Probiotic and antioxidant properties of selenium-enriched Lactobacillus brevis LSe isolated from an Iranian traditional dairy product.

The present study was designed to isolate a highly selenium-tolerant lactobacillus strain from an Iranian traditional dairy product named as Spar. Different criteria such as tolerance to the low pH, simulated gastric juice (SGJ), simulated intestinal juice (SIJ) and bile salts tolerance as well as Caco-2 cell adhesion assay were examined to evaluate the probiotic potentials of the selected isolate. Furthermore, the antioxidant properties of the isolate cultivated in medium containing and free of SeO32- ions were evaluated using DPPH scavenging and reducing power assays. The isolate was identified using conventional identification and 16S rDNA gene sequencing methods as Lactobacillus brevis LSe. The obtained results showed that the isolate was able to tolerate high concentration of sodium selenite (3.16mM). By decreasing the pH of the SGJ from 6 to 3, the survival percent of L. brevis LSe was not significantly changed over the time (p>0.05). In addition, the survival percent of the isolate in the SIJ (pH 6 and pH 8) was not statistically altered after 3h, 6h and 24h of incubation (p>0.05). In the presence of bile salts (0.3% and 0.6%) the survival rate of L. brevis LSe was not significantly decreased (p>0.05).L. brevis LSe also demonstrated the satisfactory ability to adhere to Caco-2 cells which were similar to that of the reference strain L. plantarum. The obtained results of antioxidant evaluation showed that L. brevis LSe containing elemental Se exhibited significantly higher radical scavenging ability (36.5±1.31%) and reducing power (OD700, 0.14) than L. brevis LSe cultured in selenite-free medium (p<0.05). To sum up, further investigations should be conducted to merit the probable potential health benefit of Se-enriched L. brevis LSe and its application as Se-containing supplements or fermented foods.

Antimicrobial and Antioxidant Activity of the Biologically Synthesized Tellurium Nanorods; A Preliminary In vitro Study.

Background: Recent theranostic (therapeutic or diagnostic) applications of tellurium nanoparticles have attracted a great interest for development of different methods for synthesis of this valuable nanostructure, especially via biological resources. Objectives: In the present study, the antimicrobial and antioxidant effects of the tellurium nanorods (Te NRs) biosynthesized by a bacterial strain Pseudomonas pseudoalcaligenes strain Te were evaluated. Materials and Methods: The antimicrobial effect of Te NRs and potassium tellurite against different bacterial and fungal pathogens was assessed by microdilution method. Furthermore, the disk diffusion method was used to evaluate the antibacterial effect of the biogenic Te NRs and potassium tellurite against methicillin-resistant Staphylococcus aureus, alone or in combination with various antibiotics. Also, the biogenic Te NRs were investigated for antioxidant activity using 2, 2-diphenyl- 1-picrylhydrazyl (DPPH) scavenging activity and reducing power assay. Results: Transmission electron micrograph (TEM) of the purified Te NRs showed individual and rod-shaped nanostructure (~22 nm diameter by 185 nm in length). Based on the data obtained from both microdilution and disk diffusion method the K2 TeO3 exhibited a higher antibacterial and antifungal activity compared to the Te NRs. The measured IC50 for the biogenic Te NRs (i.e. DPPH radical scavenging activity) was found to be 24.9 µg.mL-1, while, K 2 TeO3 has represented only 17.6 ± 0.8 % DPPH radical scavenging effect at the concentration of 160 µg.mL-1. The reducing power assay revealed a higher electron-donating activity for Te NRs compared to K2TeO3. Conclusions: Based on the data obtained from both microdilution and disk diffusion method the K2TeO3 exhibited a higher antimicrobial and antifungal activity than Te NRs. Te NRs didn't show the antibacterial effect against the tested bacterial strain: MRSA and showed an inhibitory effect and antibacterial activity of the effective antibiotics. However, more studies should be performed to explore the action mechanism of the produced biogenic Te NRs.

Anti-biofilm activity of biogenic selenium nanoparticles and selenium dioxide against clinical isolates of Staphylococcus aureus, Pseudomonas aeruginosa, and Proteus mirabilis.

The aim of the present study was to investigate the anti-biofilm activity of biologically synthesized selenium nanoparticles (Se NPs) against the biofilm produced by clinically isolated bacterial strains compared to that of selenium dioxide. Thirty strains of Staphylococcus aureus, Pseudomonas aeruginosa, and Proteus mirabilis were isolated from various specimens of the patients hospitalized in different hospitals (Kerman, Iran). Quantification of the biofilm using microtiter plate assay method introduced 30% of S. aureus, 13% of P. aeruginosa and 17% of P. mirabilis isolates as severely adherent strains. Transmission electron micrograph (TEM) of the purified Se NPs (produced by Bacillus sp. MSh-1) showed individual and spherical nano-structure in the size range of 80-220nm. Obtained results of the biofilm formation revealed that selenium nanoparticles inhibited the biofilm of S. aureus, P. aeruginosa, and P. mirabilis by 42%, 34.3%, and 53.4%, respectively, compared to that of the non-treated samples. Effect of temperature and pH on the biofilm formation in the presence of Se NPs and SeO2 was also evaluated.

Preparation and evaluation of niosomes containing autoclaved Leishmania major: a preliminary study.

In this study, different positively charged niosomal formulations containing sorbitan esters, cholesterol and cetyl trimethyl ammonium bromide were prepared by film hydration method for the entrapment of autoclaved Leishmania major (ALM). Size distribution pattern and stability of niosomes were investigated by laser light scattering method and ALM encapsulation per cent was measured by the bicinchoninic acid method. Finally, the selected formulation was used for the induction of the immune response against cutaneous leishmaniasis in BALB/c mice. Size distribution curves of all the formulations followed a log-normal pattern and the mean volume diameter was in the range 7.57-15.80 µm. The mean volume diameters were significantly increased by adding Tween to Span formulations (p < 0.05). The percentage of ALM entrapped in all formulations varied between 14.88% and 36.65%. In contrast to ALM, in vivo studies showed that the niosomes containing ALM have a moderate effect in the prevention of cutaneous leishmaniasis in BALB/c mice.