Candidate Probiotic Strains Research Articles

Lacticaseibacillus rhamnosus LRa05 alleviates cyclophosphamide-induced immunosuppression and intestinal microbiota disorder in mice.

Probiotics play a crucial role in regulating the gut microbiota and enhancing immune response. Oral administration of probiotics modulates intestinal microbiota composition and immune homeostasis. In this study, we investigated the immunoregulatory effect of Lacticaseibacillus rhamnosus LRa05 on cyclophosphamide (CTX)-induced immunosuppressive mice. The results showed that oral administration of LRa05 reduced weight loss, restored immune organ indices, and maintained the structural integrity of the intestinal tissue in CTX-treated mice. Moreover, oral administration of LRa05 exhibited immune-modulating properties by promoting the secretion of cytokines (tumor necrosis factor-α, interleukin-1β, interleukin-10, and secretory immunoglobulin A) in serum. Moreover, the analysis of 16S rRNA amplicon sequencing revealed that LRa05 increased gut microbiota diversity and regulated its composition. In detail, LRa05 intervention restored the Firmicutes/Bacteroidota ratio and significantly increased the relative abundance of Lachnospiraceae_NK4A136_group, Oscillibacter, Alloprevotella, Parasutterella, and Roseburia in immunocompromised mice. Conversely, the abundances of Helicobacter, Bacteroides, and unclassified_Desulfovibrionaceae were significantly decreased after administration of LRa05. Based on these findings, orally administered LRa05 could effectively maintain intestinal microbiota homeostasis and regulate immunity, suggesting the potential of L. rhamnosus LRa05 as a candidate probiotic strain in the application of dietary supplement. PRACTICAL APPLICATION: Supplement with L. rhamnosus LRa05 can improve immunity, regulate gut microbiota and promote body health.

Genome sequence of the New Zealand cheese isolate and candidate probiotic strain Lactiplantibacillus plantarum FNZ042.

The complete genome sequence of the candidate probiotic strain Lactiplantibacillus plantarum FNZ042 was determined using a hybrid genome assembly comprising data from Illumina and PacBio sequencing platforms. The genome assembly comprised 3,265,637 bp, including the complete circular chromosome and three circular plasmids.

Genome sequence of the New Zealand raw milk isolate and candidate probiotic strain Lactococcus lactis FNZ339.

The complete genome sequence of the candidate probiotic strain Lactococcus lactis FNZ339 was determined using a hybrid genome assembly comprising data from Illumina and Oxford Nanopore Technologies sequencing platforms. The genome assembly comprised 2,673,297 bp, including the complete circular chromosome and four circular plasmids.

334 Metagenomic- and culture-based characterization of the ocular microbiome in cattle with infectious bovine keratoconjunctivitis

Abstract Pinkeye, clinically known as infectious bovine keratoconjunctivitis (IBK), is one of the most highly contagious diseases impacting cattle at all ages. Despite extensive use of antibiotics and vaccines targeting Moraxella bovis, the primary IBK pathogen, the incidence of pinkeye has been increasing in North American beef cow-calf operations. This highlights the incomplete understanding of the pathogenesis of this disease and the need for novel and alternative approaches to control IBK. The objectives of this study were to: 1) characterize the ocular microbiome of beef cattle with and without IBK using shotgun metagenomic sequencing; 2) investigate the genetic diversity of M. bovis, Moraxella bovoculi, and commensal ocular bacterial isolates; 3) evaluate whether selected ocular probiotic candidate strains inhibit Moraxella pathogen growth in the presence of the ocular microbiome in culture using qPCR. A total of 143 ocular swabs were collected from cattle with (n = 102) or without IBK (n = 42) and before antibiotic treatment from beef herds across North Dakota, USA. Fifty samples from IBK (n = 38) and healthy cattle (n = 12) were also subjected to shotgun metagenomic sequencing. Seven bacterial species were relatively more abundant (P < 0.05) in the healthy cattle ocular microbiome including Bifidobacterium globosum, Bacillus licheniformis, Pasteurella multocida, Ruminococcus sp900316555, and Ruminococcus sp900100595. Arthrobacter luteus was the only bacterial species significantly associated with IBK-affected cattle. From the metagenomes, 37 high-quality dereplicated metagenome-assembled genomes (MAGs) were recovered, nearly a third of which were identified as Mesomycoplasma bovoculi (n = 10). M. bovis (n = 5) and M. bovoculi (n = 13) were also isolated from the ocular swabs of both healthy and IBK-affected cattle. These isolates represented 9 M. bovoculi and 5 M. bovis strains (average nucleotide identity < 99.99%). We also isolated and sequenced several potentially beneficial bacterial species from healthy cattle including Bacillus pumilus, Lactiplantibacillus plantarum, Lentilactobacillus buchneri, Levilactobacillus brevis, and Weizmannia coagulans. Four of these probiotic candidates were also tested for their inhibitory effects against M. bovoculi in co-culture with the ocular microbiome after 24 h incubation using qPCR. The B. pumilus, L. buchneri, L. plantarum, and W. coagulans strains, as well as a mixture of all four isolates, significantly reduced the growth of Moraxella. In summary, our results provide important information on the culturable and non-culturable fraction of the bovine ocular microbiome potentially associated with IBK and suggest that certain bacterial species in the eye may inhibit the growth of Moraxella spp.

