Probiotic screening and safety evaluation of Lactobacillus strains from plants, artisanal goat cheese, human stools, and breast milk

Characterization of probiotics isolated from dietary supplements and evaluation of metabiotic-antibiotic combinations as promising therapeutic options against antibiotic-resistant pathogens using time-kill assay

BACKGROUND

The global probiotics dietary supplements market size is continuously growing. To overcome probiotics' health concerns, metabiotics are recognized as a safer alternative. Aiming to deal with the escalating antimicrobial resistance, the current work demonstrates synergistic metabiotic-antibiotic combinations against antibiotic-resistant pathogens.

METHODS

The probiotic properties of lactic acid bacteria (LAB) strains isolated from 3 commercial dietary supplements were characterized in vitro. The combinations of the cell-free supernatants (CFS) of selected probiotic strains and conventional antibiotics against Staphylococcus aureus and Escherichia coli clinical isolates were evaluated using the time-kill assay. To our knowledge, the current literature lacks sufficient time-kill assay studies revealing the kinetics of such metabiotic-antibiotic combinations against S. aureus and E. coli.

RESULTS

Four LAB strains isolated from dietary supplements as well as two reference strains were included in this study. The isolated LAB strains were identified by MALDI-TOF mass spectrometry as follows: P2: Lactobacillus acidophilus, P3: Lactiplantibacillus plantarum, P4: Lacticaseibacillus rhamnosus, and P5: Pediococcus acidilactici. The identification matched with that annotated by the manufacturers, except for P3. The tested strains could resist the acidic environment at pH 3. Excluding P2, the examined strains showed less than 1 log reduction in survivors upon the addition of reconstituted skimmed milk to pepsin at pH 2 and displayed an acceptable tolerance to 0.3% ox-bile. All the strains tolerated pancreatin. The hydrophobicity and autoaggregation capacities ranged between 7-92% and 36-66%, respectively. P2 was excluded owing to its inferior probiotic potential. Although the remaining strains showed excellent growth at 0.2% phenol, their growth was reduced at higher concentrations. L. plantarum and P. acidilactici strains possessed bile salt hydrolysis activity. The time-kill assay revealed promising synergistic activities of the combinations of CFS of L. rhamnosus P4 with either ceftazidime or gentamicin against E. coli and with only ceftazidime against S. aureus, as well as CFS of P. acidilactici P5 and ceftazidime against S. aureus.

CONCLUSIONS

Strict identification and evaluation of the probiotic strains incorporated in dietary supplements is crucial to ensure their safety and efficacy. The CFS of probiotics could be utilized to formulate novel biotherapeutics targeting problematic pathogens. However, future in vivo studies are required to evaluate the appropriate treatment regimen.

The Effects of Lactobacillus johnsonii on Diseases and Its Potential Applications

Lactobacillus johnsonii has been used as a probiotic for decades to treat a wide range of illnesses, and has been found to have specific advantages in the treatment of a number of ailments. We reviewed the potential therapeutic effects and mechanisms of L. johnsonii in various diseases based on PubMed and the Web of Science databases. We obtained the information of 149 L. johnsonii from NCBI (as of 14 February 2023), and reviewed their comprehensive metadata, including information about the plasmids they contain. This review provides a basic characterization of different L. johnsonii and some of their potential therapeutic properties for various ailments. Although the mechanisms are not fully understood yet, it is hoped that they may provide some evidence for future studies. Furthermore, the antibiotic resistance of the various strains of L. johnsonii is not clear, and more complete and in-depth studies are needed. In summary, L. johnsonii presents significant research potential for the treatment or prevention of disease; however, more proof is required to justify its therapeutic application. An additional study on the antibiotic resistance genes it contains is also needed to reduce the antimicrobial resistance dissemination.

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.

