Characterisation and selection of probiotic lactobacilli for a preliminary minipig feeding trial and their effect on serum cholesterol levels, faeces pH and faeces moisture content

Characterization of Lactic Acid Bacterium Exopolysaccharide, Biological, and Nutritional Evaluation of Probiotic Formulated Fermented Coconut Beverage

Exopolysaccharides (EPSs), produced by lactic acid bacteria (LAB), play a crucial role in enhancing the texture and stability of yoghurt by forming a protective matrix that helps to maintain its rheological and sensory characteristics. The search for a dairy alternative for the lactose-intolerant populace is a necessity, and the use of probiotic LAB and their EPS to formulate fermented coconut beverage (FFCB) will be of added advantage. The production and characterization of EPS from a LAB strain isolated from yoghurt, its probiotic and antioxidant potential, and its application in the production of probiotic FFCB were investigated. The EPS produced by the isolate was characterized using a scanning electron microscope (SEM), high-performance liquid chromatography, Fourier transform infrared (FT-IR) spectroscopy, and energy-dispersive X-ray. The antioxidant potential of the EPS was determined. The isolate probiotic potential, such as tolerance to low pH, bile salts, gastric pH, autoaggregation, coaggregation, antimicrobial potential, and antibacterial activity, was evaluated, and the isolate was identified using 16S rRNA. The LAB strain and the EPS were used for the formulation of probiotic FFCB, and the proximate mineral composition of the enriched yoghurt was determined. Isolate W3 produced 6204.50 mg/L EPS. The EPS produced by the LAB was spherical with a coarse surface. Hydroxyl, carboxyl, and α-pyranose were the major functional groups present in the EPS. Eight monosaccharides were present in glucose, which has the highest molar ratio. The EDX spectra ascertain the presence of carbon, oxygen (carbohydrate), and other elements. The purified EPS exhibited antioxidant activity in a dose-dependent manner. DPPH, FRAP, TAC, and TPC of the EPS ranged from 42.36% to 75.88%, 2.48 to 5.31 μg/mL, 1.66 to 3.57 μg/mL, and 1.42 to 2.03 μg/mL, respectively. The LAB strain exhibited moderate tolerance to low pH, bile salts, gastric juice, good autoaggregation (13.33%), coaggregation (0%-59.09%) with E. coli, and varied sensitivity to different antibiotics used. The isolate is hemolysis, deoxyribonuclease (DNase), and lecithinase negative, possesses characteristics of probiotics, and could have the ability to confer health benefits. The LAB strain has a 100.0% pairwise identity to Pediococcus acidilactici. The FFCB has pH, lactic acid, specific gravity, total soluble solids (TSSs), and vitamin C content ranging from 5.81 to 6.8, 10.8 to 55.8 mg/L, 0.910 to 1.394 kg/m3, 0.136 to 0.196 °Bx, and 0.26% to 0.66%. The formulated beverage fermented with a commercial starter had the highest lactic acid at Day 7 of storage. The FFCB sample with the commercial starter and the probiotic strain had the highest ash and crude fiber content (1.3%, 0.68%). The FFCB fortified with EPS showed the highest protein content (4.6%). The formulated yogurt samples fortified with the highest concentration of EPS had the highest calcium content after 7 days of storage (162.31 ± 0.01a). In conclusion, EPS produced by Pediococcus acidilactici was a heteropolymeric EPS with good antioxidant activity, and the LAB strain exhibited a good starter for producing FFCB enriched with EPS. The FFCB has good nutritional characteristics and could serve as a functional and natural nutraceutical food for the lactose intolerance population.

Probiotic and immunostimulating effects of live and heat-killed Pediococcus pentosaceus TAP041

The selected strain, TAP041, showing an excellent ability to reduce the glyoxal and methylglyoxal levels, was identified by 16S rRNA gene-based phylogenetic analysis as Pediococcus pentosaceus. It demonstrated probiotic properties, including acid, bile salt, pancreatin, lysozyme tolerance, gut adhesion, and auto/coaggregation. In RAW264.7 macrophages, both live and heat-killed strains induced nitric oxide production and activated inducible nitric oxide synthase. RAW264.7 treated with P. pentosaceus TAP041 increased the expression level of tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and cyclooxygenase-2, and regulated the expression of c-Jun amino-terminal kinase, p38, and extracellular signal-regulated kinase. These findings suggest that both live and heat-killed P. pentosaceus TAP041 can be used as potential immunostimulatory agents in functional food additives.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-024-01530-2.

The role of probiotics in tissue engineering and regenerative medicine

Tissue engineering and regenerative medicine (TERM) as an emerging field is a multidisciplinary science and combines basic sciences such as biomaterials science, biology, genetics and medical sciences to achieve functional TERM-based products to regenerate or replace damaged or diseased tissues or organs. Probiotics are useful microorganisms which have multiple effective functions on human health. They have some immunomodulatory and biocompatibility effects and improve wound healing. In this article, we describe the latest findings on probiotics and their pro-healing properties on various body systems that are useable in regenerative medicine. Therefore, this review presents a new perspective on the therapeutic potential of probiotics for TERM.

Probiotic Potential of the Marine Isolate Enterococcus faecium EA9 and In Vivo Evaluation of Its Antisepsis Action in Rats

This study aims to obtain a novel probiotic strain adapted to marine habitats and to assess its antisepsis properties using a cecal ligation and puncture (CLP) model in rodents. The marine Enterococcus faecium EA9 was isolated from marine shrimp samples and evaluated for probiotic potential after phenotypical and molecular identification. In septic animals, hepatic and renal tissues were histologically and biochemically evaluated for inflammation and oxidative stress following the probiotic treatment. Moreover, gene expressions of multiple signaling cascades were determined using RT-PCR. EA9 was identified and genotyped as Enterococcus faecium with a 99.88% identity. EA9 did not exhibit any signs of hemolysis and survived at low pH and elevated concentrations of bile salts. Moreover, EA9 isolate had antibacterial activity against different pathogenic bacteria and could thrive in 6.5% NaCl. Septic animals treated with EA9 had improved liver and kidney functions, lower inflammatory and lipid peroxidation biomarkers, and enhanced antioxidant enzymes. The CLP-induced necrotic histological changes and altered gene expressions of IL-10, IL-1β, INF-γ, COX-2, SOD-1, SOD-2, HO-1, AKT, mTOR, iNOS, and STAT-3 were abolished by the EA9 probiotic in septic animals. The isolate Enterococcus faecium EA9 represents a promising marine probiotic. The in vivo antisepsis testing of EA9 highlighted its potential and effective therapeutic approach.

