Changes in chemical composition of cover crops residue during decomposition / Mudanças na composição química dos resíduos culturais de plantas de cobertura durante a decomposição

Crop residues decomposition are controlled by chemical tissue components. This study evaluated changes on plant tissue components, separated by the Van Soest partitioning method, during cover crop decomposition. The Van Soest soluble fraction was the first to be released from the crop residues, followed by cellulose and hemicellulose. Lignin was the crop residue component that suffered the least degradation, and for certain crop residue types, lignin degradation was not detected. The degradation of the main components of crop residues (soluble fraction, cellulose, hemicellulose and lignin) is determined by the chemical and structural composition of each fraction.

A decomposição de resíduos culturais é controlada pela composição química do tecido vegetal. O objetivo deste estudo foi avaliar as alterações que ocorrem nos componentes do tecido vegetal, separados pelo fracionamento de Van Soest, durante a decomposição de plantas de cobertura. A fração solúvel foi a primeira a ser liberada dos resíduos culturais, seguida pela celulose e hemicelulose. A lignina foi o componente dos resíduos culturais de menor degradação, sendo que em alguns resíduos culturais não foi possível detectar a degradação deste componente. A degradação dos principais componentes dos resíduos culturais (fração solúvel, celulose, hemicelulose e lignina) é determinada pela composição química e estrutural de cada uma destas frações.

Pachira aquatica fruits shells valorization: renewables phenolics through analytical pyrolysis study (Py-GC/MS) / Valorização das cascas dos frutos da Pachira aquática: fenólicos renováveis através de estudo analítico de pirólise (Py-GC/MS)

This research valorized Pachira aquatica Aubl.'s fruit shells (PAS) through its energetic characterization and flash pyrolysis for biofuels or chemicals production. The characterization was performed through proximate and ultimate analysis, bulk density, higher heating value (HHV), hemicellulose, cellulose and lignin content, thermogravimetric analysis and absorption spectra in the infrared region obtained by Fourier-transform infrared spectroscopy technique (FTIR). The analytical flash pyrolysis was performed at 500°C in a Py-5200 HP-R coupled to a gas chromatograph (Py-GC/MS). The PAS biomass presents potential for thermochemical energy conversion processes due to its low moisture and ash content, 76.90% of volatile matter, bulk density of 252.6 kg/m3 and HHV of 16.24 MJ/kg. Flash pyrolysis products are mostly phenols or light organic acids derived from the decomposition of polysaccharides. Results confirmed the potential of PAS to produce bio-phenolics, such as 4-methoxyphenol which is an important active ingredient for skin depigmentation used in drugs and cosmetics, and as phenolic extract that can be used as a precursor to resins, applications that convert this forest waste into bio products for industry into a green circular economy.

Este trabalho teve como objetivo a valorização das cascas dos frutos da Pachira aquatica Aubl. (PAC) através da sua caracterização energética e pirólise flash para produção de biocombustíveis ou produtos químicos. A caracterização foi realizada através de análises imediata e final, densidade aparente, poder calorífico superior (PCS), conteúdos de hemicelulose, celulose e lignina, análise termogravimétrica e espectros de absorção na região do infravermelho obtidos pela técnica de espectroscopia no infravermelho com transformada de Fourier (FTIR). A pirólise flash analítica foi realizada a 500 °C em equipamento Py-5200 HP-R acoplado a um cromatógrafo à gás (Py-GC/MS). A biomassa das PAC apresenta potencial para processos de conversão termoquímica de energia devido ao seu baixo teor de umidade e cinzas, além de 76,90% de materiais voláteis, densidade aparente de 252,6 kg/m3 e PCS igual a 16,24 MJ / kg. Os produtos da pirólise rápida são principalmente fenóis ou ácidos orgânicos leves derivados da decomposição de polissacarídeos. Os resultados confirmam o potencial das PAC para produzir bio-fenólicos, como o 4-metoxifenol que é um importante ingrediente ativo para despigmentação da pele usado em medicamentos e cosméticos, e como extrato fenólico que pode ser usado como precursor de resinas. Estas aplicações convertem esses resíduos florestais em produtos biológicos para a indústria em uma economia circular verde.

