Secretome analysis of Trichoderma reesei RUT-C30 and Penicillium oxalicum reveals their synergic potential to deconstruct sugarcane and energy cane biomasses.

The conversion of lignocellulosic polymers into monomeric sugars demands a plethora of enzymatic activities generally not produced by a single microorganism and induced by the carbon source. In this vein, this work investigates the synergy between the enzymes secreted by the cellulolytic model fungi Trichoderma reesei RUT-C30 (TR) and Penicillium oxalicum (PO) to deconstruct sugarcane straw (SCS) and energy cane bagasse (ECB). TR and PO secrete a similar profile of cellulose-active enzymes resulting in a comparable conversion of SCS and ECB into glucose. The synergy between the enzymes produced by both fungi to break down the cellulose fraction becomes evident by the improvement of glucose titers from ~35-54% and from ~10-17% in SCS and ECB conditions, respectively, reached with the mixture of the secretomes of both fungi. The effect of a hemicellulase-enriched secretome produced by TR is particularly seen in SCS where the xylose yield reached ~15% compared to 5% by PO, remaining unaltered following the mixture of secretomes. However, the secretion of enzymes active in the decorations of the main chain polymers possibly aid PO to access the hemicellulose fraction of ECB reaching xylose yields similar to TR in this condition.

Potentials, Challenges, and Genetic and Genomic Resources for Sugarcane Biomass Improvement.

Lignocellulosic biomass has become an emerging feedstock for second-generation bioethanol production. Sugarcane (Saccharum spp. hybrids), a very efficient perennial C4 plant with a high polyploid level and complex genome, is considered a top-notch candidate for biomass production due to its salient features viz. fast growth rate and abilities for high tillering, ratooning, and photosynthesis. Energy cane, an ideal type of sugarcane, has been bred specifically as a biomass crop. In this review, we described (1) biomass potentials of sugarcane and its underlying genetics, (2) challenges associated with biomass improvement such as large and complex genome, narrow gene pool in existing commercial cultivars, long breeding cycle, and non-synchronous flowering, (3) available genetic resources such as germplasm resources, and genomic and cell wall-related databases that facilitate biomass improvement, and (4) mining candidate genes controlling biomass in genomic databases. We extensively reviewed databases for biomass-related genes and their usefulness in biofuel generation. This review provides valuable resources for sugarcane breeders, geneticists, and broad scientific communities involved in bioenergy production.

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.

Techno-economic analysis and climate change impacts of sugarcane biorefineries considering different time horizons.

BACKGROUND: Ethanol production from lignocellulosic feedstocks (also known as 2nd generation or 2G ethanol process) presents a great potential for reducing both ethanol production costs and climate change impacts since agricultural residues and dedicated energy crops are used as feedstock. This study aimed at the quantification of the economic and environmental impacts considering the current and future scenarios of sugarcane biorefineries taking into account not only the improvements of the industrial process but also of biomass production systems. Technology assumptions and scenarios setup were supported by main companies and stakeholders, involved in the lignocellulosic ethanol production chain from Brazil and abroad. For instance, scenarios considered higher efficiencies and lower residence times for pretreatment, enzymatic hydrolysis, and fermentation (including pentoses fermentation); higher sugarcane yields; and introduction of energy cane (a high fiber variety of cane). RESULTS: Ethanol production costs were estimated for different time horizons. In the short term, 2G ethanol presents higher costs compared to 1st generation (1G) ethanol. However, in the long term, 2G ethanol is more competitive, presenting remarkable lower production cost than 1G ethanol, even considering some uncertainties regarding technology and market aspects. In addition, environmental assessment showed that both 1G (in the medium and long term) and 2G ethanol can reduce climate change impacts by more than 80% when compared to gasoline. CONCLUSIONS: This work showed the great potential of 2G ethanol production in terms of economic and environmental aspects. These results can support new research programs and public policies designed to stimulate both production and consumption of 2G ethanol in Brazil, accelerating the path along the learning curve. Some examples of mechanisms include: incentives to the establishment of local equipment and enzyme suppliers; and specific funding programs for the development and use of energy cane.

Effect of frequency and reaction time in focused ultrasonic pretreatment of energy cane bagasse for bioethanol production.

Pretreatment of lignocellulosic biomass is a critical steps in bioethanol production. Ultrasonic pretreatment significantly improves cellulose hydrolysis increasing sugar yields, but current system designs have limitations related to efficiency and scalability. This study evaluates the ultrasonic pretreatment of energy cane bagasse in a novel scalable configuration and by maximizing coupling of ultrasound energy to the material via active modulation of frequency. Pretreatment was conducted in 28% ammonia water mixture at a sample:ammonia:water ratio of 1:0.5:8. Process performance was investigated as a function of frequency (20, 20.5, 21kHz), reaction time (30, 45, 60min), temperature, and power levels for multiple combinations of ammonia, water and sample mixture. Results indicated an increased enzymatic digestibility, with maximum glucose yield of 24.29g/100g dry biomass. Theoretical ethanol yields obtained ranged from 6.47 to a maximum of 24.29g/100g dry biomass. Maximum energy attainable was 886.34kJ/100g dry biomass.

Lead sorptive removal using magnetic and nonmagnetic fast pyrolysis energy cane biochars.

Energy cane biochar (ECBC) was prepared in a 72 s fast pyrolysis at 425 °C in an auger-fed reactor and ground into 250-600 µm diameter particles. This biochar was magnetized by fusing an iron oxide phase to the particles by mixing aqueous biochar suspensions with aqueous Fe(3+)/Fe(2+) solutions, followed by NaOH treatment (MECBC). These biochars were characterized by Raman, FT-IR, X-ray, SEM, SEM-EDX, TEM, EDXRF, pHzpc, elemental analyses, S(BET), and magnetic moment determinations. The S(BET) of energy cane biochar was negligible and increased to 37.13 m(2)/g after Fe(3+)/Fe(2+)/NaOH magnetization. The dry biochar contains 18.4% oxygen. This allows swelling in water and permits sorption inside the solid as well as on its pore surfaces, leading to high capacities at low surface areas. Maximum lead removal occurred at pH 4-5. Sorption isotherms exhibited increasing lead removal (Q(0), mg/g) as temperature increased for nonmagnetic [Q(0)(25 °C)=45.70; Q(0)(35 °C)=52.01 and Q(0)(45 °C)=69.37] and magnetic [Q(0)(25 °C)=40.56; Q(0)(35 °C)=51.17 and Q(0)(45 °C)=51.75] biochars. Second order kinetics best fit the lead removal data. Furthermore, magnetic energy cane biochar was easily manipulated by low external magnetic field, thereby, allowing its easy recovery for further recycling and replacement from water. ECBC and MECBC were also successfully applied for Pb(2+) removal from contaminated ground water. Therefore, both chars can be used as potential green low cost sorbents for lead remediation to replace commercial activated carbon.