Lactobacillus gasseri RW2014 Ameliorates Hyperlipidemia by Modulating Bile Acid Metabolism and Gut Microbiota Composition in Rats

Hyperlipidemia is a leading risk of cardiovascular and cerebrovascular disease. Dietary supplementation with probiotics has been suggested as an alternative intervention to lower cholesterol. In the current study, we isolated a strain of Lactobacillus gasseri RW2014 (LGA) from the feces of a healthy infant fed with breast milk, and it displayed bile salt hydrolase (BSH) activity. Using this strain we determined its cholesterol-lowering and fatty liver-improving functions. SD rats were randomly divided into four groups. The control rats were fed a commercial chow diet and the other three groups were fed a high-fat diet (HFD) for a 7-week experiment period. After two weeks of feeding, the rats in PBS, simvastin, and LGA group were daily administered through oral gavage with 2 mL PBS, simvastin (1 mg/mL), and 2 × 10⁹ CFU/mouse live LGA in PBS, respectively. After five weeks of such treatment, the rats were euthanized and tissue samples were collected. Blood lipid and inflammatory factors were measured by ELISA, gut microbiota was determined by 16S rRNA sequencing, and bile acids profiles were detected by metabolomics. We found that LGA group had lower levels of blood cholesterol and liver steatosis compared to the simvastin group. LGA also significantly reducedthe levels of inflammatory factors in the serum, including TNFα, IL-1β, MCP-1, IL-6, and exotoxin (ET), and increased the levels of short-chain fatty acids in feces, including isobutyric acid, butyric acid, isovaleric acid, valeric acid, and hexanoic acid. In addition, LGA altered the compositions of gut microbiota as manifested by the increased ratio of Firmicutes/Bacteroides and the relative abundance of Blautia genus. Targeted metabolomics results showed that bile acids, especially free bile acids and secondary bile acids in feces, were increased in LGA rats compared with the control rats. Accordingly, the rats administrated with LGA also had a higher abundance of serum bile acids, including 23-norcholic acid, 7-ketolithocholic acid, β-muricholic acid, cholic acid, and deoxycholic acid. Together, this study suggests that LGA may exert a cholesterol-lowering effect by modulating the metabolism of bile acids and the composition of gut microbiota.

Versatile Triad Alliance: Bile Acid, Taurine and Microbiota

Taurine is the most abundant free amino acid in the body, and is mainly derived from the diet, but can also be produced endogenously from cysteine. It plays multiple essential roles in the body, including development, energy production, osmoregulation, prevention of oxidative stress, and inflammation. Taurine is also crucial as a molecule used to conjugate bile acids (BAs). In the gastrointestinal tract, BAs deconjugation by enteric bacteria results in high levels of unconjugated BAs and free taurine. Depending on conjugation status and other bacterial modifications, BAs constitute a pool of related but highly diverse molecules, each with different properties concerning solubility and toxicity, capacity to activate or inhibit receptors of BAs, and direct and indirect impact on microbiota and the host, whereas free taurine has a largely protective impact on the host, serves as a source of energy for microbiota, regulates bacterial colonization and defends from pathogens. Several remarkable examples of the interaction between taurine and gut microbiota have recently been described. This review will introduce the necessary background information and lay out the latest discoveries in the interaction of the co-reliant triad of BAs, taurine, and microbiota.

Polysorbate 80 improves the adhesion and survival of yogurt starters with cholesterol uptake abilities

The goal of this study is to improve the adhesion and survival of yogurt bacteria with probiotic traits by using polysorbate 80, a food additive emulsifier commonly found in milk derivative products. Polysorbate 80 was used at 1% (w/v), and its effects on yogurt bacteria's survival under simulated digestive conditions, cholesterol uptake activities, bile salt hydrolase (BSH) activity, and adhesion to HT-29 culture were studied. In the presence of 1% polysorbate 80, both starters demonstrated better cholesterol uptake and BSH activities, as well as higher bacterial survival at pH 2.5, particularly in associated cultures. In the presence of 0.3 % bile or cholic acid, polysorbate 80 reduced the drop in L. bulgaricus's survival load. However, the carbon source had a greater impact on S. thermophilus bile tolerance than the food additive emulsifier. Oleic acid was incorporated into both bacterial membranes when grown in the presence of bile and polysorbate 80, resulting in a higher unsaturated/saturated fatty acid ratio. In the presence of polysorbate 80, S. thermophilus adhered to HT-29 cells 2.3-fold better, while L. bulgaricus's adhesion remained unchanged. We suggest that polysorbate 80 may have a protective effect on cell survival under simulated digestive stress as well as a role in yogurt bacteria adhesion to the intestines, giving these bacteria more opportunities to exert their purported cholesterol-removal activities.

Psychobiotic Potential of Gamma-Aminobutyric Acid-Producing Marine Enterococcus faecium SH9 from Marine Shrimp

Psychobiotics are a novel class of probiotics with potential to confer mental wellness via production of neuroactive compounds such as gamma-aminobutyric acid (GABA). The demand for new biological sources of GABA has increased steadily. Therefore, the current study reports the isolation of 17 presumptive lactic acid bacteria (LAB) from marine samples and their screening for GABA synthesis from monosodium glutamate (MSG) using thin-layer chromatography (TLC). The isolate SH9 was selected as a high GABA producing strain. The GABA content of SH9 cell free supernatant (CFS) was quantitatively determined by high performance liquid chromatography (HPLC) to be 0.97 g/L. SH9 was identified biochemically and molecularly as Enterococcus faecium (identity 99%). Moreover, SH9 demonstrated promising probiotic potentials; it gave no signs of hemolysis and could survive at low pH values and high bile salt concentrations. It also exhibited antimicrobial activity against highly pathogenic strains and the ability to grow at 6.5% NaCl. In addition, SH9 CFS showed anti-inflammatory and antioxidant properties. The glutamate decarboxylase (GAD) gene was detected in SH9 by using specific primers. Product of 540 bp was obtained, sequenced, and analyzed (accession number: MW713382). The inferred amino acid sequence was 99.3% identical to Lactobacillus plantarum M-6 gadB gene. The findings of this study suggest that the marine isolate E. faecium SH9 could be used as a novel psychobiotics in the development of GABA rich healthy products.

Production and Characterization of Exopolysaccharide From Newly Isolated Marine Probiotic Lactiplantibacillus plantarum EI6 With in vitro Wound Healing Activity

Because of its safety, biological activities, and unique properties, exopolysaccharide (EPS) from lactic acid bacteria (LAB) has been developed as a potential biopolymer. A few studies have investigated the EPS produced by marine LAB. This study reports the wound healing activity of an EPS produced by a marine isolate identified as Lactiplantibacillus plantarum EI6, in addition to assessing L. plantarum EI6's probiotic properties. EI6 demonstrated promising antimicrobial activity against different pathogenic bacteria, as well as the ability to withstand stomach pH 3, tolerate 0.3% bile salt concentration, and exhibit no signs of hemolysis. Furthermore, EI6 was able to produce 270 mg/L of EPS upon growth for 48 h at 37°C in an MRS medium enriched with 1.0% of sucrose. The chemical features of the novel EI6-EPS were investigated: the UV-vis estimated a high carbohydrate content of ~91.5%, and the FTIR emphasized its polysaccharide nature by the characteristic hydroxyl, amide I, II, & III, and glycosidic linkage regions. The GC-MS and NMR analyses revealed the existence of five monosaccharides, namely, rhamnose, galactose, mannose, glucose, and arabinose, existing mainly in the pyranose form and linked together by α- and β-glycosidic linkages. EI6-EPS was found to be safe (IC50 > 100 μg/ml) and induced human skin fibroblasts (HSF) proliferation and migration. These findings imply that EI6 can be used as a safe source of bioactive polymer in wound care.

