Characterization of lactobacilli isolated from caper berry fermentations

Biochemical, pharmacological, and toxicological attributes of caper (Capparis ovata) flowering buds and berries pickles

Capparis ovata is a natural plant that grows widely in Turkey and its flowering buds and berry pickle are used in traditional medicine. Thus, the current study was expanded to evaluate the biochemical, pharmacological, and toxicological aspects of the Capparis ovata water extract (COWE). To determine the biochemical properties of COWE, mineral and fatty acid content, elemental analysis, flavonoid/phenolic content, radical-scavenging capacity, and pesticide analysis were performed. Furthermore, to find out whether it had anti-inflammatory properties, reverse transcription-polymerase chain reaction (RT-PCR) and nuclear factor kappa B (NF-κB) luciferase activity tests were conducted. Whole-genome transcriptomic profiling was carried out at a dose level of 500 mg/kg COWE to understand its pharmacological effect. Transaminases in serum were tested, and quantitative polymerase chain reaction (qPCR) was done using a custom design array that included the stress and molecular toxicology pathway to establish its toxicological qualities. As a result of the evaluations, it was observed that COWE has a high mineral and unsaturated fatty acid content, flavonoid/phenolic content, and radical-scavenging ability. It significantly inhibited NF-κB transcriptional activity as well as inflammatory cytokine expression in T-lymphoblast cells. Whole-genome transcriptomic profiling depicted that COWE modulates immune responses by upregulating natural killer cell activation, cellular response to type I interferon, B-cell proliferation and differentiation, and Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathways. Molecular Toxicology Pathfinder RT² Profiler PCR array analysis revealed that COWE at or lower dose of 500 mg/kg/day did not cause a comparatively adverse effect. According to the findings, COWE is a rich source of nutrients and can be used as an adjunct therapy for various inflammatory diseases.

Improving the Acid Resistance of Tannase TanBLp (AB379685) from Lactobacillus plantarum ATCC14917T by Site-Specific Mutagenesis

Tannin acyl hydrolase referred commonly as tannase catalyzes the hydrolysis of the galloyl ester bond of tannin to release gallic acid. The tannase TanBLp which cloned from Lactobacillus plantarum ATCC14917^T has high activity in the pH range (7.0-9.0) at 40 °C, it would be detrimental to the utilization at acidic environment. The catalytic sites and stability of TanBLp were analyzed using bioinformatics and site-specific mutagenesis. The results reiterated that the amino acid residues Ala164, Lys343, Glu357, Asp421 and His451 had played an important role in maintaining the activity. The optimum pH of mutants V75A, G77A, N94A, A164S and F243A were shifted from 8.0 to 6.0, and mutant V75A has the highest pH stability and activity at acidic conditions than other mutants, which was more suitable for industrial application to manufacture gallic acid. This study was of great significance to promote the industrialization and efficient utilization of tannase TanBLp.

Lactic Acid Bacteria-Fermentable Cereal- and Pseudocereal-Based Beverages

Plant beverages are becoming more popular, and fermented cereal- or pseudocereal-based beverages are increasingly used as alternatives for fermented products made from cow milk. This review aimed to describe the basic components of cereal- or pseudocereal-based beverages and determine the feasibility of fermenting them with lactic acid bacteria (LAB) to obtain products with live and active LAB cells and increased dietary value. The technology used for obtaining cereal- or pseudocereal-based milk substitutes primarily involves the extraction of selected plant material, and the obtained beverages differ in their chemical composition and nutritional value (content of proteins, lipids, and carbohydrates, glycemic index, etc.) due to the chemical diversity of the cereal and pseudocereal raw materials and the operations used for their production. Beverages made from cereals or pseudocereals are an excellent matrix for the growth of LAB, and the lactic acid fermentation not only produces desirable changes in the flavor of fermented beverages and the biological availability of nutrients but also contributes to the formation of functional compounds (e.g., B vitamins).