Metagenomics approach to identify lignocellulose-degrading enzymes in the gut microbiota of the Chinese bamboo rat cecum

BACKGROUND: Lignocellulose is considered a renewable organic material, but the industrial production of biofuel from lignocellulose is challenging because of the lack of highly active hydrolytic enzymes. The guts of herbivores contain many symbiotic microorganisms that have evolved to hydrolyze plant lignocellulose. Chinese bamboo rats mainly consume high-fiber foods, indicating that some members of the intestinal tract microbiota digest lignocellulose, providing these rats with the energy required for growth. RESULTS: Here, we used metagenomics to analyze the diversity and functions of the gut microbiota in Chinese bamboo rats. We identified abundant populations of lignocellulose-degrading bacteria, whose main functions involved carbohydrate, amino acid, and nucleic acid metabolism. We also found 587 carbohydrate-active enzyme genes belonging to different families, including 7 carbohydrate esterase families and 21 glycoside hydrolase families. The glycoside hydrolase 3, glycoside hydrolase 1, glycoside hydrolase 43, carbohydrate esterase 4, carbohydrate esterase 1, and carbohydrate esterase 3 families demonstrated outstanding performance. CONCLUSIONS: The microbes and enzymes identified in our study expand the existing arsenal of proficient degraders and enzymes for lignocellulosic biofuel production. This study also describes a powerful approach for targeting gut microbes and enzymes in numerous industries.

Progress in detoxification of inhibitors generated during lignocellulose pretreatment / 生物工程学报

Lignocellulose can be hydrolyzed by cellulase into fermentable sugars to produce hydrogen, ethanol, butanol and other biofuels with added value. Pretreatment is a critical step in biomass conversion, but also generates inhibitors with negative impacts on subsequent enzymatic hydrolysis and fermentation. Hence, pretreatment and detoxification methods are the basis of efficient biomass conversion. Commonly used pretreatment methods of lignocellulose are chemical and physic-chemical processes. Here, we introduce different inhibitors and their inhibitory mechanisms, and summarize various detoxification methods. Moreover, we propose research directions for detoxification of inhibitors generated during lignocellulose pretreatment.

Advances in lignin valorization from a biorefinery concept / 生物工程学报

Lignin valorization for fuels and value-added products is essential to enhance the profitability and sustainability of biorefineries. Due to the complex and heterogeneous structure of lignin, technical barriers hinder the implementation of economic lignin utilization. Here, we summarize the major challenges facing lignin valorization processes. Different pretreatment methods, especially emerging combinatorial pretreatment approaches for isolating and tailoring lignin are introduced. To overcome the heterogeneity of lignin structure and improve lignin processability, advances in fractionation approaches including organosolv extraction, membrane technology, and gradient precipitation are analyzed and presented. Furthermore, progress in lignin valorization by thermochemical and biological conversion coupling with pretreatment and fractionation are systematically reviewed. Finally, we discuss advanced strategies and perspectives for future research involving biomass pretreatment, lignin fractionation and conversion processes.

Progress in the production of lignocellulolytic enzyme systems using Penicillium species / 生物工程学报

The efficient production of lignocellulolytic enzyme systems is an important support for large-scale biorefinery of plant biomass. On-site production of lignocellulolytic enzymes could increase the economic benefits of the process by lowering the cost of enzyme usage. Penicillium species are commonly found lignocellulose-degrading fungi in nature, and have been used for industrial production of cellulase preparations due to their abilities to secrete complete and well-balanced lignocellulolytic enzyme systems. Here, we introduce the reported Penicillium species for cellulase production, summarize the characteristics of their enzymes, and describe the strategies of strain engineering for improving the production and performance of lignocellulolytic enzymes. We also review the progress in fermentation process optimization regarding the on-site production of lignocellulolytic enzymes using Penicillium species, and suggest prospect of future work from the perspective of building a "sugar platform" for the biorefinery of lignocellulosic biomass.