Assessment of Yeasts as Potential Probiotics: A Review of Gastrointestinal Tract Conditions and Investigation Methods

Probiotics are microorganisms (including bacteria, yeasts and moulds) that confer various health benefits to the host, when consumed in sufficient amounts. Food products containing probiotics, called functional foods, have several health-promoting and therapeutic benefits. The significant role of yeasts in producing functional foods with promoted health benefits is well documented. Hence, there is considerable interest in isolating new yeasts as potential probiotics. Survival in the gastrointestinal tract (GIT), salt tolerance and adherence to epithelial cells are preconditions to classify such microorganisms as probiotics. Clear understanding of how yeasts can overcome GIT and salt stresses and the conditions that support yeasts to grow under such conditions is paramount for identifying, characterising and selecting probiotic yeast strains. This study elaborated the adaptations and mechanisms underlying the survival of probiotic yeasts under GIT and salt stresses. This study also discussed the capability of yeasts to adhere to epithelial cells (hydrophobicity and autoaggregation) and shed light on in vitro methods used to assess the probiotic characteristics of newly isolated yeasts.

Development of Thermotolerant Lactobacilli Cultures with Improved Probiotic Properties Using Adaptive Laboratory Evolution Method

Probiotics play a significant role in functional foods. Heat stress and dehydration are the two principal mechanisms leading to inactivation and loss of probiotics viability in its production. There is a need to develop an industrial organism to withstand higher temperatures during its processing and storage. This current study aims to develop thermotolerant strains of Lacticaseibacillus casei N (N) and Lactobacillus helveticus NRRL B-4526 (H) by acclimatizing the wild-type strains to the higher temperature of 45 °C by adaptive laboratory evolution. A two-fold increase in biomass was observed in both acclimatized strains up to the 200th generation, which subsequently remained stable after 500 generations. The morphological change of these acclimatized strains was observed under scanning electron microscopy. Also, there was an increase in probiotic attributes of these acclimatized strains compared to their wild-types. Among two acclimatized strains, L. casei N-45 had shown higher tolerance in the acidic pH 3.0 (89.31%), the bile of 0.3% (84.45%), simulated gastric juice (79.12%), and simulated intestinal juice (73.86%). There was also an increase in salt tolerance (NaCl), radical scavenging activity, autoaggregation, coaggregation, and hydrophobicity of these adapted strains. The total protein profiling using 2D gel electrophoresis reveals the differences in protein expressions between wild-type and acclimatized strains. Specific protein spots from acclimatized strains of H-45 and N-45 were further subjected to MALDI-TOF MS/MS. Some of the identified proteins were recognized to play a role in RNA chaperones and protein synthesis during stress conditions.

Functional and probiotic characterization of Ligilactobacillus salivarius CPN60 isolated from calf faeces and its appraisal in rats

Emerging concern about the emergence of antimicrobial resistance has limited the use of antibiotics in calves. Hence, there is a need to find suitable alternatives to antibiotics to manage gastrointestinal infections in neonatal calves. The objective of the present study was to develop a probiotic of calf-origin for its potential application in calf nutrition. Accordingly, 69 lactic acid bacteria (LAB) strains were isolated from faeces of newborn calves, out of which 10 strains were short-listed for further in vitro testing based on the aggregation time and cell surface hydrophobicity. The results of acid-, bile- and phenol-tolerance tests indicated that out of the ten strains, the isolate CPN60 had better resistance to these adverse conditions likely to be encountered in the gastrointestinal tract. The isolate also showed an optimal ability to produce biofilm. Further assessments reiterated its superiority in terms of co-aggregation and antagonistic activity against pathogenic strains of Escherichia coli. Subsequently, the isolate was identified through 16S rRNA sequencing and sequence homology and designated as Ligilactobacillus salivarius CPN60. The candidate probiotic was evaluated in vivo using 48 male (5 weeks old) Wistar rats, divided into two equal groups viz. control (CON) and probiotic (PRO). During the 4-weeks feeding trial, the PRO group rats were gavaged with one mL culture of L. salivarius CPN60 equivalent to 10⁸ CFU/rat. The in vivo trial results indicated better nutrient utilization efficiency and growth performance (p < 0.001) of the PRO group of rats. The probiotic supplementation improved the faecal concentration of lactate (p < 0.001) and individual as well as total short-chain fatty acids (p < 0.001) production. The cell-mediated immune response, assessed as a delayed-type hypersensitivity reaction to phytohaemagglutinin-P, was improved (p < 0.001) in PRO compared to the CON rats. It is concluded that the calf-origin probiotic L. salivarius CPN60, in addition to possessing all the in vitro functional attributes of a candidate probiotic, also has desirable potential for its future use in young calves to promote gut health and immunity.

Leuconostoc mesenteroides subsp. mesenteroides SD23 Prevents Metabolic Dysfunction Associated with High-Fat Diet-Induced Obesity in Male Mice

High-fat diet (HFD) consumption induces obesity and increases blood glucose, insulin resistance, and metabolic disorders. Recent studies suggest that probiotics might be a novel approach to counteract these effects in the treatment of obesity. Here, we evaluated the effect of Leuconostoc mesenteroides subsp. mesenteroides SD23 on obesity-related metabolic dysfunction. In the present study, mice were randomly divided into four dietary groups: standard diet (C), HFD (OB), standard diet with L. mesenteroides SD23 (CP), and HFD with L. mesenteroides SD23 (OBP). Diets were maintained for 14 weeks. Animal weight was monitored and biochemical and histological analyses were performed after intervention. OB showed metabolic dysfunction, and increased the number of larger adipocytes compared to C. OB induced liver tumor necrosis factor-α (TNF-α) expression, increased cholesterol, leptin, and glucose levels compared to C. OBP reduced body weight, glucose, cholesterol, and leptin levels and improved glucose tolerance compared to OB. OBP also reduced liver steatosis, the number of larger adipocytes in adipose tissue, and reduced the villus height in the small intestine. OBP decreased expression of TNF-α and increased expression of IL-10 in liver. The parameters evaluated in the CP were similar to the C. This study provides novel evidence that dietary intervention with L. mesenteroides SD23 improves metabolic dysfunction related to obesity in HFD-fed mice.

