Isolation and characterization of probiotic properties of Lactobacilli isolated from rat fecal microbiota

Periodontal pathogen Aggregatibacter actinomycetemcomitans JP2 correlates with colonic leukocytes decrease and gut microbiome imbalance in mice

AIM

Evidence suggests that translocation of oral pathogens through the oral-gut axis may induce intestinal dysbiosis. This study aimed to evaluate the impact of a highly leukotoxic Aggregatibacter actinomycetemcomitans (Aa) strain on the gut microbiota, intestinal mucosal integrity and immune system in healthy mice.

METHODS

Eight-week-old male C57BL6 mice were divided into control (n = 16) and JP2 groups (n = 19), which received intragastric gavage with PBS and with a suspension of Aa JP2 (HK921), respectively, twice a week for 4 weeks. Colonic lamina propria, fecal material, serum, gingival tissues, and mandibles were obtained for analyses of leukocyte populations, inflammatory mediators, mucosal integrity, alveolar bone loss, and gut microbiota. Differences between groups for these parameters were examined by non-parametric tests.

RESULTS

The gut microbial richness and the number of colonic macrophages, neutrophils, and monocytes were significantly lower in Aa JP2-infected mice than in controls (p < .05). In contrast, infected animals showed higher abundance of Clostridiaceae, Lactobacillus taiwanensis, Helicobacter rodentium, higher levels of IL-6 expression in colonic tissues, and higher splenic MPO activity than controls (p < .05). No differences in tight junction expression, serum endotoxin levels, and colonic inflammatory cytokines were observed between groups. Infected animals presented also slightly more alveolar bone loss and gingival IL-6 levels than controls (p < .05).

CONCLUSION

Based on this model, intragastric administration of Aa JP2 is associated with changes in the gut ecosystem of healthy hosts, characterized by less live/recruited myeloid cells, enrichment of the gut microbiota with pathobionts and decrease in commensals. Negligible levels of colonic pro-inflammatory cytokines, and no signs of mucosal barrier disruption were related to these changes.

Isolation and characterization of novel Bacillus strains with superior probiotic potential: comparative analysis and safety evaluation

Despite the current use of some Bacillus spp. as probiotics, looking for and introducing new efficient and safe potential probiotic strains is one of the most important topics in both microbiology and food industry. This study aimed to isolate, identify, and evaluate the probiotic characteristics and safety of some Bacillus spp. from natural sources. Thirty-six spore-forming, Gram-positive, and catalase-positive Bacillus isolates were identified in 54 samples of soil, feces and dairy products. Bacterial identification was performed using 16S rDNA sequencing. To evaluate the probiotic potential of isolates, the resistance of bacterial cells to simulated gastrointestinal tract (GIT) conditions, the presence of enterotoxin genes, their susceptibility to antibiotics, antimicrobial and hemolytic activities and biochemical profiles were investigated. The results revealed that eight sporulating Bacillus spp. isolates fulfilled all tested probiotic criteria. They showed a high growth rate, non-hemolytic and lecithinase activity, and resistance to simulated GIT conditions. These strains exhibited broad-spectrum antibacterial activity against pathogenic bacteria. In addition, they did not exhibit antibacterial resistance to the 12 tested antibiotics. The results of this study suggest that these isolates can be considered as candidates for functional foods and as safe additives to improve diet quality.

Genomic and phenotypic-based safety assessment and probiotic properties of Streptococcus thermophilus FUA329, a urolithin A-producing bacterium of human milk origin

Streptococcus thermophilus FUA329, a urolithin A-producing bacterium, is isolated from human breast milk. The complete genome sequence of FUA329 did not contain any plasmids and at least 20 proteins were related to extreme environment resistance. Phenotypic assay results demonstrated that FUA329 was susceptible to 12 kinds of antibiotics and did not exhibit any hemolytic or nitrate reductase activity. Three free radical scavenging assays revealed that FUA329 have high antioxidant capability. FUA329 exhibited a cell surface hydrophobicity of 52.58 ± 1.17% and an auto-aggregation rate of 18.69 ± 2.48%. Moreover, FUA329 demonstrated a survival rate of over 60% in strong acid and bile salt environments, indicating that FUA329 may be stable colonization in the gastrointestinal tract. Additionally, we firstly found 3 potential proteins and 11 potential genes of transforming ellagic acid to urolithins in FUA329 genome. The above results indicate that FUA329 has credible safety and probiotic properties, as well as the potential to be developed as a new generation of urolithin A-producing probiotics.

16S rRNA gene sequencing reveals the effect of fluoxetine on gut microbiota in chronic unpredictable stress-induced depressive-like rats

OBJECTIVES

Gut microbiota is relevant to the pathogenesis of mental disorders including depression. This study aimed to investigate the influence of fluoxetine (FLX) on the gut microbiota in rats with Chronic Unpredictable Mild Stresses (CUMS)-induced depression.

RESULTS

We confirmed that the 28-day CUMS-induced depression rat model. Chronic FLX administration weakly improved depressive-like behaviors in rats. Illumina 16S rRNA gene sequencing on rat feces showed CUMS increased the relative abundance of Firmicutes (60.31% vs. 48.09% in Control, p < 0.05) and Lactobacillus genus (21.06% vs. 6.82% in control, p < 0.05); FLX and CUMS increased Bacilli class (20.00% ~ 24.08% vs. 10.31% in control, p < 0.05).

CONCLUSION

Collectively, our study showed that both CUMS and FLX changed the compositions of gut microbiota in rats. FLX and CUMS distinctly regulated the gut microbiota in depressed rats.

Screening for potential novel probiotic Levilactobacillus brevis RAMULAB52 with antihyperglycemic property from fermented Carica papaya L

Probiotics are live microorganisms with various health benefits when consumed in appropriate amounts. Fermented foods are a rich source of these beneficial organisms. This study aimed to investigate the probiotic potential of lactic acid bacteria (LAB) isolated from fermented papaya (Carica papaya L.) through in vitro methods. The LAB strains were thoroughly characterized, considering their morphological, physiological, fermentative, biochemical, and molecular properties. The LAB strain's adherence and resistance to gastrointestinal conditions, as well as its antibacterial and antioxidant capabilities, were examined. Moreover, the strains were tested for susceptibility against specific antibiotics, and safety evaluations encompassed the hemolytic assay and DNase activity. The supernatant of the LAB isolate underwent organic acid profiling (LCMS). The primary objective of this study was to assess the inhibitory activity of α-amylase and α-glucosidase enzymes, both in vitro and in silico. Gram-positive strains that were catalase-negative and carbohydrate fermenting were selected for further analysis. The LAB isolate exhibited resistance to acid bile (0.3% and 1%), phenol (0.1% and 0.4%), and simulated gastrointestinal juice (pH 3-8). It demonstrated potent antibacterial and antioxidant abilities and resistance to kanamycin, vancomycin, and methicillin. The LAB strain showed autoaggregation (83%) and adhesion to chicken crop epithelial cells, buccal epithelial cells, and HT-29 cells. Safety assessments indicated no evidence of hemolysis or DNA degradation, confirming the safety of the LAB isolates. The isolate's identity was confirmed using the 16S rRNA sequence. The LAB strain Levilactobacillus brevis RAMULAB52, derived from fermented papaya, exhibited promising probiotic properties. Moreover, the isolate demonstrated significant inhibition of α-amylase (86.97%) and α-glucosidase (75.87%) enzymes. In silico studies uncovered that hydroxycitric acid, one of the organic acids derived from the isolate, interacted with crucial amino acid residues of the target enzymes. Specifically, hydroxycitric acid formed hydrogen bonds with key amino acid residues, such as GLU233 and ASP197 in α-amylase, and ASN241, ARG312, GLU304, SER308, HIS279, PRO309, and PHE311 in α-glucosidase. In conclusion, Levilactobacillus brevis RAMULAB52, isolated from fermented papaya, possesses promising probiotic properties and exhibits potential as an effective remedy for diabetes. Its resistance to gastrointestinal conditions, antibacterial and antioxidant abilities, adhesion to different cell types, and significant inhibition of target enzymes make it a valuable candidate for further research and potential application in the field of probiotics and diabetes management.

