Insights into biological delignification of rice straw by Trametes hirsuta and Myrothecium roridum and comparison of saccharification yields with dilute acid pretreatment

Rice straw is the most abundant agricultural residue on a global scale and is widely available as feedstock for cellulosic fuel production. However, it is highly recalcitrant to biochemical deconstruction and also generates inhibitors that affect enzymatic saccharification. Rice straw from eastern Arkansas was subjected to dilute acid pretreatment (160 °C, 48 min and 1.0% sulfuric acid) and solid-state fermentation with two lignocellulolytic fungi, Trametes hirsuta and Myrothecium roridum, and their saccharification efficacies were compared. T. hirsuta and M. roridum were tested separately; pretreatment of rice straw with either strain for seven days resulted in 19 and 70% enrichment of its holocellulose content, respectively. However, liquid chromatography analysis of the alkali extracts showed significant differences in cell wall degradation by T. hirsuta and M. roridum. T. hirsuta removed 15% more phenolic compounds and 38% more glucan than M. roridum, while M. roridum removed 77% more xylan than T. hirsuta. Fungal and dilute acid pretreated biomass was then hydrolyzed using Accellerase^® 1500, a saccharification cocktail. Saccharification efficiency of M. roridum was 37% higher than that of dilute acid pretreatment of rice straw, requiring 8% lower enzyme loading and 50% shorter enzymatic hydrolysis duration. Alkali extraction of fungal pretreated biomass also yielded 10–15 g kg⁻¹ of acid precipitable polymeric lignin (APPL), which is a valuable co-product for biorefineries. In comparison to dilute acid pretreatment, fungal pretreatment could be a cost-effective alternative for the degradation of recalcitrant biomass, such as rice straw.     

Structure and properties of poly(butylene succinate) filled with lignin: A case of lignosulfonate

A new kind of blend material was prepared by the incorporation of lignosulfonate calcium (LS), as the filler, into biodegradable poly(butylene succinate) (PBS), as the polymeric matrix, with the process of melt mixing and subsequent compression molding. The nucleation of LS improved the crystalline properties of the PBS component in the blends. Combined with the rigidity nature of the LS filler, the Young's modulus values of the blends were enhanced. Furthermore, the introduction of LS in this biodegradable polyester slightly increased the hydrophilicity of the blends, shown as higher values of water uptake at equilibrium; this might facilitate the biodegradation of hydrophobic polyesters. Consequently, this study opened one way of enhancing the rigidity and decreasing the cost of biodegradable PBS‐based polymeric plastics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Improvement of impact properties for Nb/MoSi2 laminate composites by the interfacial modification (II)

The thermodynamical estimation of the interfacial reaction and the impact properties of Nb/MoSi₂ laminate composites containing SiC, NbSi₂ or ZrO₂ particles are investigated. Laminate composites, which comprise alternating layers of MoSi₂ with the particle and Nb foil, were fabricated by the hot press process. It is clearly found out that the interfacial reaction of Nb/MoSi₂ can be controlled by the addition of ZrO₂ particle to the MoSi₂ phase. The addition of ZrO₂ particle increases both the impact value and the sintered density of Nb/MoSi₂. The suppression of the interfacial reaction is caused by the formation of ZrSiO₄ in MoSi₂−ZrO₂ matrix mixture.     

Light interception, use-efficiency and energy yield of switchgrass (Panicum virgatum L.) grown in a short season area

Switchgrass (Panicum virgatum L.) has been identified as a potential biomass crop in North America. A two-year study was conducted to characterize leaf area development and estimate radiation-use efficiency (RUE) of switchgrass in eastern Canada. Three cultivars, Cave-in-Rock (CIR), Pathfinder (PF) and Sunburst (SB) were grown in solid stands in a randomized complete block design. Dry matter (DM) yield, leaf area development and light interception were monitored bi-weekly throughout the growing season. Herbage subsamples were hand separated into leaf and sheath-stem fractions. Mean seasonal maximum leaf area indices (LAI) were 6.1, 5.3 and 5.1 for CIR, PF and SB, respectively. By early July of each season the canopies were intercepting about 90% of the incoming light. End of season DM yields were 12.2, 11.5 and 10.6 Mg ha⁻¹ for CIR, PF and SB, respectively. The stem plus leaf sheaths constituted the major component of DM and its accumulation trend parallelled that of total DM. End of season stem-sheath components averaged 764, 714 and 691 of the total g kg⁻¹ DM for CIR, PF and SB, respectively. Energy contents of the switchgrasses averaged 17.4 MJ g⁻¹ DM and did not vary among cultivars or during the season. This translated into total energy yields ha⁻¹ of 216 GJ for CIR, 197 for PF and 186 for SB. Radiation-use efficiencies computed using total incoming solar radiation, for the near linear growth phases, averaged 1.07 g DM MJ⁻¹ for CIR, 0.90 for PF and 0.89 for SB. The respective values based on photosynthetically active radiation were 2.20, 2.00 and 1.96 g DM MJ⁻¹. Changes in LAI, relationships between LAI and light interception and DM yield could all be described by predictive regression equations. These results indicate the potential of switchgrass as a biomass crop in short season areas.     