Efficacy of lyophilized Lactobacillus sakei as a potential candidate for preventing carbapenem-resistant Klebsiella infection

BackgroundAntimicrobial resistance is considered one of the greatest threats to human health, according to the World Health Organization (WHO). Gram-negative bacteria, especially carbapenem-resistant Enterobacteriaceae (CRE), have become a significant concern in antimicrobial-resistant bacteria’s global emergence and spread. Among CRE pathogens, carbapenem-resistant Klebsiella pneumoniae (CRKP) has recently been reported as a highly infectious strain associated with high mortality and morbidity in adults and immunocompromised patients. Additionally, CRKP-related infections are challenging to treat, as carbapenems are the last resort of antibiotics. Therefore, developing novel drugs with different mechanisms of action from existing drugs is urgently required to defeat this lethal menace. Under such circumstances, probiotics can be therapeutic candidates for inhibiting pathogens. Thus, our research team has been focusing on probiotics for a long time to develop potential anti-CRKP drug agents.MethodsAfter extensive efforts, we finally found a novel probiotic strain, Lactobacillus sakei PMC104, suitable for treating CRKP infection. It was isolated from kimchi. As part of our expansion into therapeutic development, we evaluated the L. sakei strain effect against CRKP pathogens in both in vitro and in vivo experiments. Moreover, we conducted media optimization at food grade and then established a scale-up process on a pilot scale. Subsequently, a lyophilizate was obtained and used in a mouse model infected with CRKP.ResultsData demonstrated that the L. sakei strain has an inhibitory effect against CRKP infection both in in vitro and in vivo experiments and also increases the level of short-chain fatty acids in the feces of mice after receiving L. sakei strain treatment for 10 days. Furthermore, treatment with L. sakei powder remarkably diminished body weight loss, mortality, and illness severity in CRKP-infected mice, showing a preventive effect of our PMC 104 against CRKP infection.DiscussionOur results demonstrate the potential therapeutic effect of our candidate probiotic strain against CRKP, suggesting that L. sakei PMC 104 could be considered an antimicrobial candidate for treating CRKP infections. However, extensive studies, including additional toxicity tests and clinical trials, are still essential to develop it as a new anti-CRKP therapeutic agent.

In Vitro Effects of Postmetabolites from Limosilactobacillus fermentum 53 on the Survival and Proliferation of HT-29 Cells.

Naturally fermented dairy products are an important component of the human diet. They are a valuable source of nutrients as well as vitamins and minerals. Their importance as a source of probiotic bacterial strains should not be overlooked. A number of studies highlight the positive effects of species of the probiotic lactic acid bacteria on the intestinal microbiome and the overall homeostasis of the body, as well as a complementary treatment for some diseases. However, data on the effects on the intestinal epithelial cells of postmetabolites released by probiotic bacteria are incomplete. This is likely due to the fact that these effects are species- and strain-specific. In the present study, we investigated the effects of postmetabolites produced by a pre-selected candidate probiotic strain Limosilactobacillus fermentum on HT-29 intestinal epithelial cells. Our data showed a pronounced proliferative effect, evaluated by flow cytometry, quantification of the cell population and determination of the mitotic index. This was accompanied by the stabilization of the cell monolayer, measured by an increase in TEER (transepithelial electric resistance) and the reorganization of actin filaments. The data obtained are a clear indication of the positive effects that the products secreted by L. fermentum strain 53 have on intestinal epithelial cells.

