Characterization of Lactobacillus plantarum strains for functionality, safety and γ-amino butyric acid production

Studies on the Probiotic, Adhesion, and Induction Properties of Artisanal Lactic Acid Bacteria: to Customize a Gastrointestinal Niche to Trigger Anti-obesity Functions

The primary goals of this work are to explore the potential of probiotic lactic acid bacteria's (LAB) mucin/mucus layer thickening properties and to identify anti-obesity candidate strains that improve appropriate habitat for use with the Akkermansia group population in the future. The HT-29 cell binding, antimicrobial properties, adhesion to the mucin/mucus layer, growth in the presence of mucin, stability during in vitro gastrointestinal (GI) conditions, biofilm formation, and mucin/mucus thickness increment abilities were all assessed for artisanal LAB strains. Sixteen LAB strains out of 40 were chosen for further analysis based on their ability to withstand GI conditions. Thirteen strains remained viable in simulated intestinal fluid, while most showed high viability in gastric juice simulation. Furthermore, 35.9-65.4% of those 16 bacteria adhered to the mucin layer. Besides, different lactate levels were produced, and Streptococcus thermophilus UIN9 exhibited the highest biofilm development. In the HT-29 cell culture, the highest mucin levels were 333.87 µg/mL with O. AK8 at 50 mM lactate, 313.38 µg/mL with Lactobacillus acidophilus NRRL-B 1910 with initial mucin, and 311.41 µg/mL with Lacticaseibacillus casei NRRL-B 441 with initial mucin and 50 mM lactate. Nine LAB strains have been proposed as anti-obesity candidates, with olive isolates of Lactiplantibacillus plantarum being particularly important due to their ability to avoid mucin sugar consumption. Probiotic LAB's attachment to the colonic mucosa and its ability to stimulate HT-29 cells to secrete mucus are critical mechanisms that may support the development of Akkermansia.

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.

Characterization of Probiotic Properties of Antifungal Lactobacillus Strains Isolated from Traditional Fermenting Green Olives

The aim of this work is to characterize the potential probiotic properties of 14 antifungal Lactobacillus strains isolated from traditional fermenting Moroccan green olives. The molecular identification of strains indicated that they are composed of five Lactobacillus brevis, two Lactobacillus pentosus, and seven Lactobacillus plantarum. In combination with bile (0.3%), all the strains showed survival rates (SRs) of 83.19-56.51% at pH 3, while 10 strains showed SRs of 31.67-64.44% at pH 2.5. All the strains demonstrated high tolerance to phenol (0.6%) and produced exopolysaccharides. The autoaggregation, hydrophobicity, antioxidant activities, and surface tension value ranges of the strains were 10.29-41.34%, 15.07-34.67%, 43.11-52.99%, and 36.23-40.27 mN/m, respectively. Bacterial cultures exhibited high antifungal activity against Penicillium sp. The cell-free supernatant (CFS) of the cultures showed important inhibition zones against Candida pelliculosa (18.2-24.85 mm), as well as an antibacterial effect against some gram-positive and gram-negative bacteria (10.1-14.1 mm). The neutralized cell-free supernatant of the cultures displayed considerable inhibitory activity against C. pelliculosa (11.2-16.4 mm). None of the strains showed acquired or horizontally transferable antibiotic resistance or mucin degradation or DNase, hemolytic, or gelatinase activities. Lactobacillus brevis S82, Lactobacillus pentosus S75, and Lactobacillus plantarum S62 showed aminopeptidase, β-galactosidase, and β-glucosidase activities, while the other enzymes of API-ZYM were not detected. The results obtained revealed that the selected antifungal Lactobacillus strains are considered suitable candidates for use both as probiotic cultures for human consumption and for starters and as biopreservative cultures in agriculture, food, and pharmaceutical industries.