Genome Sequence and Evaluation of Safety and Probiotic Potential of Lactiplantibacillus plantarum LPJZ-658

This study aims to systematically evaluate the safety of a novel L. plantarum LPJZ-658 explored on whole-genome sequence analysis, safety, and probiotic properties assessment. Whole genome sequencing results demonstrated that L. plantarum LPJZ-658 consists of 3.26 Mbp with a GC content of 44.83%. A total of 3254 putative ORFs were identified. Of note, a putative bile saline hydrolase (BSH) (identity 70.4%) was found in its genome. In addition, the secondary metabolites were analyzed, and one secondary metabolite gene cluster was predicted to consist of 51 genes, which verified its safety and probiotic properties at the genome level. Additionally, L. plantarum LPJZ-658 exhibited non-toxic and non-hemolytic activity and was susceptible to various tested antibiotics, indicating that L. plantarum LPJZ-658 was safe for consumption. Moreover, the probiotic properties tests confirm that L. plantarum LPJZ-658 also exhibits tolerance to acid and bile salts, preferably hydrophobicity and auto-aggregation, and excellent antimicrobial activity against both Gram-positive and Gram-negative gastrointestinal pathogens. In conclusion, this study confirmed the safety and probiotic properties of L. plantarum LPJZ-658, suggesting it can be used as a potential probiotic candidate for human and animal applications.

B. C, Huligere SS, Khan MS, Alafaleq NO, Ahmad S, Akhter F, Sreepathi N, P. A, Ramu R. Inhibition of carbohydrate hydrolyzing enzymes by a potential probiotic Levilactobacillus brevis RAMULAB49 isolated from fermented Ananas comosus

The research aimed to explore the potential probiotic characteristics of Levilactobacillus brevis RAMULAB49, a strain of lactic acid bacteria (LAB) isolated from fermented pineapple, specifically focusing on its antidiabetic effects. The importance of probiotics in maintaining a balanced gut microbiota and supporting human physiology and metabolism motivated this research. All collected isolates underwent microscopic and biochemical screenings, and those exhibiting Gram-positive characteristics, negative catalase activity, phenol tolerance, gastrointestinal conditions, and adhesion capabilities were selected. Antibiotic susceptibility was assessed, along with safety evaluations encompassing hemolytic and DNase enzyme activity tests. The isolate's antioxidant activity and its ability to inhibit carbohydrate hydrolyzing enzymes were examined. Additionally, organic acid profiling (LC-MS) and in silico studies were conducted on the tested extracts. Levilactobacillus brevis RAMULAB49 demonstrated desired characteristics such as Gram-positive, negative catalase activity, phenol tolerance, gastrointestinal conditions, hydrophobicity (65.71%), and autoaggregation (77.76%). Coaggregation activity against Micrococcus luteus, Pseudomonas aeruginosa, and Salmonella enterica serovar Typhimurium was observed. Molecular characterization revealed significant antioxidant activity in Levilactobacillus brevis RAMULAB49, with ABTS and DPPH inhibition rates of 74.85% and 60.51%, respectively, at a bacterial cell concentration of 109 CFU/mL. The cell-free supernatant exhibited substantial inhibition of α-amylase (56.19%) and α-glucosidase (55.69%) in vitro. In silico studies supported these findings, highlighting the inhibitory effects of specific organic acids such as citric acid, hydroxycitric acid, and malic acid, which displayed higher Pa values compared to other compounds. These outcomes underscore the promising antidiabetic potential of Levilactobacillus brevis RAMULAB49, isolated from fermented pineapple. Its probiotic properties, including antimicrobial activity, autoaggregation, and gastrointestinal conditions, contribute to its potential therapeutic application. The inhibitory effects on α-amylase and α-glucosidase activities further support its anti-diabetic properties. In silico analysis identified specific organic acids that may contribute to the observed antidiabetic effects. Levilactobacillus brevis RAMULAB49, as a probiotic isolate derived from fermented pineapple, holds promise as an agent for managing diabetes. Further investigations should focus on evaluating its efficacy and safety in vivo to consider its potential therapeutic application in diabetes management.

Evaluation of isolated probiotics on the efficacy of immune system in male and female Wistar rats

Probiotics were isolated from fruits and vegetables. Microscopic, biochemical, and molecular tests were carried out for the characterization of strains of probiotics. To assess the effects of isolated probiotics on immunity, male and female (15 + 15) Wistar rats (n = 3) were randomly distributed into 5 groups: 0-day, negative control, positive control (commercially available Lactobacillus acidophilus-14), laboratory isolated probiotics with accession numbers; Lactobacillus plantarum (MZ707748) and Lactobacillus plantarum (MZ729681), respectively. After hematological investigations, the amounts of IgA and IgG in male and female groups were significantly different (p < 0.05). At the same time, the values of Alanine-transaminase (ALT) and Aspartate-aminotransferase (AST) in both genders were average, and there were no differences (p > 0.05). Male probiotic-treated groups had decreased levels of interleukin-6, bilirubin, and creatinine, but female probiotic-treated groups had a slight rise in bilirubin and creatinine values (p = 0.05). Cellular blood count levels of Hematocrit (HCT) and white blood cells (WBC) in male groups showed considerable differences (p < 0.05), while there were no differences (p > 0.05) in female groups. Levels of Red blood cells (RBC) and mean corpuscular hemoglobin concentration (MCHC) showed distinct changes (p < 0.05) in female groups, while these values were insignificant changes (p > 0.05) among male groups. There were considerable differences between the control and groups that were given probiotics. Histopathological results showed no damage to the liver and thymus. A fecal examination of rats was used to examine the viability and survival of Lactobacilli. Based on blood tests, it was observed that the immune system was boosted and improved in probiotic-treated groups compared to control groups.

Novel Dietary Approach with Probiotics, Prebiotics, and Synbiotics to Mitigate Antimicrobial Resistance and Subsequent Out Marketplace of Antimicrobial Agents: A Review

Antimicrobial resistance (AMR) is a significant public health concern worldwide. The continuous use and misuse of antimicrobial agents have led to the emergence and spread of resistant strains of bacteria, which can cause severe infections that are difficult to treat. One of the reasons for the constant development of new antimicrobial agents is the need to overcome the resistance that has developed against existing drugs. However, this approach is not sustainable in the long term, as bacteria can quickly develop resistance to new drugs as well. Additionally, the development of new drugs is costly and time-consuming, and there is no guarantee that new drugs will be effective or safe. An alternative approach to combat AMR is to focus on improving the body's natural defenses against infections by using probiotics, prebiotics, and synbiotics, which are helpful to restore and maintain a healthy balance of bacteria in the body. Probiotics are live microorganisms that can be consumed as food or supplements to promote gut health and improve the body's natural defenses against infections. Prebiotics are non-digestible fibers that stimulate the growth of beneficial bacteria in the gut, while synbiotics are a combination of probiotics and prebiotics that work together to improve gut health. By promoting a healthy balance of bacteria in the body, these can help to reduce the risk of infections and the need for antimicrobial agents. Additionally, these approaches are generally safe and well tolerated, and they do not contribute to the development of AMR. In conclusion, the continuous development of new antimicrobial agents is not a sustainable approach to combat AMR. Instead, alternative approaches such as probiotics, prebiotics, and synbiotics should be considered as they can help to promote a healthy balance of bacteria in the body and reduce the need for antibiotics.