Pediococcus pentosaceus ZZ61 enhances growth performance and pathogenic resistance of silkworm Bombyx mori by regulating gut microbiota and metabolites

Probiotics have attracted considerable attention in animal husbandry due to their positive effect on animal growth and health. This study aimed to screen candidate probiotic strain promoting the growth and health of silkworm and reveal the potential mechanisms. A novel probiotic Pediococcus pentosaceus strain (ZZ61) substantially promoted body weight gain, feed efficiency, and silk yield. These effects were likely mediated by changes in the intestinal digestive enzyme activity and nutrient provisioning (e.g., B vitamins) of the host, improving nutrient digestion and assimilation. Additionally, P. pentosaceus produced antimicrobial compounds and increased the antioxidant capacity to protect the host against pathogenic infection. Furthermore, P. pentosaceus affected the gut microbiome and altered the levels of gut metabolites (e.g., glycine and glycerophospholipids), which in turn promotes host nutrition and health. This study contributes to an improved understanding of the interactions between probiotic and host and promotes probiotic utilization in sericulture.

Efficacy and Mechanism of the Action of Live and Heat-Killed Bacillus coagulans BC198 as Potential Probiotic in Ameliorating Dextran Sulfate Sodium-Induced Colitis in Mice.

Inflammatory bowel disease alters the gut microbiota, causes defects in mucosal barrier function, and leads to dysregulation of the immune response to microbial stimulation. This study investigated and compared the efficacy of a candidate probiotic strain, Bacillus coagulans BC198, and its heat-killed form in treating dextran sulfate sodium-induced colitis. Both live and heat-killed B. coagulans BC198 increased gut barrier-associated protein expression, reduced neutrophil and M1 macrophage infiltration of colon tissue, and corrected gut microbial dysbiosis induced by colitis. However, only live B. coagulans BC198 could alleviate the general symptoms of colitis, prevent colon shortening, and suppress inflammation and tissue damage. At the molecular level, live B. coagulans BC198 was able to inhibit Th17 cells while promoting Treg cells in mice with colitis, reduce pro-inflammatory MCP-1 production, and increase anti-inflammatory IL-10 expression in the colonic mucosa. The live form of B. coagulans BC198 functioned more effectively than the heat-killed form in ameliorating colitis by enhancing the anti-inflammatory response and promoting Treg cell accumulation in the colon.

Mechanisms of interleukin-10 induction in murine spleen and RAW264 cells by Latilactobacillus curvatus K4G4 isolated from fermented Brassica rapa L.

Lactic acid bacteria (LAB) are commonly used in fermented foods, and some LAB modulate the immune response. We aimed to investigate the mechanism by which LAB isolates from fermented Brassica rapa L. induce the production of anti-inflammatory interleukin (IL)-10 by the murine spleen and RAW264 cells. Spleen cells from BALB/c mice or the mouse macrophage cell line RAW264 were cultured with heat-killed LAB isolated from fermented B. rapa L., and the IL-10 level in the supernatant was measured. Latilactobacillus curvatus K4G4 provided the most potent IL-10 induction among 13 isolates. Cell wall components of K4G4 failed to induce IL-10, while treatment of the bacteria with RNase A under a high salt concentration altered K4G4 induction of IL-10 by spleen cells. In general, a low salt concentration diminished the IL-10 induction by all strains, including K4G4. In addition, chloroquine pretreatment and knock down of toll-like receptor 7 through small interfering RNA suppressed K4G4 induction of IL-10 production by RAW264 cells. Our results suggest that single-stranded RNA from K4G4 is involved, via endosomal toll-like receptor 7, in the induction of IL-10 production by macrophages. K4G4 is a promising candidate probiotic strain that modulates the immune response by inducing IL-10 from macrophages.