Enriching Lactobacilli from Fermented Pulse Dal Flour-Analyzing its Efficacy in Utilizing Carbohydrates and Production of α-galactosidase Enzyme During Pigeon Pea Fermentation

Pigeon peas are an excellent source of carbohydrates, proteins and other nutrients. Many traditional fermented foods are prepared from cereals and combinations of cereals and pulses that usually contain Lactic acid bacteria (LAB), Bacillus, Enterococcus and yeast. Lactobacillus can be used as a starter culture for such fermentation using pulses, as very few reports are available on fermented pulse-based products. Hence, pulse dal flour was used as a source for isolation of Lactobacillus to maintain their functionality, growth characteristics and activity during food processing. In this study, we investigated the potential of lactobacilli from fermented pigeon pea to utilize carbohydrates, the ability to degrade non-digestible oligosaccharides and the production of the α-galactosidase enzyme. Lactobacillus isolated from six different pulse dal flour grew well during fermentation with carbohydrates in mMRS medium. Among Lactobacillus species, only Lactobacillus brevis displayed the highest α-galactosidase activity (1.24 U/ml), where raffinose was added as the sole carbohydrate source in the medium. The isolate was further tested in pigeon pea fermentation, where it showed maximum activity (1.86 U/ml) and complete hydrolysis of non-digestible oligosaccharides was observed. Overall, usage of Lactobacilli could be an excellent opportunity to design and develop a novel pulse-based fermented product contributing to beneficial bioactive compounds and improving the properties of food.

A review on enzyme-producing lactobacilli associated with the human digestive process: From metabolism to application

Complex carbohydrates, proteins, and other food components require a longer digestion process to be absorbed by the lining of the alimentary canal. In addition to the enzymes of the gastrointestinal tract, gut microbiota, comprising a large range of bacteria and fungi, has complementary action on the production of digestive enzymes. Within this universe of "hidden soldiers", lactobacilli are extensively studied because of their ability to produce lactase, proteases, peptidases, fructanases, amylases, bile salt hydrolases, phytases, and esterases. The administration of living lactobacilli cells has been shown to increase nutrient digestibility. However, it is still little known how these microbial-derived enzymes act in the human body. Enzyme secretion may be affected by variations in temperature, pH, and other extreme conditions faced by the bacterial cells in the human body. Besides, lactobacilli administration cannot itself be considered the only factor interfering with enzyme secretion, human diet (microbial substrate) being determinant in their metabolism. This review highlights the potential of lactobacilli to release functional enzymes associated with the digestive process and how this complex metabolism can be explored to contribute to the human diet. Enzymatic activity of lactobacilli is exerted in a strain-dependent manner, i.e., within the same lactobacilli species, there are different enzyme contents, leading to a large variety of enzymatic activities. Thus, we report current methods to select the most promising lactobacilli strains as sources of bioactive enzymes. Finally, a patent landscape and commercial products are described to provide the state of art of the transfer of knowledge from the scientific sphere to the industrial application.

Effect of Lactic Acid Bacteria on the Lipid Profile of Bean-Based Plant Substitute of Fermented Milk

Biological processes of legumes may change their nutritional value of lipids, but there is no research on the fatty acid profile and their position distribution in fermented beverages obtained from germinated bean seeds. The present study aimed to determine the effect of fermentation by Lactobacillus strains on the fatty acid profile and their positional distribution in triacylglycerols of beverage obtained from germinated bean “Piękny Jaś Karłowy” (Phaseolus vulgaris) fermented by Lactobacillus strains. The population of lactobacilli (the pour plate method), pH, the fatty acid profile (gas chromatograph with a flame ionization detector), and the positional distribution of fatty acids in triacylglycerols (GC-FID) were determined before and after the fermentation of received beverages. The fermentation of beverages did not change the lactobacilli population (over 7 log₁₀ CFU/g), but changed pH (to 4.7–3.7 or 5.8–5.6), fatty acid profile, and the positional distribution of fatty acids were observed. The fermentation process contributed to an increase in the share of palmitic, stearic, and oleic acids in the fatty acid profile compared to that in raw bean seeds. The fermentation processes changed the share of individual acids in positions sn–1 and sn–3 depending on Lactobacillus strain used. Compared to non-fermented beverages, in most fermented beverages, a lower share of palmitic and stearic acids, as well as a higher share of oleic acid in the sn–2 were observed.

