L.B. Acurcio

Weissella paramesenteroides WpK4 reduces gene expression of intestinal cytokines, and hepatic and splenic injuries in a murine model of typhoid fever.

Diarrhoea in piglets by Salmonella and other pathogens can be a serious health problem. Non-drug treatments such as probiotic microorganisms have various effects on the gastrointestinal microbiota dysbiosis and host immune system modulation. The aim of this study was to demonstrate the suitable use of Weissella paramesenteroides WpK4 strain isolated from healthy piglets as an alternative prophylactic or therapeutic treatment against Salmonella Typhimurium. Out of 37 lactic acid bacteria isolates, 24 strains belonging to the Weissella and Lactobacillus genera were analysed in vitro for desirable probiotic characteristics. The W. paramesenteroides WpK4 strain fulfilled all in vitro tests: resistance to acidic pH and bile salts, hydrophobic cell surface, antagonism against bacterial pathogens, H2O2 production and exopolysaccharide secretion, and non-transferable resistance to antibiotics. Mice fed with WpK4 showed no signs of bacterial translocation to the liver or spleen and decreased Salmonella translocation to these organs. Significantly, WpK4 intake attenuated the weight loss, fostered the preservation of intestinal architecture and integrity, and promoted survival in mice following infection with Salmonella Typhimurium. In addition, WpK4 modulated immune cellular response by inhibiting the production of pro-inflammatory cytokines and inducing anti-inflammatory mediators. These findings validate the probiotic properties of W. paramesenteroides WpK4 strain, and its eventual use in piglets.

Selection of new lactic acid bacteria strains bearing probiotic features from mucosal microbiota of healthy calves: Looking for immunobiotics through in vitro and in vivo approaches for immunoprophylaxis applications

From the birth, since their mucosal microbiota and immune system are not fully developed, newborn calves are susceptible to several mucosal pathogenic microorganisms. Operating through humoral and non-humoral mechanisms in the host, several lactic acid bacteria strains bearing probiotic features are often employed in livestock as food supplement, improving animal production performance, promoting health and reducing the severity of mucosal infections. Accordingly, we isolated, species-level identified and screened for their probiotic potentials seventy lactic acid bacteria strains from upper airway, vaginal and intestinal mucosa of healthy calves. Based on in vitro approaches, we selected three strains: Lactobacillus fermentum V3B-08 isolated from upper airway mucosa, Weissella hellenica V1V-30 isolated from vaginal mucosa and Lactobacillus farciminis B4F-06 isolated from intestinal mucosa were used to mono-colonize germ-free mice in the same site in which these strains were isolated, aiming to characterize their immunomodulatory features. These strains were able to colonize germ-free mice mucosa and trigger sIgA synthesis at a local level, in addition to stimulating, in different ways, adaptive immune responses at a systemic level.

Propriedades probióticas in vitro de Lactobacillus spp. isolados de queijos minas artesanais da Serra da Canastra - MG

The aim of this study was to determine some in vitro probiotic features of Lactobacillus spp. isolated from Minas artisanal cheese from Serra da Canastra in order to select some bacteria for future production of safer cheeses keeping their natural flavor and tradition. The evaluated properties were antagonism against indicator microorganisms, antimicrobial susceptibility and also sensitivity to gastric acid and to bile salts. All lactic acid bacteria tested were resistant to gastric acid (pH 2.0) and bile salts (0.3%). Antagonistic activities were detected against Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, Salmonella entericavar. Typhimurium, Enterococcus faecalisand other lactic bacteria isolated from the same cheese - Lactobacillus plantarum (D27) and Lactobacillus rhamnosus (B25). All samples were sensitive to the antimicrobials erythromycin, tetracycline and resistant to ciprofloxacin, gentamycin, oxacillin, streptomycin and vancomycin. L.plantarum (B17) presented the best probiotic potential. Further studies are needed to verify the presence and the capacity of transmission of antimicrobial resistance genes to other microorganisms and evaluate the in vivo probiotic potential of the selected microorganisms.