Therapeutic and prophylactic effects of oral administration of probiotic Enterococcus faecium Smr18 in Salmonella enterica-infected mice

Salmonella enterica serotype Typhi causes chronic enteric fever known as typhoid. Prolonged treatment regimen used for the treatment of typhoid and indiscriminate use of antibiotics has led to the emergence of resistant strains of S. enterica that has further increased the severity of the disease. Therefore, alternative therapeutic agents are urgently required. In this study, probiotic and enterocin-producing bacteria Enterococcus faecium Smr18 was compared for both its prophylactic and therapeutic efficacy in S. enterica infection mouse model. E. faecium Smr18 possessed high tolerance to bile salts and simulated gastric juice, as treatment for 3 and 2 h resulted in 0.5 and 0.23 log₁₀ reduction in the colony forming units, respectively. It exhibited 70% auto aggregation after 24 h of incubation and formed strong biofilms at both pH 5 and 7. Oral administration of E. faecium in BALB/c mice infected with S. enterica significantly (p < 0.05) reduced the mortality of the infected mice and prevented the weight loss in mice. Administration of E. faecium prior to infection inhibited the translocation of S. enterica to liver and spleen, whereas, its administration post-infection completely cleared the pathogen from the organs within 8 days. Further, in both pre- and post-E. faecium-treated infected groups, sera levels of liver enzymes were restored back to normal; whereas the levels of creatinine, urea and antioxidant enzymes were significantly (p < 0.05) reduced compared to the untreated-infected group. E. faecium Smr18 administration significantly increased the sera levels of nitrate by 1.63-fold and 3.22-fold in pre- and post-administration group, respectively. Sera levels of interferon-γ was highest (tenfold) in the untreated-infected group, whereas the levels of interleukin-10 was highest in the post-infection E. faecium-treated group thereby indicating the resolution of infection in the probiotic-treated group, plausibly due to the increased production of reactive nitrogen intermediates.

Antibiotic resistance profiling and valorization of food waste streams to starter culture biomass and exopolysaccharides through fed-batch fermentations

The present study evaluated antibiotic resistance (ABR) in bacteria isolated from different food wastes viz., meat slaughterhouses, dairy and restaurants. About 120 strains isolated from the food waste were subjected to ABR screening. More than 50% of all the strains were resistant to Vancomycin, Neomycin and Methicilin, which belong to third-generation antibiotics. Two lactic acid bacteria (LAB) free of ABR were chosen to be used as starter cultures in media formulated from food waste. Food waste combination (FWC-4) was found to be on par with the nutrient broth in biomass production. The non-ABR LAB strains showed excellent probiotic properties, and in the fed-batch fermentation process, adding a nitrogen source (soya protein) enhanced the microbial biomass (3.7 g/l). Additionally, exopolysaccharide production was found to be 2.3 g/l. This study highlights the ABR incidence in food waste medium and its economic advantage for starter culture biomass production.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01222-9.

In-vitro and in-vivo antibacterial activity of potential probiotic Lactobacillus paracasei against Staphylococcus aureus and Escherichia coli

Previous studies documented that Lactobacillus paracasei has obvious in vitro cholesterol-lowering abilities. In this study, initially, L. paracasei was tested in terms of antibacterial properties as well as antibiogram profile. Then, the safety of the mentioned strain was evaluated in rats. Evaluation of antibiotic susceptibility revealed that the L. paracasei strain had high antibiotic resistance to several antibiotics as well as a great ability to autoaggregation. After identification of the probiotic aptitude, six groups of six rats from both sexes were used (three groups of each sex). L. paracasei was administered to the experimental groups via drinking water for 28 days (1 × 108 and 1 × 109, respectively). The negative control group received only tap water during this period. Hematological indicators, serum liver enzyme activity including (alanine transaminase (ALT), alkaline phosphatase (ALP), and aspartate transaminase (AST)) as well as serum creatinine and urea were evaluated at the end of 28 days. The blood and serum factors were not changed significantly during the 28 days. The only noticeable difference was the increase of blood urea in both sexes which was in a normal range. Furthermore, the evaluation of antagonistic properties revealed that L. paracasei had antibacterial aptitude against Escherichia coli and Staphylococcus aureus. In conclusion, this strain has good cholesterol-lowering and antibacterial properties and is a safe supplement in Wistar rats.

Isolation and characterization of lactic acid bacteria with potential probiotic activity and further investigation of their activity by α-amylase and α-glucosidase inhibitions of fermented batters

Probiotic microbiota plays a vital role in gastrointestinal health and possesses other beneficial attributes such as antimicrobial and antibiotic agents along with a significant role in the management of diabetes. The present study identifies the probiotic potential of Lactobacillus spp. isolated from three traditionally fermented foods namely, jalebi, medhu vada, and kallappam batters at biochemical, physiological, and molecular levels. By 16S rRNA gene amplification and sequencing, the isolates were identified. A similarity of >98% to Lacticaseibacillus rhamnosus RAMULAB13, Lactiplantibacillus plantarum RAMULAB14, Lactiplantibacillus pentosus RAMULAB15, Lacticaseibacillus paracasei RAMULAB16, Lacticaseibacillus casei RAMULAB17, Lacticaseibacillus casei RAMULAB20, and Lacticaseibacillus paracasei RAMULAB21 was suggested when searched for homology using NCBI database. Utilizing the cell-free supernatant (CS), intact cells (IC), and cell-free extract (CE) of the isolates, inhibitory potential activity against the carbohydrate hydrolyzing enzymes α-glucosidase and α-amylase was assessed. CS, CE, and IC of the isolates had a varying capability of inhibition against α-glucosidase (15.08 to 59.55%) and α-amylase (18.79 to 63.42%) enzymes. To assess the probiotic potential of seven isolates, various preliminary characteristics were examined. All the isolates exhibited substantial tolerance toward gastrointestinal conditions and also demonstrated the highest survival rate (> 99%), hydrophobicity (> 65%), aggregation (> 76%), adherence to HT-29 cells (> 84%), and chicken crop epithelial cells suggesting that the isolates had a high probiotic attribute. Additionally, the strains showed remarkable results in safety assessment assays (DNase and hemolytic), and antibacterial and antibiotic evaluations. The study concludes that the lactic acid bacteria (LAB) characterized possesses outstanding probiotic properties and has antidiabetic effects. In order to obtain various health advantages, LAB can be utilized as probiotic supplements.

Isolation and Identification of Limosilactobacillus reuteri PSC102 and Evaluation of Its Potential Probiotic, Antioxidant, and Antibacterial Properties

We isolated and characterized Limosilactobacillus reuteri PSC102 and evaluated its probiotic, antioxidant, and antibacterial properties. We preliminarily isolated 154 candidates from pig feces and analyzed their Gram nature, morphology, and lactic acid production ability. Based on the results, we selected eight isolates and tested their ability to produce digestive enzymes. Finally, we identified one isolate using 16S rRNA gene sequencing, namely, L. reuteri PSC102. We tested its probiotic properties in vitro, including extracellular enzyme activities, low pH and bile salt tolerance, autoaggregation and coaggregation abilities, adhesion to Caco-2 cells, antibiotic susceptibility, and hemolytic and gelatinase activities. Antioxidant activity was determined using 1-diphenyl-2-picrylhydrazyl and 2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical scavenging and reducing power assays. The antibacterial activity of this strain and its culture supernatant against enterotoxigenic Escherichia coli were evaluated using a time-kill assay and disk diffusion method, respectively. L. reuteri PSC102 exhibited tolerance toward low pH and bile salt and did not produce harmful enzymes or possess hemolytic and gelatinase activities. Its intact cells and cell-free extract exhibited potential antioxidant activities, and significantly inhibited the growth of enterotoxigenic E. coli. Our results demonstrate that L. reuteri PSC102 is a potential probiotic candidate for developing functional feed.

