Ethanol production in Brazil: a bridge between science and industry

Large-scale bioenergy demand has triggered new approaches to straw management in Brazilian sugarcane fields. With the progressive shift from a burned to a nonburned harvest system, most of the straw presently retained on the soil surface has become economically viable feedstock for bioenergy production. The trade-offs between the need to preserve soil quality and produce more bioenergy have been the subject of intense discussion. This study presents a synthesis of available information on the magnitude of the main impacts of straw removal from sugarcane fields for bioenergy production and therefore represents an easily available resource to guide management decisions on the recommended amount of straw to be maintained on the field to take advantage of the agronomic, environmental, and industrial benefits. Crop residues remaining on sugarcane fields provide numerous ecosystem services including nutrient recycling, soil biodiversity, water storage, carbon accumulation, control of soil erosion, and weed infestation. Furthermore, several studies reported higher sugarcane production under straw retention on the field, while few suggest that straw may jeopardize biomass production in cold regions and under some specific soil conditions. Pest control is among the parameters favored by straw removal, while N2O emissions are increased only if straw is associated with the application of N fertilizer and vinasse. An appropriate recommendation, which is clearly site specific, should be based on a minimum mass of straw on the field to provide those benefits. Overall, this review indicates that most of the agronomic and environmental benefits are achieved when at least 7 Mg ha−1 of dry straw is maintained on the soil surface. However, modeling efforts are of paramount importance to assess the magnitude and rates of straw removal considering the several indicators involved in this complex equation, so that an accurate straw recovery rate could be provided to producers and industry toward greater sustainability.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcbb.12410

Agronomic and environmental implications of sugarcane straw removal: a major review

The Diversity of the True Hoppers (Hemiptera: Auchenorrhyncha)

The bioethanol visibility in the global matrix of fuels, linked to ecological appeal and the possibility of using new raw materials justifies the increasing investments for the development of new processes. This fuel results from fermentation of sugars by yeasts, however the growth of exogenous microorganisms is sometimes unavoidable. The lactic acid bacteria and wild yeasts are the main contaminants, affecting yeasts’ performance and leading to negative impacts such as the formation of organic acids, polysaccharides and gummy biofilms. Further undesirable effects of the microbial contamination during bioethanol processing comprise flocculation, reduction of yeast cells viability and decrease in process yield. In extreme cases, the reduction in process yield can reach 20–30%, making the process impracticable. In this article, the impact and significance of microbial contaminants (lactic acid bacteria and wild yeasts) during fermentation of must for bioethanol production are reviewed.

Impact and significance of microbial contamination during fermentation for bioethanol production

The hemipteran suborder Auchenorrhyncha is a highly diverse, ecologically and agriculturally important group of primarily phytophagous insects which has been a source of phylogenetic contention for many years. Here, we have used transcriptome sequencing to assemble 2139 orthologues from 84 auchenorrhynchan species representing 27 families; this is the largest and most taxonomically comprehensive phylogenetic dataset for this group to date. We used both maximum likelihood and multispecies coalescent analyses to reconstruct the evolutionary history in this group using amino acid, nucleotide, and degeneracy‐coded nucleotide orthologue data. Although many relationships at the superfamily level were consistent between analyses, several differing, highly supported topologies were recovered using different datasets and reconstruction methods, most notably the differential placement of Cercopoidea as sister to either Cicadoidea or Membracoidea. To further interrogate the recovered topologies, we explored the contribution of genes as partitioned by third‐codon‐position guanine‐cytosine (GC) content and heterogeneity. We found consistent support for several relationships, including Cercopoidea + Cicadoidea, most often in genes that would be expected to be enriched for the true species tree if recombination‐based dynamics in GC content have contributed to the observed GC heterogeneity. Our results provide a generally well‐supported framework for future studies of auchenorrhynchan phylogeny and suggest that transcriptome sequencing is likely to be a fruitful source of phylogenetic data for resolving its clades. However, we caution that future work should account for the potential effects of GC content heterogeneity on relationships recovered in this group.

Phylogenomics of Auchenorrhyncha (Insecta: Hemiptera) using transcriptomes: examining controversial relationships via degeneracy coding and interrogation of gene conflict

The spittlebug (Mahanarva fimbriolata) has become a key pest of the sugarcane crop in Brazil with the increase of green-cane harvesting, causing stalk yield and cane quality losses. This research was undertaken to evaluate the effects of the spittlebug (Mahanarva fimbriolata) on cane quality and juice fermentation. The experiment was arranged in a completely randomized 5 × 2 factorial design, with five spittlebug infestation levels (0-0.5; 0.6-2.5; 2.6-5; 5.1-8; 8.1-12.5 nymphs m-1), controlled or not with thiamethoxam (0.2 kg of active ingredient ha-1). To conduct fermentation, Saccharomyces cerevisiae (fresh and pressed baker's yeast) was inoculated to musts at a concentration of 30 g L-1. Microbiological analyses were performed at the beginning, middle and end of the fermentation process. The alcohol content and total residual reducing sugars were measured in the wine. Spittlebug attack influenced negatively sugarcane quality, yeast cell and bud viability, and wine alcohol content. Insecticide application resulted in higher cane quality and cell and bud viabilities, resulting in increased fermentation yield.

