Removal of Fermentation Inhibitors from Sugarcane Bagasse Hydrolysate via Post-cross-linked Hydrophilic-Hydrophobic Interpenetrating Polymer Networks.

The efficient and economical removal of fermentation inhibitors from the complex system of biomass hydrolysate was one of the basics and keys in bio-chemical transformation. In this work, post-cross-linked hydrophilic-hydrophobic interpenetrating polymer networks (PMA/PS_pc IPNs and PAM/PS_pc IPNs) were proposed to remove fermentation inhibitors from sugarcane bagasse hydrolysate for the first time. PMA/PS_pc and PAM/PS_pc IPNs can obviously enhance the adsorption performance towards fermentation inhibitors due to their higher surface area and hydrophilic-hydrophobic synergetic surface properties, especially PMA/PS_pc IPNs has higher selectivity coefficients of 4.57, 4.63, 4.85, 16.0, 49.43, and 22.69, and higher adsorption capacity of 24.7 mg/g, 39.2 mg/g, 52.4 mg/g, 9.1 mg/g, 13.2 mg/g, and 144.9 mg/g towards formic acid, acetic acid, levulinic acid (LA), 5-hydroxymethylfurfural (HMF), furfural, and acid-soluble lignin (ASL), respectively, in a lower total sugar loss of 2.03%. The adsorption kinetics and isotherm of PMA/PS_pc IPNs were studied to elucidate its adsorption behavior towards fermentation inhibitors. In addition, the cyclic utilization property of PMA/PS_pc IPNs was stable. Synthesizing PMA/PS_pc IPNs is a new strategy to provide an efficient adsorbent for the removal of fermentation inhibitors from lignocellulosic hydrolysate.

Synthesis of polyacrylamide/polystyrene interpenetrating polymer networks and the effect of textural properties on adsorption performance of fermentation inhibitors from sugarcane bagasse hydrolysate.

Economical removal of fermentation inhibitors from lignocellulosic hydrolysate plays a considerable role in bioconversion of lignocellulose biomass. In this work, the textural properties of polyacrylamide/polystyrene interpenetrating polymer networks (PAM/PS IPNs) on adsorption of fermentation inhibitors from sugarcane bagasse hydrolysate (SCBH) were investigated for the first time. The results showed that, the specific surface area, pore diameter and surface polarity had important influence on its adsorption performance towards sugars, organic acids, furans and acid-soluble lignin. The PAM/PS IPNs under the optimal copolymerization situation achieved the high selectivity coefficients of 4.07, 14.9, 21.2 and 25.8 with respective to levulinic acid, furfural, hydroxymethylfurfural (HMF) and acid-soluble lignin, and had a low total sugar loss of 2.09%. Overall, this research puts forward a design and synthetic strategy for adsorbent to remove fermentation inhibitors from lignocellulosic hydrolysate.

EGFR monoclonal antibody panitumumab inhibits chronic proliferative cholangitis by downregulating EGFR.

In hepatolithiasis, chronic proliferative cholangitis (CPC), an active and longstanding inflammation of stone­containing bile ducts with enhanced mucin­producing activity, not only affects the progression of the disease, it can also induce biliary carcinogenesis. The present study aimed to examine the effect of the epidermal growth factor receptor (EGFR) monoclonal antibody panitumumab (Pani) on CPC. Following the establishment of CPC rat models, periodic acid Schiff staining was used to observe the positive rate of EGFR expression. The expression levels of EGFR, mucin 5AC (MUC5AC), Ki­67, type I collagen and mammalian target of rapamycin (mTOR), and the activity of ß­glucuronidase (ß­G), were measured. The rats treated with Pani demonstrated a significantly lower degree of hyperproliferation of the epithelium and submucosal glands of the bile duct and collagen fibers of the bile duct wall, a significantly decreased positive rate of EGFR, reduced phosphorylation of mTOR, decreased expression of EGFR, MUC5AC, Ki­67 and type I collagen, and reduced ß­G activity. The therapeutic effects in rats treated with 4 and 6 mg/kg of Pani were more marked than those in rats treated with 2 mg/kg of Pani. Collectively, the data obtained in the present study suggest that the EGFR monoclonal antibody Pani can effectively inhibit the excessive proliferation and stone­forming potential of bile duct mucosa in CPC with a receptor saturation effect. Therefore, Pani offers promise as a treatment for the prevention and control of intrahepatic choledocholithiasis caused by CPC.