Biodegradation of furan aldehydes in lignocellulose hydrolysates / 生物工程学报

Lignocellulose is the most abundant renewable organic carbon resource on earth. However, due to its complex structure, it must undergo a series of pretreatment processes before it can be efficiently utilized by microorganisms. The pretreatment process inevitably generates typical inhibitors such as furan aldehydes that seriously hinder the growth of microorganisms and the subsequent fermentation process. It is an important research field for bio-refining to recognize and clarify the furan aldehydes metabolic pathway of microorganisms and further develop microbial strains with strong tolerance and transformation ability towards these inhibitors. This article reviews the sources of furan aldehyde inhibitors, the inhibition mechanism of furan aldehydes on microorganisms, the furan aldehydes degradation pathways in microorganisms, and particularly focuses on the research progress of using biotechnological strategies to degrade furan aldehyde inhibitors. The main technical methods include traditional adaptive evolution engineering and metabolic engineering, and the emerging microbial co-cultivation systems as well as functional materials assisted microorganisms to remove furan aldehydes.

Fiber composition and digestibility of fodder in different ryegrass fields submitted to different harvesting management systems / [Composição da fibra e digestibilidade da forragem de diferentes cultivares de azevém submetidos a diferentes sistemas de manejo de colheita]

This essay aims to evaluate the composition of fiber in neutral detergent, digestibility of plant components, as well as ruminal disappearance rate of fodder dry matter from five ryegrass fields submitted to different cut systems for the production of haylage. The experimental design was the randomized blocks one, at a 5 x 3 factorial scheme, with five cultivars (cv.) of ryegrass Lolium multiflorum (cv. Barjumbo, cv. BarHQ, cv. Ribeye, cv. Potro and cv. Willians) associated with three harvesting management systems: 1- single harvesting system at a pre-floral stage; 2 - double harvesting system, with a cut at vegetative stage and another at pre-floral stage; and 3 - triple harvesting system, with a cut at vegetative stage, a cut at full vegetative stage and a cut at pre-floral stage, with three repetitions each. Similarities were noticed on the results of fodder digestibility of different fields, however, cv. Potro presented a higher ruminal disappearance rate after 48 hours, with 69.27%. Generally, the harvesting management system with the increase of ryegrass cut frequency determined increments on the percentage of lignin and the reduction in the concentration of total nutrients and dry matter digestibility of the resulting hylage.(AU)

O objetivo do presente trabalho foi avaliar a composição da fibra em detergente neutro, digestibilidade dos componentes da planta, bem como a taxa de desaparecimento ruminal da matéria seca da forragem de cinco cultivares de azevém submetidos a diferentes sistemas de cortes para produção de silagem pré-secada. O delineamento experimental foi em blocos ao acaso,, em um fatorial 5 x 3, sendo cinco cultivares de azevém Lolium multiflorum (cv. Barjumbo, cv. BarHQ, cv. Ribeye, cv. Potro e cv. Willians) associados a três sistemas de manejo de colheita: 1 - sistema com única colheita no estádio de pré-florescimento; 2 - sistema com uma colheita no estádio vegetativo e outra no estádio de pré-florescimento; e 3 - sistema com uma colheita no estádio vegetativo, uma no estádio pleno vegetativo e outra no estádio de pré-florescimento, com três repetições cada. Notou-se similaridade entre os resultados de digestibilidade da forragem entre os cultivares, porém o cv. Potro apresentou a maior taxa de desaparecimento ruminal após 48 horas, com 69,27%. De maneira geral, o sistema de manejo de colheita mostrou que o aumento do número de cortes do azevém determinou incrementos nos teores de lignina e redução na concentração de nutrientes digestíveis totais e da digestibilidade da matéria seca nas silagens pré-secadas resultantes.(AU)

Single cell oil production by a novel yeast Trichosporon mycotoxinivorans for complete and ecofriendly valorization of paddy straw