Safety Assessment of Lactiplantibacillus (formerly Lactobacillus) plantarum Q180

The safety of the probiotic strain Q180, which exerts postprandial lipid-lowering effects, was bioinformatically and phenotypically evaluated. The genome of strain Q180 was completely sequenced, and single circular chromosome of 3,197,263 bp without any plasmid was generated. Phylogenetic and related analyses using16S rRNA gene and whole-genome sequences revealed that strain Q180 is a member of Lactiplantibacillus (Lp., formerly Lactobacillus) plantarum. Antimicrobial resistance (AMR) genes were bioinformatically analyzed using all Lp. plantarum genomes available in GenBank, which showed that AMR genes are present differently depending on Lp. plantarum strains. Bioinformatic analysis demonstrated that some mobile genetic elements such as prophages and insertion sequences were identified in the genome of strain Q180, but because they did not contain harmful genes such as AMR genes and virulence factor (VF)- and toxin-related genes, it was suggested that there is no transferability of harmful genes. The minimum inhibition concentrations of seven tested antibiotics suggested by the European Food Safety Authority guidelines were slightly lower than or equal to the microbiological cut-off values for Lp. plantarum. Strain Q180 did not show hemolytic and gelatinase activities and biogenic amine-producing ability. Taken together, this study demonstrated the safety of strain Q180 in terms of absence of AMR genes and VF- and toxin-related genes as a probiotic strain.

Improvement in Lactose Tolerance in Hypolactasic Subjects Consuming Ice Creams with High or Low Concentrations of Bifidobacterium bifidum 900791

Although Bifidobacterium bifidum expresses lactase activity, no clinical trials have determined its impact on lactose-intolerant subjects. This study evaluated whether acute and chronic ingestion of ice creams containing B. bifidum 900791 at high (10⁷ CFU/g) or low (10⁵ CFU/g) concentrations improved lactose tolerance in hypolactasic subjects. Fifty subjects were selected based on a positive lactose (20 g) hydrogen breath test (HBT0) and the presence of digestive symptoms. The recruited subjects were required to perform breath tests after the acute ingestion of: (1) ice cream containing 20 g of lactose without a probiotic (HBT1); (2) the same ice cream, accompanied by a lactase tablet (HBT2); (3) the same ice cream containing the low or high dose of probiotic (HBT3-LD and HBT3-HD); and (4) after the chronic consumption of the ice cream without (placebo) or with the low concentration of probiotic for 1 month (HBT4). Significant decreases in H₂ excretion during HBT2 and HBT3-HD as well as digestive symptoms during HBT2, HBT3-HD and HBT3-LD were observed compared to HBT0 and HBT1, while the orocecal transit time increased. Chronic consumption of the probiotic ice cream did not enhance lactose tolerance compared to the placebo. These results suggest that the acute ingestion of ice cream containing high or low concentrations of B. bifidum 900791 improves lactose tolerance in hypolactasic subjects.

Lactiplantibacillus plantarum 299v (LP299V®): three decades of research

This review aims to provide a comprehensive overview of the in vitro, animal, and clinical studies with the bacterial strain Lactiplantibacillus plantarum 299v (L. plantarum 299v; formerly named Lactobacillus plantarum 299v) published up until June 30, 2020. L. plantarum 299v is the most documented L. plantarum strain in the world, described in over 170 scientific publications out of which more than 60 are human clinical studies. The genome sequence of L. plantarum 299v has been determined and is available in the public domain (GenBank Accession number: NZ_LEAV01000004). The probiotic strain L. plantarum 299v was isolated from healthy human intestinal mucosa three decades ago by scientists at Lund University, Sweden. Thirty years later, a wealth of data coming from in vitro, animal, and clinical studies exist, showing benefits primarily for gastrointestinal health, such as reduced flatulence and abdominal pain in patients with irritable bowel syndrome (IBS). Moreover, several clinical studies have shown positive effects of L. plantarum 299v on iron absorption and more recently also on iron status. L. plantarum 299v is safe for human consumption and does not confer antibiotic resistance. It survives the harsh conditions of the human gastrointestinal tract, adheres to mannose residues on the intestinal epithelial cells and has in some cases been re-isolated more than ten days after administration ceased. Besides studying health benefits, research groups around the globe have investigated L. plantarum 299v in a range of applications and processes. L. plantarum 299v is used in many different food applications as well as in various dietary supplements. In a freeze-dried format, L. plantarum 299v is robust and stable at room temperature, enabling long shelf-lives of consumer healthcare products such as capsules, tablets, or powder sachets. The strain is patent protected for a wide range of indications and applications worldwide as well as trademarked as LP299V^®.