Genomic and phenotypic characterization of Bacillus velezensis AMB-y1; a potential probiotic to control pathogens in aquaculture

The aim of this investigation was to isolate and identify Bacillus species isolated from the internal microbiota of Red sea stingrays as potential probiotics. An initial assay on the ability of the isolates to control stingray pathogens of Vibrio species led to the selection of one highly antagonistic isolate. The most potent isolate was identified based on whole genome phylogeny as Bacillus velezensis AMB-y1. Genome mining for secondary metabolites identified five antibacterial biosynthetic clusters that produce, bacilysin, bacillaene, difficidin, macrolactin and mersacidin. Genome mining also identified two antifungal biosynthetic clusters which encode genes to produce bacillomycin D and fengycin. The genome mining also identified an unknown NRPS-transAT-PKS cluster that likely produced another compound with antibiotic activity. The strain was further characterized by the assessment of abiotic stress tolerances that are required in potential probiotic agents. The selected isolate had promising results in abiotic stress tolerance; pH tolerance within the range from 4.0 to 8.0, able to survive concentrations of bile salt up to 0.4% and sodium chloride from 0 to 6.5%. In addition, the strain showed a value of hydrophobicity (31%) along with a higher value of auto-aggregation (49.9%), which demonstrates its potential ability to adhere to the intestinal wall on the basis of its cell surface traits. The strain was evaluated for susceptibility to antimicrobials and the novel B. velezensis AMB-y1 has potential to be used as a probiotic in aquaculture to control marine fish and stingray pathogens.

Isolation, identification, and selection of strains as candidate probiotics and starters for fermentation of Swedish legumes

BACKGROUND

The non-dairy sector is growing, fermented alternatives to dairy are sparse. Adapted starter cultures to substituting raw materials needs to be developed.

OBJECTIVE

Aims of this study were to isolate, identify, and phenotypically characterize lactic acid bacteria (LAB) that inhabit Swedish legumes, and assess properties necessary for selecting strains with the ability to ferment a bean beverage and with potential health beneficial properties.

DESIGN

Isolates of presumed LAB were obtained from legumes collected at Öland, Sweden. Strain diversity was assessed by repetitive polymerase chain reaction (rep-PCR). The strains were identified using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Species belonging to Enterococcus were predominant along with Pediococcus and closely related Bacillus. Strains were tested for tolerance to low pH, phenol, and bile as well as their bile salt hydrolase (BSH) activity. In addition, Enterococcus strains were tested for antibiotic resistance, and Pediococcus strains for their ability to ferment a bean beverage.

RESULTS

From the 25 strains characterized, five were found resistant to low pH, bile, and phenol, suggesting that they can survive a passage through the gastrointestinal tract (GIT) and hence potentially exert beneficial effects in the host. These are suggested for further investigation on specific host-beneficial properties. Two of these, belonging to Pediococcus pentosaceus, were able to ferment a bean beverage without any added nutrients, indicating that the Pediococcus strains are well adapted to the bean substrate. One of the P. pentosaceus strains were also able to markedly improve the reduction of phytate by the phytase-producing yeast strain Pichia kudriavzevii TY1322 during co-fermentation as well as increase the final cell count of the yeast strain.

CONCLUSION

Strain isolation and characterization performed in this study aids in selecting starter cultures for legume fermentation. Nutritional properties can be improved by co-fermentation with yeast indicating that novel nutritious fermented non-dairy products could be developed.

Synbiotic Combination of Djulis (Chenopodium formosanum) and Lactobacillus acidophilus Inhibits Colon Carcinogenesis in Rats

Djulis is a functional grain containing prebiotic dietary fiber, which has an anti-cancer potential. This study examined the preventive effect of djulis alone or in combination with Lactobacillus acidophilus on colon carcinogenesis induced by 1,2-dimethylhydrazine (DMH) and dextran sulfate sodium (DSS). Rats were divided into five groups and fed B (AIN-93G, blank), C (AIN-93G, control), D (10% djulis), DLA (10% djulis plus 5 × 10⁶ cfu L. acidophilus/g), and DHA (10% djulis plus 5 × 10⁷ cfu L. acidophilus/g) diets, respectively. All rats except for those in group B received three doses of DMH (40 mg/kg) by intraperitoneal injection and 3% DSS in drinking water. After 10 weeks of feeding, the colon was analyzed for precancerous lesions and biomarkers. DMH and DSS treatment induced aberrant crypt foci (ACF), especially in the distal colon. D, DLA, and DHA significantly reduced the numbers of total ACF, sialomucin-producing ACF (SIM-ACF), and mucin-depleted foci (MDF) in the distal colon compared to C. Additionally, DLA and DHA further downregulated the expressions of proliferating cell nuclear antigen (PCNA) and cyclooxygenase-2 (COX-2) and regulated apoptosis-related proteins. These results suggest that synbiotic combination of djulis and L. acidophilus shows the best inhibitory effect on colon carcinogenesis via regulation of proliferative, inflammatory, and apoptotic pathways.

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.

Toward rational selection criteria for selection of probiotics in pigs

An accurate understanding of properties of probiotics is a prerequisite for selecting probiotic organisms for use in swine production. This review aims to review selection criteria for probiotic organism in swine. The systematically investigated ecological history rather than the source of isolates should be regarded as the natural origin of probiotic strains, which helps to correct the inconsistencies arising from incorrect identification of the source. Moreover, in vivo studies are suggested as follow-up assessment to validate the characteristics of probiotic predicted by in vitro experiments. In addition, the intended probiotic effect depends on the age of the animal and disease prevention in young animals may require different probiotic strains when compared to growth promotion in older animals. With adequate selection criteria, the inclusion of probiotic in feed supplementation is a promising way to exert positive effects on sows, newborns, weanling animals and grower-finisher pigs. Both host-adapted probiotics and nomadic probiotics can be applied for pathogen inhibition but host adapted organisms appear to have a different mode of action. Host-adapted probiotic strains are likely to be associated with exclusive colonization while the nomadic or environmental strain exert better immune stimulating functions. Strains with potent enzymatic activity are fitter for grower pigs favoring feed digestion and enhancing growth performance.

Effect of probiotic Pediococcus acidilactici FT28 on growth performance, nutrient digestibility, health status, meat quality, and intestinal morphology in growing pigs

Aim

The experiment was conducted to evaluate the effect of swine-origin probiotic Pediococcus acidilactici FT28 on growth, nutrient utilization, health status, meat quality and intestinal morphology in growing female pigs.

Materials and Methods

Pigs (n=27) were distributed into three groups (3 replicates of 3 each) and supplemented with basal diet either without probiotics (C) or with a probiotic of dairy-based (Lactobacillus acidophilus NCDC-15; TLact) or swine based (P. acidilactici FT28; TPedic). The probiotics were fed as fermented feed at 200 g/pig/day. At the end of the trial, six pigs from each group were selected for metabolism trial and then sacrificed to determine meat quality and intestinal morphology.

