Utilization of lignocellulosic biomass by glycerol organosolv pretreatment for biobutanol production integrated with bioconversion of residual glycerol into value-added products.

Glycerol organosolv pretreatment (GOP) is considered an efficient method to deconstruct lignocellulose for producing fermentable sugars. Herein, the liquid fraction containing glycerol after GOP was utilized for recycled pretreatment of corn stover (CS) for four cycles. Enzymatic yield of glucose after recycled pretreatment was enhanced by 2.4-3.5 folds compared with untreated CS. Meanwhile, residual glycerol was used as carbon source for cultivation of Pichia pastoris to obtain high cell-density, and a final titer of 1.3 g/L human lysozyme was produced by P. pastoris under low temperature methanol induction strategy. Additionally, the pretreated CS was mixed with cassava as fermentable substrates for butanol production by wild-type Clostridium acetobutylicum ATCC 824. Final butanol production of 13.9 g/L was obtained from mixed substrates (25%:75% of CS/cassava) at 10% solids loading by simultaneous saccharification and fermentation. Overall, integration of residual glycerol utilization and butanol production by microbial fermentation provided an efficient strategy for biorefinery.

A new l-cysteine-assisted glycerol organosolv pretreatment for improved enzymatic hydrolysis of corn stover.

Deconstruction of lignocellulose via efficient pretreatment is crucial for producing fermentable sugars. In this study, effects of glycerol organosolv pretreatment (GOP) on main chemical composition of corn stover were investigated. Results indicate that the residual corn stover after 80 wt% glycerol pretreatment (at 220 °C for 0.5 h) yielded 75.97 % glucose and 78.21 % xylose after enzymatic hydrolysis, which were enhanced by 3.39- and 6.08-fold compared to the untreated corn stover. Subsequently, an l-cysteine-assisted GOP was proposed with higher yields of glucose (86.20 %) and xylose (91.13 %). When pretreating corn stover with 80 wt% glycerol containing 0.07 wt% l-cysteine at 220 °C for 0.5 h, higher fermentable sugars of 26.08 g were produced from 100 g feedstock after enzymolysis. Intrinsic mechanisms of the proposed pretreatment for enhancing enzymatic digestibility were elucidated by physiochemical characterization technologies and techno-economic analysis was also studied. This study provides guidance for fermentable sugars production from renewable lignocellulose.

Alkalibacillus aidingensis sp. nov., an Bacterium Isolated from Aiding Lake in Xinjiang Province, North-West China.

A bacterial strain, Gram staining negative, aerobic, long rod, motile bacterium with flagellum, designated strain YIM 98829T, was isolated from the Aiding Lake in Xinjiang province, North-West China. The isolate produced oval subterminal endospores in swollen sporangia. The predominant menaquinone was MK-7. The cell wall peptidoglycan contained ornithine, serine, aspartic acid, glutamic acid, and alanine, while diaminopimelic acid could not be detected. The major whole-cell sugars contained xylose, glucose, galactose, and mannose. Diphosphatidylglycerol, phosphatidylglycerol, one unknown phospholipid, and two unidentified aminophospholipids were part of the polar lipid profile. Iso-C15:0 and anteiso-C15:0 were the major fatty acids. The DNA G + C content of the type strain was 38.0 mol%. Phylogenetic analysis indicated that the isolate belongs to the genus Alkalibacillus. However, it differed from its closest relatives, A. haloalkaliphilus DSM 5271T (97.04%), A. filiformis 4AGT (96.99%), and A. silvisoli BM2T (96.95%) in some physiological characteristics. DNA-DNA hybridization result indicated low levels of relatedness between strain YIM 98829T and A. haloalkaliphilus JCM 12303T (16.9%). On the basis of physiological, phenotypic, and chemotaxonomic data, strain YIM 98829T represents a novel species of genus Alkalibacillus, for which the name Alkalibacillus aidingensis sp. nov. is proposed. The type strain is YIM 98829T (= NBRC 114103T = CGMCC 1.17260T = DSM 112470T).

Haloechinothrix aidingensis sp. nov., an actinomycete isolated from salt lake in Xinjiang province, north-west China.