Determining intracellular lipid content of different oleaginous yeasts by one simple and accurate Nile Red fluorescent method.

A simple and accurate Nile Red fluorescent method was built to evaluate the lipid content of three different oleaginous yeasts by one standard curve. The staining of cells can be observed clearly by laser scanning confocal microscope, showing that Nile Red can enter into the cells of oleaginous yeasts easily. A series of conditions such as pretreating temperature, cell suspension concentration (OD600), staining time, Nile Red concentration and the type of suspension solvent were learnt systematically to obtain the optimal process parameters for Nile Red staining. After optimization, the fitting curve of Nile Red fluorescent method was established under suitable conditions (pretreating temperature: 50 °C, OD600: 1.0; staining time: 5 mins; Nile Red concentration: 1.0 µg/mL; suspension solvent: PBS) and it had a suitable correlation coefficient (R2 = 0.95) for lipid content measurement of different oleaginous yeasts. By this study, the possibility of lipid content determination of different oleaginous yeasts by one fitting curve can be proven and this will improve the efficiency of researches related to microbial lipid production.

Anaerobic digestion of elephant grass hydrolysate: Biogas production, substrate metabolism and outlet effluent treatment.

Elephant grass (Pennisetum purpureum) acid hydrolysate was used as substrate for anaerobic digestion for the first time. Within short period (ten days), the organic materials (sugars and organic acids) in the elephant grass hydrolysate could be utilized efficiently for stable biogas production that the COD removal, biogas yield, and CH4 content were 91.3 ±â€¯2.0%, 0.561 ±â€¯0.014 m3/kg COD consumption, and 68.1 ±â€¯4.6%, respectively throughout this bioprocess. During anaerobic digestion, almost no volatile fatty acids (VFAs) was accumulated (merely <0.1 g/L acetic acid was found) and the outlet pH was very stable (7.3 ±â€¯0.1). Meanwhile, the furans including furfural and 5-hydroxymethylfurfural (HMF) existing in the inlet substrate could be degraded. After anaerobic digestion, the outlet effluent was treated by combination of Fe-C micro-electrolysis and Fenton reaction to remove 93.1% of residual COD and 98.6% of color. Considering the performance, cost, operation, and environmental influence, this technology is suitable for industrial treatment of waste elephant grass.

Introduction of one efficient industrial system for turpentine processing wastewater reuse and treatment.

Wastewater treatment is one important issue for turpentine plant and more wastewater generated by greater turpentine processing will prevent its further development. To solve this issue without extra place and new equipment, one industrial system for reuse and treatment of turpentine processing wastewater was introduced for the first time. For wastewater reuse, the technology was simple and easy to control that after neutralization by lime and absorption with activated carbon (optional, mostly not necessary), the wastewater could be reused for turpentine processing. After reuse, the wastewater was further treated by a biological system. During long-term application of wastewater reuse in this plant, it showed little influence on the products performance (mainly acid value) and final wastewater COD. Base on above advantages, the plant could decide when for wastewater drainage, and thus the amount of wastewater was reduced greatly. For the biological treatment, the COD of wastewater could be degraded to suitable level stably and the wastewater after treatment could be applied for daily life in the plant. Overall, considering the cost, operation, and performance, the whole system shows great potential and possibility of industrial application and therefore can be applied widely in the turpentine processing industry.

Bacterial cellulose based superabsorbent production: A promising example for high value-added utilization of clay and biology resources.