Probiotic Properties and Potentiality of Lactiplantibacillus plantarum Strains for the Biological Control of Chalkbrood Disease

Ascosphaera apis is an entomopathogenic fungus that affects honeybees. In stressful conditions, this fungus (due not only to its presence, but also to the combination of other biotic and abiotic stressors) can cause chalkbrood disease. In recent years, there has been increasing attention paid towards the use of lactic acid bacteria (LAB) in the honeybees' diets to improve their health, productivity and ability to resist infections by pathogenic microorganisms. The screening of 22 strains of Lactiplantibacillus plantarum, isolated from the gastrointestinal tracts of honeybees and beebread, led to the selection of five strains possessing high antagonistic activity against A. apis. This study focused on the antifungal activity of these five strains against A. apis DSM 3116 and DSM 3117 using different matrices: cell lysate, broth culture, cell-free supernatant and cell pellet. In addition, some functional properties and the antioxidant activity of the five L. plantarum strains were evaluated. All five strains exhibited high antagonistic activity against A. apis, good surface cellular properties (extracellular polysaccharide (EPS) production and biofilm formation) and antioxidant activity. Although preliminary, these results are encouraging, and in future investigations, the effectiveness of these bacteria as probiotics in honeybee nutrition will be tested in vivo in the context of an eco-friendly strategy for the biological control of chalkbrood disease.

Isolation of Bile Salt Hydrolase and Uricase Producing Lactobacillus brevis SF121 from Pak Sian Dong (Fermented Spider Plant) for using as Probiotics

The interesting application of bile salt hydrolase enzyme is reduction of cholesterol in serum and amelioration lipid profile. While uricase enzyme can be applied to convert insoluble uric acid to be soluble form and excrete from the body. Probiotics are living organisms with generally know that they can provide beneficial effects to their host. Several reports show that probiotic bacteria with bile salt hydrolase and uricase can improve hypercholesterolemia and hyperuricemia patient. The novel isolate of Lactobacillus from Pak Sian Dong in this study is identified as L. brevis SF121 and probably use as probiotic bacteria in the future. However, this isolate still need further experiments to investigate and improve properties of probiotics. Moreover, this finding suggests that Pak Sian Dong or fermented spider plant can be designated as a good source for probiotic screening and also defines as health-promoting diet.

A newly isolated E. thailandicus strain d5B with exclusively antimicrobial activity against C. difficile might be a novel therapy for controlling CDI

Colitis induced by C. difficile is one of the most common and costly healthcare-related infections for humans. Probiotics are one of the most promising approaches for controlling CDI. Here, we presented the isolation, safety, and probiotic property evaluation of a novel E. thailandicus strain, d5B, with effective antimicrobial activity against C. difficile. Strain d5B showed strong bactericidal effects on at least 54C. difficile strains. Safety tests showed that strain d5B was sensitive to clinically important antibiotics, and had no haemolytic and cytotoxic activities. Whole genomic analysis showed strain d5B only contained one aminoglycoside resistance gene located in the chromosome. Moreover, d5B was devoid of functional virulence genes. Finally, strain d5B exhibited probiotic properties, such as tolerance to the gastrointestinal tract, and adhered well to HT-29 cells. In conclusion, the E. thailandicus strain d5B should be investigated further for useful properties as a novel candidate probiotic for controlling CDI.