Background: Oleaginous yeasts can be grown on different carbon sources, including lignocellulosic hydrolysate containing a mixture of glucose and xylose. However, not all yeast strains can utilize both the sugars for lipogenesis. Therefore, in this study, efforts were made to isolate dual sugar-utilizing oleaginous yeasts from different sources. Results: A total of eleven isolates were obtained, which were screened for their ability to utilize various carbohydrates for lipogenesis. One promising yeast isolate Trichosporon mycotoxinivorans S2 was selected based on its capability to use a mixture of glucose and xylose and produce 44.86 ± 4.03% lipids, as well as its tolerance to fermentation inhibitors. In order to identify an inexpensive source of sugars, nondetoxified paddy straw hydrolysate (saccharified with cellulase), supplemented with 0.05% yeast extract, 0.18% peptone, and 0.04% MgSO4 was used for growth of the yeast, resulting in a yield of 5.17 g L−1 lipids with conversion productivity of 0.06 g L−1 h−1 . Optimization of the levels of yeast extract, peptone, and MgSO4 for maximizing lipid production using Box­Behnken design led to an increase in lipid yield by 41.59%. FAME analysis of single cell oil revealed oleic acid (30.84%), palmitic acid (18.28%), and stearic acid (17.64%) as the major fatty acids. Conclusion: The fatty acid profile illustrates the potential of T. mycotoxinivorans S2 to produce single cell oil as a feedstock for biodiesel. Therefore, the present study also indicated the potential of selected yeast to develop a zero-waste process for the complete valorization of paddy straw hydrolysate without detoxification

Progress in applying surfactants to lignocellulose hydrolysis for sugar production / 生物工程学报

Lignocellulose is a major biomass resource for the production of biofuel ethanol. Due to its abundance, environmental friendliness and renewability, the utilization of lignocellulose is promising to solve energy shortage. Surfactant can effectively promote the enzymatic hydrolysis of lignocellulose. By discussing the influence and mechanism of different surfactants on the enzymatic hydrolysis, we provide references for finding appropriate surfactants in enzymatic hydrolysis process.

Advances in the synthesis of biobutanol by consolidated bioprocessing from lignocellulose / 生物工程学报

Consolidated bioprocessing (CBP) is a multi-step process in a bioreactor, which completes hydrolase production, enzymatic hydrolysis, and microbial fermentation. It is considered to be the most promising process for the production of second-generation biofuels because of its simple steps and low cost. Due to the complexity of lignocellulose degradation and the butanol synthesis pathway, few wild microorganisms can directly utilize lignocellulose to synthesize butanol. With the development of synthetic biology, single-bacterium directly synthesizes butanol using lignocellulose by introducing a butanol synthesis pathway in the cellulolytic Clostridium. However, there are still some problems such as heavy metabolic load of single bacterium and low butanol yield. Co-culture can relieve the metabolic burden of single bacterium through the division of labor in different strains and can further improve the efficiency of butanol synthesis. This review analyzes the recent research progress in the synthesis of biobutanol using lignocellulose by consolidated bioprocessing from both the single-bacterium strategy and co-culture strategy, to provide a reference for the research of butanol and other biofuels.

Assessment of wasteland derived biomass for bioethanol production

Background: The bioethanol produced from biomass is a promising alternative fuel. The lignocellulose from marginal areas or wasteland could be a promising raw material for bioethanol production because it is present in large quantities, is cheap, renewable and has favorable environmental properties. Despite these advantages, lignocellulosic biomass is much more difficult to process than cereal grains, due to the need for intensive pretreatment and relatively large amounts of cellulases for efficient hydrolysis. Therefore, there is a need to develop an efficient and cost-effective method for the degradation and fermentation of lignocellulosic biomass to ethanol. Results: The usefulness of lignocellulosic biomass from wasteland for the production of bioethanol using pretreatment with the aid of ionic liquids of 1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium chloride was evaluated in this study. The pretreatment process, enzymatic hydrolysis and alcoholic fermentation lasted a total of 10 d. The largest amounts of bioethanol were obtained from biomass originating from agricultural wasteland, in which the dominant plant was fireweed (Chamaenerion angustifolium) and from the field where the common broom (Cytisus scoparius) was the dominant. Conclusions: The plants such as fireweed, common broom, hay and goldenrod may be useful for the production of liquid biofuels and it would be necessary in the further stage of research to establish and optimize the conditions for the technology of ethyl alcohol producing from these plant species. Enzymatic hydrolysis of biomass from agricultural wastelands results in a large increase in fermentable sugars, comparable to the enzymatic hydrolysis of rye, wheat, rice or maize straw.

