Antimicrobial and Safety Properties of Lactobacilli Isolated from two Cameroonian Traditional Fermented Foods

Evaluation Recovery of Ulcerative Colitis with a Lactobacillus Cocktail Derived from Traditional Dairy Products: In vivo Study

Background

This investigation investigates the anti-inflammatory and fibrinolytic effects of a cocktail of probiotics derived from traditional dairy products in a murine model of ulcerative colitis (UC).

Materials and Methods

A mix of newly isolated probiotics containing L. plantarum, L. brevis, L. delbrueckii, and L. helveticus was characterized and orally administered to inbred eight-week-old C57BL/6 male mice (n = 6). Clinical symptoms, pathohistological changes, and inflammatory and fibrosis markers were analyzed in the existence and absence of probiotics in colitis mice.

Results

Dairy lactobacillus probiotics potently attenuated colitis symptoms by decreasing dextran sulfate sodium (DSS)-induced body weight loss, colon shortening, rectal bleeding, and rectal prolapse. Consistently, a cocktail of probiotics could significantly improve histopathological grading by suppressing crypt loss, mucosal damage, and inflammation scores in colitis tissues. Moreover, the mix of probiotics suppressed pro-inflammatory genes including interleukin (IL)-1β, IL-6, tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ), and increased anti-oxidant markers and activity such as superoxide dismutase and catalase in colon tissue. Furthermore, compared to the no-treated group, the administration of probiotics reduced fibrosis by decreasing collagen deposition in tissue sections and down-regulating levels of pro-fibrotic genes including alpha-actin-2 (Acta2), collagen (Col) 1a1, and Col 1a2 in colitis tissue homogenates.

Conclusions

The results show the newly isolated cocktail of probiotics elicits a potent protective effect on UC symptoms in mice model. Further study on these probiotics is required to fully explore their effectiveness, strength, and safety considerations.

Co-occurrence of Lactobacillus Species During Fermentation of African Indigenous Foods: Impact on Food Safety and Shelf-Life Extension

The benefits derived from fermented foods and beverages have placed great value on their acceptability worldwide. Food fermentation technologies have been employed for thousands of years and are considered essential processes for the production and preservation of foods, with the critical roles played by the autochthonous fermenting food-grade microorganisms in ensuring food security and safety, increased shelf life, and enhanced livelihoods of many people in Africa, particularly the marginalized and vulnerable groups. Many indigenous fermented foods and beverages of Africa are of plant origin. In this review, the predominance, fermentative activities, and biopreservative role of Lactobacillus spp. during production of indigenous foods and beverages, the potential health benefit of probiotics, and the impact of these food-grade microorganisms on food safety and prolonged shelf life are discussed. During production of African indigenous foods (with emphasis on cereals and cassava-based food products), fermentation occurs in succession; the first group of microorganisms to colonize the fermenting substrates are lactic acid bacteria (LAB) with the diversity and dominance of Lactobacillus spp. The Lactobacillus spp. multiply rapidly in the fermentation matrix, by taking up nutrients from the surrounding environments, and cause rapid acidification in the fermenting system via the production of organic compounds that convert fermentable sugars into mainly lactic acid. Production of these compounds in food systems inhibits spoilage microorganisms, which has a direct effect on food quality and safety. The knowledge of microbial interaction and succession during food fermentation will assist the food industry in producing functional foods and beverages with improved nutritional profiling and technological attributes, as Lactobacillus strains isolated during fermentation of several African indigenous foods have demonstrated desirable characteristics that make them safe for use as probiotic microorganisms and even as a starter culture in small- and large-scale/industrial food production processes.