Antimicrobial and antiadhesive effects of Lactobacillus isolates of healthy human gut origin on Enterotoxigenic Escherichia coli (ETEC) and Enteroaggregative Escherichia coli (EAEC)

PURPOSE

Diarrhea is one of the five leading causes of mortality in children under the age of five, especially in developing countries. Nowadays, by increasing the resistance of pathogens to antibiotics, employment of probiotics as novel therapeutic method, could be considered as a necessity.The aim of this study was to examine the features and antagonistic action of Lactobacillus strains, against the growth and adhesion of Enterotoxigenic Escherichia coli (ETEC) and Enteroaggregative Escherichia coli (EAEC) strains creating diarrhea in children. Then, we introduced new strains of Lactobacillus as probiotic candidates, to prevent diarrheal infections in children.

METHODS

Stool samples were collected from healthy individuals, and Lactobacillus strains were isolated. The antimicrobial effect of the isolates against ETEC and EAEC strains investigated by agar well diffusion method and their resistance to acidic and bile conditions. The potency of selected isolates in adhesion to HT-29 epithelial cells and their ability to inhibit the adhesion of ETEC and EAEC strains to this cell were measured. At the end, identification of the optimally efficient Lactobacillus isolates was performed by 16S rDNA sequencing and making Phylogenetic tree using MEGA (version 4.0) software.

RESULTS

In total, 157 isolates suspected to Lactobacillus were isolated from 115 stool samples. In antimicrobial activity test, ETEC and EAEC growth was inhibited by 132 and 84 isolates respectively, while 17 isolates showed resistance to Bile. Of 17 Bile resistant Lactobacillus isolates, 15 isolates were resistant to pH: 3.2. Further, among 15 isolates, only two isolates, were resistant to pH: 2.5. In the adhesion assay, five isolates had more adhesion tendency to HT-29 epithelial cells than L. rhamnosus GG, which was considered as a positive control. Investigation of isolates that inhibit adhesion of ETEC and EAEC strains to HT-29 cells showed that four isolates were able to inhibit ETEC adhesion. However, only one out of four isolates was relatively able to have an impact on EAEC adhesion.

CONCLUSION

In conclusion, three species of Lactobacillus including L. paracasei (two strain), L. fermentum (two strain) and L. plantarum showed good probiotic properties compared to other isolates that were identified by sequencing. In this study, strain L. fermentum 61.1 had the highest adhesion ability to HT-29 cells and strain L. paracasei 47.2 had the highest potency to inhibit ETEC adhesion to HT-29 cells. These isolates have good probiotic properties and are likely to be effective in preventing or treating diarrheal infections, especially in children.

Functional probiotics of lactic acid bacteria from Hu sheep milk

Background

Probiotics are being considered as valuable microorganisms related to human health. Hu sheep is referred as one of the important sheep breeds in China. Goat milk produced by Hu sheep is characterized with high nutritional value and hypoallergenic in nature. Particularly, this milk contains plenty of milk prebiotic and probiotic bacteria. This study was aimed to scrutinize more bacterial strains from Hu sheep milk with potential probiotic activity.

Results

Based on 16S rRNA sequence analysis, pool of forty bacterial strains were identified and evaluated their antimicrobial activities against Staphylococcus aureus, enterohemorrhagic Escherichia coli (EHEC), Salmonella typhimurium, Listeria monocytogenes enterotoxigenic E. coli (ETEC) and Aeromonas caviae. Four out of these isolated strains demonstrated their efficient bacteriostatic ability and potential healthy properties. We also examined the safety aspects of these bacterial candidates including three Lactococcus lactis strains (named as HSM-1, HSM-10, and HSM-18) and one Leuconostoc lactis strain (HSM-14), and were further evaluated via in vitro tests, including antimicrobial activity, cell surface characteristics (hydrophobicity, co-aggregation, and self-aggregation), heat treatment, antibiotic susceptibility, simulated transport tolerance in the gastrointestinal tract, and acid/bile tolerance. The obtained results revealed that HSM-1, HSM-10, HSM-14, and HSM-18 showed high survival rate at different conditions for example low pH, presence of bovine bile and demonstrated high hydrophobicity. Moreover, HSM-14 had an advantage over other strains in terms of gastrointestinal tract tolerance, antimicrobial activities against pathogens, and these results were significantly better than other bacterial candidates.

