Investigating the Probiotic Properties and Antimicrobial Activity of Lactic Acid Bacteria Isolated from an Iranian Fermented Dairy Product, Kashk

Screening and Whole-Genome Analysis of Probiotic Lactic Acid Bacteria with Potential Antioxidants from Yak Milk and Dairy Products in the Qinghai-Tibet Plateau

This study aimed to isolate lactic acid bacteria (LAB) with strong antioxidant activity and potential probiotic properties from yak milk and dairy products in the Qinghai-Tibet Plateau. Initial screening of the isolates was performed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assay and a hydrogen peroxide tolerance test. Subsequently, the antioxidant capacity of the isolates was assessed through five distinct assays: 2,2'-azino-bis (3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging ability, superoxide anion radical scavenging ability, hydroxyl radical scavenging ability, a DPPH scavenging assay, and a reducing activity assay. The strains with the stronger antioxidant potential were then further evaluated for their probiotic properties. Whole-genome sequencing was conducted on Lactobacillus plantarum QL01. Among 1205 isolates, 9 strains exhibited potential antioxidant capabilities. Following probiotic property evaluation, QL01 was identified as a safe candidate due to its strong growth, strong adhesion ability, and resilience to acidic, bile, and simulated gastrointestinal conditions. Genome analysis revealed that most of QL01's genes were involved in carbohydrate metabolism. Further examination of antibiotic resistance and virulence factors confirmed its safety, meanwhile genes linked to adhesion and stress responses underscored its probiotic potential. In conclusion, QL01, a strong antioxidant strain, was successfully isolated, and its probiotic potential was confirmed through comprehensive in vitro and genomic analyses.

Anticancer effect of a combinatorial treatment of 5-fluorouracil and cell extract of some probiotic lactobacilli strains isolated from camel milk on colorectal cancer cells

Colorectal cancer (CRC) has the highest mortality rate among cancer types, emphasizing the need for auxiliaries to 5-fluorouracil (5-FU) due to resistance and side effects. Metabolites produced by probiotic bacteria exhibit promising anticancer properties against CRC. In the current study, the anticancer effects of cell extract of three potential probiotic lactobacilli strains isolated from camel milk, Lactobacillus helveticus, Lactobacillus gallinarum, and Lactiplantibacillus plantarum, as well as that of the standard probiotic strain Lacticaseibacillus rhamnosus GG (LGG), on the human colon cancer cell line (HT-29) and the normal HEK293 cell line separately or in combination with 5-FU, were evaluated. This study isolated strains from camel milk and compared their probiotic properties to those of LGG. The cell viability, cell apoptosis, and Th17 cytokine production were assessed using the MTT assay, acridine orange/ethidium bromide (AO/EB) staining, and flow cytometry techniques, respectively. The cell extracts of lactobacilli strains combined with 5-FU reduced HT-29 cell viability effectively and increased cell apoptosis. Nevertheless, the cell extracts of lactobacilli strains combined with 5-FU controlled the cytotoxic impact of 5-FU on HEK-293 cell viability and reduced cell apoptosis. No significant differences were observed among the strains. Moreover, the cell extracts from the strains combined with 5-FU increased the levels of cytokines IFN-γ, TNF-α, and IL-17A, all of which contribute to immunity against tumors. The performance of the studied strains was similar to that of the standard probiotic strain (LGG). The investigation revealed that cell extracts from lactobacilli strains may serve as a promising complementary anticancer treatment.

Isolation, identification, and evaluation of lactic acid bacteria with probiotic potential from traditional fermented sour meat

Sour meat is a popular traditional fermented product and is a rich source of novel strains with probiotic potential. In this study, we aimed to assess the probiotic potential of lactic acid bacteria (LAB) strains isolated from fermented sour meat. Firstly, the microbial diversity of sour meat from four different areas in China was analyzed. The results showed that LAB were predominant in all samples. Subsequently, LAB were isolated from sour meat and a series of in vitro probiotic tests were carried out. A total of 130 bacterial strains with dissolved calcium were obtained and 10 strains showed a range of 89-97% survival in an acidic environment and high tolerance to bile salts. The ranges of hydrophobicity and auto-aggregation of 10 strains were 4.85-80.75% and 1.58-84.2%, respectively. Besides, all 10 strains exhibited high antimicrobial activity and antioxidant activity, of which, DZ24 possessed the strongest free radical scavenging (45.1%) and anti-lipid oxidizing ability (90.3%). Furthermore, DZ24 was identified as Lactiplantibacillus plantarum by 16S rRNA gene sequencing. Moreover, the fermentation indexes showed that DZ24 could rapidly reduce the pH to 4.14 and showed high salt and nitrite resistance and antioxidant ability. All the above experimental results indicate that Lactiplantibacillus plantarum DZ24 promise a suitable probiotic candidate for future applications in the fermented functional meats.

