Abstract
Lactococcus lactis (L. lactis) NZ9000, which has been genetically modified, is the most commonly used host strain for nisin regulated gene expression. Selenium (Se) is an essential trace element in the diet of humans and animals important for the maintenance of health and growth. Biosynthesized Se nanoparticles (SeNPs) that use microorganisms as a vehicle are uniquely advantages in terms of low costs, low toxicity and high bioavailability. This study was aimed at preparing novel functionalized SeNPs by L. lactis NZ9000 through eco-friendly and economic biotechnology methods. Moreover, its physicochemical characteristics, antioxidant and anti-inflammatory activities were investigated. L. lactis NZ9000 synthesized elemental red SeNPs when co-cultivated with sodium selenite under anaerobic conditions. Biosynthesized SeNPs by L. lactis NZ9000 were mainly capped with polysaccharides and significantly alleviated the increase of malondialdehyde (MDA) concentration, the decrease of glutathione peroxidase (GPx) and total superoxide dismutase (T-SOD) activity in porcine intestinal epithelial cells (IPEC-J2) challenged by hydrogen peroxide (H2O2). SeNPs also prevented the H2O2-caused reduction of transepithelial electrical resistance (TEER) and the increase of FITC-Dextran fluxes across IPEC-J2. Moreover, SeNPs attenuated the increase of reactive oxygen species (ROS), the reduction of adenosine triphosphate (ATP) and the mitochondrial membrane potential (MMP) and maintained intestinal epithelial permeability in IPEC-J2 cells exposed to H2O2. In addition, SeNPs pretreatment alleviated the cytotoxicity of Enterotoxigenic Escherichia coli (ETEC) K88 on IPEC-J2 cells and maintained the intestinal epithelial barrier integrity by up-regulating the expression of Occludin and Claudin-1 and modulating inflammatory cytokines. Biosynthesized SeNPs by L. lactis NZ9000 are a promising selenium supplement with antioxidant and anti-inflammatory activities.
Highlights
Selenium (Se), as an essential trace element, is closely related to human and animal health
The growth of L. lactis NZ9000 entered the stationary phase when it was cultivated for 6 h. (B) The growth curve of L. lactis NZ9000 cultivated with sodium selenite
The growth of L. lactis NZ9000 entered the stationary phase at 17 h. (C) Apparent color of L. lactis NZ9000 culture medium when cultivated with a different concentration of sodium selenite. (D) Effect of sodium selenite with different concentration on the growth of L. lactis NZ9000. (E) The selenite percent conversion when L. lactis NZ9000 was cultivated with a different concentration of sodium selenite
Summary
Selenium (Se), as an essential trace element, is closely related to human and animal health. Se deficiency is associated with nutritional muscle dystrophy or “white muscle disease” in farm animals (Humann-Ziehank, 2016). The synthesis and functions of selenoproteins is dependent on dietary Se (Zoidis et al, 2018). Se exists in nature in two chemical forms including inorganic selenium (selenite, selenate, elemental Se, Se nanoparticles (SeNPs)) and organic Se (selenocysteine, selenomethionine, selenoproteins, etc.) (Biswas et al, 2011; Li et al, 2017). The toxicity order is as follows: selenate > selenite > Se methionine (SeMet) > SeNPs (Nagy et al, 2016; Xu et al, 2018b). SeNPs are considered a novel and promising nutritional supplementation (Skalickova et al, 2017)
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