is widely spread also in commensal species.

Antibacterial potential of lactic acid bacteria isolated from raw cow milk in Sylhet district, Bangladesh: A molecular approach

BACKGROUND

The most prevalent probiotic bacterium employed in the food industry is Lactobacillus because it can produce metabolites with antibacterial capabilities and exhibits hostility towards infections and microorganisms that cause spoilage.

AIM

This study set out to identify naturally occurring Lactobacillus and plantaricin (pln EF) coding genes in raw cow milk and to assess the antibacterial potency of isolated Lactobacillus isolates.

METHODS

Following enrichment in De Man, Rogosa and Sharpe (MRS) broth, single colonies were isolated, and pure colonies were obtained by streaking on MRS agar. The 16S rRNA gene was amplified using polymerase chain reaction (PCR) to confirm the cultural positivity of all isolates. Additionally, the presence of plantaricin was verified by targeting the pln EF gene through PCR.

OUTCOME

Out of the 166 raw milk specimens acquired from cows, 153 (91.17%; CI: 86.98-95.76) were identified as positive for Lactobacillus through both culture and biochemical screening. Subsequently, 121 (72.89%; CI: 65.46-79.49) of the isolates were affirmed to harbour Lactobacillus through PCR analysis. Within this subset, 6 isolates (4.96%; CI: 1.84-10.48) were found to possess the plnEF gene. When exposed to Lactobacillus isolates, Salmonella Typhimurium and Salmonella enterica displayed an average maximum zone of inhibition with a diameter measuring 24 mm. In contrast, Escherichia coli exhibited an average minimum zone of inhibition, featuring a diameter of 11 mm. Additionally, the Lactobacillus isolates demonstrated inhibitory zones against Staphylococcus aureus, Klebsiella pneumoniae and Klebsiella oxytoca, measuring 14, 22 and 19 mm, respectively.

CLINICAL SIGNIFICANCE

Lactic acid bacteria, particularly Lactobacilli, are plentiful in cow milk and possess broad-spectrum antibacterial properties.

Community-forming traits play role in effective colonization of plant-growth-promoting bacteria and improved plant growth

Community-forming traits (CFts) play an important role in the effective colonization of plant-growth-promoting bacterial communities that influence host plants positively by modulating their adaptive functions. In this study, by considering plant-growth-promoting traits (PGPts) and community-forming traits (CFts), three communities were constructed, viz., SM1 (PGPts), SM2 (CFts), and SM3 (PGPts+CFts). Each category isolates were picked up on the basis of their catabolic diversity of different carbon sources. Results revealed a distinctive pattern in the colonization of the communities possessed with CF traits. It was observed that the community with CFts colonized inside the plant in groups or in large aggregations, whereas the community with only PGPts colonized as separate individual and small colonies inside the plant root and leaf. The effect of SM3 in the microcosm experiment was more significant than the uninoculated control by 22.12%, 27.19%, and 9.11% improvement in germination percentage, chlorophyll content, and plant biomass, respectively. The significant difference shown by the microbial community SM3 clearly demonstrates the integrated effect of CFts and PGPts on effective colonization vis-à-vis positive influence on the host plant. Further detailed characterization of the interaction will take this technology ahead in sustainable agriculture.

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.

Fermentation of Peanut Slurry with Lactococcus lactis Species, Leuconostoc and Propionibacterium freudenreichii subsp. globosum Enhanced Protein Digestibility

Peanuts contain nutritionally relevant levels of protein, yet are poorly digestible. Fermentation is a promising technique to boost legume protein quality, but its effect on the protein quality of raw peanuts has not been investigated. This study aimed to assess the impact of fermentation on the in vitro protein digestibility and free amino acid profile of cooked peanut slurry (peanut to water ratio 1:1). Cultures used were Propionibacterium freudenreichii subsp. globosum and a commercial fresh cheese culture that contained Lactococcus lactis subsp. cremoris, lactis, lactis biovar diacetylactis, and Leuconostoc, fermenting at 38 °C for 48 h. Samples fermented with the combination of cultures showed higher protein digestibility, as well as softer texture. Significant increases were observed only in the sample fermented with the fresh cheese culture. While the fresh cheese culture improved the free amino acid profile after fermentation, the combination of the cultures decreased all free amino acid concentrations except for glutamine, alanine, and proline. The observed increases in in vitro protein digestibility and the free amino acid profile may be attributed to the proteolytic activities of the cultures.