/pdf/spittlebug-infestation-in-sugarcane-affects-ethanolic-5bjl5y75nl.pdf

Spittlebug infestation in sugarcane affects ethanolic fermentation

The objective of this work was to evaluate the impacts of spittlebug (Mahanarva fimbriolata) attack on sugarcane quality and ethanol production. Technological and microbiological parameters of juice and fermentation process were evaluated in ten fermentation cycles and two harvest seasons. Treatments consisted of different spittlebug stalk damage levels: control, with 100% of apparently healthy stalks; medium, with 15% of damaged or dry stalks (DDS); high, with 30% of DDS; and very high, with 60% of DDS. Spittlebug attack caused significant losses in cane quality, reducing total soluble solids, sucrose content, total reducing sugars, and pH, and increasing total phenolic compounds, and total and volatile juice acidity. The fermentation process was also significantly affected, resulting in lower ethanol content in wine. There was an increase in acetaldehyde concentration in the distillate. The spittlebug attack caused negative impacts on sugarcane quality and fermentation process, and these impacts are stronger in late season harvests.

/pdf/spittlebug-impacts-on-sugarcane-quality-and-ethanol-40yh505ucr.pdf

Spittlebug impacts on sugarcane quality and ethanol production

Mahanarva fimbriolata (Stal) is an important pest in Latin America and causes significant reduction in sugarcane productivity. There is no information regarding the effect of this pest on the quality of cane juice used for sugar and alcohol production. This work aimed at evaluating the quality of sugarcane juice from plants attacked by spittlebugs. The experiment was arranged in a completely randomized design with 15 replications, and comprised two treatments: control and chemical treatment with thiamethoxam. An average of 9.2 +/- 4.44 spittlebug nymphs m-1 were found in the plots prior to insecticide application. Nymphs were counted 18, 35, 55, and 82 days after the initial sampling (december/2003). During the mid growing season (July 2004), the juice was extracted from stalks and analyzed for Brix, Pol, RS, pH, fiber, purity, TRS, dextran, starch, and total phenolic compounds. Stalk yield was also measured. Chemical treatment was efficient in reducing spittlebug population, and elevated both stalk yield and juice pH. The accumulated infestation expressed as insect-days was significantly and negatively correlated to yield, Pol, pH, and purity. The concentration of phenolic compounds increased with pest infestation, while dextran and starch levels were not affected. The infestation of 2.4 and 7.3 nymphs m-1 day-1 caused reductions of 8.3% and 29.8% in yield; 1.9% and 5.8% in Pol; 0.4% and 1.1% in pH and 0.4% and 1.2% in purity, respectively, in comparison to areas where the pest population was extremely low (< 0.1 nymphs m-1).

http://www.scielo.br/pdf/ne/v37n1/a10v37n1.pdf

Influence of Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae) injury on the quality of cane juice

Characterization and Impact of the Sugarcane Borer on Sugarcane Yield and Quality

The quality of the raw material defines the industrial potential production. The harvest of raw sugarcane promoted a favorable environment for the increase of Mahanarva fimbriolata (Stal, 1854) pest that affects the plant development. This research was undertaken to evaluate the effects of M. fimbriolata on sugarcane quality and fermentation process. For the technological analysis, four damage levels and two evaluation periods were evaluated, while four fermentation cycles and two evaluation periods were tested for microbiological analysis, with three replications. The determined parameters were Brix (soluble solids), Pol (apparent sucrose), Purity, reducing sugars (RS), total reducing sugars (TRS), Total Acidity, pH and Total Phenolic Compounds in juice. In the fermentation process cellular viability analysis, yeast sprout and bacterial concentration were carried out. The wine was submitted to alcohol content, TRRS (total residual reducing sugars) and fermentation efficiency. The treatment with 60% of damage steams exhibited the lowest averages of Brix, Pol, Purity and TRS of the juice. An increase of the RS% of the juice and content of total phenolic compounds was observed. The cellular and sprouts viability were reduced with the increase in the damages caused by M. fimbriolata. The fermentation process exhibited larger quantities of contaminators. With the damages, the wine TRRS quantity was superior and, consequently there was a decrease of the alcoholic content and fermentation efficiency. The damages caused by M. fimbriolata affected the quality of the raw material, compromising the fermentative process, and increase the production of phenolic compounds and contaminators.

/pdf/damages-of-spittlebug-on-sugarcane-quality-and-fermentation-2ze7wrqgzc.pdf

Leonardo Lucas Madaleno

Papers

Spittlebug infestation in sugarcane affects ethanolic fermentation

Spittlebug impacts on sugarcane quality and ethanol production

Influence of Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae) injury on the quality of cane juice

Characterization and Impact of the Sugarcane Borer on Sugarcane Yield and Quality

Damages of spittlebug on sugarcane quality and fermentation process