A Holistic Review on Euro-Asian Lactic Acid Bacteria Fermented Cereals and Vegetables

Lactic acid fermentation is one of the oldest methods used worldwide to preserve cereals and vegetables. Europe and Asia have long and huge traditions in the manufacturing of lactic acid bacteria (LAB)-fermented foods. They have different cultures, religions and ethnicities with the available resources that strongly influence their food habits. Many differences and similarities exist with respect to raw substrates, products and microbes involved in the manufacture of fermented products. Many of them are produced on industrial scale with starter cultures, while others rely on spontaneous fermentation, produced homemade or in traditional events. In Europe, common LAB-fermented products made from cereals include traditional breads, leavened sweet doughs, and low and non-alcoholic cereal-based beverages, whereas among vegetable ones prevail sauerkraut, cucumber pickles and olives. In Asia, the prevailing LAB-fermented cereals include acid-leavened steamed breads or pancakes from rice and wheat, whereas LAB-fermented vegetables are more multifarious, such as kimchi, sinki, khalpi, dakguadong, jiang-gua, soidon and sauerkraut. Here, an overview of the main Euro-Asiatic LAB-fermented cereals and vegetables was proposed, underlining the relevance of fermentation as a tool for improving cereals and vegetables, and highlighting some differences and similarities among the Euro-Asiatic products. The study culminated in "omics"-based and future-oriented studies of the fermented products.

Screening of lactic starter from Tunisian fermented vegetables and application for the improvement of caper (Capparis spinosa) fermentation through an experimental factorial design

Purpose

This study aims at designing a lactic starter for caper fermentation isolated from Tunisian fermented vegetables to improve the process and produce consistent and high-quality product.

Methods

In this study, the lactic starter was isolated by exploring the lactic acid bacteria (LAB) of Tunisian artisanal fermented vegetables. Identification was carried out by partial 16S rRNA gene sequencing. Screening was based on salt tolerance and antagonistic activities against Escherichia coli ATCC 10536 and Enterococcus faecalis ATCC 10541. Caper fermentation was optimized through a full factorial experimental design (23), by exploring three factors: starter inoculum size, NaCl concentration, and acetate content. Differences in pH values, Total aerobic mesophilic bacteria and LAB counts between the beginning and end of fermentation are selected as responses and corresponding regression coefficients were calculated.

Results

The lactic microbiota is mainly represented by Lactobacillus plantarum group. Based on salt tolerance and antimicrobial activity, the strain Lactobacillus plantarum F3 was selected as starter for caper fermentation. The effect of NaCl concentration, acetate content, and inoculum size on acidity, total aerobic mesophilic bacteria count, and LAB count after 1 week and 1 month of caper fermentation was studied. Depending on the fermentation time, either 1 week or 1 month, the initial conditions should comprise 0% acetate, 108 CFU/mL inoculum, and 5% NaCl for 1 week against 5% acetate, 107 CFU/mL inoculum, and 10% NaCl for 1 month lasting caper fermentation. A protocol for caper fermentation was set up ensuring hygienic quality and LAB viability.

Conclusion

Lb. plantarum F3 was selected as lactic starter for caper fermentation, and initial fermentation conditions were optimized through a full factorial design. This work has shown loss in LAB viability after 1 week of fermentation. Based on results obtained, an optimized fermentation protocol was set up. This protocol ensures LAB survival and high hygienic quality of the product.

Phytases of Probiotic Bacteria: Characteristics and Beneficial Aspects

Probiotics play a vital role in clinical applications for the treatment of diarrhea, obesity and urinary tract infections. Phytate, an anti-nutrient, chelates essential minerals that are vital for human health. In the past few decades, research reports emphasize extensively on phytate degradation in animals. There is a growing need for finding alternate strategies of phytate utilization in human, as they are unable to produce phytase. At this juncture, probiotics can be utilized for phytase production to combat mineral deficiency in humans. The main focus of this review is on improving phosphate bioavailability by employing two approaches: supplementation of (1) fermented food products that contain probiotics and (2) recombinant phytase producing bacteria. In addition, several factors influencing phytase activity such as bacterial viability, optimal pH, substrate concentration and specificity were also discussed.