Whole-Bacterium SELEX Aptamer Selection of Fusobacterium nucleatum and Application to Colorectal Cancer Noninvasive Screening in Human Feces

In terms of cancer diagnoses and cancer-related deaths worldwide, colorectal cancer (CRC) is now the third most common malignancy. The drawbacks of current screening methods are their exorbitant costs, difficult procedures, and lengthy implementation timelines. The benefits of fecal screening for CRC are ease of operation, noninvasiveness, cost-effectiveness, and superior sensitivity. As a result of its enrichment in the malignant tissues and feces of CRC patients, Fusobacterium nucleatum (F. nucleatum) has emerged as a crucial biomarker for the incipient detection, identification, and prognostic prediction of CRC. Here, for the first time, the whole-bacterium SELEX method was used to screen the highly specific and affinity aptamers against F. nucleatum by 13 cycles of selection. The Apt-S-5 linear correlation equation is y = 0.7363x2.8315 (R2 = 0.9864) with a limit of detection (LOD) of 851 CFU/mL. The results of the experiment using fecal samples revealed a substantial disparity between the microorganisms in the CRC patients' feces and those in the feces of healthy individuals and were consistent with those of qPCR. The aptamers may therefore offer a crucial approach to identifying F. nucleatum and hold tremendous promise for CRC diagnosis and prognostic prediction.

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.

The Characterization and Beta-Lactam Resistance of Staphylococcal Community Recovered from Raw Bovine Milk

Staphylococci is an opportunistic bacterial population that is permanent in the normal flora of milk and poses a serious threat to animal and human health with some virulence factors and antibiotic-resistance genes. This study was aimed at identifying staphylococcal species isolated from raw milk and to determine hemolysis, biofilm, coagulase activities, and beta-lactam resistance. The raw milk samples were collected from the Düzce (Türkiye) region, and the study data represent a first for this region. The characterization of the bacteria was performed with MALDI-TOF MS and 16S rRNA sequence analysis. The presence of coa, icaB, blaZ, and mecA was investigated with PCR. A nitrocefin chromogenic assay was used for beta-lactamase screening. In this context, 84 staphylococci were isolated from 10 different species, and the dominant species was determined as S. aureus (32.14%). Although 32.14% of all staphylococci were positive for beta hemolysis, the icaB gene was found in 57.14%, coa in 46.42%, mecA in 15.47%, and blaZ in 8.33%. As a result, Staphylococcus spp. strains that were isolated from raw milk in this study contained some virulence factors at a high level, but also contained a relatively low level of beta-lactam resistance genes. However, considering the animal–environment–human interaction, it is considered that the current situation must be monitored constantly in terms of resistance concerns. It must not be forgotten that the development of resistance is in constant change among bacteria.

Antibacterial and Immunostimulatory Activity of Potential Probiotic Lactic Acid Bacteria Isolated from Ethiopian Fermented Dairy Products

Lactic acid bacteria (LAB) form a group of bacteria to which most probiotics belong and are commonly found in fermented dairy products. Fermented foods and beverages are foods made through desired microbial growth and enzymatic conversions of food components. In this study, 43 LAB were isolated from Ethiopian traditional cottage cheese, cheese, and yogurt and evaluated for their functional and safety properties as candidate probiotics. Twenty-seven isolates, representative of each fermented food type, were selected and identified to the species level. Limosilactobacillus fermentum was found to be the predominant species in all samples studied (70.4%), while 11.1% of isolates were identified as Lactiplantibacillus plantarum. All 27 isolates tested showed resistance to 0.5% bile salt, while 26 strains were resistant to pH 3. The LAB isolates were also evaluated for antagonistic properties against key pathogens, with strain-specific features observed for their antimicrobial activity. Five strains from cottage cheese (Lactiplantibacillus plantarum 54B, 54C, and 55A, Lactiplantibacillus pentosus 55B, and Pediococcus pentosaceus 95E) showed inhibitory activity against indicator pathogens that are key causes of gastrointestinal infections in Ethiopia, i.e., Escherichia coli, Salmonella enterica subsp. enterica var. Typhimurium, Staphylococcus aureus, Shigella flexneri, and Listeria monocytogenes. Strain-specific immunomodulatory activity monitored as nuclear factor kappa B (NF-κB) and interferon regulatory factor (IRF) activation was documented for Lactiplantibacillus plantarum 54B, 55A and P. pentosaceus 95E. Antibiotic susceptibility testing confirmed that all LAB isolates were safe concerning their antibiotic resistance profiles. Five isolates (especially Lactiplantibacillus plantarum 54B, 54C, and 55A, Lactiplantibacillus pentosus 55B, and P. pentosaceus 95E) showed promising results in all assays and are novel probiotic candidates of interest for clinical trial follow-up.