Isolation, enumeration, molecular identification and probiotic potential evaluation of lactic acid bacteria isolated from sheep milk

Lactic acid bacteria species were molecularly identified in milk from Lacaune, Santa Ines and crossbred sheep breeds and their in vitro probiotic potential was evaluated. The species identified were Enterococcus faecium (56.25%), E. durans (31.25%) and E. casseliflavus (12.5%). No other lactic acid bacteria species, such as lactobacilli, was identified. Most of the isolated enterococci were resistant to gastric pH (2.0) and to 0.3% oxgall. All tested enterococci were resistant to ceftazidime, oxacillin and streptomycin and sensible to clindamycin, erythromycin and penicillin. The resistance to ciprofloxacin, gentamicin, tetracycline and vancomycin varied among tested species. All tested enterococci strongly inhibited (P<0.05) Escherichia coli and Listeria monocytogenes, moderately inhibited E. faecalis and Staphylococcus aureus and did not inhibit Pseudomonas aeruginosa, Salmonella enterica var. Typhimurium and also one E. durans sample isolated from sheep milk. Four samples of E. faecium, one of E. durans and one of E. casseliflavus presented the best probiotic potential.

Changes in mouse gut bacterial community in response to different types of drinking water

Gut microbiota exerts a fundamental role on host physiology, and how extrinsic perturbations influence its composition has been increasingly examined. However, the effect of drinking water on gut microbiota is still poorly understood. In this study, we explored the response of mouse gut bacterial community (fecal and mucosa-adhered) to the ingestion of different types of drinking water. The experimental cohort was divided according to different water sources into four groups of mice that consumed autoclaved tap water (control group), water collected directly from a drinking water treatment plant, tap water, and commercial bottled mineral water. Differences among groups were observed, especially related to control group, which exhibited the smallest intra-group variation, and the largest distance from test groups on the last experimental day. Clinically important taxa, such as Acinetobacter and Staphylococcus, increased in feces of mice that drank tap water and in mucosa-adhered samples of animals from disinfected and tap water groups. Furthermore, statistical analyses showed that both time elapsed between samplings and water type significantly influenced the variation observed in the samples. Our results reveal that drinking water potentially affects gut microbiota composition. Additionally, the increase of typical drinking water clinically relevant and antibiotic resistance-associated bacteria in gut microbiota is a cause of concern.

In vivo probiotic and antimicrobial photodynamic therapy as alternative therapies against cryptococcosis are ineffective

Cryptococcosis, an invasive fungal infection distributed worldwide that affects both domestic and wild animals, has incredible rates regarding treatment failure, leading to the necessity of the development of new therapies. In this way, we aimed to evaluate the probiotic (Saccharomyces boulardii, Lactobacillus paracasei ST-11, and Lactobacillus rhamnosus GG) and antimicrobial photodynamic alternative therapies against Cryptococcus gattii in a murine model. Although previous studies suggest that these therapies can be promising against cryptococcosis, our experimental conditions for both probiotic and antimicrobial photodynamic therapies (aPDT) were not able to improve the survival of mice with cryptococcosis, even with the treatment combined with fluconazole. Our results may help other researchers to find the best protocol to test alternative therapies against Cryptococcus gattii.

Evaluation of colonisation resistance in stool of human donors using ex vivo, in vitro and in vivo assays

The indigenous microbiota is the population of microorganisms normally present on the surface and mucosa of an individual, where it performs essential health functions, including the colonisation resistance (CR) against pathogens. To identify the bacteria responsible and the mechanisms involved in the CR, the germ-free (GF) animal model has been used, because in vitro studies cannot always be extrapolated to what occurs in vivo. In this study, ex vivo antagonism assays against seven enteropathogenic bacteria using stools from 15 healthy human donors confirmed that the CR showed individual variation. Using in vitro antagonism assays, 14 strains isolated from dominant faecal microbiota of donors with elevated CR were selected for mono-association in GF mice to test the in vivo antagonism against Salmonella enterica ser. Typhimurium. Mice mono-associated with Enterococcus hirae strain 8.2, Bacteroides thetaiotaomicron strain 16.2 and Lactobacillus ruminis strain 18.1 had significant reductions in faecal counts of the pathogen during the challenge. After five days of infection, the group associated with E. hirae 8.2 showed a reduction in the translocation of S. Typhimurium to the spleen, while the group associated with L. ruminis 18.1 presented an increased translocation to the liver. The histological data confirmed these results and revealed that the mice associated with E. hirae 8.2 showed fewer lesions on ileum and liver, compared to the damage caused by S. Typhimurium alone, while in mice associated with L. ruminis 18.1 there was significantly worse lesions. Concluding, from the dominant faecal microbiota from healthy human with high CR, through ex vivo, in vitro and in vivo assays, a bacterium was characterised for its high CR potential, being a candidate for probiotic use.