Gamma-aminobutyric acid fermentation in MRS-based medium by the fructophilic Lactiplantibacillus plantarum Y7

Among the key metabolites produced by probiotic lactic acid bacteria (LAB), the use of gamma-aminobutyric acid (GABA), which alleviates hypertension, depression, and sleepiness in humans, is gaining popularity. Thus, GABA-producing LAB are sought after. GABA-producing LAB were preliminarily screened in acidified-MRS broth and quantified via GABase assays. The one-factor-at-a-time strategy was applied to determine the optimal conditions for GABA production. GABA production in reconstituted skim milk medium (RSM) and antibiotic susceptibility testing were performed to evaluate the potential of the strain as a yogurt starter. L. plantarum Y7 produced 4,856.86 ± 82.47 μg/mL of GABA at optimal culture conditions. Co-cultivation of Y7 and commercial Lactobacillus bulgaricus affected the amount of GABA production (6.85 ± 0.20 μg/mL) in RSM. Y7 was susceptible to ampicillin, erythromycin, and tetracycline. Therefore, L. plantarum Y7 represents a promising strain for GABA production in the food industry.

Enterococcus faecium PNC01 isolated from the intestinal mucosa of chicken as an alternative for antibiotics to reduce feed conversion rate in broiler chickens

Background

The development and utilization of probiotics had many environmental benefits for replacing antibiotics in animal production. Bacteria in the intestinal mucosa have better adhesion to the host intestinal epithelial cells compared to bacteria in the intestinal contents. In this study, lactic acid bacteria were isolated from the intestinal mucosa of broiler chickens and investigated as the substitution to antibiotic in broiler production.

Results

In addition to acid resistance, high temperature resistance, antimicrobial sensitivity tests, and intestinal epithelial cell adhesion, Enterococcus faecium PNC01 (E. faecium PNC01) was showed to be non-cytotoxic to epithelial cells. Draft genome sequence of E. faecium PNC01 predicted that it synthesized bacteriocin to perform probiotic functions and bacteriocin activity assay showed it inhibited Salmonella typhimurium from invading intestinal epithelial cells. Diet supplemented with E. faecium PNC01 increased the ileal villus height and crypt depth in broiler chickens, reduced the relative length of the cecum at day 21, and reduced the relative length of jejunum and ileum at day 42. Diet supplemented with E. faecium PNC01 increased the relative abundance of Firmicutes and Lactobacillus, decreased the relative abundance of Bacteroides in the cecal microbiota.

Conclusion

E. faecium PNC01 replaced antibiotics to reduce the feed conversion rate. Furthermore, E. faecium PNC01 improved intestinal morphology and altered the composition of microbiota in the cecum to reduce feed conversion rate. Thus, it can be used as an alternative for antibiotics in broiler production to avoid the adverse impact of antibiotics by altering the gut microbiota.

Graphic Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12934-021-01609-z.

Gardnerella vaginalis and Neisseria gonorrhoeae Are Effectively Inhibited by Lactobacilli with Probiotic Properties Isolated from Brazilian Cupuaçu (Theobroma grandiflorum) Fruit

In recent years, certain Lactobacillus sp. have emerged in health care as an alternative therapy for various diseases. Based on this, this study is aimed at evaluating in vitro the potential probiotics of five lactobacilli strains isolated from pulp of cupuaçu fruit fermentation against Gardnerella vaginalis and Neisseria gonorrhoeae. Our lactobacilli strains were classified as safe for use in humans, and they were tolerant to heat and pH. Our strains were biofilm producers, while hydrophobicity and autoaggregation varied from 13% to 86% and 13% to 25%, respectively. The coaggregation of lactobacilli used in this study with G. vaginalis and N. gonorrhoeae ranged from 15% to 36% and 32% to 52%, respectively. Antimicrobial activity was present in all tested Lactobacillus strains against both pathogens, and the growth of pathogens in coculture was reduced by the presence of our lactobacilli. Also, all tested lactobacilli reduced the pH of the culture, even in incubation with pathogens after 24 hours. The cell-free culture supernatants (CFCS) of all five lactobacilli demonstrated activity against the two pathogens with a halo presence and CFCS characterization assay together with gas chromatography revealed that lactic acid was the most abundant organic acid in the samples (50% to 62%). Our results demonstrated that the organic acid production profile is strain-specific. This study revealed that cupuaçu is a promising source of microorganisms with probiotic properties against genital pathogens. We demonstrated by in vitro tests that our Lactobacillus strains have probiotic properties. However, the absence of in vivo tests is a limitation of our work due to the need to evaluate the interaction of our lactobacilli with pathogens in the vaginal mucosa. We believe that these findings may be useful in developing a product containing our lactobacilli and their supernatants in order to support with vaginal health.

