Genome Mining Associated with Analysis of Structure, Antioxidant Activity Reveals the Potential Production of Levan-Rich Exopolysaccharides by Food-Derived Bacillus velezensis VTX20

Abstract

Exopolysaccharides (EPSs) produced by Bacillus species have recently emerged as promising commercial antioxidants in various industries, such as pharmaceutics and biomedicine. However, little is known about EPS production and function from Bacillus velezensis so far. In the present study, the effect of sugar sources on EPS production by B. velezensis VTX20 and the genetic biosynthesis, characteristics, and antioxidant activity of the resulting EPS were evaluated. The strain VTX20 produced the maximum EPS yield of 75.5 ± 4.8 g/L from an initial 200 g/L of sucrose after a 48-h cultivation. Through genomic analysis, ls-levB operon was found, for the first time, to be responsible for the levan-type EPS production in B. velezensis. Biochemical and structural characterization further confirmed the majority of levan, followed by an extremely low level of dextran biopolymer. The water solubility index and water holding capacity of the EPSs were 81.9 ± 3.4% and 100.2 ± 3.4%, respectively. In vitro antioxidant activity analyses showed strong scavenging activity for 1,1-diphenyl-2-picrylhydrazyl and hydroxyl radical values of 40.1–64.0% and 16.0–40%, respectively. These findings shed light on the EPS biosynthesis of B. velezensis at both structural and genetic levels and the potential application of EPS as a natural antioxidant for pharmaceutical and biomedical industries.

Production and Characterisation of an Exopolysaccharide by Bacillus amyloliquefaciens: Biotechnological Applications

“…The hydroxyl radical is one of the most reactive free radicals in a biological system [ 84 ]. This is a type of free radical with the most active chemical properties and that can cause the most harm in comparison to other free radicals, as it damages DNA base sequences [ 85 ]. The scavenging activity of the hydroxyl radical is commonly used to evaluate the ability of compounds to scavenge free radicals.…”

Efficacy of the incorporation between self-encapsulation and cryoprotectants on improving the freeze-dried survival of probiotic bacteria

“…They are two strains of gram‐positive bacteria known for their exopolysaccharides production capacity (Ansorena & Astiasarán, 2016; Nguyen et al, 2021) which are the main component of EPSs (Costa et al, 2018). For gram‐negative bacteria, although no study reported an increase in EPS synthesis under environmental stresses, it was demonstrated that there are functional exopolysaccharide genes (Whitney & Howell, 2013; Zeidan et al, 2017) which are also regulated expression by environmental conditions (Vu et al, 2021; Wen & Zhang, 2015). This demonstrates the possibility of applying environmental stresses to the self‐encapsulation of different probiotics.…”

Genome-Guided Investigation Provides New Insights into Secondary Metabolites of Streptomyces parvulus SX6 from Aegiceras corniculatum

“…The hydroxyl radical scavenging activity. The hydroxyl radical scavenging activity of SX6 extract was evaluated with slight modifications (Liu et al 2009;Vu et al 2021). About 1.0 ml of 70% ethanol extract was added to the mixture containing 1.0 ml of 0.75 mM 1,10-phenanthroline, 1.0 ml of 0.75 mM FeSO 4 , 1.0 ml of 0.01% H 2 O 2 , and 1.5 ml of 0.15 M sodium phosphate buffer (pH 7.4).…”

“…DPPH-radical scavenging activity. The 2-diphenyl-1-picrylhydrazyl (DPPH) assay was carried out as in the previous studies (Kadaikunnan et al 2015;Vu et al 2021). The crude extract dissolved in 70% ethanol was reacted with 0.2 ml of 0.1 mM 2,2-diphenyl-1-picrylhydrazyl (DPPH) followed by 2.0 ml of deionized water.…”