Isolation and characterization of potential Lactobacillus acidophilus strains isolated from pig feces

The aim of this study was to isolate and characterize Lactic Acid Bacteria (LAB) from 16 feces samples of pig farm, and to evaluate the probiotic potential of these isolates as potential oral probiotic candidates. The selection process was based on the isolation, identification, and a series of experiments for the selection of appropriate candidates with beneficial properties. The results demonstrated that most of LAB showed relatively strong resistance to pH 2.5 and high bile salts (1%), and had good survival in simulated gastric and intestinal juice. 9 isolates displayed antimicrobial activities against Bacillus cereus, Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa and Enterobacter sakazakii. Almost all isolates were sensitive to ampicillin, chloramphenicol, vancomycin and amoxicillin, and most of isolates exhibited resistance against tetracycline and vancomycin. The adhesion rates of LAB varied greatly. The results of the study suggested that the Lactobacillus acidophilus NCUA065001 have the important functional property of probiotic candidates to enhance gut integrity and could considered to be the potential antibiotic alternatives in the pig feed industry.

Assessment of probiotic and technological properties of Bacillus spp. isolated from Burkinabe Soumbala

BACKGROUND

Soumbala is a highly loved alkaline traditional fermented food condiment in Burkina Faso. It harbors various microbiota dominated by fermentative Bacillus spp. as functional microorganism with little confirmed health-promoting properties.

METHODS

The present study aimed to evaluate six Bacillus strains previously isolated and identified from soumbala. These strains were selected as presumptively safe bacteria for probiotic and technological characteristics. These strains were assessed for in vitro probiotic criteria (tolerance to acidic pH, gastric juice, 0.3% (m/v) bile salts, intestinal juice and 0.4% (w/v) phenol, cell surface hydrophobicity, auto-aggregation capacity, antimicrobial activity against foodborne pathogens, antibiotic susceptibility and biofilm production) and technological properties, including protease, amylase, lipase, and tannase activity, as well as poly-γ-glutamic acid (PGA) production and thermo-tolerance.

RESULTS

All tested Bacillus strains (B54, F20, F24, F21, F26 and F44) presented variable relevant probiotic properties (good tolerance to pH 2 and pH 4, gastric juice, bile salts, intestinal juice and phenol), with marked differences in hydrophobicity and auto-aggregation capacity ranging from 73.62-94.71% and 49.35-92.30%, respectively. They exhibited a broad spectrum of activity against foodborne pathogens depending on target pathogen, with the highest activity exhibited by strain F20 (29.52 mm) against B. cereus 39 (p <  0.001). They also showed good biofilm production as well as variable hydrolytic enzyme activities, including protease (43.00-60.67 mm), amylase (22.59-49.55 mm), lipase (20.02-24.57 mm), and tannase (0-10.67 mm). All tested Bacillus strains tolerated temperature up to 50 °C, while only strains F26 and F44 showed the best PGA production.

CONCLUSION

Overall, the tested cultures exhibiting potential probiotic and technological characteristics; particularly B. cereus F20, B. benzoevorans F21, B. cabrialessi F26, and B. tequilensis F44 could be a source of probiotic-starters of commercial interest in the production of high-quality soumbala.

Lactic Acid Bacteria in Raw-Milk Cheeses: From Starter Cultures to Probiotic Functions

Traditional cheeses produced from raw milk exhibit a complex microbiota, characterized by a sequence of different microorganisms from milk coagulation and throughout maturation. Lactic acid bacteria (LAB) play an essential role in traditional cheese making, either as starter cultures that cause the rapid acidification of milk or as secondary microbiota that play an important role during cheese ripening. The enzymes produced by such dynamic LAB communities in raw milk are crucial, since they support proteolysis and lipolysis as chief drivers of flavor and texture of cheese. Recently, several LAB species have been characterized and used as probiotics that successfully promote human health. This review highlights the latest trends encompassing LAB acting in traditional raw milk cheeses (from cow, sheep, and goat milk), and their potential as probiotics and producers of bioactive compounds with health-promoting effects.

Evaluation of Probiotic and Antidiabetic Attributes of Lactobacillus Strains Isolated From Fermented Beetroot

Fermented foods are sources of functionally salient microbes. These microbes when ingested can regulate biomolecule metabolism which has a plethora of health benefits. Lactic acid bacteria species (LABs) isolated from fermented beetroot were biochemically characterized and validated using 16s rRNA sequence. Also, an in vitro assay was conducted to confirm the probiotic activity of the isolates. The cell-free supernatant (CS), cell-free extract (CE), and intact cell (IC) were evaluated for α-glucosidase and α-amylase inhibition. The six isolates RAMULAB01–06 were categorized to be Lactobacillus spp. by observing phenotypic and biochemical characters. Molecular validation using 16S rDNA sequencing, followed by homology search in NCBI database, suggested that the isolates are >95% similar to L. paracasei and L. casei. Also, isolates exhibited probiotic potential with a high survival rate (>96%) in the gastrointestinal condition, and adherence capability (>53%), colonization (>86%), antibacterial, and antibiotic activity. The safety assessments expressed that the isolates are safe. The α-glucosidase and α-amylase inhibition by CS, CE, and IC ranged from 3.97 ± 1.42% to 53.91 ± 3.11% and 5.1 ± 0.08% to 57.15 ± 0.56%, respectively. Hence, these species have exceptional antidiabetic potential which could be explicated to its use as a functional food and health-related food products.

K. J, S. JC, Ramu R. Probiotic Potential Lacticaseibacillus casei and Limosilactobacillus fermentum Strains Isolated from Dosa Batter Inhibit α-Glucosidase and α-Amylase Enzymes

Fermented food plays a major role in gastrointestinal health, as well as possesses other health benefits, such as beneficiary effects in the management of diabetes. Probiotics are thought to be viable sources for enhancing the microbiome of the human gut. In the present study, using biochemical, physiological, and molecular approaches, the isolated Lactobacillus spp. from dosa batter were identified. The cell-free supernatant (CS), cell-free extract (CE), and intact cells (IC) were evaluated for their inhibitory potential against the carbohydrate hydrolyzing enzymes α-glucosidase and α-amylase. Then, 16S rDNA amplification and sequencing were used to identify the species. A homology search in NCBI database was performed that suggests the isolates are >95% similar to Limosilactobacillus fermentum and Lacticaseibacillus casei. Different standard parameters were used to evaluate the probiotic potential of strains RAMULAB07, RAMULAB08, RAMULAB09, RAMULAB10, RAMULAB11, and RAMULAB12. The strains expressed a significant tolerance to the gastric and intestinal juices with a higher survival rate (>98%). A high adhesion capability was observed by the isolates exhibited through hydrophobicity (>65%), aggregation assays (>75%), and adherence assay on HT-29 cells (>82%) and buccal epithelial cells. In addition, the isolates expressed antibacterial and antibiotic properties. Safety assessments (DNase and hemolytic assay) revealed that the isolates could be classified as safe. α-glucosidase and α-amylase inhibition of the isolates for CS, CE, and IC ranged from 7.50% to 65.01% and 20.21% to 56.91%, respectively. The results suggest that these species have exceptional antidiabetic potential, which may be explained by their use as foods that can have health-enhancing effects beyond basic nutrition.

A Potential Probiotic Lactobacillus plantarum JBC5 Improves Longevity and Healthy Aging by Modulating Antioxidative, Innate Immunity and Serotonin-Signaling Pathways in Caenorhabditis elegans

Since the hypothesis of Dr. Elie Metchnikoff on lactobacilli-mediated healthy aging, several microbes have been reported to extend the lifespan with different features of healthy aging. However, a microbe affecting diverse features of healthy aging is of choice for broader acceptance and marketability as a next-generation probiotic. We employed Caenorhabditis elegans as a model to understand the potential of Lactobacillus plantarum JBC5 (LPJBC5), isolated from fermented food sample on longevity and healthy aging as well as their underlying mechanisms. Firstly, LPJBC5 enhanced the mean lifespan of C. elegans by 27.81% compared with control (untreated). LPBC5-induced longevity was accompanied with better aging-associated biomarkers, such as physical functions, fat, and lipofuscin accumulation. Lifespan assay on mutant worms and gene expression studies indicated that LPJBC5-mediated longevity was due to upregulation of the skinhead-1 (skn-1) gene activated through p38 MAPK signaling cascade. Secondly, the activated transcription factor SKN-1 upregulated the expression of antioxidative, thermo-tolerant, and anti-pathogenic genes. In support, LPJBC5 conferred resistance against abiotic and biotic stresses such as oxidative, heat, and pathogen. LPJBC5 upregulated the expression of intestinal tight junction protein ZOO-1 and improved gut integrity. Thirdly, LPJBC5 improved the learning and memory of worms trained on LPJBC5 compared with naive worms. The results showed upregulation of genes involved in serotonin signaling (ser-1, mod-1, and tph-1) in LPJBC5-fed worms compared with control, suggesting that serotonin-signaling was essential for LPJBC5-mediated improved cognitive function. Fourthly, LPJBC5 decreased the fat accumulation in worms by reducing the expression of genes encoding key substrates and enzymes of fat metabolism (i.e., fat-5 and fat-7). Lastly, LPJBC5 reduced the production of reactive oxygen species and improved mitochondrial function, thereby reducing apoptosis in worms. The capability of a single bacterium on pro-longevity and the features of healthy aging, including enhancement of gut integrity and cognitive functions, makes it an ideal candidate for promotion as a next-generation probiotic.