Characterization of Lactic Acid Bacteria in Raw Buffalo Milk: a Screening for Novel Probiotic Candidates and Their Transcriptional Response to Acid Stress

Lactic acid bacteria (LAB) are important microorganisms for the food industry due to their functional activity, as starters and potential probiotic strains. With that in mind, we explored the LAB diversity in raw buffalo milk, screening for novel potential probiotic strains. A total of 11 strains were identified by combination of MALDI-TOF and partial 16S rDNA sequencing and selected as potential probiotic candidates. Bacteria innocuity assessment was performed by determining antimicrobial susceptibility and the presence of virulence factors. Antagonism activity against Escherichia coli, Pseudomonas aeruginosa, Listeria monocytogenes and Staphylococcus aureus was assessed, as well as milk proteolytic activity and exopolysaccharides production. Seven strains were identified as innocuous and two of them, Lactobacillus rhamnosus LB1.5 and Lactobacillus paracasei LB6.4 were selected for further probiotic potential analyses. Both strains demonstrated adhesion ability to Caco-2 cells, coaggregated with S. aureus and E. coli and maintained cell viability after gastrointestinal simulation in vitro, suggesting their probiotic potential. Furthermore, the transcriptional response of Lact. rhamnosus LB1.5 and Lact. paracasei LB6.4 to in vitro acid stress was assessed by RT-qPCR targeting seven genes related to adhesion, aggregation, stress tolerance, DNA repair and central metabolism. The association between the transcriptional responses and the maintenance of cell viability after gastrointestinal simulation highlights the genetic ability as probiotic of the two selected strains. Finally, we have concluded that Lact. rhamnosus LB1.5 and Lact. paracasei LB6.4 are important probiotic candidates to further in vivo studies.

Changes Occurring in Spontaneous Maize Fermentation: An Overview

Maize and its derived fermented products, as with other cereals, are fundamental for human nutrition in many countries of the world. Mixed cultures, principally constituted by lactic acid bacteria (LAB) and yeasts, are responsible for maize fermentation, thus increasing its nutritional value and extending the products’ shelf-life. Other microorganisms involved, such as molds, acetic acid bacteria, and Bacillus spp. can contribute to the final product characteristics. This review gives an overview of the impact of the activities of this complex microbiota on maize product development and attributes. In particular, starting from amylolytic activity, which is able to increase sugar availability and influence the microbial succession and production of exopolysaccharides, vitamins, and antimicrobial compounds, which improve the nutritional value. Further activities are also considered with positive effects on the safety profile, such as phytates detoxification and mycotoxins reduction.

Autochthonous lactic acid bacteria-presentation of potential probiotics application

OBJECTIVE

The objective of this study was to evaluate the probiotic potential as well as the ability of adhesion and aggregation of natural and autochthonous lactic acid bacteria, isolated from traditionally made cheese.

RESULTS

Lactic acid bacteria from natural food sources can be promising probiotic candidates and they can be used in natural food preservation or like starter cultures. Tested autochthonous isolates showed tolerance to the simulated gastrointestinal condition as well as the sensitivity to clinically relevant antibiotics, especially to ampicillin (MIC at 0.195 μg mL^-1 for lactobacilli and from 0.195 to 3.125 μg mL^-1 for lactococci). Among isolates, the highest percentage of adhesion was detected with chloroform, while the adhesion ability of selected isolates to pig intestinal epithelium was in the correlation with the results of adhesion ability with solvents. The auto-aggregation ability of isolates was demonstrated, while co-aggregation with Escherichia coli was strain specific.

CONCLUSION

The results indicated the potential probiotic properties of the isolates and give evidence for further investigation and potential application in the dairy industry.

