Inhibition of bacteriochlorophyll biosynthesis in the purple phototrophic bacteria Rhodospirillumrubrum and Rhodobacter capsulatus grown in the presence of a toxic concentration of selenite

Biogenic Selenium Nanoparticles Synthesized by L. brevis 23017 Enhance Aluminum Adjuvanticity and Make Up for its Disadvantage in Mice

The most popular vaccine adjuvants are aluminum ones, which have significantly reduced the incidence and mortality of many diseases. However, aluminum-adjuvanted vaccines are constrained by their limited capacity to elicit cellular and mucosal immune responses, thus constraining their broader utilization. Biogenic selenium nanoparticles are a low-cost, environmentally friendly, low-toxicity, and highly bioactive form of selenium supplementation. Here, we purified selenium nanoparticles synthesized by Levilactobacillus brevis 23017 (L-SeNP) and characterized them using Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results indicate that the L-SeNP has a particle size ranging from 30 to 200 nm and is coated with proteins and polysaccharides. Subsequently, we assessed the immune-enhancing properties of L-SeNP in combination with an adjuvant-inactivated Clostridium perfringens type A vaccine using a mouse model. The findings demonstrate that L-SeNP can elevate the IgG and SIgA titers in immunized mice and modulate the Th1/Th2 immune response, thereby enhancing the protective effect of aluminum-adjuvanted vaccines. Furthermore, we observed that L-SeNP increases selenoprotein expression and regulates oxidative stress in immunized mice, which may be how L-SeNP regulates immunity. In conclusion, L-SeNP has the potential to augment the immune response of aluminum adjuvant vaccines and compensate for their limitations in eliciting Th1 and mucosal immune responses.

Tellurite and Selenite: how can these two oxyanions be chemically different yet so similar in the way they are transformed to their metal forms by bacteria?

This opinion review explores the microbiology of tellurite, TeO32- and selenite, SeO32- oxyanions, two similar Group 16 chalcogen elements, but with slightly different physicochemical properties that lead to intriguing biological differences. Selenium, Se, is a required trace element compared to tellurium, Te, which is not. Here, the challenges around understanding the uptake transport mechanisms of these anions, as reflected in the model organisms used by different groups, are described. This leads to a discussion around how these oxyanions are subsequently reduced to nanomaterials, which mechanistically, has controversies between ideas around the molecule chemistry, chemical reactions involving reduced glutathione and reactive oxygen species (ROS) production along with the bioenergetics at the membrane versus the cytoplasm. Of particular interest is the linkage of glutathione and thioredoxin chemistry from the cytoplasm through the membrane electron transport chain (ETC) system/quinones to the periplasm. Throughout the opinion review we identify open and unanswered questions about the microbial physiology under selenite and tellurite exposure. Thus, demonstrating how far we have come, yet the exciting research directions that are still possible. The review is written in a conversational manner from three long-term researchers in the field, through which to play homage to the late Professor Claudio Vásquez.

Integrated biohydrogen production via lignocellulosic waste: Opportunity, challenges & future prospects

Hydrogen production through biological route is the cleanest, renewable and potential way to sustainable energy generation. Productions of hydrogen via dark and photo fermentations are considered to be more sustainable and economical approach over numerous existing biological modes. Nevertheless, both the biological modes suffer from certain limitations like low yield and production rate, and because of these practical implementations are still far away. Therefore, the present review provides an assessment and feasibility of integrated biohydrogen production strategy by combining dark and photo-fermentation as an advanced biochemical processing while using lignocellulosics biomass to improve and accelerate the biohydrogen production technology in a sustainable manner. This review also evaluates practical viability of the integrated approach for biohydrogen production along with the analysis of the key factors which significantly influence to elevate this technology on commercial ground with the implementation of various environment friendly and innovative approaches.