Results

Supplementation of both probiotics improved growth performance, whereas feed intake, digestibility of CP and N retention were better (p<0.05) in P. acidilactici FT28-fed group. However , the digestibility of dry matter (DM), organic matter (OM), ether extracts (EE), crude fiber and nitrogen free extract did not show any significant effect on probiotic supplementation. The serum A: G ratio, triglyceride, and cholesterol level were also improved (p<0.05) in TPedic group compared to other treatment groups. Both probiotic supplementations showed lower (p<0.05) serum glucose level with similar protein and albumin value, which indicated good utilization of feed as well as health status of growing pigs. Dressing percentage, vital organ weight, and EE of loin meat were higher (p<0.05) in probiotic-supplemented groups compared to control. However, P. acidilactici FT28-fed animals showed higher (p<0.05) CP and total ash percentage of meat without affecting pH, water holding capacity, and extract release volume of loin muscle. The villi height and crypt depth were better in both supplemented groups compared to control.

Conclusion

Results of the present study revealed that P. acidilactici FT28 could serve as better probiotic source in swine production for the better utilization of CP and N-retention in meat with improved health status and intestinal morphology.

In vitro and in vivo evidences for innate immune stimulators lactic acid bacterial starters isolated from fermented camel dairy products

Probiotics are commensals with special characteristics that are essential for the development of the immune system, and may protect mucosal surfaces against pathogens. In this study, a total of 40 lactic acid bacteria (LAB) were isolated from different raw and fermented camel's milk samples collected from Saudi Arabia (Makkah area) and Egypt (Fayoum), and tested for the probiotic properties. Among them, Pro 4 and Pro 7 isolates exhibited excellent probiotic potential including bile salt (0.2-0.6%), phenol tolerance (0.2-0.4%) and salt tolerance (0.0-10%). Furthermore, both strains exhibited antimicrobial activity against wide range of food-borne pathogens and Dermatophytes with average zone inhibition of 37.5, 35.5, 34.5, 27.5, 25 and 23.5 mm for Staphylococcus aureus, Trichophyton mentagrophytes, Escherichia coli, Listeria monocytogens, Candida albicans and Salmonella typhi, respectively. Furthermore, the in vivo study indicated that these strains significantly improved the mucosal immune responses through an increase in expression of TLR2 and IFNγ mRNA in mice intestine as well as increased the synthesis of polyclonal IgG, IgM and IgA in mice blood sera. Accordingly, due to these unique probiotic properties, both selected strains could be potentially used as probiotic starter cultures for fermented dairy foods as well as functional food and health products.

Effect of swine-origin probiotic Pediococcus acidilactici FT28 on maintenance of antioxidant status, blood haematology and biochemical profile in early weaned grower-finisher pigs

An experiment was conducted with early weaned crossbred piglets (36) to evaluate antioxidant status and blood biochemical profile in grower-finisher pigs. The piglets were distributed into three groups (4 replicates of 3 each) and supplemented with basal diet either without probiotics (T0) or with a probiotic of dairy based (Lactobacillus acidophilus NCDC-15; T1) or swine based (Pediococcus acidilactici FT28; T2). Blood was collected at 45, 90 days (grower phase) and 136, 180 days (finisher phase) of feeding and analysed for various antioxidants and metabolites. Results of the study revealed that supplementation of probiotics improved superoxide dismutase (SOD), catalase and reduced glutathione (GSH) activity in early weaned grower-finisher pigs. Whereas, GSH activity was better in P. acidilactici FT28 fed group compared to L. acidophilus fed group. Serum glucose level was reduced in both T1 and T2 groups compared to control, which was further reduced in T2 group compared to T1. The total protein, albumin and globulin level in serum remained higher in T2 group in comparison to other dietary groups. Serum triglyceride and LDL-cholesterol was lower in P. acidilactici FT28 fed group. The HDL-cholesterol level was better by probiotic supplementation in grower-finisher pigs. It was concluded that supplementation of hostorigin probiotic was effective to reduce stress besides having potential to improve blood biochemical profile.

Selection and characterization of probiotic lactic acid bacteria and its impact on growth, nutrient digestibility, health and antioxidant status in weaned piglets

The present study was aimed to develop an effective probiotic lactic acid bacteria (LAB) from piglet feces and in vitro characterization of probiotic properties. To confirm host-species specificity of probiotics, the efficacy of isolated LAB on growth, nutrient utilization, health and antioxidant status was observed in early weaned piglets. A total of 30 LAB were isolated from feces of five healthy piglets (28d old). All isolates were Gram positive, cocco-bacilli and catalase negative. Out of thirty LAB isolates, twenty were shortlisted on the basis of their tolerance to pH (3.0, 4.0, 7.0 and 8.0) and bile salts (0.075, 0.15, 0.3 and 1.0%). Whereas, fourteen isolates were selected for further in vitro probiotic characterization due higher (P<0.05) cell surface hydrophobicity to toluene (>45 percent). These isolates fermented twenty-seven different carbohydrates but were negative for ONPG, citrate and malonate. Also enabled to synthesize amylase, protease, lipase and phytase. They were sensitive to penicillin, azithromycin, lincomycin, clindamycin, erythromycin, cephalothin and chloramphenicol and resistant to ciprofloxacin, ofloxacin, gatifloxacin, vancomycin and co-trimoxazole. Except three isolates, all showed antagonistic activity (>60% co-culture activity) against Escherichia coli, Salmonella Enteritidis, Salmonella serotype (ser.) Typhimurium, Staphylococcus intermedius, Staph. chromogenes, Proteus mirabillis, Areomonas veonii, Bordetella bronchioseptica and Klebsialla oxytoca. The isolate Lacp28 exhibited highest tolerance to acidic pH and bile salts (up to 0.3%), phytase activity, cell surface hydrophobicity, antagonistic activity and co-culture assay (>80% growth inhibition). Host specificity of Lacp28 was further confirmed by heavy in vitro adhesion to pig intestinal epithelium cells compared to chicken. Hence, Lacp28 was selected and identified by phylogenetic analysis of 16S rRNA as Pediococcus acidilactici strain FT28 with 100% similarity (GenBank accession nos. KU837245, KU837246 and KU837247). The Pediococcus acidilactici FT28 was selected as potential probiotic candidature for in vivo efficacy in weaned pigs. Thirty-six crossbred piglets (28d) were randomly distributed into three groups (four replicates of three each) namely, basal diet without probiotics (T0) or with Lactobacillus acidophilus NCDC15 (conventional dairy-specific probiotic; T1) or Pediococcus acidilactici FT28 (swine-specific probiotic; T2). At end of the experiment, six piglets of similar body weight were selected to conduct digestion trial for estimation of nutrient digestibility. Results of the study indicated that supplementation of both probiotics improved (P<0.001) FCR compared to control without significant effect in average daily gain and DM intake. However, the apparent digestibility of crude protein and ether extract was better (P<0.01) in pigs fed P. acidilactici FT28 compared control and L. acidophilus fed groups. The total WBC and RBC count, serum glucose, total protein, albumin and globulin concentration was higher (P<0.05) in P. acidilactici FT28 fed group with better (P<0.05) catalase and superoxide dismutase activity measured in erythrocyte. It is concluded that species-specific Pediococcus acidilactici FT28 isolated with potential in vitro probiotic properties and also hold probiotic candidature by showing the potential capabilities with higher nutrient digestibility, heamato-biochemical and antioxidant status compared to control and Lactobacillus acidophilus NCDC15.

