Search

Hydrogen, volatile fatty acids (VFAs), and methane coproduction from sweet sorghum stems using bacterial consortium was investigated as an efficient and sustainable pre-treatment strategy to improve energy recovery. Integrated two-stage dark fermentation and methanization approach aimed to reduce fractionation, juice extraction, and pre-treatment steps to improve the efficiency and sustainability of stalks energy bioconversion. Stems biomass loading did not significantly influence hydrogen and VFAs productivities. Energy recovery yields were (7.07) and (10.01) MJ/kg dry matter (DM), respectively, for raw stem single dark fermentation (DF) and methanization processes, corresponding to 41.22% and 58.37% of raw stalk energy potential. Methanogenic potential increase of 31.9% and energy bioconversion yield of 13.21 MJ/kg DM were reached for solid residues from DF (80.75% of their energy content), suggesting that bacterial consortium efficiently pre-treated sorghum stalk fibers. Coupling process led to 88.74% net biomass energy recovery yield, corresponding respectively to 57.38% and 40.23% more than single DF and methanization. Fiber degradation ability of DF bacterial consortium significantly contributed to improve sorghum stalk energy recovery efficiency and cost-competitiveness. [ABSTRACT FROM AUTHOR]

Flintiella sanguinaria is a red unicellular microalgae belonging to Porphyridiophyceae with a high potential as an exopolysaccharide producer. A new culture medium was developed by a stoichiometry approach based on elemental analysis of microalgae, and culture conditions were improved after measurements of photosynthetic activity as a function of irradiance, temperature and pH. These optimal conditions were thus validated in a photobioreactor for the production of biomass and exopolysaccharide (EPS). After extraction and purification of the EPS, it was characterised by HPAEC-PAD, HPLC and FT-IR as a methylated and acetylated galactoxylan including a significant amount of rhamnose and glucuronic acid in its structure. Macromolecular conformation in dilute solution of native, deproteinised and desubstituted EPS from F. sanguinaria revealed that this polysaccharide had a strong associative behaviour in which hydrophobic interactions or hydrogen bonding but also proteins were implicated. [ABSTRACT FROM AUTHOR]

In the present study, we aimed to extract, purify, analyze monosaccharide composition of  exopolysaccharide (EPS) produced by Halorubrum sp. TBZ112 (KCTC 4203 and IBRC-M 10773) and also to evaluate its possible antiproliferative activity against human gastric cancer (MKN-45) cell line and its biocompatibility effect on normal cells using human dermal fibroblast (HDF) cell line. Average molecular weight and monosaccharide composition were determined by high-pressure size exclusion chromatography (HPSEC) with multi-angle laser light scattering (MALLS) and high-pressure anion exchange chromatography (HPAEC), respectively. Fourier transform infrared (FTIR) spectroscopy was used for the partial characterization of the EPS. The EPS effect on the cell proliferation and viability of MKN-45 and HDF cells was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and trypan blue dye exclusion, respectively. Strain TBZ112 excreted 480 mg.l−1 of the EPS under optimal growth conditions. The EPS had a molecular weight of 5.052 kDa and was a heteropolysaccharide containing ten moieties mainly composed of mannose (19.95%), glucosamine (15.55%), galacturonic acid (15.43%), arabinose (12.24%), and glucuronic acid (12.05%). No significant difference of the EPS treatments on the proliferation activity of MKN-45 and HDF cells were observed (P > 0.05). For the first time, the EPS from Halorubrum sp. TBZ112, an extremely halophilic archaeon related to Halorubrum genus, was isolated and chemically characterized. The EPS from Halorubrum sp. TBZ112 possesses a relatively low molecular weight and might be applied as a biocompatible compound. More investigations are needed to determine other biological activities of the EPS along with further details of its chemical structure. [ABSTRACT FROM AUTHOR]