Superabsorbent was synthesized from bacterial cellulose (BC) generated by in situ fermentation on bentonite inorganic gel (BIG). For BIG preparation, the effect of sodium agent's type and content, temperature and time of sodium-modification, and gelling agent's type and content on the viscosity of BIG were learned to optimize the synthesis process. For polymerization, the effect of different factors including ratio of monomer to substrate (modified BC from in situ fermentation), content of initiator and crosslinker, monomer neutralization degree, reaction temperature and time on the performance of composite (superabsorbent) synthesized were analyzed. Under optimal condition, the composite showed good water absorption, salts absorption, and water retention capacity. The original bentonite, sodium-based bentonite, BIG and composite structure was characterized by X-ray fluorescence (XRF), nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and thermogravimetric analysis (TGA), and the characterization partly explained the performance of water absorption and thermal stability of the composite. Overall, this study provides one method for superabsorbent synthesis from low-cost and natural resources.

Adsorption Study of Acid Soluble Lignin Removal from Sugarcane Bagasse Hydrolysate by a Self-Synthesized Resin for Lipid Production.

An adsorption resin CX-6 was synthesized and used for acid soluble lignin (ASL) removal from sugarcane bagasse hydrolysate (SCBH). The adsorption conditions of pH value, amount of adsorbent, initial ASL concentration, and temperature on ASL adsorption were discussed. The results showed the adsorption capacity of ASL was negatively affected by increasing temperature, solution pH, and adsorbent dose, and was positively affected by increasing initial concentration. The maximum adsorption capacity of ASL was 135.3 mg/g at initial ASL concentration 6.46 g/L, adsorption temperature 298 K, and pH 1. Thermodynamic study demonstrated that the adsorption process was spontaneous and exothermic. Equilibrium and kinetics experiments were proved to fit the Freundlich isotherm model and pseudo-second-order model well, respectively. Fermentation experiment showed that the SCBH after combined overliming with resin adsorption as fermentation substrate for microbial lipid production by Trichosporon cutaneum and Trichosporon coremiiforme was as better as that of SCBH by combined overliming with active charcoal adsorption, and more efficient than that of SCBH only by overliming. Moreover, the regeneration experiment indicated that the CX-6 resin is easy to regenerate and its recirculated performance is stable. In conclusion, our results provide a promising adsorbent to detoxify lignocellulose hydrolysate for further fermentation.

Cellulose-Based Absorbent Production from Bacterial Cellulose and Acrylic Acid: Synthesis and Performance.

Cellulose-based superabsorbent was synthesized by bacterial cellulose (BC) grafting acrylic acid (AA) in the presence of N,N'-methylenebisacrylamide (NMBA) as a crosslinker and ammonium persulfate (APS) as an initiator. The influence of different factors on composite synthesis, including the weight ratio of the monomer to BC, initiator content, crosslinker content, AA neutralization degree, reaction temperature, and reaction time on the water absorbency of the composite, were systematically learned. Under the optimized conditions, the maximum water absorbency of the composite was 322 ± 23 g/g distilled water. However, the water absorbency was much less for the different salt solutions and the absorption capacity of the composite decreased as the concentration of the salt solutions increased. The pH value had a significant influence on water absorption performance, and with the increase of temperature, the water retention rate of the composite decreased. Additionally, the structure of this composite was characterized with nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results of NMR and FT-IR provided evidence that the composite was synthesized by BC and AA, and the microstructure showed that it had good performance for water absorption. In addition, the composite possessed suitable thermal stability, and that it could be used in a few high-temperature environments. Overall, this composite is promising for application in water absorption.

Fast Startup of Semi-Pilot-Scale Anaerobic Digestion of Food Waste Acid Hydrolysate for Biogas Production.