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

BACKGROUND

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

RESULTS

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

CONCLUSION

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

Microbial production of gamma-aminobutyric acid: applications, state-of-the-art achievements, and future perspectives

Gamma-aminobutyric acid (GABA) is an important non-protein amino acid with wide-ranging applications. Currently, GABA can be produced by a variety of methods, including chemical synthesis, plant enrichment, enzymatic methods, and microbial production. Among these methods, microbial production has gained increasing attention to meet the strict requirements of an additive in the fields of food, pharmaceutical, and livestock. In addition, renewable and abundant resources, such as glucose and lignocellulosic biomass can also be used for GABA microbial production under mild and environmentally friendly processing conditions. In this review, the applications, metabolic pathways and physiological functions of GABA in different microorganisms were firstly discussed. A comprehensive overview of the current status of process engineering strategies for enhanced GABA production, including fermentation optimization and whole-cell conversion from different feedstocks by various host strains is also provided. We also presented the state-of-the-art achievements in strain development strategies for industrial lactic acid bacteria (LAB), Corynebacterium glutamicum and Escherichia coli to enhance the performance of GABA bioproduction. In order to use bio-based GABA in the fields of food and pharmaceutical, some Generally Recognized as Safe (GRAS) strains such as LAB and C. glutamicum will be the promising chassis hosts. Toward the end of this review, current challenges and valuable research directions/strategies on the improvements of process and strain engineering for economic microbial production of GABA are also suggested.

GABA-producing Lactobacillus plantarum inhibits metastatic properties and induces apoptosis of 5-FU-resistant colorectal cancer cells via GABAB receptor signaling

5-Fluorouracil (5-FU) is an essential drug in systemic chemotherapy treatments for colorectal cancer (CRC). Despite the development of several treatment strategies over the past decades, the patient benefits of 5-FU-based therapies have been compromised by the development of chemoresistance. Differences in treatment responses among CRC patients may be due to genetic and epigenetic factors unique to individuals. Therefore, important factors for realizing personalized medicine are to accurately understand the causes and mechanisms of drug resistance to 5-FU-based therapies and to identify and validate prognostic biomarkers. Gut microbes that interact directly with the host contribute to human health and cancer control. Lactobacillus plantarum, in particular, has the potential to be a therapeutic agent by producing bioactive compounds that may benefit the host. Here, we investigated the gamma-aminobutyric acid (GABA) and GABAB receptor (GABABR)-dependent signaling pathway as a treatment option for 5-FU-resistant HT-29 cells. GABA-producing L. plantarum activates anti-proliferative, anti-migration, and anti-invasion effects against 5-FU-resistant HT-29 cells. The inhibitory effects of GABA-producing L. plantarum are mediated via GABABR. Activated GABABR induces apoptosis through the inhibition of cAMP-dependent signaling pathways and cellular inhibitor of apoptosis protein 2 (cIAP2) expression. Thus, the GABAergic system has potential in 5-FU-resistant HT-29 cells as a predictive biomarker. In addition, GABA-producing L. plantarum is promising as an adjuvant treatment for 5-FU-resistant CRC, and its intervention in neurobiological signaling imply new possibilities for chemoprevention and the treatment of colon cancer-related diseases.

Screening of GABA-Producing Lactic Acid Bacteria from Thai Fermented Foods and Probiotic Potential of Levilactobacillus brevis F064A for GABA-Fermented Mulberry Juice Production

Gamma-aminobutyric acid (GABA), the inhibitory neurotransmitter, can be naturally synthesized by a group of lactic acid bacteria (LAB) which is commonly found in rich carbohydrate materials such as fruits and fermented foods. Thirty-six isolates of GABA-producing LAB were obtained from Thai fermented foods. Among these, Levilactobacillus brevis F064A isolated from Thai fermented sausage displayed high GABA content, 2.85 ± 0.10 mg/mL and could tolerate acidic pH and bile salts indicating a promising probiotic. Mulberry (Morus sp.) is widely grown in Thailand. Many mulberry fruits are left to deteriorate during the high season. To increase its value, mulberry juice was prepared and added to monosodium glutamate (MSG), 2% (w/v) prior to inoculation with 5% (v/v) of L. brevis F064A and incubated at 37 °C for 48 h to obtain the GABA-fermented mulberry juice (GABA-FMJ). The GABA-FMJ obtained had 3.31 ± 0.06 mg/mL of GABA content, 5.58 ± 0.52 mg gallic acid equivalent/mL of antioxidant activity, 234.68 ± 15.53 mg cyanidin-3-glucoside/mL of anthocyanin, an ability to inhibit growth of Bacillus cereus TISTR 687, Salmonella Typhi DMST 22842 and Shigella dysenteriae DMST 1511, and 10.54 ± 0.5 log₁₀ colony-forming units (CFU)/mL of viable L. brevis F064A cell count. This GABA-FMJ was considered as a potential naturally functional food for human of all ages.