Fermented Aloreña Table Olives as a Source of Potential Probiotic Lactobacillus pentosus Strains

A collection of 31 Lactobacillus pentosus strains isolated from naturally fermented Aloreña green table olives were screened in depth in the present study for their probiotic potential. Several strains could be considered promising probiotic candidates since they showed good growth capacity and survival under simulated gastro-intestinal conditions (acidic pH of 1.5, up to 4% of bile salts and 5 mM of nitrate), good ability to auto-aggregate which may facilitate their adhesion to host cells as multiple aggregates and the subsequent displacement of pathogens. Moreover, co-aggregation of lactobacilli with pathogenic bacteria was shown with Listeria innocua, Staphylococcus aureus, Escherichia coli, and Salmonella Enteritidis as good defense strategy against gut and food pathogens. Furthermore, they exhibited adherence to intestinal and vaginal cell lines, such property could be reinforced by their capacity of biofilm formation which is also important in food matrices such as the olive surface. Their antagonistic activity against pathogenic bacteria by means of acids and plantaricins, and also their different functional properties may determine their efficacy not only in the gastro-intestinal tract but also in food matrices. Besides their ability to ferment several prebiotics, the new evidence in the present study was their capacity to ferment lactose which reinforces their use in different food matrices including dairy as a dietary adjunct to improve lactose digestibility. Lactobacillus pentosus CF2-10N was selected to have the best probiotic profile being of great interest in further studies. In conclusion, spontaneous fermented Aloreña table olives are considered a natural source of potential probiotic L. pentosus to be included as adjunct functional cultures in different fermented foods.

Bacterial community dynamics, lactic acid bacteria species diversity and metabolite kinetics of traditional Romanian vegetable fermentations

BACKGROUND

Artisanal vegetable fermentations are very popular in Eastern European countries. Fresh vegetables undergo a spontaneous fermentation in the presence of salt, which is mainly carried out by lactic acid bacteria (LAB).

RESULTS

Culture-dependent and culture-independent analyses of end-samples of various spontaneous vegetable fermentations carried out in houses of the Chiodju region (central Romania) revealed Lactobacillus plantarum and Lactobacillus brevis as the most frequently isolated LAB species. Leuconostoc mesenteroides and Leuconostoc citreum were also found. Furthermore, the community dynamics of spontaneous cauliflower and mixed-vegetable (green tomatoes, carrots and cauliflower) fermentations revealed three steps: an initial phase characterised by the presence of Enterobacteriaceae and a wide LAB species diversity, encompassing Weissella species; a second phase from day 3 onwards wherein L. citreum and Lb. brevis occurred; and a final phase characterised by the prevalence of Lb. brevis and Lb. plantarum. Metabolite target analysis revealed that glucose and fructose were mostly depleted at the end of fermentation. The main products of carbohydrate metabolism were lactic acid, acetic acid, ethanol and small amounts of mannitol, indicating heterolactate fermentation.

CONCLUSION

Given their prevalence at the end of vegetable fermentations, Lb. brevis and Lb. plantarum appear to be good candidate starter cultures for controlled vegetable fermentation processes.

Identification and cloning of a gene encoding tannase (tannin acylhydrolase) from Lactobacillus plantarum ATCC 14917(T)

The gene tanLpl, encoding a novel tannase enzyme (TanLpl), has been cloned from Lactobacillus plantarum ATCC 14917(T). This is the first report of a tannase gene cloned from a bacterial source other than from Staphylococcus lugdunensis, which has been reported elsewhere. The open reading frame of tanLpl, spanning 1410 bp, encoded a 469-amino-acid protein that showed 28.8% identity to the tannase of S. lugdunensis with several commonly conserved sequences. These sequences could not be found in putative tannases reported for other bacteria and fungi. TanLpl was expressed in Escherichia coli DH5alpha from a pGEM-T expression system and purified. SDS-PAGE analysis indicated that purified TanLpl was a monomer polypeptide of approximately 50 kDa in size. Subsequent enzymatic characterization revealed that TanLpl was most active in an alkaline pH range at 40 degrees C, which was quite different from that observed for a fungal tannase of Aspergillus oryzae. In addition, the Michaelis-Menten constant of TanLpl was markedly lower than that of A. oryzae tannase. The evidence suggests that TanLpl should be classified into a novel family of tannases.