Evaluation of new candidate probiotic lactobacillus strains isolated from a traditional fermented food- multigrain-millet dosa batter

The food industry is constantly developing new products to meet the increasing global demand of fermented foods, for its health benefits. In this study, the potential probiotics in traditional fermented food - “multigrain-millet” based Dosa batter, and their significant probiotic characteristics was investigated. In addition, the ability of probiotic Lactobacillus to prevent foodborne pathogens was explored. A total collection of 70 isolates were examined from the batter. The six isolates with the best in vitro probiotic characteristics were studied. The six isolates MYSDS57, MYSDS68, MYSDV3, MYSDV2, MYSDV5 and MYSDV6 were identified as Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, Lactobacillus pentosus, Lactiplantibacillus plantarum, Lactiplantibacillus plantarum and Limosilactobacillus fermentum respectively based on 16 S rRNA gene sequencing analysis. All six Lactobacillus were able to tolerate acidic pH (45 %–80 % survivability) and 0.3% bile salt (50 %–80.4 % survivability) up to 5 h of incubation. All tested strains showed higher growth at 37 °C, resistance to different concentrations of phenols (53.3 %–83.6 % of viability) and NaCl (38.2%–49.5% of viability). However, the strains exhibited resistance to antibiotic vancomycin, but no hemolytic and DNase activity. Moreover, six strains showed significantly high values of autoaggregation (54.6%-78.8 %) and cell surface hydrophobicity (70 %-81.7%). The α-glucosidase and α-amylase inhibitory activity ranged from 15.08% to 67.22 % and 50.15%–92.13% respectively. Additionally, the intracellular cell-free supernatant of all six Lactobacillus demonstrated antibacterial activity with the inhibition rate of 64.8 %–86 % (Salmonella typhi), 51.8 %–95.2 % (Escherichia coli), 59.9 %–76.6 % (Listeria monocytogenes), 39.6% −74.3 % (Salmonella paratyphi), 57.4 %–81.3 % (Klebsiella pneumonia), 44 %-67.1% (Staphylococcus aureus) and 7.2 %–54.7 % (Pseudomonas aeruginosa). The strains exhibited higher viability (5.8–7.5 log CFU/mL) to simulated gastric juice, high adhesion to chicken crop epithelial cells and buccal cells. These isolates also reduced the cholesterol level in vitro. Overall, the selected Lactobacillus can be considered promising probiotic candidates for future applications.

Distinctive features of the oropharyngeal microbiome in Inuit of Nunavik and correlations of mild to moderate bronchial obstruction with dysbiosis

Inuit of Nunavik are coping with living conditions that can influence respiratory health. Our objective was to investigate associations between respiratory health in Inuit communities and their airway microbiome. Oropharyngeal samples were collected during the Qanuilirpitaa? 2017 Inuit Health Survey and subjected to metagenomic analyses. Participants were assigned to a bronchial obstruction group or a control group based on their clinical history and their pulmonary function, as monitored by spirometry. The Inuit microbiota composition was found to be distinct from other studied populations. Within the Inuit microbiota, differences in diversity measures tend to distinguish the two groups. Bacterial taxa found to be more abundant in the control group included candidate probiotic strains, while those enriched in the bronchial obstruction group included opportunistic pathogens. Crossing taxa affiliation method and machine learning consolidated our finding of distinct core microbiomes between the two groups. More microbial metabolic pathways were enriched in the control participants and these were often involved in vitamin and anti-inflammatory metabolism, while a link could be established between the enriched pathways in the disease group and inflammation. Overall, our results suggest a link between microbial abundance, interactions and metabolic activities and respiratory health in the Inuit population.

Development of a workflow for the selection, identification and optimization of lactic acid bacteria with high γ-aminobutyric acid production

Lactic acid bacteria produce γ-aminobutyric acid (GABA) as an acid stress response. GABA is a neurotransmitter that may improve sleep and resilience to mental stress. This study focused on the selection, identification and optimization of a bacterial strain with high GABA production, for development as a probiotic supplement. The scientific literature and an industry database were searched for probiotics and potential GABA producers. In silico screening was conducted to identify genes involved in GABA production. Subsequently, 17 candidates were screened for in vitro GABA production using thin layer chromatography, which identified three candidate probiotic strains Levilactobacillus brevis DSM 20054, Lactococcus lactis DS75843and Bifidobacterium adolescentis DSM 24849 as producing GABA. Two biosensors capable of detecting GABA were developed: 1. a transcription factor-based biosensor characterized by the interaction with the transcriptional regulator GabR was developed in Corynebacterium glutamicum; and 2. a growth factor-based biosensor was built in Escherichia coli, which used auxotrophic complementation by expressing 4-aminobutyrate transaminase (GABA-T) that transfers the GABA amino group to pyruvate, hereby forming alanine. Consequently, the feasibility of developing a workflow based on co-culture with producer strains and a biosensor was tested. The three GABA producers were identified and the biosensors were encapsulated in nanoliter reactors (NLRs) as alginate beads in defined gut-like conditions. The E. coli growth factor-based biosensor was able to detect changes in GABA concentrations in liquid culture and under gut-like conditions. L. brevis and L. lactis were successfully encapsulated in the NLRs and showed growth under miniaturized intestinal conditions.