Isolation of Lactococcus garvieae NEP21 from raw cow (Bos indicus) milk in Nepal

Lactococcus garvieae is an emerging zoonotic pathogen impacting both humans and animals. Infection of this bacterium is known to cause mastitis in cattle, and endocarditis, osteomyelitis, liver abscess, and gastrointestinal problems are reported in immunocompromised and elderly people that regularly consume or handle raw meat, milk, dairy products, and seafood. This study aimed at investigating and detecting lactic acid bacteria in raw cow (Bos indicus) milk samples from a smallholder farm in Nepal. Based on the plate culture, biochemical tests, and molecular sequencing of 16 s ribosomal RNA coding nuclear DNA region followed by phenotypic and genotypic analyses, L. garvieae NEP21 was detected and identified for the first time in Nepal in raw cow milk samples. This finding suggests the prevalence of L. garvieae NEP21 in raw cow milk and recommends further research and surveillance for understanding the extent of its presence in Nepal and globally for informed management of its infection in cattle and humans.

Screening for Antifungal Indigenous Lactobacilli Strains Isolated from Local Fermented Milk for Developing Bioprotective Fermentates and Coatings Based on Acid Whey Protein Concentrate for Fresh Cheese Quality Maintenance

The demand for healthy foods without artificial food additives is constantly increasing. Hence, natural food preservation methods using bioprotective cultures could be an alternative to chemical preservatives. Thus, the main purpose of this work was to screen the indigenous lactobacilli isolated from fermented cow milk for their safety and antifungal activity to select the safe strain with the strongest fungicidal properties for the development of bioprotective acid whey protein concentrate (AWPC) based fermentates and their coatings intended for fresh cheese quality maintenance. Therefore, 12 lactobacilli strains were isolated and identified from raw fermented cow milk as protective cultures. The safety of the stains was determined by applying antibiotic susceptibility, haemolytic and enzymatic evaluation. Only one strain, Lacticaseibacillus paracasei A11, met all safety requirements and demonstrated a broad spectrum of antifungal activity in vitro. The strain was cultivated in AWPC for 48 h and grew well (biomass yield 8 log10 cfu mL−1). L. paracasei A11 AWPC fermentate was used as a vehicle for protective culture in the development of pectin-AWPC-based edible coating. Both the fermentate and coating were tested for their antimicrobial properties on fresh acid-curd cheese. Coating with L. paracasei A11 strain reduced yeast and mould counts by 1.0–1.5 log10 cfu mL−1 (p ≤ 0.001) during cheese storage (14 days), simultaneously preserving its flavour and prolonging the shelf life for six days.

Levilactobacillus yiduensis sp. nov., Isolated from Zha-chili in Yidu County, Hubei Province, China

The zha-chili isolate HBUAS62285^T is a facultative anaerobic strain. This bacterium was gram-positive, but it could not generate catalase, was not motile, did not form spores, had no flagella, and produced gamma-aminobutyric acid (GABA). Comparing of HBUAS62285^T with its related type strains Levilactobacillus suantsaiihabitans BCRC 81129^T, Levilactobacillus angrenensis M1530-1^T, Levilactobacillus cerevisiae DSM 100836^T, Levilactobacillus wangkuiensis 6-5(1)^T, Levilactobacillus lanxiensis 13B17^T, and Levilactobacillus mulengensis 112-3^T showed that the similarity of 16S rRNA gene sequence was less than 99.13%. Strain HBUAS62285^T has a G+C content of 50.57 mol%, an ANI value of less than 86.61%, an AAI value of less than 92.9%, and a dDDH value of less than 32.9% when compared to the aforementioned closely related strains. In the end, the most major fatty acids in cells were determined to be C_16:0, C_18:1 ω9c, C_19:1 cyclo ω9,10c, and summed feature 10. Overall, the results of the phenotypic, genomic, chemotaxonomic, and phylogenetic studies indicate that strains HBUAS62285^T and CD0817 constitute a new species within the genus Levilactobacillus, and the name Levilactobacillus yiduensis sp. nov. is proposed. The type strain is HBUAS62285^T (= JCM 35804^T = GDMCC 1.3507^T).

Isolation and Characterization of Lactobacillus crispatus, Lactococcus lactis, and Carnobacterium divergens as Potential Probiotic Bacteria from Fermented Black and Green Olives (Olea europaea): An Exploratory Study

Background

Table olives are becoming well recognized as a source of probiotic bacteria that might be used to create a health-promoting fermented food product by traditional procedures based on the activities of indigenous microbial consortia present in local environments. Methodology. In the present study, the characterization of probiotic bacteria isolated from mince, chunks, and brine of fermented green and black olives (Olea europaea) was done based on morphological, biochemical, and physiological characteristics.