Anti-biofilm Properties of the Fecal Probiotic Lactobacilli Against Vibrio spp

Diarrheal disease caused by Vibrio cholerae is endemic in developing countries including India and is associated with high rate of mortality especially in children. V. cholerae is known to form biofilms on the gut epithelium, and the biofilms once formed are resistant to the action of antibiotics. Therefore agents that prevent the biofilm formation and disperse the preformed biofilms are associated with therapeutic benefits. The use of antibiotics for the treatment of cholera is associated with side effects such as gut dysbiosis due to depletion of gut microflora, and the increasing problem of antibiotic resistance. Thus search for safe alternative therapeutic agents is warranted. Herein, we screened the lactobacilli spp. isolated from the fecal samples of healthy children for their abilities to prevent biofilm formation and to disperse the preformed biofilms of V. cholerae and V. parahaemolyticus by using an in vitro assay. The results showed that the culture supernatant (CS) of all the seven isolates of Lactobacillus spp. used in the study inhibited the biofilm formation of V. cholerae by more than 90%. Neutralization of pH of CS completely abrogated their antimicrobial activities against V. cholera, but had negligible effects on their biofilm inhibitory potential. Further, CS of all the lactobacilli isolates caused the dispersion of preformed V. cholerae biofilms in the range 62–85%; however, pH neutralization of CS reduced the biofilm dispersal potential of the 4 out of 7 isolates by 19–57%. Furthermore, the studies showed that CS of none of the lactobacilii isolates had antimicrobial activity against V. parahaemolyticus, but 5 out of 7 isolates inhibited the formation of its biofilm in the range 62–82%. However, none of the CS dispersed the preformed biofilms of V. parahaemolyticus. The ability of CS to inhibit the adherence of Vibrio spp. to the epithelial cell line was also determined. Thus, we conclude that the biofilm dispersive action of CS of lactobacilli is strain-specific and pH-dependent. As Vibrio is known to form biofilms in the intestinal niche having physiological pH in the range 6–7, the probiotic strains that have dispersive action at high pH may have better therapeutic potential.

Indigenous Probiotic Lactobacillus Isolates Presenting Antibiotic like Activity against Human Pathogenic Bacteria

Background: Indigenous lactic acid bacteria are well known probiotics having antibacterial activity against potentially pathogenic bacteria. This study aims to characterize the curd lactobacilli for their probiotic potentiality and antagonistic activity against clinical bacteria. Methods: Four curd samples were processed microbiologically for the isolation of lactic acid bacteria (LAB). The LAB strains obtained were identified by conventional methods: cultural aspect, gram-staining, biochemical and sugar fermentation tests. The probiotic properties were justified with tolerance to low-pH, bile salt and sodium chloride, and the antagonistic activity of the lactobacilli against human pathogenic bacteria (Escherichia coli, Proteus vulgaris, Acinetobacter baumannii and Salmonella enterica serovar Typhi) was assessed. Hemolytic activity and antibiotic susceptibility were determined for the lactobacilli isolates, and the cumulative probiotic potential (CPP) values were recorded. Result: Four lactobacilli isolates, L. animalis LMEM6, L. plantarum LMEM7, L. acidophilus LMEM8 and L. rhamnosus LMEM9, procured from the curd samples, survived in low-pH and high bile salt conditions, and showed growth inhibitory activity against the indicator bacteria by agar-well (zone diameter of inhibition; ZDIs: 13.67 ± 0.58–29.50 ± 2.10 mm) and agar overlay (ZDIs: 11.33 ± 0.58–35.67 ± 2.52 mm) methods; the average growth inhibitory activity of lactobacilli ranged 233.34 ± 45.54–280.56 ± 83.67 AU/mL, against the test bacterial pathogens. All the lactobacilli were non-hemolytic and sensitive to most of the test antibiotics. The CPP values of the isolated LAB were recorded as 80–100%. Conclusion: The curd lactobacilli procured might be used as the valid candidates of probiotics, and bio-therapeutics against bacterial infection to humans.

