Speeding up bioproduction of selenium nanoparticles by using Vibrio natriegens as microbial factory

Abstract

Selenium and selenium nanoparticles (SeNPs) are extensively used in biomedicine, electronics and some other industrial applications. The bioproduction of SeNPs is gaining interest as a green method to manufacture these biotechnologically relevant products. Several microorganisms have been used for the production of SeNPs either under aerobic or anaerobic conditions. Vibrio natriegens is a non-pathogenic fast-growing bacterium, easily cultured in different carbon sources and that has recently been engineered for easy genetic manipulation in the laboratory. Here we report that V. natriegens was able to perfectly grow aerobically in the presence of selenite concentrations up to 15 mM with a significant survival still observed at concentrations as high as 100 mM selenite. Electron microscopy and X-ray spectroscopy analyses demonstrate that V. natriegens cells growing aerobically in selenite-containing LB medium at 30 °C produced spherical electron-dense SeNPs whose size ranged from 100–400 nm. Selenite reduction just started at the beginning of the exponential growth phase and the release of SeNPs was observed after cell lysis. Remarkably, V. natriegens produced SeNPs faster than other described microorganisms that were proposed as model bioreactors for SeNPs production. Thus, the fast-growing V. natriegens bacterium becomes a suitable biocatalyst for bioremediation of selenite and for speeding-up the eco-friendly synthesis of SeNPs.

Exploiting the Feedstock Flexibility of the Emergent Synthetic Biology Chassis Vibrio natriegens for Engineered Natural Product Production

“…These pathways, cloned from three different bacteria, did not need to be codon optimized for expression in V. natriegens. Overall, this first demonstration of heterologous natural product production using these different carbon sources serves to further develop the biotechnological usefulness of this organism, which has also been investigated for production of alanine, poly-ß-hydroxybutyrate, and selenium nanoparticles, all using native genes [5,7,73]. We anticipate that these results will encourage future efforts at optimizing bioproduction of other complex natural products in this chassis.…”

Phytogreen synthesis of multifunctional nano selenium with antibacterial and antioxidant implications

“…Briefly, acidified KMnO 4 solution (0.630 mM, 10 ml) was prepared in 0.5 M H 2 SO 4 . Simultaneously, ascorbic acid standard solutions of varying concentrations (1,4,8,12,16, and 20 μg ml −1 ) were also prepared. Then, 0.1 ml of KMnO 4 was added to 1 ml of ascorbic acid solutions and incubated at room temperature for 5 min.…”

“…It also forms an essential component of selenoproteins that are required for antioxidant activities such as protection of DNA from oxidative stress [15]. Several studies have demonstrated that nSe exhibit size dependent biological activities [14,16]. For instance, the capability of nSe to scavenge free radicals enhances as the particle size decreases, thereby preventing oxidative stress efficiently compared to the larger particles [15,17,18].…”

“…The antibacterial responses of nSe have been documented against major infection causing bacteria including E. coli [10,22], S. aureus [9,22,23], P. aeruginosa, and Proteus mirabilis [23]. Nanoselenium can be synthesized by different methods such as: (a) physical which include laser ablation, ultraviolet (UV) irradiation, hydrothermal [22,24,25], (b) chemical which include catalytic reduction, acid decomposition [26] and, (c) biogreen synthesis which rely on the use of certain bacteria [9,16,27,28], fungi [29] or plants species [30][31][32]. Amongst all, biogreen synthesis of nSe avoids the utilization of toxic reducing agents and post-modification steps which promotes their swift application in the food and medical industries.…”

Establishing a cell-freeVibrio natriegensexpression system

“…With the shortest doubling time of all known organisms, Vibrio natriegens has garnered considerable interest as a promising microbial host to accelerate research and biotechnology [1][2][3][4] . Its rapid growth rate, which has been linked to high rates of protein synthesis 5 and metabolic efficiency 6,7 suggests that this host may be harnessed as a powerful cell-free expression system.…”