Conclusion

Hu sheep milk as a source of exploration of potential lactic acid bacteria (LAB) probiotics open the new horizon of probiotics usage from unconventional milk sources. The selected LAB strains are excellent probiotic candidates which can be used for animal husbandry in the future. Rationale of the study was to utilize Hu sheep milk as a source of potential probiotic LABs. The study has contributed to the establishment of a complete bacterial resource pool by exploring the Hu sheep milk microflora.

Faecalibacterium diversity in dairy cow milk

The bacterial species, Faecalibacterium prausnitzii, beneficial to humans and animals and found in mammalian and avian gut, is also occasionally found in dairy cow milk. It is one of the butyrate-producing bacteria of the colon, has anti-inflammatory properties and its abundance in the gut is negatively correlated with obesity in humans. Several strains differing in their functional capability, have been identified. It is important therefore, milk being a potential source of F. prausnitzii as a novel probiotic, to investigate the diversity of this species in bovine milk. Using 16s rRNA gene amplicons we find 292 different dereplicated Faecalibacterium-related amplicons in a herd of 21 dairy cows. The distribution of the 20 most abundant amplicons with >97% identity to a Greengenes OTU varies from cow to cow. Clustering of the 292 pooled sequences from all cows at 99.6% identity finds 4 likely Faecalibacterium phylotypes with >98.5% identity to an F. prausnitzii reference sequence. Sequence alignment and phylogenetic analysis shows these phylotypes are distinct from 34 other species from the Ruminococcaceae family and displaying the sequence clusters as a network illustrates how each cluster is composed of sequences from multiple cows. We conclude there are several phylotypes of Faecalibacterium prausnitzii (the only species so far defined for the genus) in this dairy herd with cows being inoculated with a mixture of several strains from a common source. We conclude that not only can Faecalibacterium be detected in dairy cow milk (as noted by others) but that there exist multiple different strains in the milk of a dairy herd. Therefore milk, as an alternative to faeces, offers the opportunity of discovering new strains with potential probiotic application.

Cocoa Pulp as Alternative Food Matrix for Probiotic Delivery

BACKGROUND

For screening probiotic strains with viability and stability in non-dairy foods for health benefits, we revised all patents relating to probiotics in food.

OBJECTIVE

Screening of potential probiotics from Brazilian Minas artisanal cheese and verify their survival in frozen Brazilian cocoa pulp.

METHODS

Isolation and identification of the strains. The potential probiotic characterization involved gastric juice and bile resistance, antibiotic and antimicrobial activity, hydrophobicity, autoaggregation, coaggregation and adhesion assay in HT-29 cells. Organoleptic, viability and stability of probiotic strain in frozen cocoa pulp were evaluated.

RESULTS

Fourteen strains of Lactobacillus plantarum (9), Weissella paramesenteroides (3), Lactobacillus fermentum (1), and Leuconostoc mesenteroides (1) were obtained. Most of the strains were resistant to simulated gastric acidity and bile salts. Almost all strains were sensitive to the antibiotics tested, except to ciprofloxacin and vancomycin. About 47% of the strains are potential producers of bacteriocins. High hydrophobicity was observed for four strains. Autoaggregation ranged from 8.3-72.6% and the coaggregation capacity from 5.2-60.2%. All of the assessed strains presented more than 90% of adhesion to HT-29 intestinal cells. The percentage of Salmonella inhibition in HT-29 cells ranged from 4.7-31.1%. No changes in color, aroma, and pH were observed in cocoa pulps after storage at -20 °C for 90 days.

CONCLUSION

Wild strains of acid lactic bacteria from cheese proved to be viable and stable in frozen Brazilian cocoa pulp. This work showed a promising application of L. plantarum isolated strains to be used with frozen cocoa pulp matrix in probiotics food industry.