Improvement of ethanol production from birch and spruce pretreated with 1-H-3-methylmorpholinium chloride

Background: Pretreatment is the critically important step for the production of ethanol from lignocelluloses. In this study, hardwood birch (Betula pendula) and softwood spruce (Norway spruce) woods were pretreated with a newly synthesized morpholinium ionic liquid, 1-H-3-methylmorpholinium chloride ([HMMorph][Cl]), followed by enzymatic hydrolysis and fermentation to ethanol. Results: [HMMorph][Cl] was synthesized using inexpensive raw materials, i.e., hydrochloric acid and N-methyl morpholine, following a simple process. The influence of pretreatment time (2, 3, 5, and 8 h) and temperature (120 and 140°C) in terms of hydrolysis efficiency was investigated. Glucose yields from enzymatic hydrolysis were improved from 13.7% to 45.7% and 12.9% to 51.8% after pretreatment of birch and spruce woods, respectively, under optimum pretreatment conditions (i.e., at 140°C for 3 h) as compared to those from pristine woods. Moreover, the yields of ethanol production from birch and spruce were increased to 34.8% and 44.2%, respectively, while the yields were negligible for untreated woods. Conclusions: This study demonstrated the ability of [HMMorph][Cl] as an inexpensive agent to pretreat both softwood and hardwood.

Evaluation of Lysinibacillus SP, isolated from coptotermes curvignathus gut, for the delignification of oil palm residues / Avaliação de Lysinibacillus SP, isolado a partir do intestino de Coptotermes curvignathus, para a deslignificação de resíduos de óleo de palma (Dendê)

The application of ligninolytic bacteria and enzymes is a green pre-treatment alternative in the production of paper and biofuel from oil palm residues. In this study we investigated the ability of Lysinibacillus pakistanensis isolated from termite gut in degrading the lignin component of oil palm residues. The residues were biotreated with the bacterial strain in an aerated submerged fermentation system for 7 days at 30 , pH 7 and compared with untreated control. Enzyme activities were determined using specific substrates. Peak lignin peroxidase (377.6 U/L), manganese peroxidase (218.19 U/L), and laccase (405.4 U/L) activity were recorded after 4,4, and 5 days of incubation respectively, using oil palm leaf as substrates. Lignin loss of 4.5%, 5.7% and 6.6% in oil palm leaf, oil palm trunk and empty fruit bunch respectively was achieved after treatment with the microorganism. SEM images revealed structural changes in the cell wall of the residues. Pre-treatment with this bacterial strain has promising prospects of improving the efficiency of the pulping process in an environmentally safe manner.

A aplicação de bactérias e enzimas ligninolíticas é uma alternativa verde de pré-tratamento na produção de papel e biocombustível a partir de resíduos de óleo de palma. Neste estudo, investigamos a capacidade de Lysinibacillus pakistanensis isolado do intestino de cupins na degradação do componente de lignina dos resíduos de dendê. Os resíduos foram biotratados com a estirpe bacteriana num sistema de fermentação submersa arejado durante 7 dias a 30ºC, pH 7 e comparados com controle não tratado. As atividades enzimáticas foram determinadas usando substratos específicos. Pico de lignina peroxidase (377,6 U/L), peroxidase de manganês (218,19 U/L) e atividade de lacase (405,4 U/L) foram registradas após 4,4 e 5 dias de incubação, respectivamente, utilizando como substratos a folha da palmeira de dendê. A perda de lignina de 4,5%, 5,7% e 6,6% na folha da palmeira, no tronco do dendezeiro e cacho de frutas vazio, respectivamente, foi alcançada após o tratamento com o microorganismo. Imagens de MEV revelaram alterações estruturais na parede celular dos resíduos. O pré-tratamento com esta cepa bacteriana tem perspectivas promissoras de melhorar a eficiência do processo de polpação de maneira ambientalmente segura.