Identification and Characterisation of Potential Probiotic Lactic Acid Bacteria Extracted from Pig Faeces

Given that probiotics always have host-homologous and strain-specific effects on the hosts, lactic acid bacteria extracted and identified from porcine specimens can be potentially developed as probiotics for pig production. We aimed to identify lactic acid bacteria that are potentially probiotic, have good capacity of inhibiting pathogenic bacteria in intestine and are promising to be used as substitutes for antibiotics in pig production. Potential probiotic strains were extracted from 15 fecal specimens collected from 15 apparently healthy pigs, and were identified via 16S rDNA sequencing. The antimicrobial activity, tolerance to acid and bile salts, Caco-2 cell adhesiveness and susceptibility to antibiotics of the isolates were evaluated in vitro, and oral toxicity of the isolates were evaluated in mice. One Lactiplantibacillus plantarum (BJR2), two Lacticaseibacillus casei (HJD and TH2), one Lacticaseibacillus rhamnosus (MRS1), and two Enterococcus faecium (S-3 and S-4-H) were extracted from healthy pigs and underwent 16S rDNA sequencing identification. L. plantarum BJR2 and L. casei HJD exhibited broad-spectrum and higher antimicrobial activity against indicator enteric pathogens, including Salmonella choleraesuis CVCC 2139, Escherichia coli (O147:K89) CVCC 199, Escherichia coli (O141:K99) CVCC 223 and Escherichia coli (O139) CVCC 1496, among 6 tested strains. In addition, both L. plantarum BJR2 and L. casei HJD exhibited good tolerance to low pH (pH 2.5 and pH 3.5) and 0.30% bile salts, had relatively strong Caco-2 adhesiveness and carried no transferable resistant genes against antibiotics encoded by plasmid. In safety trials, these two isolates had no α or β-hemolysis activity, and were proved safe through oral toxicity tests in mice. It is concluded that L. plantarum BJR2 and L. casei HJD are potential probiotic candidate strains and their probiotic effects need to be further studied in pigs.

From In Vitro to In Vivo: A Rational Flowchart for the Selection and Characterization of Candidate Probiotic Strains in Intestinal Disorders.

Experimental and clinical evidence has demonstrated the potential of probiotic strains in the prevention or treatment of inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). However, there is little data on what the methodology leading to the identification of such strains should be. In this work, we propose a new flowchart to identify strains with probiotic potential for the management of IBS and IBD, which we tested on a collection of 39 lactic acid bacteria and Bifidobacteria strains. This flowchart included in vitro tests of immunomodulatory properties on intestinal and peripheral blood mononuclear cells (PBMCs), assessment of the barrier-strengthening effect by measuring transepithelial electric resistance (TEER) and quantification of short-chain fatty acids (SCFAs) and aryl hydrocarbon receptor (AhR) agonists produced by the strains. The in vitro results were then combined in a principal component analysis (PCA) to identify strains associated with an anti-inflammatory profile. To validate our flowchart, we tested the two most promising strains identified in the PCA in mouse models of post-infectious IBS or chemically induced colitis to mimic IBD. Our results show that this screening strategy allows the identification of strains with potential beneficial effects on colonic inflammation and colonic hypersensitivity.

Microbiota in the stomach and application of probiotics to gastroduodenal diseases

