The final products of the ethanol industry are alcoholic beverages, industrial ethanol and biofuels. They are produced by the same production process, which includes fermentation and distillation of raw materials which come from plant biomass. At the end of the distillation process a waste effluent is obtained called vinasse or stillage. The direct disposal of stillages on land or in groundwater (rivers, streams or lakes), or even for the direct irrigation of crops, pollutes the environment due to their high organic contents, dissolved solids and many other compounds which are toxic or could be contaminants under certain environmental conditions. This work reviews the characterization of vinasses from different feedstock sources and the main treatments for conditioning the soluble solids of vinasses before their disposal.
BackgroundA modified laboratory-scale upflow anaerobic sludge blanket (UASB) reactor was used to obtain methane by treating hydrous ethanol vinasse. Vinasses or stillage are waste materials with high organic loads, and a complex composition resulting from the process of alcohol distillation. They must initially be treated with anaerobic processes due to their high organic loads. Vinasses can be considered multipurpose waste for energy recovery and once treated they can be used in agriculture without the risk of polluting soil, underground water or crops. In this sense, treatment of vinasse combines the elimination of organic waste with the formation of methane. Biogas is considered as a promising renewable energy source. The aim of this study was to determine the optimum organic loading rate for operating a modified UASB reactor to treat vinasse generated in the production of hydrous ethanol from sugar cane molasses.ResultsThe study showed that chemical oxygen demand (COD) removal efficiency was 69% at an optimum organic loading rate (OLR) of 17.05 kg COD/m3-day, achieving a methane yield of 0.263 m3/kg CODadded and a biogas methane content of 84%. During this stage, effluent characterization presented lower values than the vinasse, except for potassium, sulfide and ammonia nitrogen. On the other hand, primers used to amplify the 16S-rDNA genes for the domains Archaea and Bacteria showed the presence of microorganisms which favor methane production at the optimum organic loading rate.ConclusionsThe modified UASB reactor proposed in this study provided a successful treatment of the vinasse obtained from hydrous ethanol production.Methanogen groups (Methanobacteriales and Methanosarcinales) detected by PCR during operational optimum OLR of the modified UASB reactor, favored methane production.
Genetic improvement of coffee, an important commercial crop, through classical breeding is slow and cumbersome. Biotechnology offers alternative strategies for generating new and improved coffee varieties, including those resistances to environmental extremes, pests, and diseases, low in caffeine, and with uniform fruit maturation. Large improvements in somatic embryogenesis, development of haploids, and scale-up of micropropagation have been accomplished in the last 5 yr. The recent identification of expressed sequence tags (EST) that are differentially expressed during the infestation of coffee plants by coffee leaf miners and the isolation and cloning of the promoter for the N-methyltransferase gene associated with caffeine production open up the possibility of producing varieties of coffee with new traits. This review provides a summary of in vitro biological advances and directions as to how they could be applied to improve the production and quality of coffee.
The classification of Mexican maize (Zea mays L.) begun since the early 20th century, it was consolidated during the middle of this century, but recent additions and rearrangements have been performed by several authors employing new methods of analysis and collections from diverse origin; nevertheless, maize from the State of Michoacan, Mexico has received little attention in regard to its systematic classification. Maize populations from the Tarasca Mountain Chain in Michoacan are commonly considered in literature, as belonging to the Chalquen˜o race; however, closer observations indicate that significant differences do exist, suggesting the necessity of performing an in-depth study on this respect. Thirty nine native maize populations from the Tarasca Mountain Chain region were evaluated along with 19 typical populations of the Chalquen˜o, Celaya and Conico races coming from the States of Mexico, Puebla, Hidalgo, Quere´taro and Oaxaca. Populations were evaluated in Aranza, Michoacan and Montecillo, Mexico State. Seventeen morphological characters were scored and analyzed by one-way analyses of variance and multivariate techniques. Populations were also genetically analyzed through 17 isozyme loci. Native populations had some alleles not found either in the Chalquen˜o, Celaya or Conico races, and possess larger genetic diversity. Local populations were congregated into a discrete group apart from the typical Chalquen˜o populations, suggesting that landraces from the Tarasca Mountain Chain region might not be considered as belonging to the Chalquen˜o race, but they integrate by themselves a different race.
El chile habanero (Capsicum chinense Jacq.) es distintivo de la Península de Yucatán, México; sin embargo, los estudios de diversidad genética a nivel molecular en este cultivo son escasos. El presente trabajo se planteó con el objetivo de caracterizar la diversidad genética del germoplasma de chile habanero, mediante marcadores ISSR. El material genético consistió en 60 poblaciones criollas de chile habanero recolectadas en los estados de Yucatán, Campeche, Quintana Roo y Tabasco, México, las cuales fueron genéticamente analizadas con tres loci ISSRs. El ADN fue extraído por el método de CTAB y los fragmentos se amplificaron por la reacción en cadena de la polimerasa (PCR). Los datos se analizaron con los programas POPGENE V 1.31 y NTSYS V 2.0 mediante un análisis de componentes principales y las relaciones entre las poblaciones se obtuvieron con un análisis jerárquico de conglomerados usando el método UPGMA. Se detectaron un total 32 bandas y 98 % de ellas fueron polimórficas. Los resultados indican que la diversidad genética en poblaciones de chile habanero es alta, en donde el 95.5 % de la variación observada se encuentra dentro de las poblaciones y sólo el 4.5 % entre ellas. Se detectó un alto flujo génico entre las poblaciones. Los resultados de los análisis multivariados sugieren que gran cantidad de germoplasma de chile habanero se ha dispersado del estado de Yucatán a los estados de Campeche, Quintana Roo y Tabasco. El patrón de distribución de la diversidad genética de chile habanero no se asoció con el lugar de origen de las poblaciones analizadas.
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