Bifidobacteria and its rice fermented products on diet induced obese mice: analysis of physical status, serum profile and gene expressions

Obesity is highly correlated with the dysbiosis of intestinal microbiota, and bifidobacteria are one of the soft targets of this metabolic syndrome. The aim of this study is to evaluate the efficacy of Bifidobacterium sp. MKK4 and rice-based fermented foods on physical, haematological, gut microbiota and lypogenic-lypolytic marker genes in diet-induced obese mice. Adult male mice (21±0.7 g) were randomly divided into four groups (n=10) according to the type of diet: normal diet (ND), high fat diet (HFD), HFD supplemented with Bifidobacterium sp. MKK4 and HFD supplemented with MKK4 associated rice-fermented food. 8 weeks of bacterial therapy in the obese mice resulted in significant reduction of body and organ weights, improved serum levels of glucose, triglyceride and cholesterol, the histological structure of the liver (steatosis), and re-establishment of gut Lactobacillus, Bifidobacterium and Bacteroides species. The bacterial therapy led to up-regulation of lipolytic transcription factors, such as peroxisome proliferator-activated receptor (PPAR)-α, PPAR-δ, and their regulated gene products in fatty acid metabolism and glucose uptake, such as acyl-CoA oxidase, carnitine palmitoyl-transferase-1, uncoupling protein-3 and glucose transporter-4. Concomitantly, both adipocytogenesis and fatty acid synthesis were arrested as reflected by the down-regulation of sterol regulatory element binding protein-1c, acetyl-CoA carboxylase, fatty acid synthase and tumour necrosis factor alpha genes. The effectiveness of the fermented product was more profound than the single bacterium. These data provide experimental support with regard to the use of Bifidobacterium sp. MKK4 as a natural therapeutic agent to control obesity.

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.

An in vivo assessment of the cholesterol-lowering efficacy of Lactobacillus plantarum ECGC 13110402 in normal to mildly hypercholesterolaemic adults

Coronary heart disease (CHD) is one of the major causes of death and disability in industrialised countries, with elevated blood cholesterol an established risk factor. Total plasma cholesterol reduction in populations suffering from primary hypercholesterolemia may lower CHD incidence. This study investigated the cholesterol reducing capacity of Lactobacillus plantarum ECGC 13110402, a strain selected for its high bile salt hydrolase activity, in 49 normal to mildly hypercholesterolaemic adults. Primary efficacy outcomes included effect on blood lipids (total cholesterol (TC), low density lipoproteins (LDL-C), high density lipoproteins (HDL-C) and triacylgycerides (TAG), inflammatory biomarkers and occurrence/severity of gastrointestinal side effects to establish safety and tolerance of the intervention. Secondary outcomes included blood pressure, immune biomarkers, gut microbiota characterisation and metabonome changes. The study was run in a parallel, double blind, placebo controlled, randomised design in which the active group ingested 2x10⁹ CFU encapsulated Lactobacillus plantarum ECGC 13110402 twice daily. Daily ingestion of the active treatment resulted in a statistically significant reduction in LDL-C in volunteers with baseline TC<5mM during the 0–12 week period (13.9%, P = 0.030), a significant reduction in TC in volunteers with baseline TC≥6mM in the 0–6 week period (37.6%, P = 0.045), a significant decrease in TAG (53.9% P = 0.030) and an increase in HDL-C (14.7%, P = 0.007) in the over 60 years population in the 6–12 week period. A statistically significant reduction in systolic blood pressure was also observed across the active study group in the 6-12-week period (6.6%, P = 0.003). No impact on gastrointestinal function and side effects was observed during the study. Similar to blood and urine metabonomic analyses, faecal metagenomics did not reveal significant changes upon active or placebo intake. The results of this study suggest that Lactobacillus plantarum ECGC 13110402 is a well-tolerated, natural probiotic, that may be used as an alternative or supplement to existing treatments to reduce cardiovascular risk.

Trial registration: Clinical trials.gov NCT03263104

Bacterial bile salt hydrolase: an intestinal microbiome target for enhanced animal health

To effectively mitigate antimicrobial resistance in the agricultural ecosystem, there is an increasing pressure to reduce and eliminate the use of in-feed antibiotics for growth promotion and disease prevention in food animals. However, limiting antibiotic use could compromise animal production efficiency and health. Thus, there is an urgent need to develop effective alternatives to antibiotic growth promoters (AGPs). Increasing evidence has shown that the growth-promoting effect of AGPs was highly correlated with the reduced activity of bile salt hydrolase (BSH), an intestinal bacterial enzyme that has a negative impact on host fat digestion and energy harvest; consistent with this finding, the population of Lactobacillus species, the major intestinal BSH-producer, was significantly reduced in response to AGP use. Thus, BSH is a key mechanistic microbiome target for developing novel alternatives to AGPs. Despite recent significant progress in the characterization of diverse BSH enzymes, research on BSH is still in its infancy. This review is focused on the function of BSH and its significant impacts on host physiology in human beings, laboratory animals and food animals. The gaps in BSH-based translational microbiome research for enhanced animal health are also identified and discussed.

Effect of three lactobacilli with strain-specific activities on the growth performance, faecal microbiota and ileum mucosa proteomics of piglets

Background

The beneficial effects of Lactobacillus probiotics in animal production are often strain-related. Different strains from the same species may exert different weight-gain effect on hosts in vivo. Most lactobacilli are selected based on their in vitro activities, and their metabolism and regulation on the intestine based on strain-related characters are largely unexplored. The objective of the present study was to study the in vivo effects of the three lactobacilli on growth performance and to compare the differential effects of the strains on the faecal microbiota and ileum mucosa proteomics of piglets.

Methods

Three hundred and sixty piglets were assigned to one of four treatments, which included an antibiotics-treated control and three experimental groups supplemented with the three lactobacilli, L. salivarius G1-1, L. reuteri G8-5 and L. reuteri G22-2, respectively. Piglets were weighed and the feed intake was recorded to compare the growth performance. The faecal lactobacilli and coliform was quantified using quantitative PCR and the faecal microbiota was profiled by denaturing gradient gel electrophoresis (DGGE). The proteomic approach was applied to compare the differential expression of proteins in the ileum mucosa.