Safety characterization and antimicrobial properties of kefir-isolated Lactobacillus kefiri

Lactobacilli are generally regarded as safe; however, certain strains have been associated with cases of infection. Our workgroup has already assessed many functional properties of Lactobacillus kefiri, but parameters regarding safety must be studied before calling them probiotics. In this work, safety aspects and antimicrobial activity of L. kefiri strains were studied. None of the L. kefiri strains tested caused α- or β-hemolysis. All the strains were susceptible to tetracycline, clindamycin, streptomycin, ampicillin, erythromycin, kanamycin, and gentamicin; meanwhile, two strains were resistant to chloramphenicol. On the other hand, all L. kefiri strains were able to inhibit both Gram(+) and Gram(-) pathogens. Regarding the in vitro results, L. kefiri CIDCA 8348 was selected to perform in vivo studies. Mice treated daily with an oral dose of 10(8) CFU during 21 days showed no signs of pain, lethargy, dehydration, or diarrhea, and the histological studies were consistent with those findings. Moreover, no differences in proinflammatory cytokines secretion were observed between treated and control mice. No translocation of microorganisms to blood, spleen, or liver was observed. Regarding these findings, L. kefiri CIDCA 8348 is a microorganism isolated from a dairy product with a great potential as probiotic for human or animal use.

Prevalence of antibiotic resistance in lactic acid bacteria isolated from the faeces of broiler chicken in Malaysia

BACKGROUND

Probiotics are commonly used as feed additive to substitute antibiotic as growth promoter in animal farming. Probiotic consists of lactic acid bacteria (LAB), which enhance the growth and health of the animal. Probiotic also have higher possibility to become pathogenic bacteria that may carry antibiotic resistant gene that can be transmitted to other LAB species. The aim of this study was to identify the LAB species in the faeces of broiler chicken and to determine the prevalence of antibiotic resistant in LAB of broiler chicken.

METHODS

Sixty faeces samples were collected from wet markets located in Klang Valley of Malaysia for the isolation of LAB using de-Mann Rogosa Sharpe medium. Thirteen species of LAB were obtained in this study and the identification of LAB was performed by using API test kit on the basis of carbohydrate fermentation profile. Antibiotic susceptibility assay was then carried out to determine the prevalence of LAB antibiotic resistance.

RESULTS

Lactococcus lactis subsp lactis was found in nine out of sixty faecal samples. Lactobacillus paracasei was the second common LAB species isolated from chicken faecal. No significant difference (P > 0.05) was found between the occurrence of Lactobacillus brevis, Lactobacillus curvatus, Lactobacillus plantarum, Leuconostoc lactis mesenteroides subsp mesenteroides/dectranium and Pediococcus pentosaceus isolated from 5 different locations. Most of the isolated LAB was resistant to antibiotic and high variability of the antibiotic resistance was observed among the LAB against 15 types of antibiotics. Penicillin, amoxicillin, chloramphenicol, and ampicillin had significant higher (P< 0.05) inhibitory zone than nalidixic acid, gentamycin, sulphamethoxazole, kanamycin, and streptomycin.

CONCLUSIONS

Many species of LAB were isolated from the faecal samples of broiler chicken that resistance to the common antibiotics used in the farm. The development of resistant against antibiotics in LAB can be attributed to the long term exposure of antibiotic as growth promoter and therapeutic agents. Thus, it is essential to advise farmer the safety measure of antibiotic application in animal farming. Additionally, the supplementation of probiotic in animal feeding also needs more attention and close monitoring.

Probiotics and nutrients for the first 1000 days of life in the developing world

Clinically proven probiotics are, for the most part, not available in the developing world and certainly not affordable for the majority of people. This is unconscionable considering these products can alleviate diarrhoea and various infections, which are by far the major cause of death in children and in adults who are HIV positive. Indeed, some of these products have been proven in developing world settings. Distribution networks exist along with pharmacies and clinics that dispense drugs and products that require refrigeration. So, are lack of profit or company resources the problem? Our university has shown that alternative community based kitchen models that produce probiotics can be established. These empower local people, are socially responsible, produce affordable products and deliver benefits to over 3,000 children and adults daily. Surely, other institutions and corporations can multiply this effect and develop social business models across the developing world that are supported by clinical and basic science studies? In this review, we will discuss the application of probiotics and selected nutrients in the first 1000 days of life, a critical timepoint which is particularly challenging in resource disadvantaged countries.