The stomach is a hostile environment for most microbes because strong gastric acid kills indigenous microorganisms. Thus, the mass of indigenous microbes detected by traditional culturing method in a highly acidic stomach is reported to be very small. However, in a stomach with less acidity due to atrophic changes of the gastric mucosa, the number of live gastric microbiota dramatically increases and their composition changes. A probiotic is defined as a live microorganism that, when administered in adequate amounts, confers a health benefit on the host. The administration of probiotics to the stomach has thus far been considered impractical, mainly due to the strong acidity in the stomach. The identification of candidate probiotic strains with sufficient resistance to acidity and the ability to achieve close proximity to the gastric mucosa could enable the application of probiotics to the stomach. The utilization of probiotics alone for Helicobacter pylori (H. pylori) infection significantly improves gastric mucosal inflammation and decreases the density of H. pylori on the mucosa, although complete eradication of H. pylori has not yet been demonstrated. The use of probiotics in combination with antimicrobial agents significantly increases the H. pylori eradication rate, especially when the H. pylori strains are resistant to antimicrobial agents. While H. pylori has been considered the most important pathogenic bacterium for the development of gastric cancer, bacteria other than H. pylori are also suggested to be causative pathogens that promote the development of gastric cancer, even after the eradication of H. pylori. Increased non-H. pylori Gram-negative bacteria in the stomach with weak acidity accompanying atrophic gastritis may perpetuate gastric mucosal inflammation and accelerate carcinogenic progression, even after H. pylori eradication. Probiotics restore the acidity in this stomach environment and may therefore prevent the development of gastric cancer by termination of Gram-negative bacteria-induced inflammation. Functional dyspepsia (FD) is defined as the presence of symptoms that are thought to originate in the gastroduodenal region in the absence of any organic, systematic or metabolic diseases. Accumulating evidence has pointed out the duodenum as a target region underlying the pathophysiology of FD. A randomized placebo-controlled clinical trial using a probiotic strain (LG21) demonstrated a significant improving effect on major FD symptoms. One of the possible mechanisms of this effect is protection of the duodenal mucosa from injurious intestinal bacteria through the resolution of small intestinal bacterial over growth.

In Vivo Efficacy of Bacillus velezensis Isolated from Korean Gochang Bokbunja Vinegar against Carbapenem-Resistant Klebsiella pneumoniae Infections.

Outbreaks of carbapenem-resistant Enterobacteriaceae (CRE), especially Klebsiella pneumoniae (CRKP), are commonly reported as severe infections in hospitals and long-term care settings, and their occurrence is increasing globally. Conventional antibiotics used for treating CRE have become ineffective due to resistance development. Furthermore, their safety issues restrict their availability and use for CRE treatment. Therefore, developing new drugs different from existing drugs to combat this deadly menace is urgently needed. Probiotics can be a potential option in this context, as probiotics' efficacy against a variety of infectious illnesses has already been well established. Here, we report the effect of the Bacillus velezensis strain isolated from Gochang Bokbunja vinegar in Korea on CRE infection using two mouse models. Data showed that pretreatment with B. velezensis significantly reduced body weight loss and mortality of CRKP-infected mice in the preventive model. The oral administration of B. velezensis in a therapeutic model also decreased the mortality and illness severity in CRKP-infected mice. Moreover, a two-week oral acute toxicity assay in guinea pigs did not reveal any aberrant clinical signs. Our findings demonstrate the potential effectiveness of our candidate probiotic strain, B. velezensis, against CRKP, suggesting that it could be used as an antimicrobial agent for treating CRKP-related infections.

Lacticaseibacillus rhamnosus CA15 (DSM 33960) as a Candidate Probiotic Strain for Human Health.

Lactobacilli with probiotic properties have emerged as promising tools for both the prevention and treatment of vaginal dysbiosis. The present study aimed to study the in vitro probiotic potential of the Lacticaseibacillus rhamnosus CA15 (DSM 33960) strain isolated from a healthy vaginal ecosystem. The strain was evaluated for both functional (antagonistic activity against pathogens; H2O2, organic acid, and lactic acid production; antioxidant and anti-inflammatory activities; ability to adhere to intestinal mucus and to both CaCo-2 and VK7/E6E7 cell lines; exopolysaccharide production; surface properties; and ability to survive during gastrointestinal transit) and safety (hemolytic, DNase, and gelatinase activities; mucin degradation ability; production of biogenic amines; and resistance to antimicrobials) characteristics. Data revealed that the tested strain was able to antagonize a broad spectrum of vaginal pathogens. In addition, the adhesion capacity to both vaginal and intestinal cell lines, as well as anti-inflammatory and antioxidant activities, was detected. The ability of the Lacticaseibacillus rhamnosus CA15 (DSM 33960) strain to survive under harsh environmental conditions occurring during the gastrointestinal passage suggests its possible oral delivery. Thus, in vitro data highlighted interesting probiotic properties of the CA15 (DSM 33960) strain, which could represent a valuable candidate for in vivo vaginal infections treatment.