Characterization of bacteriocin production in Lactobacillus spp. isolated from mother's milk

The purpose of the present study was to isolate Lactobacillus bacteria from mother's milk and to assess their probiotic potential. Sixty breast milk samples were collected from the volunteered mothers aged from 19 to 35 and from rural areas of Lorestan and Markazi Provinces, Iran. At first, 970 bacill-shaped bacterial colonies were isolated from these samples and stored in proper condition. Two hundred isolates were randomly selected and investigated for their ability to tolerate acidic condition and to tolerate bile salt as well. Only 33 isolates could withstand the exposure to low pH and bile salt. The isolates were identified using PCR primer specific to Lactobacillus and it was demonstrated that eighteen of thirty-three isolates were belonged to the Lactobacillus. Among the isolates, 16 and 2 of them were Lactobacillus reuteri and L. gasseri, respectively. In addition, the antibiotic resistance of the isolates was determined using disc diffusion method and all of the isolates were shown to be sensitive to eight out of the twelve investigated antibiotics. Moreover, the antagonistic effect of the isolates was inspected on ten indicator pathogens. Interestingly, all of the pathogenic bacteria were inhibited by Lactobacillus isolates. In addition, to partially understand the nature of inhibition mechanism, well diffusion deployed for two randomly-selected indicator bacteria and the resulting halos of three isolates were statistically significant compared to other lactobacillus (p < 0.05). Subsequently, bacteriocin genes (plnS, Laf, gasA) were identified by PCR among the isolates. The results showed that only 2 isolates possessed the gasA gene which were in accordance with well diffusion test. Consequently, eighteen Lactobacillus isolated from breast milk samples which all of them were able to tolerate low pH and bile salt. Similarly, all of the Lactobacillus isolates were proved to inhibit the growth of pathogen strains and two of them possess a bacteriocin-related gene.

Acemannan and Fructans from Aloe vera (Aloe barbadensis Miller) Plants as Novel Prebiotics

The nutraceutical properties of Aloe vera have been attributed to a glucomannan known as acemannan. Recently information has been published about the presence of fructans in Aloe vera but there are no publications about acemannan and fructans as prebiotic compounds. This study investigated in vitro the prebiotic properties of these polysaccharides. Our results demonstrated that fructans from Aloe vera induced bacterial growth better than inulin (commercial FOS). Acemannan stimulated bacterial growth less than fructans, and as much as commercial FOS. Using qPCR to study the bacterial population of human feces fermented in a bioreactor simulating colon conditions, we found that fructans induce an increase in the population of Bifidobacterium spp. Fructans produced greater amounts of short chain fatty acids (SCFA), while the branched-chain fatty acids (BCFA) did not increase with these polysaccharides. Acemannan increased significantly acetate concentrations. Therefore, both Aloe vera polysaccharides have prebiotic potentials.

Draft genome sequence of Lactobacillus plantarum strains E2C2 and E2C5 isolated from human stool culture

Probiotic Lactobacillus species offer various health benefits, thus have been employed in treatment and prevention of various diseases. Due to the differences in the isolation source and the site of action, most of the lactobacilli tested in-vitro for probiotics properties fail to extend similar effects in-vivo. Consequently, the search of autochthonous, efficacious and probably population specific probiotics is a high priority in the probiotics research. In this regards, whole genome sequencing of as many Lactobacillus as possible will help to deepen our understanding of biology and their health effects. Here, we provide the genomic insights of two coherent oxalic acid tolerant Lactobacillus species (E2C2 and E2C5) isolated from two different healthy human gut flora. These two isolates were found to have higher tolerance towards oxalic acid (300 mM sodium oxalate). The draft genome of strain E2C2 consists of 3,603,563 bp with 3289 protein-coding genes, 94 RNA genes, and 43.99% GC content, while E2C5 contained 3,615,168 bp, 3293 coding genes (93.4% of the total genes), 95 RNA genes and 43.97% GC content. Based on 16S rRNA gene sequence analysis followed by in silico DNA-DNA hybridization studies, both the strains were identified as Lactobacillus plantarum belonging to family Lactobacillaceae within the phylum Firmicutes. Both the strains were genomically identical, sharing 99.99% CDS that showed 112 SNPs. Both the strains also exhibited deconjugation activity for the bile salts while genome analysis revealed that the L. plantarum strains E2C2 and E2C5 also have the ability to produce vitamins, biotin, alpha- and beta- glucosidase suggesting potential probiotic activities of the isolates. The description presented here is based on the draft genomes of strains E2C2 and E2C5 which are submitted to GenBank under the accession numbers LSST00000000.1 and LTCD00000000.1, respectively.