Results

No statistical difference was found among the three Lactobacillus-treated groups in animal growth performance compared with the antibiotics-treated group (P > 0.05). Supplementation of lactobacilli in diets significantly increased the relative 16S rRNA gene copies of Lactobacillus genus on both d 14 and d 28 (P < 0.05)., and the bacterial community profiles based on DGGE from the lactobacilli-treated groups were distinctly different from the antibiotics-treated group (P < 0.05). The ileum mucosa of piglets responded to all Lactobacillus supplementation by producing more newly expressed proteins and the identified proteins were all associated with the functions beneficial for stabilization of cell structure. Besides, some other up-regulated and down-regulated proteins in different Lactobacillus-treated groups showed the expression of proteins were partly strain-related.

Conclusions

All the three lactobacilli in this study show comparable effects to antibiotics on piglets growth performance. The three lactobacilli were found able to modify intestinal microbiota and mucosa proteomics. The regulation of protein expression in the intestinal mucosa are partly associated with the strains administrated in feed.

Development of putative probiotics as feed additives: validation in a porcine-specific gastrointestinal tract model

Enforced restrictions on the use of antibiotics as growth promoters (AGPs) in animal production have prompted investigations into alternative feed additives in recent decades. Probiotics are currently the main feed additive used in livestock. However, the selection of probiotic candidates relies on human-based methods and little is known about the verification criteria for host-specific selection. We investigated the probiotic potential of Lactobacillus salivarius strains isolated from fed pig feces for their use as porcine feed additives. Two methods were developed that simulated the pig gastrointestinal (GI) tract and the intestinal epithelium, and these were compared with human-based in vitro methods and used for selecting porcine probiotics. Lactobacillus salivarius strain LS6 was identified as a promising probiotic strain for potential use as a porcine feed additive. This strain prevented disruption of the epithelial integrity of pig small intestine (PSI) cells by inhibiting the adherence of enterotoxigenic Escherichia coli K88. It also showed high survival rates in the in vitro pig GI tract model and good adhesion to PSI cells. We propose that host target-specific screening and validation methods are important tools in the development of effective probiotic feed additives, and this approach may support future-oriented agriculture.

Probiotic bacteria: a viable adjuvant therapy for relieving symptoms of rheumatoid arthritis

The burgeoning use of probiotics has proliferated during the past two decades. However, the effect of probiotic administration for either the prevention or treatment of rheumatoid arthritis (RA) has been investigated in a limited number of studies. Randomized controlled clinical trials have provided evidences that specific probiotics supplementation exhibit anti-inflammatory effects, help to increase daily activities and alleviate symptoms in patients with RA. Therefore, using probiotic bacteria as an adjuvant therapy may be considered as a promising treatment option for RA. This review summarizes the available data about the therapeutic and preventive effect of probiotics in RA, together with probiotic supplement as a possible therapy in clinical treatment.

Bile Salt Hydrolase (Bsh) Activity Screening of Lactobacilli: In Vitro Selection of Indigenous Lactobacillus Strains with Potential Bile Salt Hydrolysing and Cholesterol-Lowering Ability

The bile salt hydrolase (Bsh) activity of probiotic bacterium residing in gastrointestinal tract has often being associated with its cholesterol-lowering effects. Hence, Bsh activity was explored in this study as the criterion for the selection of most potential Bsh-active and cholesterol-lowering indigenous Lactobacillus strains. Forty lactobacilli were adjudged Bsh active after a preliminary screening of 102 lactobacilli and occurrence of Bsh activity correlated well with their natural habitats. Of the 40 shortlisted lactobacilli, fifteen putative Lactobacillus strains were selected and further tested for their comparative Bsh activity. In the end, indigenous Lactobacillus plantarum strains Lp91 and Lp21 were emerged as the promising Bsh-active lactobacilli with their substrate preference inclined more towards glycocholate than other bile acid amino conjugates. In addition, strains Lp91 and Lp21 also exhibited significantly high bile salt deconjugation, cholesterol assimilation and cholesterol co-precipitation ability in vitro. In conclusion, indigenous L. plantarum strains Lp91 and Lp21 may be the promising candidate probiotics to elucidate the ecological significance of probiotic Bsh activity in vivo.

In vitro assessment of the antimicrobial potentials of Lactobacillus helveticus strains isolated from traditional cheese in Sinkiang China against food-borne pathogens

KLDS 1.8701 showed a wide antimicrobial spectrum resulting from organic acids and contact dependent inhibition.

The pan-genome of Lactobacillus reuteri strains originating from the pig gastrointestinal tract

BACKGROUND

Lactobacillus reuteri is a gut symbiont of a wide variety of vertebrate species that has diversified into distinct phylogenetic clades which are to a large degree host-specific. Previous work demonstrated host specificity in mice and begun to determine the mechanisms by which gut colonisation and host restriction is achieved. However, how L. reuteri strains colonise the gastrointestinal (GI) tract of pigs is unknown.

RESULTS

To gain insight into the ecology of L. reuteri in the pig gut, the genome sequence of the porcine small intestinal isolate L. reuteri ATCC 53608 was completed and consisted of a chromosome of 1.94 Mbp and two plasmids of 138.5 kbp and 9.09 kbp, respectively. Furthermore, we generated draft genomes of four additional L. reuteri strains isolated from pig faeces or lower GI tract, lp167-67, pg-3b, 20-2 and 3c6, and subjected all five genomes to a comparative genomic analysis together with the previously completed genome of strain I5007. A phylogenetic analysis based on whole genomes showed that porcine L. reuteri strains fall into two distinct clades, as previously suggested by multi-locus sequence analysis. These six pig L. reuteri genomes contained a core set of 1364 orthologous gene clusters, as determined by OrthoMCL analysis, that contributed to a pan-genome totalling 3373 gene clusters. Genome comparisons of the six pig L. reuteri strains with 14 L. reuteri strains from other host origins gave a total pan-genome of 5225 gene clusters that included a core genome of 851 gene clusters but revealed that there were no pig-specific genes per se. However, genes specific for and conserved among strains of the two pig phylogenetic lineages were detected, some of which encoded cell surface proteins that could contribute to the diversification of the two lineages and their observed host specificity.

CONCLUSIONS

This study extends the phylogenetic analysis of L. reuteri strains at a genome-wide level, pointing to distinct evolutionary trajectories of porcine L. reuteri lineages, and providing new insights into the genomic events in L. reuteri that occurred during specialisation to their hosts. The occurrence of two distinct pig-derived clades may reflect differences in host genotype, environmental factors such as dietary components or to evolution from ancestral strains of human and rodent origin following contact with pig populations.

