Volume 8 Issue 4

Corn stover was pretreated with liquid hot water (LHW) to enhance its enzymatic hydrolysis and L-lactic fermentation. The cellulose conversion rate and L-lactic acid concentration were used to evaluate LHW pretreatment performance. Results showed that the optimum conditions for the LHW pretreatment of corn stover are a reaction temperature of 190 °C for 20 min and a solid-to-liquid ratio of 1:10. The cellulase loading was 30 filter paper units per gram of oven-dried, water-insoluble solid. These conditions resulted in 92.3% conversion of cellulose to glucose. Sequential hydrolysis and fermentation using pretreated water-insoluble solid (WIS) produced an L-lactic acid concentration of 45 g/L. This study indicated that LHW pretreatment of corn stover is a suitable method for achieving high cellulose conversion and L-lactic acid concentration.

The phenylpropanoid pathway serves as a rich source of metabolites in plants. It is required for the biosynthesis of lignin and acts as a starting point for the production of many other important compounds involved in growth and development. Phenylalanine ammonia-lyase (PAL) catalyzes the first step of the phenylpropanoid pathway. PAL gene expression changes during the growth and development of plants as it regulates the synthesis of lignin and other phenylpropanoid compounds. The gene expression of sugarcane (Saccharum officinarum L.) PAL (SoPAL) was analyzed using quantitative real-time PCR (qPCR) and the comparative ΔΔCt method in different tissues during different developmental stages. The results showed that SoPAL was expressed in all tissues and developmental stages. SoPAL mRNA levels were increased from germination to tillering stages, except in the sheath, and from tillering to grand growth stages in the leaf and stem. PAL expression decreased from the grand growth to maturation stages in all tissues except the sheath. The highest expression of SoPAL occurred in the stem during the grand growth stage, while its lowest expression occurred in the leaf during germination (p<0.05). In conclusion, PAL, as a rate-limiting enzyme of the phenylpropanoid pathway, displays critical roles in the development of sugarcane, particularly in lignified tissues.

Chitosan was used as a sizing promoter to improve the sizing performance of ASA emulsion stabilized by montmorillonite. It was found that chitosan with low molecular weight significantly improved the sizing performance of ASA emulsion without inducing the flocculation of the ASA droplets when the amount was less than 0.125% based on ASA. Confocal fluorescence microscopy revealed the formation of chitosan shell around the ASA droplet. Adding ammonia into the emulsion induced desorption of chitosan from the ASA droplet surface and the ammonolysis of ASA. The former reduced the ASA emulsion stability, while the latter resulted in the secondary emulsification of ASA-water system. Meanwhile, the presence of ammonia was demonstrated to be detrimental to the sizing performance of the ASA emulsion. The hydrolysis resistance of the ASA emulsion was higher when chitosan was present.

A phenol-formaldehyde (PF) resin treatment of OPTL with various concentrations of finely ground palm shell, together abbreviated PF-FGPS, has been used to improve termite resistance. Termite resistance was evaluated in two ways, in a laboratory test and in a field test that lasted 3 months. A feeding arena sample was prepared for the first experiment so that the responses of the subterranean termite (Coptotermes curvignathus (Holmgren)) and the drywood termite (Cryptotermes cynocephalus (Light)) to the laboratory test could be observed for 4 weeks and 12 weeks, respectively. In general, the PF-FGPS led to greater termite resistance than did the control (dried OPTL and rubberwood), and the resistance of the samples to the subterranean termite C. curvignathus was classified as moderate when the samples were treated with OPS meal. Meanwhile, the resistance of the samples to the drywood termite C. cynocephalus was classified as moderate when samples were treated with OPS meal concentrations of 0, 1, and 3%. The samples treated with 5% OPS meal were classified as resistant. In the field test, samples impregnated with OPS meal at levels of 3%, 5%, and 10% were classified as resistant, while those impregnated with OPS meal at levels of 0 and 1% were classified as moderately resistant to attack by the subterranean termite.

Continuous and batch tests were conducted to evaluate fermentative biohydrogen production from starch wastewater via a mesophillic up-flow anaerobic staged reactor (UASR). The effects of organic loading rate (OLR) and food to micro-organisms ratio (F/M) on hydrogen yield (HY) and hydrogen production rate (HPR) were investigated. The bioreactor was continuously operated at a constant hydraulic retention time (HRT) of 6.7 h. The optimal OLR and F/M ratios were 54 g-COD/L.d and 1.4 g-COD/g-VSS.d, respectively. The maximum HY and HPR were 1.87 mol-H2/mol-glucose and 246 mmol-H2/L.d, respectively. Batch experimental results indicated that the optimal initial cultivation pH ranged from 5.5 to 6.5 with a hydrogen potential (P) of 1435-1420 mL-H2, while the initial substrate concentration of 20 g-starch/L showed a maximum HPR (Rm) of 300 mL-H2/h. Zero, 1st and 2nd order kinetic studies were used to develop a model of the experimental data. The 2nd order model adequately fitted with the experimental results (R2>0.97) better than those for a zero- or a 1st order kinetic reaction.