Results

Bacterial isolates demonstrated excellent survival abilities at 25, 37, and 45°C and at a variable range of pH. However, the optimum temperature is 37 and the optimum pH is 7 for all three isolates. An antimicrobial susceptibility pattern was found among these isolates through the disc diffusion method. Most of the isolates were susceptible to streptomycin, imipenem, and chloramphenicol, whereas, amoxicillin showed resistance to these isolates, and variable results were recorded for the rest of the antibiotics tested. The growth of the isolates was optimum with the supplementation of 3% NaCl and 0.3% bile salt. The isolated bacteria were able to ferment skimmed milk into yogurt, hence making it capable of producing organic acid.

Conclusion

Isolates of Lactobacillus crispatus MB417, Lactococcus lactis MB418 from black olives, and Carnobacterium divergens MB421 from green olives were characterized as potential candidates for use as starter cultures to induce fermentation of other probiotic food products.

In Vitro Probiotic Characterization and Safety Assessment of Lactic Acid Bacteria Isolated from Raw Milk of Japanese-Saanen Goat (Capra hircus)

Two novel probiotic strains of lactic acid bacteria were successfully isolated from the raw milk of dairy Japanese-Saanen goats. Selection criteria for positive candidates were grown on de Man-Rogosa-Sharpe or M17 selective medium at 30, 35, or 42 °C anaerobically, and characterized based on Gram reaction, catalase test, and tolerance to low pH and bile salts. Among the 101 isolated positive candidates, two strains, YM2-1 and YM2-3, were selected and identified as Lacticaseibacillus rhamnosus using 16S rDNA sequence similarity. Culture supernatants of the two strains exhibited antipathogenic activity against Salmonella enterica subsp. enterica serovar. Typhimurium, Shigella sonnei, methicillin-resistant Staphylococcus aureus, methicillin-sensitive Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli O157. The antipathogenic activities were retained to some extent after neutralization, indicating the presence of antipathogenic substances other than organic acids in the culture supernatants. The two strains were sensitive with coincidental minimum inhibition concentrations (indicated in the parentheses hereafter) to ampicillin (0.25 μg/mL), chloramphenicol (4 μg/mL), gentamycin (4 μg/mL), kanamycin (64 μg/mL), streptomycin (16 μg/mL), and tetracycline (4 μg/mL). Furthermore, the two strains were resistant to clindamycin (16 μg/mL) and erythromycin (4 μg/mL). In addition, both YM2-1 and YM2-3 strains showed less unfavorable activities, including bile acid bioconversion, carcinogenic-related enzymes, mucin degradation, plasminogen activation, and hemolysis, than the detection limits of in vitro evaluation methods used in this study. In summary, L. rhamnosus YM2-1 and YM2-3 are highly safe and promising probiotic strains applicable in the dairy industry, and were first isolated from the raw milk of Japanese-Saanen goats.

Probiotics: Evolving as a Potential Therapeutic Option against Acetaminophen-Induced Hepatotoxicity

Acetaminophen (APAP) is the most common prescription medicine around the world for the treatment of pain and fever and is considered to be a safe drug at its therapeutic dose. However, a single overdose or frequent use of APAP can cause severe acute liver injury. APAP hepatotoxicity is a prevalent cause of acute liver disease around the world and the lack of suitable treatment makes it a serious problem. In recent years, there has been a surge in interest in using probiotics and probiotic-derived products, known as postbiotics, as health and disease negotiators. A growing body of evidence revealed that they can be equally effective against APAP hepatotoxicity. Different probiotic bacteria were found to be pre-clinically effective against APAP hepatotoxicity. Different postbiotics have also shown exciting results in preclinical models of APAP hepatotoxicity. This review summarized the protective roles and mechanisms of the different probiotic bacteria and postbiotics against APAP hepatotoxicity, with critical discussion. A brief discussion on potential novel probiotics and postbiotics for oxidative liver injury was also included. This review was written in an attempt to pique the interest of researchers in developing a safe therapeutic option against oxidative liver damage using probiotics and/or postbiotics as dietary supplements.

Lactic acid bacteria: isolation-characterization approaches and industrial applications

The current state-of-art research pertaining to lactic acid bacteria (LAB) calls for the screening and isolation of robust LAB strains to achieve holistic exploitation of LAB and their metabolites of marketable importance. Hence it is imperative to comprehend LAB sources, growth requisites, isolation and characterization strategies necessary for featured cataloging and appropriate culturing. This review comprehensively describes various growth media and biomasses used for supporting LAB sustenance, assay procedures needed for the isolation and characterization of LAB strains, and their application in diverse sectors. The various industrial patents and their summarized claims about novel LAB strains isolated and identified, methods and media (used for detection/screening, isolation, adaptation, culturing, preservation, growth improvement), the techniques and/or methodologies supporting LAB fermentation, and applications of produced industrial metabolites in various market scenarios are detailed.