Technological properties and probiotic potential of Lactobacillus fermentum strains isolated from West African fermented millet dough

BACKGROUND

Throughout Africa, food fermentations are still driven by indigenous microorganisms which influence the nutritional, organoleptic and safety of the final products. However, for improved safety, consistent quality and beneficial health effects, a trend has emerged which involves the isolation of indigenous strains from traditional fermented products to be used as functional starter cultures. These functional starter cultures possess inherent functional characteristics and can contribute to food quality and safety by offering one or more organoleptic, nutritional, technological or health advantage (probiotics). With the aim of selecting potential probiotic starter cultures, Lactobacillus fermentum strains isolated from fermented millet dough were investigated for technological properties and probiotic traits in-vitro.

RESULTS

A total of 176 L. fermentum strains were assessed for technological properties including rate of acidification, exopolysaccharide production and amylase activity. Following this, 48 strains showing desirable technological properties were first screened for acid resistance. Sixteen acid resistant strains were assessed for additional probiotic properties including resistance to bile salts, bile salt hydrolysis, antimicrobial property, haemolysis and antibiotics resistance. L. fermentum strains clustered into 3 groups represented by 36 %, 47 % and 17 % as fast, medium and slow acidifiers respectively. About 8 %, 78 % and 14 % of the strains showed strong, weak and no exopolysaccharides production respectively. Amylase activity was generally weak or not detected. After exposure of 48 L. fermentum strains to pH 2.5 for 4 h, 16 strains were considered to be acid resistant. All 16 strains were resistant to bile salt. Four strains demonstrated bile salt hydrolysis. Antimicrobial activity was observed towards Listeria monocytogenes and Staphylococcus aureus but not E. coli and Salmonella enteritidis. Lactobacillus fermentum strains were generally susceptible to antibiotics except 6 strains which showed resistance towards streptomycin, gentamicin and kanamycin.

CONCLUSION

In vitro determination of technological and probiotic properties have shown strain specific difference among L. fermentum strains isolated from fermented millet dough. Sixteen (16) L. fermentum strains have been shown to possess desirable technological and probiotic characteristics in vitro. These strains are therefore good candidates for further studies to elucidate their full potential and possible application as novel probiotic starter cultures.

Draft Genome Sequence of Lactobacillus johnsonii Strain 16, Isolated from Mice

Here, we report the genome sequence of Lactobacillus johnsonii, a member of the gut lactobacilli. This draft genome of L. johnsonii strain 16 isolated from C57BL/6J mice enables the identification of bacterial genes responsible for host-specific gut persistence.

Characterization of Selected Lactobacillus Strains for Use as Probiotics

The aim of this study was to evaluate the functional properties of lactic acid bacteria from various sources and to identify strains for use as probiotics. Ten Lactobacillus strains were selected and their properties such as bile tolerance, acid resistance, cholesterol assimilation activity, and adherence to HT-29 cells were assessed to determine their potential as probiotics. Lactobacillus sp. JNU 8829, L. casei MB3, L. sakei MA9, L. sakei CH8, and L. acidophilus M23 were found to show full tolerance to the 0.3% bile acid. All strains without L. acidophilus M23 were the most acid-tolerant strains. After incubating the strains at pH 2.5 for 2 h, their viability decreased by 3 Log cells. Some strains survived at pH 2.5 in the presence of pepsin and 0.3% bile acid. Lactobacillus sp. JNU 8829, L. acidophilus KU41, L. acidophilus M23, L. fermentum NS2, L. plantarum M13, and L. plantarum NS3 were found to reduce cholesterol levels by >50% in vitro. In the adhesion assay, Lactobacillus sp. JNU 8829, L. casei MB3, L. sakei MA9, and L. sakei CH8 showed higher adhesion activities after 2 h of co-incubation with the intestinal cells. The results of this comprehensive analysis shows that this new probiotic strain named, Lactobacillus sp. JNU 8829 could be a promising candidate for dairy products.

Lactobacillus fermentum NCIMB 5221 and NCIMB 2797 as cholesterol-lowering probiotic biotherapeutics: in vitro analysis

Cardiovascular and coronary artery disease risk are correlated with cholesterol levels and are significant health concerns. Current cholesterol-lowering approaches includes lifestyle and diet modifications, as well as statins which presents numerous shortcomings. The probiotic bacteria, Lactobacillus fermentum NCIMB 5221 and NCIMB 2797, have demonstrated cholesterol-lowering potential in animal studies. However, there is a lack in understanding the mechanism(s) behind these observed effects. The goal of this work is to investigate, in vitro, the cholesterol-lowering mechanisms of these two strains. To determine the cholesterol-lowering mechanisms, probiotic cholesterol assimilation, colon epithelial adhesion and inhibition of cholesterol uptake by colon epithelial (Caco-2) cells were investigated. L. fermentum NCIMB 2797 (P=0.012) and NCIMB 5221 (P=0.003) assimilated cholesterol and their cell surface hydrophobicity was 70.30±8.85% and 55.60±2.59%, respectively. Both L. fermentum strains showed no significant impact (P>0.05) on Caco-2 cell viability. Of most interest, Caco-2 pre-exposure to L. fermentum NCIMB 5221 significantly decreased (P=0.015) cholesterol uptake, with 85.98±2.07% uptake compared to the untreated cells. Similarly, L. fermentum NCIMB 2797 probiotic cells significantly decreased (P=0.019) cholesterol uptake by Caco-2 cells, with 86.45±1.71% uptake observed compared to the control cells. The results demonstrate that L. fermentum NCIMB 5221 and L. fermentum NCIMB 2797 have the potential via various modes of action to lower cholesterol. Additional studies are required to understand the mechanism(s) of action behind probiotic cholesterol assimilation and behind the cholesterol uptake inhibition by colon epithelial cells.

Isolation of strong constitutive promoters from Lactococcus lactis subsp. lactis N8

The synthesis of heterologous proteins in Lactococcus lactis is strongly influenced by the promoter selected for the expression. The nisin A promoter is commonly used for induced expression of proteins in L. lactis, whereas few constitutive promoters (P45 and the weaker P32) have been used for protein expression studies. In this study, eight different putative strong constitutive promoters were identified through transcriptional analysis of L. lactis N8 and were investigated for their capability to drive nisZ gene expression with promoters P45 and P32 as control. Four strong promoters (P8, P5, P3 and P2) were identified as having a transcriptional activity that was higher than that of P45 through RT-qPCR and agar-diffusion experiments. In addition, these four promoters were fused to the erythromycin resistant gene (ermC) with promoter P45 as control and inserted into the backbone of the pNZ8048 vector. The transcriptional efficiencies of promoters P8, P5, P2 and P3 were all higher than promoter P45 based on the obtained MIC50 values and they all showed different activity levels. In conclusion, four strong constitutive promoters with a wide range of promoter activities were identified and are suitable for protein production in L. lactis.