In this study, a fast startup of semi-pilot-scale anaerobic digestion of food waste acid hydrolysate for biogas production was carried out for the first time. During the period of fast startup, more than 85% of chemical oxygen demand (COD) can be degraded, and even more than 90% of COD can be degraded during the later stage of anaerobic digestion. During this anaerobic digestion process, the biogas yield, the methane yield, and the CH4 content in biogas were 0.542 ± 0.056 m3/kgCOD consumption, 0.442 ± 0.053 m3/kgCOD consumption, and 81.52 ± 3.05%, respectively, and these values were high and stable. Besides, the fermentation pH was very stable, in which no acidification was observed during the anaerobic digestion process (outlet pH was 7.26 ± 0.05 for the whole anaerobic digestion). Overall, the startup of this anaerobic digestion can be completed in a short period (the system can be stable 2 days after the substrate was pumped into the bioreactor), and anaerobic digestion of food waste acid hydrolysate is feasible and attractive for industrial treatment of food waste and biogas production.

Efficient Using Durian Shell Hydrolysate as Low-Cost Substrate for Bacterial Cellulose Production by Gluconacetobacter xylinus.

Durian is one important tropical fruit with high nutritional value, but its shell is usually useless and considered as waste. To explore the efficient and high-value utilization of this agricultural and food waste, in this study, durian shell was simply hydrolyzed by dilute sulfuric acid, and the durian shell hydrolysate after detoxification was used for bacterial cellulose (BC) production by Gluconacetobacter xylinus for the first time. BC was synthesized in static culture for 10 days and the highest BC yield (2.67 g/L) was obtained at the 8th day. The typical carbon sources in the substrate including glucose, xylose, formic acid, acetic acid, etc. can be utilized by G. xylinus. The highest chemical oxygen demand (COD) removal (16.40%) was obtained at the 8th day. The highest BC yield on COD consumption and the highest BC yield on sugar consumption were 93.51% and 22.98% (w/w), respectively, suggesting this is one efficient bioconversion for BC production. Durian shell hydrolysate showed small influence on the BC structure by comparison with the structure of BC generated in traditional Hestrin-Schramm medium detected by FE-SEM, FTIR, and XRD. Overall, this technology can both solve the issue of waste durian shell and produce valuable bio-polymer (BC).

Efficient bioconversion from acid hydrolysate of waste oleaginous yeast biomass after microbial oil extraction to bacterial cellulose by Komagataeibacter xylinus.

Biomass acid hydrolysate of oleaginous yeast Trichosporon cutaneum after microbial oil extraction was applied as substrate for bacterial cellulose (BC) production by Komagataeibacter xylinus (also named as Gluconacetobacter xylinus previously) for the first time. BC was synthesized in static culture for 10 days, and the maximum BC yield (2.9 g/L) was got at the 4th day of fermentation. Most carbon sources in the substrate (glucose, mannose, formic acid, acetic acid) can be utilized by K. xylinus. The highest chemical oxygen demand (COD) removal (40.7 ± 3.0%) was obtained at the 6th day of fermentation, and then the COD increased possibly due to the degradation of BC. The highest BC yield on COD consumption was 38.7 ± 4.0% (w/w), suggesting that this is one efficient bioconversion for BC production. The BC structure was affected little by the substrate by comparison with that generated in classical HS medium using field-emission scanning electron microscope (FE-SEM), Fourier transform infrared, and X-ray diffraction. Overall, this technology can both solve the issue of waste oleaginous yeast biomass and produce valuable biopolymer (BC).

Lumping kinetics of ABE fermentation wastewater treatment by oleaginous yeast Trichosporon cutaneum.

Lumping kinetics models were built for the biological treatment of acetone-butanol-ethanol (ABE) fermentation wastewater by oleaginous yeast Trichosporon cutaneum with different fermentation temperatures. Compared with high temperature (33°C, 306 K) and low temperature (23°C, 296 K), medium temperature (28°C, 301 K) was beneficial for the cell growth and chemical oxygen demand (COD) degradation during the early stage of fermentation but the final yeast biomass and COD removal were influenced little. By lumping method, the materials in the bioconversion network were divided into five lumps (COD, lipid, polysaccharide, other intracellular products, other extracellular products), and the nine rate constants (k1-k9) for the models can well explain the bioconversion laws. The Gibbs free energy (G) for this bioconversion was positive, showing that it cannot happen spontaneous, but the existence of yeast can after the chemical equilibrium and make the bioconversion to be possible. Overall, the possibility of using lumping kinetics for elucidating the laws of materials conversion in the biological treatment of ABE fermentation wastewater by T. cutaneum has been initially proved and this method has great potential for further application.