Influence of soaking time and sodium hydroxide concentration on the chemical composition of treated mango seed shell flour for composite application

ABSTRACT: Lignin and hemicelluloses are the major impurities to be removed in natural fibers for it to be suitable in composite application and other uses. This research is based on evaluating the influence of soaking time and sodium hydroxide concentration on the chemical composition of treated mango seed shell (MSSF) by immersing the MSSF in NaOH solution at concentration of 2.5 - 7.5 wt % and soaking time of 2-6 hr, in order to decrease the lignin and hemicellulose content while increasing its cellulose content. The optimum conditions obtained for concentration and soaking time of NaOH were 6.09 % and 5.22 hr, respectively. At these conditions, cellulose content was increased to 94.8002%, while the hemicelluloses and lignin content were reduced to 2.2779% and 0.508502%, respectively. The process parameter of MSSF was optimized using central composite design (CCD) to predict the cellulose, hemicelluloses, and lignin content. The quadratic model of response surface model (RSM) was adopted for the prediction of cellulose, hemicelluloses, and lignin content. The maximum error between the predicted using CCD and experimental results was less 0.38%. These errors in variation for both the predicted by the RSM and the actual gave good alignment with both results. Therefore, at these treatment conditions, MSSF can be utilized for composite application and other industrial purpose

Co-expression of lignocellulase from termite and their endosymbionts / 生物工程学报

Natural lignocellulosic materials contain cellulose, hemicellulose, and lignin. Cellulose hydrolysis to glucose requires a series of lignocellulases. Recently, the research on the synergistic effect of lignocellulases has become a new research focus. Here, four lignocellulase genes encoding β-glucosidase, endo-1,4-β-glucanase, xylanase and laccase from termite and their endosymbionts were cloned into pETDuet-1 and pRSFDuet-1 and expressed in Escherichia coli. After SDS-PAGE analysis, the corresponding protein bands consistent with the theoretical values were observed and all the proteins showed enzyme activities. We used phosphoric acid swollen cellulose (PASC) as substrate to measure the synergistic effect of crude extracts of co-expressing enzymes and the mixture of single enzyme. The co-expressed enzymes increased the degradation efficiency of PASC by 44% compared with the single enzyme mixture; while the degradation rate increased by 34% and 20%, respectively when using filter paper and corn cob pretreated with phosphoric acid as substrates. The degradation efficiency of the co-expressed enzymes was higher than the total efficiency of the single enzyme mixture.

Multi-enzyme complex of white rot fungi in saccharification of lignocellulosic material

ABSTRACT The multi-enzyme complex (crude extract) of white rot fungi Pleurotus ostreatus, Pleurotus eryngii, Trametes versicolor, Pycnosporus sanguineus and Phanerochaete chrysosporium were characterized, evaluated in the hydrolysis of pretreated pulps of sorghum straw and compared efficiency with commercial enzyme. Most fungi complexes had better hydrolysis rates compared with purified commercial enzyme.

Evaluation of biogas and syngas as energy vectors for heat and power generation using lignocellulosic biomass as raw material

The use of nonrenewable energy sources to provide the worldwide energy needs has caused different problems such as global warming, water pollution, and smog production. In this sense, lignocellulosic biomass has been postulated as a renewable energy source able to produce energy carriers that can cover this energy demand. Biogas and syngas are two energy vectors that have been suggested to generate heat and power through their use in cogeneration systems. Therefore, the aim of this review is to develop a comparison between these energy vectors considering their main features based on literature reports. In addition, a techno-economic and energy assessment of the heat and power generation using these vectors as energy sources is performed. If lignocellulosic biomass is used as raw material, biogas is more commonly used for cogeneration purposes than syngas. However, syngas from biomass gasification has a great potential to be employed as a chemical platform in the production of value-added products. Moreover, the investment costs to generate heat and power from lignocellulosic materials using the anaerobic digestion technology are higher than those using the gasification technology. As a conclusion, it was evidenced that upgraded biogas has a higher potential to produce heat and power than syngas. Nevertheless, the implementation of both energy vectors into the energy market is important to cover the increasing worldwide energy demand.