Lactobacillus intestinalis YT2 restores the gut microbiota and improves menopausal symptoms in ovariectomized rats

There are many studies focusing on the alleviation of menopausal symptoms; however, little is known about the role of gut microorganisms in menopausal symptoms. Ovariectomized (OVX) rats were administered a novel strain (YT2) of Lactobacillus intestinalis (a species with significantly reduced abundance in OVX rats) and the potential probiotic effect on the improvement of menopausal symptoms was evaluated. Of note, the gut microbial composition completely shifted after ovariectomy in rats. Treatment with L. intestinalis YT2 significantly alleviated menopausal symptoms, such as increased fat mass, decreased bone mineral density, increased pain sensitivity, depression-like behaviour, and cognitive impairment. Additionally, the administration of L. intestinalis YT2 restored the intestinal microbial composition, including an increased Firmicutes/Bacteroides ratio. L. intestinalis YT2 also promoted gut barrier integrity by increasing the mRNA levels of tight junction-related markers. In conclusion, L. intestinalis YT2 treatment alleviated menopausal symptoms via the modulation of the gut microbiota. Importantly, these results suggest that L. intestinalis YT2 should be considered as a therapeutic probiotic agent for menopausal women.

Molecular identification and in vitro evaluation of probiotic functional properties of some Egyptian lactic acid bacteria and yeasts

BACKGROUND

The health-promoting effects along with global economic importance of consuming food products supplemented with probiotic microorganisms encouraged the researchers to discover new probiotics.

RESULTS

Fourteen lactic acid bacterial isolates were identified as Enterococcus mediterraneensis, Lactobacillus fermentum, and Streptococcus lutetiensis by 16S rRNA gene sequencing, and in vitro characterized for their actual probiotic potential. All E. mediterraneensis isolates were resistant to clindamycin, whereas Lb. fermentum isolates were resistant to ampicillin, clindamycin, and vancomycin. The E. mediterraneensis and Lb. fermentum isolates displayed high overall digestive survival, ranged from 1.35 ± 0.06 to 32.73 ± 0.84% and from 2.01 ± 0.01 to 23.9 ± 1.85%, respectively. All isolates displayed cell surface hydrophobicity, ranged between 15.44 ± 6.72 and 39.79 ± 2.87%. The strongest auto-aggregation capability, higher than 40%, was observed for most E. mediterraneensis and Lb. fermentum isolates. The E. mediterraneensis isolates (L2, L12, and L15), Lb. fermentum (L8, L9, and L10), and Strep. lutetiensis (L14) exhibited the greatest co-aggregation with Salmonella typhimurium, Escherichia coli O157:H7, Staphylococcus aureus, and Bacillus cereus. Fifty-seven and fourteen hundredth percent of E. mediterraneensis isolates could be considered bacteriocinogenic against E. coli O157:H7, B. cereus, and S. aureus.

CONCLUSION

This study is the first one to isolate Enterococcus mediterraneensis in Egypt and to characterize it as new species of probiotics globally. According to the results, E. mediterraneensis (L2, L12, and L15), Lb. fermentum (L8, L9, and L10), and Strep. lutetiensis (L14) are the most promising in vitro probiotic candidates.

Safety, probiotic properties, antimicrobial activity, and technological performance of Lactobacillus strains isolated from Iranian raw milk cheeses

The objective of this study was to investigate probiotic, antimicrobial, technological and safety properties of lactobacillus strains isolated from local Iranian cheese made from raw milk. Six different samples were prepared, after serial dilution, culture was performed on MRS culture medium. The gram-positive and catalase-negative lactobacillus strains were subjected to grouping and identifying using biochemical tests, carbohydrates fermentation profiles, and 16S rDNA analysis. The results of sequence analysis showed the Lactobacillus spp. belonged to Lactobacillus brevis, Lactobacillus acidophilus, Lactobacillus plantarum, and Lactobacillus casei. After 3 hr incubation at pH=2, 3-6 log units of strains decreased which Lactobacillus acidophilus (B14) and Lactobacillus brevis (B2) showed highest resistance to low pH as well as simulated GIT juices. The highest and lowest hydrophobicity degree was belonged to L. acidophilus (B14) (65.9%) and L. casei (B22) (25.6%), respectively. Also, the highest auto-aggregation and coaggregation were observed in L. acidophilus (B14) (51.3%) and L. plantarum (B20) (43.6%). The adhered percentage of strains varied from 2.5% to 14.6%. L. plantarum (B20) showed highest proteolytic activity followed by L. acidophilus (B14). Also, the highest autolytic activity belonged to L. acidophilus (B14). All of the strains showed low acidifying potential, except for L. acidophilus (B17) which decreased 2.05 unit of pH after 24 hr. The isolates did not show lipolytic activity as well as biogenic amines production (except L. brevis B3). All of the strains were sensitive to chloramphenicol and erythromycin except L. acidophilus (B15) and L. casei (B22). All strains showed no hemolysis activity which make them safe for consumption. Based on the obtained results, L. acidophilus (B14) presented the best probiotic and technological characteristics and is proposed for using as coculture in the dairy industrial.

Probiotics in Fish Nutrition—Long-Standing Household Remedy or Native Nutraceuticals?

Over the last decades, aquaculture production increased rapidly. The future development of the industry highly relies on the sustainable utilization of natural resources. The need for improving disease resistance, growth performance, food conversion, and product safety for human consumption has stimulated the application of probiotics in aquaculture. Probiotics increase growth and feed conversion, improve health status, raise disease resistance, decrease stress susceptibility, and improve general vigor. Currently, most probiotics still originate from terrestrial sources rather than fish. However, host-associated (autochthonous) probiotics are likely more persistent in the gastrointestinal tract of fish and may, therefore, exhibit longer-lasting effects on the host. Probiotic candidates are commonly screened in in vitro assays, but the transfer to in vivo assessment is often problematic. In conclusion, modulation of the host-associated microbiome by the use of complex probiotics is promising, but a solid understanding of the interactions involved is only in its infancy and requires further research. Probiotics could be used to explore novel ingredients such as chitin-rich insect meal, which cannot be digested by the fish host alone. Most importantly, probiotics offer the opportunity to improve stress and disease resistance, which is among the most pressing problems in aquaculture.