Combined "de novo" and "ex novo" lipid fermentation in a mix-medium of corncob acid hydrolysate and soybean oil by Trichosporon dermatis.

BACKGROUND: Microbial oil is one important bio-product for its important function in energy, chemical, and food industry. Finding suitable substrates is one key issue for its industrial application. Both hydrophilic and hydrophobic substrates can be utilized by oleaginous microorganisms with two different bio-pathways ("de novo" lipid fermentation and "ex novo" lipid fermentation). To date, most of the research on lipid fermentation has focused mainly on only one fermentation pathway and little work was carried out on both "de novo" and "ex novo" lipid fermentation simultaneously; thus, the advantages of both lipid fermentation cannot be fulfilled comprehensively. RESULTS: In this study, corncob acid hydrolysate with soybean oil was used as a mix-medium for combined "de novo" and "ex novo" lipid fermentation by oleaginous yeast Trichosporon dermatis. Both hydrophilic and hydrophobic substrates (sugars and soybean oil) in the medium can be utilized simultaneously and efficiently by T. dermatis. Different fermentation modes were compared and the batch mode was the most suitable for the combined fermentation. The influence of soybean oil concentration, inoculum size, and initial pH on the lipid fermentation was evaluated and 20 g/L soybean oil, 5% inoculum size, and initial pH 6.0 were suitable for this bioprocess. By this technology, the lipid composition of extracellular hydrophobic substrate (soybean oil) can be modified. Although adding emulsifier showed little beneficial effect on lipid production, it can modify the intracellular lipid composition of T. dermatis. CONCLUSIONS: The present study proves the potential and possibility of combined "de novo" and "ex novo" lipid fermentation. This technology can use hydrophilic and hydrophobic sustainable bio-resources to generate lipid feedstock for the production of biodiesel or other lipid-based chemical compounds and to treat some special wastes such as oil-containing wastewater.

Recent advances and industrial viewpoint for biological treatment of wastewaters by oleaginous microorganisms.

Recently, technology of using oleaginous microorganisms for biological treatment of wastewaters has become one hot topic in biochemical and environmental engineering for its advantages such as easy for operation in basic bioreactor, having potential to produce valuable bio-products, efficient wastewaters treatment in short period, etc. To promote its industrialization, this article provides some comprehensive analysis of this technology such as its advances, issues, and outlook especially from industrial viewpoint. In detail, the types of wastewaters can be treated and the kinds of oleaginous microorganisms used for biological treatment are introduced, the potential of industrial application and issues (relatively low COD removal, low lipid yield, cost of operation, and lack of scale up application) of this technology are presented, and some critical outlook mainly on co-culture method, combination with other treatments, process controlling and adjusting are discussed systematically. By this article, some important information to develop this technology can be obtained.

Preparation of Bacterial Cellulose/Inorganic Gel of Bentonite Composite by In Situ Modification.

To evaluate the possibility of Bacterial cellulose/Inorganic Gel of Bentonite (BC/IGB) composite production using in situ method, the BC/IGB composite was successfully produced by in situ modification of BC in both HS medium and corncob hydrolysate. The results showed that the BC/IGB composite obtained in HS medium (one classical medium for BC production) had a higher water holding capacity, but the water retention capacity of the BC/IGB composite obtained in corncob hydrolysate was better. The performance of BC/IGB composite depended on the environment of in situ modification. Using different media showed significant influence on the sugar utilization and BC yield. In addition, BC/IGB composite produced by in situ method was compared with that produced by ex situ method, and the results shows that water holding capacity of BC/IGB composite obtained through in situ method was better. XRD results showed the crystallinity of BC/IGB composite related little to its performance as water absorbent. Overall, in situ modification is appropriate for further production of BC composite and other clay materials.

Semi-pilot Scale Microbial Oil Production by Trichosporon cutaneum Using Medium Containing Corncob Acid Hydrolysate.