Draft genome sequences of Bacillus pumilus 36R ATNSAL and B. safensis 13L LOBSAL, two potential candidate probiotic strains for shrimp aquaculture

This work aimed to isolate bacterial strains with antagonist activity against Vibrio parahaemolyticus, the causative agent of acute hepatopancreatic necrosis disease (VPAHPND) that was isolated from outbreaks in Mexico. Here, we report the draft genome sequences of two antagonistic strains, isolated from saline sediment in Sonora, Mexico. Cross-streak and well diffusion tests were employed to find the bacterial strains with higher inhibitory activity against VPAHPND. The whole genomes of B. pumilus 36R ATNSAL and B. safensis 13L LOBSAL were sequenced using Ion TorrentTM (PGM) and Illumina MiseqTM platforms, respectively. Annotation was performed using the RAST server, and the genes involved in the biosynthesis of bacterial secondary metabolites were predicted using antiSMASH. Two bacterial isolates, B. safensis 13L LOBSAL and B. pumilus 36R ATNSAL, were chosen based on their strong antagonistic profiles. The genome of 36R ATNSAL was 3.94 Mbp in length and contained 3824 genes and a total of 4116 coding sequences (CDSs); the genome of 13L LOBSAL was 3.68 Mbp and contained 3619 genes and 3688 CDSs. Twenty-eight and 32 biosynthetic gene clusters responsible for putative antimicrobial metabolite production were identified in 36R ATNSAL and 13L LOBSAL, respectively. The two strains 13L LOBSAL and 36R ATNSAL showed excellent probiotic profiles in vitro. The genome sequences will help with the mining and reconstruction of metabolic pathways in Bacillus strains. Genome sequence-guided strain improvement could augment the probiotic potential of Bacillus strains for applications in shrimp aquaculture.

Impact of Putative Probiotics on Growth, Behavior, and the Gut Microbiome of Farmed Arctic Char (Salvelinus alpinus).

Beneficial bacteria promise to promote the health and productivity of farmed fish species. However, the impact on host physiology is largely strain-dependent, and studies on Arctic char (Salvelinus alpinus), a commercially farmed salmonid species, are lacking. In this study, 10 candidate probiotic strains were subjected to in vitro assays, small-scale growth trials, and behavioral analysis with juvenile Arctic char to examine the impact of probiotic supplementation on fish growth, behavior and the gut microbiome. Most strains showed high tolerance to gastric juice and fish bile acid, as well as high auto-aggregation activity, which are important probiotic characteristics. However, they neither markedly altered the core gut microbiome, which was dominated by three bacterial species, nor detectably colonized the gut environment after the 4-week probiotic treatment. Despite a lack of long-term colonization, the presence of the bacterial strains showed either beneficial or detrimental effects on the host through growth rate enhancement or reduction, as well as changes in fish motility under confinement. This study offers insights into the effect of bacterial strains on a salmonid host and highlights three strains, Carnobacterium divergens V41, Pediococcus acidilactici ASG16, and Lactiplantibacillus plantarum ISCAR-07436, for future research into growth promotion of salmonid fish through probiotic supplementation.

Inhibitory effect of probiotic Bacillus spp. isolated from the digestive tract of Rhynchocypris Lagowskii on the adhesion of common pathogenic bacteria in the intestinal model

Diseases of fish caused by pathogenic bacteria are an important constraint on aquaculture production. Antibiotics have been widely used to control infectious diseases, but this has led to the emergence of drug-resistant bacteria and affected human health. In this context, probiotics are used as an alternative to antibiotics for the prevention and control of diseases in aquaculture. The aim of this study was to obtain probiotic candidate strains of Bacillus spp. from the gut of Rhynchocypris Lagowskii. Strains were screened by enzyme-producing ability, antagonism assay and antibiotic susceptibility. The safety of the strains to host fish has also been established. The isolated Bacillus licheniformis (LSG1-1) and Bacillus subtilis (LSG2-1) were characterized and performed well in tolerance experiments. In addition, LSG1-1 and LSG2-1 were detected to have higher self-aggregation ability and surface hydrophobicity. In the in vitro adhesion model, LSG1-1 and LSG2-1 showed good adhesion ability and had obvious adhesion inhibitory effect on three pathogens of Aeromonas. Based on the characteristics observed so far, Bacillus licheniformis LSG1-1 and Bacillus subtilis LSG2-1 could form potential probiotic candidates in the digestive tract of R. lagowskii to help combat diseases in aquaculture.