Investigation of Antibacterial Activity and Probiotic Properties of Strains Belonging to Lactobacillus and Bifidobacterium Genera for Their Potential Application in Functional Food and Feed Products

For novel food/feed product formulation, the selection of the right culture with probiotic properties is essential. The purpose of this research was to evaluate antibacterial activity and probiotic features of Lactobacillus and Bifidobacterium spp. for its potential application in functional food/feed products as supplement. The evaluation of antibacterial activities was carried out by agar diffusion assay and broth inhibition assay methods against twelve pathogenic strains belonging to Staphylococcus aureus, Escherichia coli, Staphylococcus chromogenes, and Staphylococcus hyicus species. Metabolites produced by Lactobacillus paracasei subsp. paracasei DSM 20020, L. paracasei subsp. paracasei DSM 4905, and L. gasseri DSM 20077 inhibited the growth of all tested pathogens. The strains were characterized in vitro for their probiotic characteristics such as resistance to low pH and bile salts, antibiotic sensitivity by gradient diffusion using MIC Test Strips, autoaggregation and coaggregation assay with E. coli DSM 27503, and antioxidant activity by 1-diphenyl-2-picrylhydrazyl (DPPH) and 2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging assays. The results demonstrated that tested probiotic properties varied among the strains. Lactobacillus spp. tolerated pH 3 for 4 h, while 8 of 14 strains survived 4 h in pH 2. Most of tested strains were able to tolerate 0.3% bile salts for 4 h. All tested strains were sensitive to ampicillin. No gelatinase and hemolytic activities were detected. These results suggest Lactobacillus acidophilus DSM 20079, Bifidobacterium pseudolongum DSM 20099, and Bifidobacterium animalis DSM 20105 as probiotic candidates for the development of functional food/feed.

Potential benefits of L. acidophilus in dyslipidemic rats

Several studies have shown that probiotics and synbiotics ameliorate dyslipidemia. However, the molecular mechanisms mediating their effects remain to be determined. Therefore, we aimed to compare the effects of a probiotic, a prebiotic, and a synbiotic in dyslipidemic Sprague–Dawley rats, and explore the mechanisms involved using a proteomic approach. The rats were allocated to five groups: a control group that was fed normal chow, and four high-fat diet-fed groups, three of which were administered a probiotic (Lactobacillus acidophilus), a prebiotic (inulin), or a combination of the two (a synbiotic) for 30 days. We showed that the administration of inulin, and especially L. acidophilus, improved the lipid profile and reduced the serum concentrations of inflammatory markers in high-fat diet-fed rats. Proteomic analysis showed changes in lipid elongation, glycerolipid metabolism, activation of antioxidants, and a reduction in the activation of the mitogen-activated protein kinase signaling pathway in the livers of rats administered L. acidophilus, which likely mediate its beneficial effects on inflammation and dyslipidemia by reduced the levels of 18.56% CRP, 35.71% TNF-α 25.6% LDL-C and 28.57% LDL-C/HDL-C ratio when compared to HF group. L. acidophilus and inulin may represent effective natural means of maintaining inflammation and dyslipidemia.

Probiotic potential and anticancer properties of Pediococcus sp. isolated from traditional dairy products

Herein, 18 lactic acid bacteria isolated from 30 samples of traditional dairy products were identified, and their probiotic potential was evaluated. According to the results, almost all strains showed the probiotic properties sufficiently, though M1 had better characterise. 16S rRNA gene sequencing revealed that this strain belongs to the Pediococcus sp. (<95 % similarity). This strain had substantial antipathogenic activity and did not show any worrying antibiotic resistance. Also, the strain was resistant to high concentrations of bile salt (1 %), NaCl (6.5 %), and low pH (2). Furthermore, it was revealed that cell-free supernatant (CFS), heat-killed cells and live cells derived from M1 significantly decreased the viability of MCF-7 cells so that the CFS resulted in 85 % cell death. Flow cytometry and western blot analysis determined that this compound induced apoptosis in the cancerous cells through increasing the BAX protein expression and decreasing the Bcl-2 protein expression.

Isolation and characterization of Lactococcus garvieae from the fish gut for in vitro fermentation with carbohydrates from agro-industrial waste

This study focused on agro-industrial waste such as fruit peels by extracting prebiotics as a carbon source for lactic acid bacteria (LAB). Four strains of LAB were selected from Oreochromis niloticus (B2 and B3) and Nemipterus japonicas (R4 and R5), and identified as Lactococcus garvieae through 16S rRNA gene sequencing. The analysis of probiotic characteristics revealed that all four strains were able to tolerate sodium chloride (up to 7 %), bile salt (up to 3 %), and broad range of pH (2-9). Further, analysis of polysaccharide contents in the agro-industrial waste materials such as peels of pineapple, orange, lemon, sugarcane, pomegranate, and sweet lemon revealed that the concentration ranged from 3.91-163.85 mg/g. It was observed that orange peels (20.38-140.99 mg/g), sweet lemon peels (22.03-161.93 mg/g), and pomegranate peels (38.19-163.85 mg/g) yielded maximum indigestible polysaccharide. Evaluation of synbiotic combination of probiotic and prebiotic revealed that L. garvieae strains had better fermentation efficiency with orange, sweet lemon, and pineapple compared to lemon, sugarcane, and pomegranate. In nutshell, different types of agro-industrial waste evaluated in this research were found to be a cheap and fermentable carbon sources for LAB. Further study should be conducted to analyze this symbiotic combination as feed supplements for fish in aquaculture as well as various fermentation industries.

Prebiotic Properties of Green and Dark Tea Contribute to Protective Effects in Chemical-Induced Colitis in Mice: A Fecal Microbiota Transplantation Study

Green and dark tea extract (GTE/DTE) ameliorate chemical-induced colitis in mice; however, the role of gut microbiota in the anticolitis effects of green and dark tea in mice remains unclear. This study aims to explore the role of modulations in gut microbes mediated by green and dark tea in colitis mice by fecal microbiota transplantation (FMT). Our results indicated that GTE and DTE (5 mg/kg bodyweight/day for 4 weeks) exhibited prebiotic effects on the donor mice. Moreover, the FMT treatments (transferring the microbiota daily from the 1 g/kg bodyweight fecal sample to each recipient) indicated that, compared with the fecal microbiota from the normal diet-treated donor mice, the fecal microbiota from the GTE- and DTE-treated donor mice significantly ameliorate colitis-related symptoms (e.g., loss of bodyweight, colonic inflammation, loss of barrier integrity, and gut microbiota dysbiosis) and downregulated the TLR4/MyD88/NF-κB pathway. Collectively, GTE and DTE ameliorate chemical-induced colitis by modulating gut microbiota.

Evaluation of the probiotic attributes of Bacillus strains isolated from traditional fermented African locust bean seeds (Parkia biglobosa), “daddawa”

Background

The involvement of probiotic cultures in food fermentation guarantees enhanced organoleptic properties and maximum consumer health benefits. In this study, isolated Bacillus cultures used in the fermentation of African locust bean seeds “Parkia biglobosa” into the food condiment “daddawa” were evaluated for probiotic attributes. Bacillus cereus strains BC1 and BC2 were tested for tolerance to acid, common salt (NaCl), and bile salt. Auto-aggregation and adhesion to epithelial cells, antibiotic sensitivity profile, hemolytic pattern, and antibacterial activity were also evaluated. To demonstrate further health benefit, spores of strain BC1 were investigated for anti-inflammatory potential employing the rat paw edema technique.

Results

Both Bacillus cereus strains showed antagonistic activity against pathogenic Escherichia coli and Staphylococcus aureus. BC1 was more acid-stress tolerant than BC2, maintaining 107.6% viability after 3 h incubation in MRS broth of pH 2.5. However, at 97.74% viability after incubation for 3 h, BC2 was more tolerant to 0.4 % bile salt. The Bacillus cereus strains were susceptible to all antibiotics tested with the exception of norfloxacin and thrived under high saline stress. Both strains were protease producers and non-hemolytic on sheep blood agar. The edema inhibition study revealed that spores of Bacillus cereus strain BC1 had anti-inflammation potential and produced no physiological toxicity on the animals.

Conclusion

These results indicate that the Bacillus cultures for “daddawa” production are good candidates for probiotics and have the potential for application in both animal and human formulations for increased health benefit to consumers.