Probiotic potential of lyophilized Lactobacillus plantarum GP

Purpose

Freeze drying of Lactobacillus plantarum GP in the presence of wall materials to achieve improved survival and retention of probiotic functionality during storage.

Methods

L. plantarum cells were lyophilized in the presence of inulin, fructooligosaccharides, lactulose, and/or skim milk. The lyophilized vials were stored at 8–10 °C up to 6 months and cells from these vials were evaluated for their probiotic functionality.

Results

L. plantarum GP freeze dried in the presence of wall material lactulose displayed viability of 98 ± 2.8% promising survival rate in the stress conditions of human digestive tract. The freeze dried cells of Lactobacilli retained the ability to adhere intestinal mucin layer, form biofilm, inhibit food spoilage and enteropathogens, produce β-galactosidase, bile salt hydrolase and γ-amino butyric acid, remove cholesterol, and scavenge DPPH radical.

Conclusion

Lyophilized cells of L. plantarum GP retained all the functional characteristics without any significant loss during storage, which prompts to incorporate prebiotics for the development of stable functional food products.

Probiotic Properties of Lactobacillus paracasei subsp. paracasei L1 and Its Growth Performance-Promotion in Chicken by Improving the Intestinal Microflora

Lactobacillus paracasei subsp. paracasei L1 was previously isolated from sweet potato sour liquid. This bacterial species specifically binds onto starch granular surfaces, triggering the enzymatic hydrolysis of raw starch. We investigated the functional and safety properties of strain L1 in vitro to establish its probiotic potential, and analyzed its effect on growth performance and intestinal microflora of chicken in feeding experiments. The optimal growth conditions of strain L1 included low pH and high concentrations of bile salts and NaCl. Its 1-, 2-, and 24-h autoaggregation values were 15.8 ± 1.2%, 20.4 ± 2.3%, and 47.2 ± 0.8%, respectively, with the surface hydrophobicity value at 560 nm of 38.1 ± 2.7%. Further, its adhesion rate to Caco-2 cells was 22.37 ± 1.44%. Strain L1 was resistant to erythromycin and azithromycin, but sensitive to other antibiotics tested. For the feeding experiments, 240 chickens with similar weights were randomly divided into a control (C) group and strain L1 (L) group and fed for 8 weeks. Strain L1 promoted the weight gain of chickens in L group. A significant increase in the population size of the two phyla and 23 genera in the small intestine was observed in the presence of strain L1 (P < 0.05), with 0 phyla and 4 genera showing significant increase in the cecum (P < 0.05). In the small intestine, the abundance of six functional genes at Kyoto Encyclopedia of Genes and Genomes (KEGG) level 2 and 49 genes at KEGG level 3 was significantly increased in group L (P < 0.05), with lesser changes noted in the cecum. An increase in the metabolic pathway functions, including enzyme families and the digestive system, was observed in the intestinal microbiota in the L group compared to the C group. However, the other metabolic pathway functions, including metabolism of fatty acid biosynthesis, as well as metabolism of glycerolipids and propanoate, increased in the cecal microbiota of the L group relative to the C group. These changes are most likely related to the changes in the gut microbiota composition. Collectively, strain L1 supplementation may promote growth performance and improve the intestinal microflora in chicken although further studies are needed to confirm this.

Enzymes and Dairy Products

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

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.