Sixty-two fungal isolates were screened for lignin peroxidase production. The most potent isolates for lignin peroxidase production were identified using the DNA sequence of the internal transcribed spacer (ITS) region of Phanerochaete chrysosporium and Pleurotus ostreatus. The pretreatment of rice straw with P. chrysosporium, Pl. ostreatus, or lignin peroxidase for use in the biopulping process was studied. Great variations in the loss of pulp yield and kappa number were recorded with different fungal and enzyme treatments. Pretreatment of rice straw with P. chrysosporium for 25 days resulted in a substantial decrease in pulp yield (by 9.1%) and kappa number (by 25.6%). Losses of pulp yield and kappa number were considerably lower with lignin peroxidase treatment (3.7 and 14.1%, respectively). However, the pretreatment of rice straw with the Pl. ostreatus isolate caused moderate pulp yield losses (5.8%) and preferential lignin degradation (kappa number losses of 34.6%). This indicated that the Pl. ostreatus isolate might be superior to both the isolate of P. chrysosporium and lignin peroxidase for use in the biopulping process or other processes in which preferential lignin degradation is desired.

Ferulic acid is present at relatively high concentrations in the cell walls of several plants. Agricultural lignocelluloses are now used as bioresources in industry. This study attempted to increase the free ferulic acid content present in lignocellulose by using thermostable esterase produced from thermophilic actinomycetes to hydrolyze ester bonds. Destarched wheat bran was used as a carbon source for the production of esterases from the newly isolated thermophilic actinomycetes species Thermobifida fusca. After 96 h of cultivation, the esterase activity that accumulated in the culture broth was 946.0 U/mL. Two percent of the destarched wheat bran was then hydrolyzed by crude esterase preparation for 16 h. The ferulic acid was accumulated in the culture broth at a concentration of 310.0 mM. The hydrolysate had better radical-scavenging ability for both 1,1-diphenyl-2-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical-scavenging ability, as well as reducing power than ferulic acid. These results showed that the ferulic acid-rich destarched wheat bran hydrolysate had good antioxidant properties. It is suggested that this process can be advantageous for the industrial production of antioxidants derived from agricultural bioresources.

The effect of pyrolysis temperature on the characteristics and metal sorption capacity of sugar cane straw derived–biochar (BC) was investigated. Biochar was produced at four temperatures (400, 500, 600, and 700 °C) before characterization for yield, ash and moisture content, pH, EC, pHPZC, elemental composition, nutrient content, CEC, TGA, and functional groups (FT-IR). Biochar alone and in mixtures containing 10%, w/w biochar with one of two different tropical soils (Entisol and Oxisol) was shaken for 24 h with a 2.0 mM solution (pH 4.5) of Zn or Cd in a batch sorption test. Increasing the pyrolysis temperature led to a reduction in the O/C and H/C molar ratios. The sorption capacity of biochar pyrolyzed at 700 °C was nearly four times greater than that produced at 400 °C. In the Entisol mixture, there was an increase up to seven-fold in the sorption of both Cd and Zn compared with the control (without BC). In the Oxisol mixture, there was a maximum 20% increase in sorption compared with the control. For the remediation of Cd- and Zn-contaminated substrates, the use of higher pyrolysis temperature biochars are recommended because of their higher metal sorption capacities.

The alkali-cellulase processing of biomass into glucose near where it is grown has already been demonstrated at laboratory scale. Glucose can be fermented locally or transported to distant facilities for the production of bioethanol as fuel. This renewable energy process uses materials and methods that are readily available and that can be implemented at local or regional sites near growing fields. This study evaluated the effects on glucose production of different durations and amounts of NaOH pretreatment as well as different lengths of time for adsorption of cellulase. The pretreatment of corn stover (CS) with NaOH at 0.1 g/g CS for 6 h at a temperature of 100 °C resulted in the most acceptable glucose release following enzymatic hydrolysis. The exposure of pretreated CS solids to cellulase for 1 h resulted in the most acceptable release of glucose following the volume expansion at 10-fold dilution. The residual solids remaining after 3 h of enzymatic hydrolysis can be recycled to increase yields. The resulting glucose solution can be concentrated to minimize transportation costs when delivered to conventional grain fermentation facilities. This study introduced new conditions that enhanced practicality of the alkali-cellulase processing of biomass by allowing the processing time to be reduced to 10 h.

Chinese fir (Cunninghamia lanceolata) has great potential as a future bio-energy resource in China. Thermogravimetry (TG) was used to investigate the thermal decomposition process of Chinese fir, including heartwood and sapwood. The Flynn-Wall-Ozawa and Coats-Redfern (modified) methods were used to determine the activation energy. A combination of TG and Fourier transform infrared spectrometry (TG-FTIR) was used to analyze the pyrolysis products. The TG curve indicated that the degradation processes of heartwood and sapwood were similar, but the degradation temperature of heartwood was lower than that of sapwood. The main decomposition occurred within the temperature range of 500 K to 660 K, and over 70% of the mass was degraded. The activation energy of Chinese fir with heartwood and sapwood changed slightly with an increase in conversion rate from 10 to 70. That of heartwood and sapwood was 155.38 to 158.37 KJ/mol and 155.93 to 180.04 KJ/mol, respectively, using the Flynn-Wall-Ozawa method. TG-FTIR analysis showed that the main pyrolysis products included absorbed water (H2O), methane gas (CH4), carbon dioxide (CO2), carbon monoxide (CO), acids and aldehydes, nitrogen dioxide (NO2), nitric oxide (NO), and ammonia gas (NH3). The results from this study are helpful for designing a better bio-energy manufacturing process for Chinese fir via gasification and pyrolysis methods.