In this study, semi-pilot scale microbial oil production by Trichosporon cutaneum using medium containing corncob acid hydrolysate was carried out in a 50-L fermentor. Scale up showed no negative influence on lipid fermentation that no obvious lag phase was observed. Both glucose and xylose could be utilized simultaneously by T. cutaneum, but the utilization rate of xylose was much slower than that of glucose. After 7.6 days of fermentation, the biomass, lipid content, and lipid yield were 21.8 g/L, 53.7 %, and 11.7 g/L, respectively. Also, a high lipid coefficient (lipid yield on sugars consumption) of 26.3 was obtained. Besides microbial oil, polysaccharide was another main product of lipid fermentation that the remaining biomass residue full of polysaccharides after lipid extraction could be one important by-product in future. Overall, this study showed the great potential of industrialization for lipid production by T. cutaneum on low-cost substrates especially for lignocellulosic hydrolysates.

Use of elephant grass (Pennisetum purpureum) acid hydrolysate for microbial oil production by Trichosporon cutaneum.

Elephant grass (Pennisetum purpureum) dilute acid hydrolysate contains 34.6 g/L total sugars. The potential of lipid production by oleaginous yeast Trichosporon cutaneum grown on elephant grass acid hydrolysate was investigated for the first time. During the fermentation process on the elephant grass acid hydrolysate, glucose, xylose, and arabinose could be well utilized as carbon sources by T. cutaneum. Interestingly, xylose was almost no use before glucose was consumed completely. This illustrated that simultaneous saccharification of xylose and glucose by T. cutaneum did not occur on elephant grass acid hydrolysate. The highest biomass, lipid content, lipid yield, and lipid coefficient of T. cutaneum were measured after the sixth day of fermentation and were 22.76 g/L, 24.0%, 5.46 g/L, and 16.1%, respectively. Therefore, elephant grass is a promising raw material for microbial oil production by T. cutaneum.

Elucidating the Beneficial Effect of Corncob Acid Hydrolysate Environment on Lipid Fermentation of Trichosporon dermatis by Method of Cell Biology.

In present study, the beneficial effect of corncob acid hydrolysate environment on lipid fermentation of Trichosporon dermatis was elucidated by method of cell biology (mainly using flow cytometry and microscope) for the first time. Propidium iodide (PI) and rhodamine 123 (Rh123) staining showed that corncob acid hydrolysate environment was favorable for the cell membrane integrity and mitochondrial membrane potential of T. dermatis and thus made its lipid fermentation more efficient. Nile red (NR) staining showed that corncob acid hydrolysate environment made the lipid accumulation of T. dermatis slower, but this influence was not serious. Moreover, the cell morphology of T. dermatis elongated in the corncob acid hydrolysate, but the cell morphology changed as elliptical-like during fermentation. Overall, this work offers one simple and effective method to evaluate the influence of lignocellulosic hydrolysates environment on lipid fermentation.

Using wastewater after lipid fermentation as substrate for bacterial cellulose production by Gluconacetobacter xylinus.

In this study, lipid fermentation wastewater (fermentation broth after separation with yeast biomass) with high Chemical Oxygen Demand (COD) value of 25,591 mg/L was used as substrate for bacterial cellulose (BC) production by Gluconacetobacter xylinus for the first time. After 5 days of fermentation, the highest BC yield (0.659 g/L) was obtained. Both monosaccharide and polysaccharides present in lipid fermentation wastewater could be utilized by G. xylinus simultaneously during fermentation. By this bioconversion, 30.0% of COD could be removed after 10 days of fermentation and the remaining wastewater could be used for further BC fermentation. The crystallinity of BC samples in lipid fermentation wastewater increased gradually during fermentation but overall the environment of lipid fermentation wastewater showed small influence on BC structure by comparison with that in traditional HS medium by using FE-SEM, FTIR, and XRD. By this work, the possibility of using lipid fermentation wastewater containing low value carbohydrate polymer (extracellular polysaccharides) for high value carbohydrate polymer (BC) production was proven.