Identification of olfactory cues used in host-plant finding by diamondback moth,Plutella xylostella (Lepidoptera: Plutellidae)

Olfactory attraction of female diamondback moths (Plutella xylostella) to odors of intact and homogenized host plants, as well as individual compounds characteristic of host plants, were investigated by behavioral and electrophysiological methods. Moths were attracted to odors ofBrassica juncea andB. napus seedlings in a Y-tube bioassay. Solvent fractions of homogenizedB. juncea leaves were attractive to moths whether or not isothiocyanates (IC) were present. Moths were attracted in Y-tube bioassays and to field traps baited with individual ICs. Volatiles fromB. juncea andB. napus elicited an electroantennogram (EAG) response and were attractive in the Y-tube bioassay. Allyl IC was shown to be the attractive component in homogenized plant volatiles but was found to be virtually absent from intact plant volatiles. Gas chromatographic fractionation of intact plant volatiles revealed a terpene-containing fraction to be most attractive to the moths. We were unable to isolate individual attractive compounds from this fraction. Our results suggest that certain elements of this fraction, possibly in combination, are important olfactory cues for host-plant finding by the diamondback moth with mustard oils playing an important and possibly synergistic role, particularly when plants are damaged.     

An International Collaborative Study on Trypsin Inhibitor Assay for Legumes,Cereals, and Related Products

For determining trypsin inhibitor activity (TIA) in soy products, the American Oil Chemists' Society (AOCS) Method Ba 12-75 has been used. It measures differences in absorbance at 410 nm of bovine trypsin activity toward a synthetic substrate (Nα-benzoyl-DL-arginine-p-nitroanilide) in the absence and presence of an inhibitor. Recently, a significantly improved method was developed (JAOCS, 2019, 96:635–645), featuring 5 mL of total assay volume, enzyme-last sequence, and single inhibitor level in duplicate. It is proposed as the AOCS Method Ba 12a-2020. As a part of the AOCS method approval process, a collaborative study involving 12 international laboratories was conducted to evaluate the performance of the proposed method. The study involved measuring TIA in 10 selected test samples plus a blind duplicate. They included soybeans, pulses, cereals, and their processed products (flours, concentrates, and isolates). After rigorous statistical treatment of the data, only three outliers were removed from the data of two samples. Repeatability relative standard deviations (RSDr) for the 11 samples ranged from 0.99% to 5.52%. Reproducibility RSD (RSD_R) ranged from 7.07% to 22.92%, with seven samples having RSD_R around 10% or less. The remaining four samples had very low TIA, and their RSD_R values ranged from 13.34% to 22.92%. The study has demonstrated reliable performance of the proposed AOCS method. Several collaborators carried out additional experiments addressing some aspects of the method, leading to further refinements. The proposed method is undergoing evaluation by the AOCS Uniform Methods Committee for adoption as an Official Method for measuring TIA in various legume and grain products.     

Simultaneous reinforcing and toughening: New nanocomposites of waterborne polyurethane filled with low loading level of starch nanocrystals

New nanocomposites of waterborne polyurethane (WPU) as a matrix were prepared by filling low loading of starch nanocrystals (StNs) as a nano-phase. It is worth noting that the resultant StN/WPU nanocomposites showed significant enhancements in strength, elongation and Young's modulus. Herein, the key role of StN in simultaneous reinforcing and toughening was disclosed, namely active surface and rigidity facilitated forming the interface of transferring stress and contributed to enduring stress, respectively. The preserving of original structure and interaction in WPU matrix was also the essential guarantee of improving mechanical performances. As the StN loading increased, the self-aggregation of StNs caused size expansion of nano-phase along with the increase of number, and hence they decreased the mechanical performances. Furthermore, it was verified that chemical grafting onto the StN surface didn't favor enhancing the strength and elongation, due to inhibiting the formation of physical interaction and increasing network density in nanocomposites.     

