New Exopolysaccharides Produced by Bacillus licheniformis 24 Display Substrate-Dependent Content and Antioxidant Activity

Abstract

Bacillus licheniformis is a soil bacterium with many industrial applications. In addition to enzymes, platform chemicals, antibiotics and phytohormones, the species produces exopolysaccharides (EPSs) of various biological activities. This study revealed that Bulgarian isolate B. licheniformis 24 produced EPSs consisting of galactose, glucose and mannose with substrate-dependent ratio. From glucose, B. licheniformis 24 secreted EPS1, consisting of 54% galactose, 39% glucose and 7% mannose. From fructose, the strain formed EPS2, containing 51% glucose, 30% mannose and 19% galactose. Batch cultivation in flasks yielded 2.2–2.6 g/L EPS1 and 1.90–2.11 g/L EPS2. Four to five times higher yields of EPS were obtained from both substrates during batch and fed-batch processes in a fermenter at 37.8 °C, pH 6.2 and aeration 3.68 vvm. The batch process with 200 g/L of starting substrates received 9.64 g/L EPS1 and 6.29 g/L EPS2, reaching maximum values at the 33rd and 24th h, respectively. Fed-batch fermentation resulted in the highest yields, 12.61 g/L EPS1 and 7.03 g/L EPS2. In all processes, EPSs were produced only in the exponential growth phase. Both EPSs exhibited antioxidant activity, but EPS2 was much more potent in this regard, reaching 811 μM Vitamin C Equivalent Antioxidant Capacity (versus 135 μM for EPS1). EPS1 displayed antibacterial activity against a non-O1 strain of Vibrio cholerae.

Optimization and Characterization of a Novel Exopolysaccharide from Bacillus haynesii CamB6 for Food Applications

“…was already noted earlier as being mainly composed of these three monosaccharides in a different ratio [ 70 ]. Other Bacillus species are reported with similar monosaccharide constituents with different molar ratios, making each one unique [ 71 , 72 ]. As mentioned earlier, from the FTIR analysis, both α- and β-anomeric configurations were suggested as being part of the EPS structure.…”

Effects of Compound Probiotics on Cecal Microbiome and Metabolome of Shaoxing Duck

“…B. licheniformis is widely used in industry, horticulture, and pharmacy. It is a promising producer of enzymes, platform chemicals ( Petrova et al, 2020 ), antibiotics ( Cheng et al, 2021 ), and EPSs with antimicrobial, antioxidant, and anticancer activities ( Xu et al, 2019 ; Petrova et al, 2021 ; Vinothkanna et al, 2021 ). Probiotics are widely regarded as one of the most effective alternatives to antibiotics because they maintain or restore normal microbiome, inhibit pathogen adhesion to intestinal wall, prevent inflammation, and protect intestinal barrier function ( Van Baarlen et al, 2013 ; Cisek and Binek, 2014 ; Gresse et al, 2017 ).…”

Anionic exopolysaccharide from Cryptococcus laurentii 70766 as an alternative for alginate for biomedical hydrogels

“…EPSs can be divided into homopolysaccharides (comprised of repeating units of monosaccharides like glucose, mannose, etc.) and heteropolysaccharides (containing three or more monosaccharides, e.g., arabinose, mannose, N-acetyl galactosamine, glucuronides and different derivatives of these subunits having phosphates, glycerol, or acetyl groups) [15][16][17].…”