Probiotic properties of a phytase producing Pediococcus acidilactici strain SMVDUDB2 isolated from traditional fermented cheese product, Kalarei

The nutritional challenge faced by the monogastric animals due to the chelation effects of phytic acid, fuel the research on bioprospecting of probiotics for phytase production. Pediococcus acidilactici SMVDUDB2 isolated from Kalarei, exhibited extracellular phytase activity of 5.583 U/mL after statistical optimization of fermentation conditions viz. peptone (1.27%); temperature (37 °C); pH (6.26) and maltose (1.43%). The phytase enzyme possessed optimum pH and temperature of 5.5 and 37 °C, respectively and was thermostable at 60 °C. The enzyme was purified 6.42 fold with a specific activity of 245.12 U/mg with hydrophobic interaction chromatography. The purified enzyme had K_m and V_max values of 0.385 mM and 4.965 μmol/min respectively, with sodium phytate as substrate. The strain depicted more than 80% survival rate at low pH (pH 2.0, 3.0), high bile salt concentration (0.3 and 0.5%), after gastrointestinal transit, highest hydrophobicity affinity with ethyl acetate (33.33 ± 0%), autoaggregation (77.68 ± 0.68%) as well as coaggregation (73.57 ± 0.47%) with Staphylococcus aureus (MTCC 3160). The strain exhibited antimicrobial activity against Bacillus subtilis (MTCC 121), Mycobacterium smegmatis (MTCC 994), Staphylococcus aureus (MTCC 3160), Proteus vulgaris (MTCC 426), Escherichia coli (MTCC 1652) and Lactobacillus rhamnosus (MTCC 1408). The amount of exopolysaccharide produced by the strain was 2 g/L. This strain having the capability of phytate degradation and possessing probiotic traits could find application in food and feed sectors.

Probiotic Properties of Bacillus Strains Isolated from Stingless Bee (Heterotrigona itama) Honey Collected across Malaysia

This study aimed to isolate, identify, and evaluate the probiotic properties of Bacillus species from honey of the stingless bee Heterotrigona itama. Bacillus spp. were isolated from five different H. itama meliponicultures, and the isolates were characterized through Gram-staining and a catalase test. Tolerance to acidic conditions and bile salt (0.3%), hydrophobicity, and autoaggregation tests were performed to assess the probiotic properties of the selected isolates, B. amyloliquefaciens HTI-19 and B. subtilis HTI-23. Both Bacillus isolates exhibited excellent antimicrobial activity against both Gram-positive and Gram-negative bacteria and possessed significantly high survival rates in 0.3% bile solution for 3 h. Their survival rates in acidic conditions were also comparable to a commercial probiotic strain, Lactobacillus rhamnosus GG. Interestingly, the hydrophobicity and autoaggregation percentage showed no significant difference from L. rhamnosus GG, a commercial probiotic strain. The results from this study suggest that B. amyloliquefaciens HTI-19 and B. subtilis HTI-23 isolated from stingless bee honey have considerably good probiotic properties. Therefore, more studies should be done to investigate the effects of these bacteria cultures on gastrointestinal health.

Characterisation of Lactic Acid Bacteria Isolated from the Gut of Cyprinus carpio That May Be Effective Against Lead Toxicity

The present study was conducted to isolate and characterise Pb-resistant lactic acid bacteria (LAB), and thus determine their potential for use as probiotics against Pb toxicity. A total of 107 Pb-resistant LAB strains were isolated from the gut content of Cyprinus carpio, of which 41 were established to be gram-positive and catalase-negative. Investigation of the Pb-binding ability of these isolated LAB identified seven strains (P2, P6, P7, P9, P16, P19 and P22) with comparatively high Pb-binding activities. These were selected for further screening to establish their Pb tolerance, anti-oxidative capacity and in vitro probiotic characteristics. Strain P16 exhibited both the highest Pb-binding and a relatively good antioxidant capacity. Furthermore, P16 displayed a high survival rate during 4 h of exposure to both low-pH (2.5-3.5) conditions and 10.0% fish bile, and a strong capacity to adhere to fish intestinal mucus (62.4%). Furthermore, P16 showed strong antibacterial activities against all tested fish pathogens. Strains P6, P9, P16, P19 and P22 were susceptible to a range of tested antibiotics, but not to vancomycin. Thus, of the isolated lactobacilli, strain P16 exhibited the best Pb-binding ability, a high level of antioxidant activity and satisfactory in vitro probiotic properties. Biochemical and 16S-rRNA gene analyses identified P16 as Lactobacillus reuteri. Thus, the results of the conducted in vitro tests suggest that the fish-associated P16 Lact. reuteri strain is a promising candidate probiotic, which should undergo further investigation to assess its suitability for use in protecting against lead-exposure-induced toxicities in aquaculture.

Probiotic Properties of Lactic Acid Bacteria Isolated From Neera: A Naturally Fermenting Coconut Palm Nectar

Probiotic bacteria were isolated from different traditional fermented foods as there are several such foods that are not well explored for their probiotic activities. Hence, the present study was conducted to find the potential of lactic acid bacteria (LAB) as probiotics that were isolated from the sap extract of the coconut palm inflorescence - Neera, which is a naturally fermented drink consumed in various regions of India. A total of 75 isolates were selected from the Neera samples collected aseptically in the early morning (before sunrise). These isolates were initially screened for cultural, microscopic, and biochemical characteristics. The initial screening yielded 40 Gram-positive, catalase-negative isolates that were further subjected to acid - bile tolerance with resistance to phenol. Among 40 isolates, 16 survived screening using analysis of cell surface hydrophobicity, auto aggregation with adhesion to epithelial cells, and gastric-pancreatic digestion for gastrointestinal colonization. The isolates were also assessed for antimicrobial, antibiotic sensitivity, and anti-oxidative potential. The safety of these isolates was evaluated by their hemolytic and deoxyribonuclease (DNase) activities. Based on these results, seven isolates with the best probiotic attributes were selected and presented in this study. These LAB isolates, with 51.91-70.34% survival at low pH, proved their resistance to gastric conditions. The cell surface hydrophobicity of 50.32-77.8% and auto aggregation of 51.02-78.95% represented the adhesion properties of these isolates. All the seven isolates exhibited good antibacterial and antifungal activity, showing hydroxyl-scavenging activity of 32.86-77.87%. The results proved that LAB isolated from Neera exhibited promising probiotic properties and seem favorable for use in functional fermented foods as preservatives.

Properties of potentially probiotic Lactobacillus isolates from poultry intestines

The most commonly used probiotic bacteria belong to the genus Lactobacillus, being regarded as beneficial for poultry health and production. However, commercial probiotics do not always ensure both expected effects. In order to improve the utility properties of new preparations, the selection of new probiotic candidates should be made on the basis of the performance of the species within the poultry digestive tract. The aim of this study was to isolate and identify lactobacilli from poultry intestines, and to select probiotic candidates for subsequent in vivo trials. Digesta from 18 poultry specimens were collected, serially diluted, plated onto Wilkins-Chalgren anaerobe agar supplemented with 30% of rumen fluid and onto De Man, Rogosa and Sharpe agar plates, and incubated at 37 °C for 48 h under anaerobic conditions. Isolated colonies were subjected to Gram staining and catalase reaction. They were then pre-identified using matrix-assisted laser desorption ionization (MALDI) time of flight (TOF) mass spectrometry (MS). Forty-four Lactobacillus strains belonging to 16 species were identified and subjected to evaluations of survival under simulated gastrointestinal conditions, autoaggregation and hydrophobicity. Most of the screened Lactobacillus reuteri strains as well as individual strains of L. acidophilus, L. salivarius, L. saerimneri, and L. vaginalis showed high survival rates under gastrointestinal tract conditions and good surface properties. The results suggest their potential for further testing as probiotic candidates in in vivo trials.

