Selenium Nanoparticles Induce Potent Protective Immune Responses against Vibrio cholerae WC Vaccine in a Mouse Model

The aim of this study was to evaluate the efficacy of selenium nanoparticle (an immune booster) and naloxone (an opioid receptor antagonist) as a new adjuvant in increasing immune responses against killed whole-cell Vibrio cholerae in a mouse cholera model. The Se NPs were synthesized and characterized by UV-visible, DLS, and zeta potential analysis. The SEM image confirmed the uniformity of spherical morphology of nanoparticle shape with 34 nm in size. The concentration of the Se NPs was calculated as 0.654 μg/ml in the ICP method. The cytotoxic activity of Se NPs on Caco-2 cells was assessed by the MTT assay and revealed 82.05% viability of cells after 24 h exposure with 100 μg/ml of Se NPs. Female BALB/C mice were orally immunized three times on days 0, 14, and 28, and challenge experiments were performed on immunized neonates with toxigenic V. cholerae. Administration of Se NP diet led to significant increase in V. cholerae-specific IgG and IgA responses in serum and saliva and caused protective immunity and 83.3% survival in challenge experiment against 1 LD50 V. cholerae in a group receiving diet of Se NPs compared with other groups including Dukoral vaccine. The IL-4 and IL-5 were significantly increased in response to WC+daily diet of Se NPs with or without naloxone. Naloxone proved no effect on IL-4 and IL-5 increase and is proposed as null in the cytokine and antibody production process. These results reveal that daily diet of Se NPs could efficiently induce immune cell effectors in both humoral and mucosal levels.

Developments in the study and applications of bacterial transformations of selenium species

Microbial bio-transformations of the essential trace element selenium are now recognized to occur among a wide variety of microorganisms. These transformations are used to convert this element into its assimilated form of selenocysteine, which is at the active center of a number of key enzymes, and to produce selenium nanoparticles, quantum dots, metal selenides, and methylated selenium species that are indispensable for biotechnological and bioremediation applications. The focus of this review is to present the state-of-the-art of all aspects of the investigations into the bacterial transformations of selenium species, and to consider the characterization and biotechnological uses of these transformations and their products.

Enhanced and sustainable pretreatment for bioconversion and extraction of resveratrol from peanut skin using ultrasound-assisted surfactant aqueous system with microbial consortia immobilized on cellulose

In this study, the ultrasound-assisted surfactant aqueous system coupled with microbial consortia immobilized by cellulose has been created as an enhanced and sustainable method for the bioconversion and extraction of resveratrol from peanut skin. Based on central composite design, and several single-factor experiments, we derived the optimal bioconversion and extraction system. Microbial consortia consist of Yeast CICC 1912, Aspergillus oryzae 3.951 and Aspergillus niger 3.3148 were chosen to be immobilized using cellulose. Other treatment conditions include concentration of surfactant as 3% (w/v), temperature as 30 °C, time as 36 h, ultrasonic power as 250 W and liquid to solid ratio as 25:1 mL/g. Under these conditions, we achieved a promising yield of resveratrol 96.58 μg/g, which is 4.02 folds compared to the untreated sample. This sustainable and green method not only enhanced the production of resveratrol but also improved the safety and reliability of the bioconversion and extraction process. Our novel method has shown great potential to realize large-scale bioconversion and extraction of bioactive compounds from plant waste.