Production of Exopolysaccharides by Cultivation of Halotolerant Bacillus atrophaeus BU4 in Glucose- and Xylose-Based Synthetic Media and in Hydrolysates of Quinoa Stalks

A halotolerant, exopolysaccharide-producing bacterium isolated from the Salar de Uyuni salt flat in Bolivia was identified as Bacillus atrophaeus using next-generation sequencing. Comparisons indicate that genome most likely (p-value: 0.0024) belongs to a subspecies previously not represented database. The growth of bacterial strain and its ability produce exopolysaccharides (EPS) synthetic media with glucose or xylose carbon sources, hydrolysates quinoa stalks, investigated. grew well all media, but better than xylose. Sugar consumption when initial concentrations were low. good enzymatically produced cellulosic inhibited hemicellulosic hydrothermal pretreatment. EPS yields up 0.064 g/g on 0.047 xylose, higher relatively low sugar concentrations. purified by sequential procedure including centrifugation, cold ethanol precipitation, trichloroacetic acid treatment, dialysis, freeze-drying. Glucose mannose main sugars hydrolyzed EPS. characterized size-exclusion chromatography, Fourier-transform infrared (FTIR) spectroscopy, heteronuclear single-quantum coherence nuclear magnetic resonance (HSQC NMR) scanning electron microscopy, X-ray diffraction, thermogravimetric analysis. No major differences elucidated between resulting cultivations glucose- or-xylose-based while some divergences regard molecular-weight averages FTIR HSQC NMR spectra detected for hydrolysate-based media.