Probiotic Characteristics and the Anti-Inflammatory Effects of Lactiplantibacillus plantarum Z22 Isolated from Naturally Fermented Vegetables

Currently, there is increasing interest in the commercial utilization of probiotics isolated from traditional fermented food products. Therefore, this study aimed to investigate the probiotic potential of Lactiplantibacillus plantarum (L. plantarum) Z22 isolated from naturally fermented mustard. The results suggest that L. plantarum Z22 exhibits good adhesion ability, antibacterial activity, safety, and tolerance to acidic conditions and bile salts. We further determined the anti-inflammatory mechanism and properties of L. plantarum Z22 and found that L. plantarum Z22 could significantly reduce the secretion of pro-inflammatory cytokines, including interleukin-6 (IL-6), interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and the expression of the pro-inflammatory mediator cyclooxygenase-2 (COX-2) protein in LPS-induced RAW 264.7 cells. In addition, L. plantarum Z22 also effectively inhibited the signaling pathways of nuclear factor κB (NF-κB) and mitogen-activated protein kinases (MAPKs). This effect can be attributed to a decrease in the levels of reactive oxygen species (ROS) and increased heme oxygenase-1 (HO-1) expression. Moreover, whole-genome sequencing revealed that L. plantarum Z22 contains gene-encoding proteins with anti-inflammatory functions, such as beta-glucosidase (BGL) and pyruvate kinase (PK), as well as antioxidant functions, including thioredoxin reductase (TrxR), tyrosine-protein phosphatase, and ATP-dependent intracellular proteases ClpP. In summary, these results indicated that L. plantarum Z22 can serve as a potential candidate probiotic for use in fermented foods such as yogurt (starter cultures), providing a promising strategy for the development of functional foods to prevent chronic diseases.

Evaluation of probiotic bifidobacteria strains from Iranian traditional dairy products for their anti-hyperlipidemic potential

This study investigated the therapeutic potential of probiotic bifidobacteria, isolated from Iranian fermented dairy products, in a hyperlipidemic animal model. Bifidobacterium strains were extracted from traditional dairy samples and screened using physiological and phenotypic examinations, 16S rRNA analysis, and probiotic properties such as tolerance to gastrointestinal juice, antimicrobial activity, and antibiotic susceptibility. The ability of the screened bifidobacteria to reduce serum and liver lipids in vivo was tested using male Wistar rats. Six strains of bifidobacteria were isolated from traditional Iranian fermented dairy. These strains showed promising in vitro activity in lowering triglyceride and cholesterol, tolerance to simulated gastrointestinal juice, the ability to adhere to Caco-2 cells, acceptable antibiotic susceptibility, and a broad spectrum of antibacterial activity. The diet supplemented with isolated bifidobacteria significantly reduced serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), liver tissue lipid levels, and hepatic enzymes in animals when compared to a high-fat diet without strains (p < 0.01). Additionally, the potential probiotic-supplemented diet significantly increased bile acid excretion in the feces and upregulated hepatic CYP7A1 expression levels (p < 0.05), while NPC1L1, ACAT2, and MTP gene expressions in small intestinal cells were downregulated (p < 0.05). Bifidobacteria isolated from Iranian traditional dairy showed potential for use in the production of fermented foods that have hypolipemic activity in the host.

Preparation and characterization of pectin/hydroxyethyl cellulose/clay/TiO2 bionanocomposite films for microbial pathogen removal from contaminated water

Some of conventional wastewater disinfectants can have a harmful influence on the environment as well as human health. The aim of this investigation was synthesis and characterizes ecofriendly pectin/hydroxyethyl cellulose (HEC)/clay and pectin/HEC/clay incorporated with titanium dioxide nanoparticles (TiO2NPs) and use the prepared bionanocomposite as microbial disinfectants for real wastewater. Pectin/HEC/clay and pectin/HEC/clay/TiO2 bionanocomposite were characterized by various methods including X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier-transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA). Mechanical properties and water vapor permeability (WVP) were carried out. The results of SEM showed that, the prepared bionanocomposite had a smooth surface. Additionally, TiO2 nanoparticles to the pectin/HEC/clay composites may lead to changes in the FTIR spectrum. The intensity of XRD peaks indicated that, TiO2NPs was small size crystallite. TGA illustrated that pectin has moderate thermal stability, while HEC generally exhibits good thermal stability. The TEM showed that, TiO2 nanoparticles have diameters <25 nm. On the other hand, antimicrobial activities of pectin/HEC/clay against Escherichia coli (E. coli), Staphylococcus aureus and Candida albicans have been enhanced by adding TiO2NPs. The minimum inhibitory concentration (MIC) of pectin/HEC/clay/TiO2 against E. coli was 200 mg/mL. Moreover, complete eradication of E. coli, Salmonella and Candida spp. from real wastewater was observed by using pectin/HEC/clay/TiO2 bionanocomposite. Finally, it can be concluded that, the synthesized bionanocomposite is environmentally friendly and considered an excellent disinfectant matter for removal of the microbial pathogens from wastewater to safely reuse.