Antimicrobial activity of lactobacillus strains against uropathogens

BACKGROUND

The use of lactobacillus probiotics has been proposed as an alternative to prophylactic antibiotics for preventing urinary tract infection (UTI) in the era of antibiotic resistance. In this study, the antimicrobial activity of lactobacillus strains against uropathogens, was evaluated and compared with that of antibiotics.

METHODS

To evaluate inhibitory activities of lactobacilli against uropathogens, six lactobacillus strains (L. gasseri, L. rhamnosus, L. acidophilus, L. plantarum, L. paracasei, L. acidophilus) and four representative uropathogens of infantile UTI (extended-spectrum beta-lactamase [ESBL](-) Escherichia coli, ESBL(+) E. coli, Proteus vulgaris, Enterococcus fecalis) were selected. Lactobacillus strain in vitro inhibition of each uropathogen was evaluated on MRS agar well diffusion assay and compared with that of commercial antibiotic discs.

RESULTS

Average inhibitory zone for each of the six lactobacillus strains against the four uropathogens showed slightly different but consistent inhibition (inhibitory zone diameter, 10.5-20.0 mm). This was different to that of the antibiotic discs, which had a wider range of inhibition (inhibitory zone diameter, <6.0-27.5 mm) depending on the uropathogen resistance pattern. The inhibitory zone of the six lactobacillus strains was between that of sensitive and resistant antibiotics (P < 0.05).

CONCLUSIONS

Lactobacillus strains had similar moderate antimicrobial activities against uropathogens. Further research is needed to ascertain the strains with the best probiotic potential.

What goes around comes around: novel pharmacological targets in the gut-brain axis

The gut and the brain communicate bidirectionally through anatomic and humoral pathways, establishing what is known as the gut-brain axis. Therefore, interventions affecting one system will impact on the other, giving the opportunity to investigate and develop future therapeutic strategies that target both systems. Alterations in the gut-brain axis may arise as a consequence of changes in microbiota composition (dysbiosis), modifications in intestinal barrier function, impairment of enteric nervous system, unbalanced local immune response and exaggerated responses to stress, to mention a few. In this review we analyze and discuss several novel pharmacological targets within the gut-brain axis, with potential applications to improve intestinal and mental health.

Complete genome sequences and comparative genome analysis of Lactobacillus plantarum strain 5-2 isolated from fermented soybean

Lactobacillus plantarum is an important probiotic and is mostly isolated from fermented foods. We sequenced the genome of L. plantarum strain 5-2, which was derived from fermented soybean isolated from Yunnan province, China. The strain was determined to contain 3114 genes. Fourteen complete insertion sequence (IS) elements were found in 5-2 chromosome. There were 24 DNA replication proteins and 76 DNA repair proteins in the 5-2 genome. Consistent with the classification of L. plantarum as a facultative heterofermentative lactobacillus, the 5-2 genome encodes key enzymes required for the EMP (Embden-Meyerhof-Parnas) and phosphoketolase (PK) pathways. Several components of the secretion machinery are found in the 5-2 genome, which was compared with L. plantarum ST-III, JDM1 and WCFS1. Most of the specific proteins in the four genomes appeared to be related to their prophage elements.