Proteins of Brassicaceae oilseeds and their potential as a plant protein source

Among the commercially cultivated Brassicaceae (Cruciferae) plants, Brassica juncea, Brassica napus, Brassica rapa, and Sinapis alba store significant amounts of oil and protein in the seed. At present, Brassica seed proteins are primarily used for livestock feeding based on the nutritional value. The point of curiosity is whether the present knowledge on the protein structure, biochemical characteristics, nutritive value, and the recovery processes are inadequate to develop Brassica proteins into a usable plant protein source or these proteins are of substandard for uses beyond animal nutrition applications. Cruciferin (11S) and napin (2S) are the predominant storage proteins of Brassicaceae seeds that contribute to different properties and functions. A gamut of information is available on the chemistry, nutritional value, as well as the functionality in foods, and associated non-protein components of canola/rapeseed storage proteins. The intention of this article is to critically review what is known about the predominant storage proteins of commercially produced Brassicaceae seeds relative to the above aspects and identify the knowledge gaps.     

Modeling degradation ratios and nutrient availability of anthocyanidin-accumulating Lc-alfalfa populations in dairy cows

Dairy cattle eating fresh or ensiled alfalfa as the main portion of their diet often have low protein efficiency because of the rapid initial rate of ruminal protein degradation of fresh and ensiled alfalfa. Ruminal protein degradation of alfalfa might be reduced by introducing a gene that stimulates the accumulation of mono- or polymeric anthocyanidins in alfalfa. The objectives of this study were to fractionate protein and carbohydrates by in situ and chemical approaches, to evaluate in situ ruminal degradation characteristics and synchronization ratios, to determine protein availability to dairy cattle using the 2007 digestible intestinal protein/rumen-degraded protein balance (DVE/OEB) protein system, and to determine net energy for lactation using the Dutch net energy for lactation (VEM) system for 3 newly developed transgenic winter hardy anthocyanidin-accumulating T₁Lc-alfalfa populations. These T₁Lc-alfalfa populations, called ^T1BeavLc1, ^T1RambLc3, and ^T1RangLc4, had an average anthocyanidin accumulation of 163.4 μg/g of DM, whereas AC Grazeland (selected for a low initial rate of degradation) did not accumulate anthocyanidin. The basic chemical composition of the original samples, soluble and potentially degradable fractions, and degradation characteristics of crude protein and carbohydrates were similar in T₁Lc-alfalfa and AC Grazeland. The undegradable in situ crude protein and neutral detergent fiber fraction had 1.3% lower CP and 4.8% lower CHO, respectively, in T₁Lc-alfalfa compared with the amounts in AC Grazeland. The T₁Lc-alfalfa had a 0.34 MJ/kg of DM higher calculated net energy for lactation and 1.9% of CP higher buffer soluble protein compared with that in AC Grazeland. By the protein evaluation model, it was predicted that T₁Lc-alfalfa tended to have 11.9, 6.9, and 8.4 g/kg of DM higher rumen degradable protein, OEB, and intestinal available protein, respectively, compared with the amounts in AC Grazeland. The hourly OEB included an initial and substantial peak (oversupply) of protein relative to energy, which was highest in ^T1RangLc4 and lowest in ^T1RambLc3. The hourly OEB between 4 and 24 h was similar and more balanced for all 4 alfalfa populations. In conclusion, T₁Lc-alfalfa accumulated anthocyanidin, tended to have higher predicted intestinal protein availability, and had higher predicted net energy of lactation availability for dairy cattle than did AC Grazeland.     

Responses of Flea Beetle <Emphasis Type="Italic">Phyllotreta cruciferae</Emphasis> to Synthetic Aggregation Pheromone Components and Host Plant Volatiles in Field Trials

Male-specific compounds, previously identified from Phyllotreta cruciferae and synthesized or isolated from natural sources, attracted both sexes of the beetle in field trials and therefore function as components of a male-produced aggregation pheromone. Six field experiments of 7 to 10 d duration each were conducted over 2 yr using modified boll weevil traps and two doses of pheromone. Treatments containing two doses of allyl isothiocyanate (AITC), a breakdown product of glucosinolates in Brassica napus L., a host plant of the beetles, were included in the study. A dose response was observed for both the pheromone components and AITC, and combinations of the pheromone and AITC generally attracted greater numbers of flea beetles than did either component itself. This increased attraction to a combination of beetle-produced compounds and host odors has not been previously demonstrated in halticine beetles and could help explain patterns of movement by P. cruciferae into field crops.