An actinomycete strain, designated YIM 98757T, was isolated from the hypersaline sediment of Aiding Lake in Xinjiang province, north-west China. The strain grew well on most media tested and no diffusible pigment was produced. The substrate mycelium was well developed and fragmented. No spores were formed. The whole-cell hydrolysates contained meso-diaminopimelic acid as the cell-wall diamino acid. Xylose, galactose, ribose were the major whole-cell sugars. The phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositol mannosides and an unknown phospholipid. The predominant menaquinone was MK-8(H4). The major fatty acid was iso-C16:0. The DNA G + C content was 69.1 mol%. Phylogenetic analysis indicated that the isolate belongs to the genus Haloechinothrix. However, it differed from its closest relative, H. alba YIM 98757 T in many phenotypic and chemotaxonomic characteristics. Moreover, the DNA-DNA and ANI relatedness values between the novel isolate and H. alba YIM 93221 T were 53.3% and 92.5%, respectively. Based on comparative analysis of polyphasic taxonomic data, strain YIM 98757 T represents a novel species of the genus Haloechinothrix, for which the name Haloechinothrix aidingensis sp. nov. is proposed. The type strain is YIM 98757T (= CGMCC 4.7627T = CCTCC AA 2020012).

Prediction of phenolic compounds and glucose content from dilute inorganic acid pretreatment of lignocellulosic biomass using artificial neural network modeling.

Dilute inorganic acids hydrolysis is one of the most promising pretreatment strategies with high recovery of fermentable sugars and low cost for sustainable production of biofuels and chemicals from lignocellulosic biomass. The diverse phenolics derived from lignin degradation during pretreatment are the main inhibitors for enzymatic hydrolysis and fermentation. However, the content features of derived phenolics and produced glucose under different conditions are still unclear due to the highly non-linear characteristic of biomass pretreatment. Here, an artificial neural network (ANN) model was developed for simultaneous prediction of the derived phenolic contents (CPhe) and glucose yield (CGlc) in corn stover hydrolysate before microbial fermentation by integrating dilute acid pretreatment and enzymatic hydrolysis. Six processing parameters including inorganic acid concentration (CIA), pretreatment temperature (T), residence time (t), solid-to-liquid ratio (RSL), kinds of inorganic acids (kIA), and enzyme loading dosage (E) were used as input variables. The CPhe and CGlc were set as the two output variables. An optimized topology structure of 6-12-2 in the ANN model was determined by comparing root means square errors, which has a better prediction efficiency for CPhe (R2 = 0.904) and CGlc (R2 = 0.906). Additionally, the relative importance of six input variables on CPhe and CGlc was firstly calculated by the Garson equation with net weight matrixes. The results indicated that CIA had strong effects (22%-23%) on CPhe or CGlc, then followed by E and T. In conclusion, the findings provide new insights into the sustainable development and inverse optimization of biorefinery process from ANN modeling perspectives.

Oceanobacillus halotolerans sp. nov., a bacterium isolated from salt lake in Xinjiang province, north-west China.

A bacterial strain, designated YIM 98839T, was isolated from the hypersaline sediment of Aiding Lake in Xinjiang province, North-West China. The strain was Gram-stain-positive, motile, aerobic, produced oval subterminal or central endospores in swollen sporangia. The whole-cell hydrolysates contain meso-diaminopimelic acid as the diagnostic cell-wall diamino acid. Galactose, fucose and ribose are the major whole-cell sugars. The phospholipids are diphosphatidylglycerol, phosphatidylglycerol and one unknown phospholipid. The predominant menaquinone is MK-7. The major fatty acids are anteiso-C15:0, anteiso-C17:0 and iso-C15:0. The DNA G + C content of the type strain is 37.0 mol%. Phylogenetic analysis indicated that the isolate belongs to the genus Oceanobacillus. However, it differed from its closest relative, Oceanobacillus limi H9BT in many physiological characteristics. Moreover, the DNA-DNA relatedness values between the novel isolate and the relative type strain was 20.2%. Based on comparative analysis of polyphasic taxonomic data, strain YIM 98839T represents a novel species of the genus Oceanobacillus, for which the name Oceanobacillus halotolerans sp. nov. is proposed. The type strain is YIM 98839T (= CGMCC 1.17002T = KCTC 43140T).