In Vitro Selection and Identification of Potential Probiotics Isolated from the Gastrointestinal Tract of Nile Tilapia, Oreochromis niloticus

Fish gut bacteria can be used as probiotics for aquaculture. The aim of this study is to screen and identify beneficial probiotic bacteria from the gut of Nile tilapia, Oreochromis niloticus. Nine out of one hundred thirty-five isolates were non-pathogenic through intraperitoneal injection and had antibacterial activities with at least a strain from the five isolated fish pathogens, Aeromonas sobria, Aeromonas hydrophila, Pseudomonas aeruginosa, Pseudomonas putida, and Staphylococcus aureus. Further tests showed that such isolates can survive in the presence of high bile concentration (10%) and at different acidic pH values. A strains (14HT) was sensitive to all selected antibiotics, two strains were (9HT and 11HT) resistant to streptomycin and three strains (9HT, 11HT and 38HT) had resistance to two antibiotics. Four isolates (11HT, 33HT, 38HT and 41HT) had an amylase and a protease activities and one strain (47HT) showed only amylase activity. Based on 16S rRNA gene analysis, the isolated strains were identified as follows: Lactococcus lactis (8HT, 9HT, 11HT and 33HT); Enterococcus faecalis (14HT), Lysinibacillus sp. (38HT) and Citrobacter freundii (39HT, 41HT and 47HT).

Relationship between tetracycline antibiotic susceptibility and genotype in oral cavity Lactobacilli clinical isolates

Background

Antibiotic resistance, is often conferred by the presence of antibiotic resistance genes. This study aimed to investigate the relationship between tetracycline resistance (Tet-R) and genotype in 31 Lactobacillus isolates from caries-active patients.

Methods

The tetracycline susceptibility of Lactobacillus isolates was determined using the agar spot test and the genetic characteristics associated with tetracycline resistance using whole-genome sequencing (WGS).

Results

The minimum inhibitory concentration (MIC) values of most isolates were equal to or lower than the breakpoint MIC values. Four strains that were phenotypically more sensitive (L. fermentum B09, S23 and L. rhamonsus B17) or more resistant (L. plantarum B43) than other isolates to tetracycline were subjected to conduct whole-genome sequencing in order to detect the tetracycline resistance genes. The results revealed that the most common Tet-R genes in Lactobacillus strains were tetT, tetW, tetO and tetL. In addition, tetPB, tcr3 and otrA were detected for the first time. There were distinct Tet-R gene mutations in Lactobacillus isolates. Overall, the mean expression values of Tet-R-mutated genes in L. plantarum B43 were elevated, and the relative expression levels of tetT and tetW genes in L. rhamonsus B17 L. fermentum B09 and S23 were decreased relative to reference strains.

Conclusion

The results of this study indicate that Lactobacillus isolates from saliva of caries-active patients do not present considerable tetracycline resistance reservoirs. However, genetic compounds associated with tetracycline resistance were identified by whole-genome sequencing, providing meaningful insights into tetracycline resistance mechanisms.

Characterization of Diversity and Probiotic Efficiency of the Autochthonous Lactic Acid Bacteria in the Fermentation of Selected Raw Fruit and Vegetable Juices

The diversity of indigenous lactic acid bacteria (LAB) in fermented broccoli, cherry, ginger, white radish, and white-fleshed pitaya juices was analyzed using culture-independent and -dependent approaches. The major properties of selected probiotic strains, including dynamic variations in pH, viable cell counts, antibiotic resistance, bacterial adhesion to hydrophobic compounds, and survivability during simulated gastrointestinal transit, were investigated using broccoli as the fermentation substrate. In broccoli and ginger juices, the genus Lactobacillus occupied the dominant position (abundances of 79.0 and 30.3%, respectively); in cherry and radish juices, Weissella occupied the dominant position (abundances of 78.3 and 83.2%, respectively); and in pitaya juice, Streptococcus and Lactococcus occupied the dominant positions (52.2 and 37.0%, respectively). Leuconostoc mesenteroides, Weissella cibaria/soli/confusa, Enterococcus gallinarum/durans/hirae, Pediococcus pentosaceus, Bacillus coagulans, and Lactococcus garvieae/lactis subspecies were identified by partial 16S rRNA gene sequencing. In general, the selected autochthonous LAB isolates displayed no significant differences in comparison with commercial strains with regard to growth rates or acidification in fermented broccoli juice. Among all the isolates, L. mesenteroides B4-25 exhibited the highest antibiotic resistance profile (equal to that of L. plantarum CICC20265), and suitable adhesion properties (adhesion of 13.4 ± 5.2% ∼ 36.4 ± 3.2% and 21.6 ± 1.4% ∼ 69.6 ± 2.3% to ethyl acetate and xylene, respectively). Furthermore, P. pentosaceus Ca-4 and L. mesenteroides B-25 featured the highest survival rates (22.4 ± 2.6 and 21.2 ± 1.4%, respectively), after simulated gastrointestinal transit. These results indicated a high level of diversity among the autochthonous bacterial community in fermented fruit and vegetable juices, and demonstrated the potential of these candidate probiotics for applications in fermentation.

Antagonistic Activities and Probiotic Potential of Lactic Acid Bacteria Derived From a Plant-Based Fermented Food

In this study, antagonistic activities and probiotic potential of lactic acid bacteria (LAB) derived from a plant-based fermented food, kimchi, were demonstrated. The cell free supernatants (CFS) from Lactobacillus curvatus KCCM 43119, Leuconostoc mesenteroides KCCM 43060, Weissella cibaria KCTC 3746, and W. koreensis KCCM 41517 completely inhibited the growth of foodborne pathogenic bacteria, while neutralized CFS (pH 6.5) partially inhibited the growth. The competition, exclusion, and displacement of foodborne pathogenic bacteria by the LAB strains from adhesion to HT-29 cells were investigated. The LAB strains were able to compete with, exclude, and displace the foodborne pathogenic bacteria. However, the degree of inhibition due to the adhesion was found to be a LAB strain-dependent phenomenon. The LAB strains showed high coaggregation with foodborne pathogenic bacteria, and they also exhibited high resistance to acidic condition. Except W. cibaria KCTC 3746, all LAB strains were capable of surviving in the presence of bile salts. Furthermore, while all LAB strains were resistant to chloramphenicol, kanamycin, streptomycin, gentamicin, and erythromycin, only W. cibaria KCTC 3746 and W. koreensis KCCM 41517 displayed resistance to vancomycin. These results suggest that the LAB strains derived from kimchi exerted antagonistic activities against foodborne pathogenic bacteria with probiotic potential.

Probiotic Potential of a Lactobacillus Bacterium of Canine Faecal-Origin and Its Impact on Select Gut Health Indices and Immune Response of Dogs

The objective of the present study was to develop a probiotic of canine-origin for its potential application in pet nutrition. Accordingly, 32 lactic acid bacteria (LAB) strains were isolated from faeces of dogs, out of which 9 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 nine, isolate cPRO23 was having better resistance to these adverse conditions likely to be encountered in the gastrointestinal tract. The isolate also showed optimal enzymatic activities for amylase, lipase and protease. Further assessments also indicated its superiority in terms of co-aggregation and antagonistic activity against pathogenic strains of Salmonella typhimurium and Salmonella enteritidis. Subsequently, the isolate was identified through 16S rRNA sequencing and sequence homology, and designated as Lactobacillus johnsonii CPN23. The candidate probiotic was then evaluated in vivo using 15 adult Labrador dogs, divided into 3 groups, viz. CON (with no probiotics), dPRO (with Lactobacillus acidophilus NCDC 15 as a conventional dairy-origin probiotic) and cPRO (with L. johnsonii CPN23 as a canine-origin probiotic). Results of the 9-week study indicated that supplementation of cPRO improved (P < 0.05) the faecal concentration of acetate and butyrate with a concomitant reduction (P < 0.05) in faecal ammonia. The cell-mediated immune response, assessed as delayed-type hypersensitivity reaction to phytohaemagglutinin-P, was better (P < 0.05) in dogs fed cPRO as compared to the CON dogs. There were, however, no variations evident in the antibody response to sheep-erythrocytes among the three groups. It is concluded that the canine-origin L. johnsonii CPN23, in addition to possessing all the in vitro functional attributes of a candidate probiotic, also has the potential to be used as a probiotic in pet nutrition programs.