The anticancer effect of potential probiotic L. fermentum and L. plantarum in combination with 5-fluorouracil on colorectal cancer cells

5-Fluorouracil (5-FU) is an effective chemotherapy drug in the treatment of colorectal cancer (CRC). However, auxiliary or alternative therapies must be sought due to its resistance and potential side effects. Certain probiotic metabolites exhibit anticancer properties. In this study evaluated the anticancer and potential therapeutic activities of cell extracts potential probiotic strains, Limosilactobacillus fermentum and Lactiplantibacillus plantarum isolated from the mule milk and the standard probiotic strain Lacticaseibacillus rhamnosus GG (LGG) against the human colon cancer cell line (HT-29) and the normal cell line (HEK-293) alone or in combination with 5-FU. In this study, L. plantarum and L. fermentum, which were isolated from mule milk, were identified using biochemical and molecular methods. Their probiotic properties were investigated in vitro and compared with the standard probiotic strain of the species L. rhamnosus GG. The MTT assay, acridine orange/ethidium bromide (AO/EB) fluorescent staining, and flow cytometry were employed to measure the viability of cell lines, cell apoptosis, and production rates of Th17 cytokines, respectively. The results demonstrated that the combination of lactobacilli cell extracts and 5-FU decreased cell viability and induced apoptosis in HT-29 cells. Furthermore, this combination protected HEK-293 cells from the cytotoxic effects of 5-FU, enhancing their viability and reducing apoptosis. Moreover, the combination treatment led to an increase in the levels of IL-17A, IFN-γ, and TNF-α, which can enhance anti-tumor immunity. In conclusion, the cell extracts of the lactobacilli strains probably can act as a potential complementary anticancer therapy.

Molecular identification and probiotic potential characterization of lactic acid bacteria isolated from the pigs with superior immune responses

Lactic acid bacteria (LAB) belong to a significant group of probiotic bacteria that provide hosts with considerable health benefits. Our previous study showed that pigs with abundant LAB had more robust immune responses in a vaccination experiment. In this study, 52 isolate strains were isolated from the pigs with superior immune responses. Out of these, 14 strains with higher antibacterial efficacy were chosen. We then assessed the probiotic features of the 14 LAB strains, including such as autoaggregation, coaggregation, acid resistance, bile salt resistance, and adhesion capability, as well as safety aspects such as antibiotic resistance, hemolytic activity, and the presence or absence of virulence factors. We also compared these properties with those of an opportunistic pathogen EB1 and two commercial probiotics (cLA and cLP). The results showed that most LAB isolates exhibited higher abilities of aggregation, acid and bile salt resistance, adhesion, and antibacterial activity than the two commercial probiotics. Out of the 14 strains, only LS1 and LS9 carried virulence genes and none had hemolytic activity. We selected three LAB strains (LA6, LR6 and LJ1) with superior probiotic properties and LS9 with a virulence gene for testing their safety in vivo. Strains EB1, cLA and cLP were also included as control bacteria. The results demonstrated that mice treated LAB did not exhibit any adverse effects on weight gain, organ index, blood immune cells, and ileum morphology, except for those treated with LS9 and EB1. Moreover, the antimicrobial effect of LR6 and LA6 strains was examined in vivo. The results indicated that these strains could mitigate the inflammatory response, reduce bacterial translocation, and alleviate liver, spleen, and ileum injury caused by Salmonella typhimurium infection. In addition, the LR6 treatment group showed better outcomes than the LA6 treatment group; treatment with LR6 substantially reduced the mortality rate in mice. The study results provide evidence of the probiotic properties of the LAB isolates, in particular LR6, and suggest that oral administration of LR6 could have valuable health-promoting benefits.

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.