Nutritional evaluation of millet at different seeding rates and cutting heights / Avaliação nutricional do milheto submetido a diferentes taxas de semeadura e alturas de corte

This study evaluated the effect of different seeding rates and cutting heights on production and composition of millet. Two randomized block design experiments were performed. In the first trial, 32 parcels (1.2 × 1.2 m) were used for evaluation of seeding rate of 24, 35, 50 and 60 kg/ha. Three cuts were carried out to evaluate plant height, fresh and dry mass yield, dry matter (DM), neutral detergent fiber (NDF), crude protein (CP) and acid detergent lignin (ADL) concentration and in situ DM and NDF digestibility. In the second trial, 20 parcels (1.2 × 3.0 m) were used to evaluate 20, 30, 40 and 50 cm of cutting heights for two growing cycles, performing the evaluations previously listed. Seeding rate linearly increased plant height, fresh and dry mass production, and tended to linearly decrease dry matter in situ digestibility, without effects on forage composition. Cutting height had no effect on crude protein (CP) concentration, but linearly increased plant height, dry mass production, DM content and tended to decrease NDF in situ digestibility and ADL content. Thus, the use of the highest evaluated seeding rates (60 kg/ha) and cutting height (50 cm) increased forage production; however, the use of the lowest residual height increased forage quality.(AU)

Os efeitos de diferentes taxas de semeadura e altura de corte na produção e composição bromatológica do milheto foram avaliados em dois experimentos executados em delineamento em blocos casualizados. No primeiro experimento, foram utilizadas 32 parcelas (1,2 x 1,2 m) e avaliadas as taxas de semeadura de 24, 35, 50 e 60 kg/ha. Três cortes foram realizados para avaliar a altura das plantas, a produção de massa fresca e seca, os teores de matéria seca (MS), fibra em detergente neutro (FDN), proteína bruta (PB) e lignina, assim como a digestibilidade in situ da matéria seca e FDN. No segundo experimento, 20 parcelas (1,2 x 3,0 m) foram usadas para avaliar o efeito das alturas de corte de 20, 30, 40 e 50 cm, sobre as variáveis previamente citadas. De acordo com o aumento da taxa de semeadura, houve aumento linear da altura das plantas e da produção de massa seca e fresca e tendência de redução linear da digestibilidade in situ da matéria seca, sem afetar a composição da forragem. A altura de corte não afetou a concentração de proteína bruta, mas aumentou linearmente a altura das plantas, a produção de massa seca e o teor de matéria seca e tendeu a reduzir a digestibilidade in situ da FDN e a concentração de lignina. Assim, o emprego de maiores taxas de semeadura (60 kg/ha) e de altura de corte (50 cm) aumentam a produção de forragem, enquanto que menores alturas de corte aumentam a qualidade da forragem.(AU)

Optimization of RT-PCR reactions in studies with genes of lignin biosynthetic route in Saccharum spontaneum

ABSTRACT Saccharum spontaneum has been used for the development of energy cane a crop aimed to be used for the production of second-generation ethanol, or lignocellulosic ethanol. Lignin is a main challenge in the conversion of cell wall sugars into ethanol. In our studies to isolate the genes the lignin biosynthesis in S. spontaneum we have had great difficulty in RT-PCR reactions. Thus, we evaluated the effectiveness of different additives in the amplification of these genes. While COMT and CCoAOMT genes did not need any additives for other genes there was no amplification (HCT, F5H, 4CL and CCR) or the yield was very low (CAD and C4H). The application of supplementary cDNA was enough to overcome the non-specificity and low yield for C4H and C3H, while the addition of 0.04% BSA + 2% formamide was effective to amplify 4CL, CCR, F5H and CCR. HCT was amplified only by addition of 0.04% BSA + 2% formamide + 0.1 M trehalose and amplification of PAL was possible with addition of 2% of DMSO. Besides optimization of expression assays, the results show that additives can act independently or synergistically.