Enterococcus montenegrensis sp. nov., isolated from artisanal Montenegrin dry sausage

A novel, Gram-positive, facultative anaerobe, coccoid and non-motile bacterium, designated as CoE-012-22T was isolated from dried beef sausage (the original name in Montenegro is Govedji Kulen) manufactured in the municipality of Rozaje (Montenegro) in 2021. Cells of this strain were oxidase- and catalase-negative. Growth occurred at 4-50 °C, at pH 5.0-8.0 and with 0-6.5 % (w/v) NaCl in diverse growth media. MALDI-TOF analysis identified the strain as Enterococcus canintestini (log score 2). Phylogenetic analysis of the 16S rRNA gene and whole genome sequences assigned the strain to the genus Enterococcus. The closest relatives were E. canintestini DSM 21207T and E. dispar ATCC 51266T with 16S rRNA gene sequence pairwise similarities of 99.34 and 98.59 %, respectively. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between isolate CoE-012-22T and other enterococci species were below the thresholds for species delineation thresholds (95.0 % ANI; 70.0 % dDDH) with maximum identities of 84.13 % (ANIb), 86.43 % (ANIm) and 28.4 % (dDDH) to E. saigonensis JCM 31193T and 70.97 % (ANIb), 88.99 % (ANIm) and 32.4 % (dDDH) to E. malodoratus ATCC 43197T. Two unknown Enterococcus isolates, Enterococcus sp. MJM12 and Enterococcus SMC-9, showed identities of 99.87 and 99.94 % (16S rRNA), 98.57 and 98.65 % (ANIb), 98.93 and 99.02 % (ANIm), and 89.8 and 90.0 % (dDDH) to strain CoE-012-22T and can therefore be regarded as the same species. Based on the characterization results, strain CoE-012-22T was considered to represent a novel species, for which the name Enterococcus montenegrensis sp. nov. is proposed. The type strain is CoE-012-22T (=DSM 115843T=NCIMB 15468T).

Systematic investigation of simultaneous copper biosorption and nitrogen removal from wastewater by an aerobic denitrifying bacterium of auto-aggregation

Finding effective methods for simultaneous removal of eutrophic nutrients and heavy metals has attracted increasing concerns for the environmental remediation. Herein, a novel auto-aggregating aerobic denitrifying strain (Aeromonas veronii YL-41) was isolated with capacities for copper tolerance and biosorption. The denitrification efficiency and nitrogen removal pathway of the strain were investigated by nitrogen balance analysis and amplification of key denitrification functional genes. Moreover, the changes in the auto-aggregation properties of the strain caused by extracellular polymeric substances (EPS) production were focused on. The biosorption capacity and mechanisms of copper tolerance during denitrification were further explored by measuring changes in copper tolerance and adsorption indices, as well as by variations in extracellular functional groups. The strain showed extremely strong total nitrogen removal ability, with 67.5%, 82.08% and 78.48% of total nitrogen removal when NH4+-N, NO2--N, and NO3--N were used as the only initial nitrogen source, respectively. The successful amplification of napA, nirK, norR, and nosZ genes further demonstrated that the strain accomplished nitrate removal through a complete aerobic denitrification pathway. The production of protein-rich EPS of up to 23.31 mg/g and an auto-aggregation index of up to 76.42% may confer a strong biofilm-forming potential to the strain. Under the stress of 20 mg/L copper ions, the removal of nitrate-nitrogen was still as high as 71.4%. In addition, the strain could achieve an efficient removal of 96.9% of copper ions at an initial concentration of 80 mg/L. Scanning electron microscopy and deconvolution analysis of characteristic peaks confirmed that the strains encapsulate heavy metals by secreting EPS and, meanwhile, form strong hydrogen bonding structures to enhance intermolecular forces to resist copper ion stress. This study provides an innovative and effective biological approach for the synergistic bioaugmentation removal of eutrophic substances and heavy metals from aquatic environments.

Characterization of Potential Probiotic Activity of Lactic Acid Bacteria Isolated from Camel Colostrum by Biochemical and Molecular Methods

A total of 60 isolates of lactic acid bacteria (LAB) were isolated from Jordanian camel colostrum using biochemical and molecular methods. Two dominant species were identified, and they were Lactobacillus salivarius and Enterococcus faecium. The entire 60 isolated LAB were tested for their acidity and bile tolerance, antimicrobial activity, and antibiotic sensitivity to test their potential probiotic activity. All 60 isolates were tolerant to different pH concentrations (2, 3, 4, 5, 6, 7, 8, 9, and 10) with different survival rates (%). The entire isolates were also tolerant to different bile salt concentrations (0.2, 0.4, 0.6, 0.8, 1, 2, and 3) with different bile resistance (%). All isolates have a different range of antimicrobial activity against Staphylococcus aureus, E. coli, and Salmonella typhimurium. The 60 isolates were almost sensitive to ampicillin, amoxicillin, and clarithromycin when different concentrations were used except some isolates of intermediate resistance. Only 6% of the isolates were resistant to clarithromycin at a concentration of 15 µg per disc.