Livestock Methane Emission: Microbial Ecology and Mitigation Strategies

Rumen microbiome plays a critical role in the development and nutrition of the host, and any alteration in the rumen microbiome has an important effect on the animal. Rumen microbial ecology is always dynamic in response to the diets and physiological conditions of the host. Ruminal microorganisms are mainly anaerobic and provide around 75% of the energy needed by the animal. The importance of microbial diversity in rumen has gained attention not only due to its significance on the productivity of the host, but also due to the emission of greenhouse gases (GHGs) and their environmental impact. Livestock is one of the most important sources of GHGs from agriculture, contributing more than 25% of global GHGs emissions. However, the variations in livestock emission in different regions of the world could be attributed to the changes in diversity and abundance of rumen microbial communities, which vary according to the type and age of animal, type of feeds, feeding strategies, climate, etc. This chapter deals on rumen microbial ecology, the role of microorganisms in enteric fermentation and the different mitigation strategies based on manipulation of rumen microbial diversity to reduce the methane emissions from livestock

Bioprospecting arsenite oxidizing bacteria in the soil of the Comarca Lagunera

Resumen El arsénico es uno de los metaloides más tóxicos presente en el ambiente y la exposición prolongada a este metal causa efectos crónicos en la salud. Por ello, la búsqueda de alternativas amigables con el medio ambiente, para el tratamiento de agua y suelos contaminados con arsénico es importante. En este trabajo se aislaron cepas bacterianas de suelos con presencia de arsénico en la Comarca Lagunera, para analizar aquellas con capacidad oxidante de arsenito. Las cepas 04-SP1qa y 14-SP1qh de metabolismo quimiolitoautotrófico y quimioheterotrófico, respectivamente, tuvieron mayor actividad de la enzima arsenito oxidasa. Las condiciones óptimas de crecimiento y la actividad enzimática de dichas cepas se investigaron. La cepa 04-SP1qa presentó actividad enzimática específica de 0.162 μmol·min- 1 ·mg-1, constante de Michaelis-Menten (Km) de 3.37 μM y velocidad máxima (Vmax) de 5.20 μM·min-1·mg-1 en condiciones óptimas de pH 8.0 y 40 °C. La cepa 14-SP1qh presentó actividad enzimática específica de 0.16 μmol·min-1·mg-1, Km de 3.70 μM y Vmax de 14.39 μM·min-1·mg-1 a pH 7.0 y 40 °C. Los resultados demostraron la presencia de bacterias oxidantes de arsenito con actividad enzimática en suelos de la Comarca Lagunera, identificando potencial para desarrollar nuevas tecnologías de biorremediación de aguas y suelos contaminados con arsénico en la región

Scale-Up Operations for Biogas Production: Analysis on Critical Factors Governing Large-Scale Operations

Anaerobic digestion (AD) is a unique process where different microbial species decompose organic materials in the absence of oxygen and has been widely practiced in full-scale facilities all over the world. Several AD techniques have been applied to convert livestock manures, wastewaters, and solid lignocellulosic waste into biogas. Despite the progress on the engineering of AD systems, several challenges exist for the economically and environmentally efficient way to recover carbon in the form of renewable biogas fuel. The complexity of the challenges poses constraints into the understanding of the factors associated to the scale-up of the AD operations. This study aims to review the critical factors of biogas plant project development

IMPACTO DEL ARSÉNICO EN EL AMBIENTE Y SU TRANSFORMACIÓN POR MICROORGANISMOS

El arsénico (As) es uno de los metaloides más tóxicos presentes en el medio ambiente y la especiación de éste depende de diversos factores químicos, físicos y biológicos. La distribución y contaminación del arsénico se debe a procesos naturales y antropogénicos, y su problemática se debe a su fácil movilización en el ambiente. Las altas concentraciones de arsénico en agua y suelo se han convertido en un problema global, ya que las exposiciones prolongadas a este metaloide pueden causar daños crónicos a la salud. Dicha situación es particularmente importante en la Comarca Lagunera en México. Por lo tanto, se ha vuelto necesaria la búsqueda de nuevas estrategias para la remoción de este metaloide, entre las cuales, la biorremediación microbiana ha cobrado importancia como una alternativa amigable con el ambiente en la solución de este problema. Los microorganismos juegan un papel fundamental en la especiación del arsénico, ya que un gran número de estos tiene la capacidad de transformar el arsénico a pesar de su toxicidad puesto que han desarrollado diferentes mecanismos que les permiten utilizar el arsénico en su metabolismo, ya sea en su forma reducida de arsenito, o en su forma oxidada de arseniato mediante reacciones de óxido-reducción transformación enzimática, metilación, quelación, exclusión e inmovilización. Este trabajo, trata sobre el impacto que tiene la especiación de arsénico, especialmente del arsenito (As III), en el medio ambiente, el riesgo que representa la contaminación para la salud, así como los mecanismos bioquímicos microbianos para la oxidación del arsenito, disminuir su toxicidad y el desarrollo de estrategias limpias y amigables con el medio ambiente para la remoción de arsénico de aguas y suelos contaminados

Potencial bioquímico de metano de pollinaza adicionada con propionato en condiciones mesofílicas

El objetivo del trabajo fue determinar el potencial bioquímico de metano de pollinaza en combinación con una alta concentración de propionato, empleando un consorcio microbiano previamente adaptado a elevadas cantidades de este metabolito. La pollinaza al 3 % de sólidos totales (ST) con 4895 ppm de propionato fue degradada en condiciones mesofílicas empleando microcosmos con un volumen de trabajo de 250 mL. Los resultados del rendimiento de metano acumulado indicaron un comportamiento triple sigmoidal; lo cual podría atribuirse a la diferencia en las velocidades de degradación de los componentes, tales como macromoléculas y ácidos grasos volátiles. El potencial bioquímico de metano fue de 364,52 mL CH4 gSValimentados-1.

A Genome-Wide Identification and Comparative Analysis of the Heavy-Metal-Associated Gene Family in Cucurbitaceae Species and Their Role in <i>Cucurbita pepo</i> under Arsenic Stress

The heavy-metal-associated (HMA) proteins are a class of PB1-type ATPases related to the intracellular transport and detoxification of metals. However, due to a lack of information regarding the HMA gene family in the Cucurbitaceae family, a comprehensive genome-wide analysis of the HMA family was performed in ten Cucurbitaceae species: Citrullus amarus, Citrullus colocynthis, Citrullus lanatus, Citrullus mucosospermus, Cucumis melo, Cucumis sativus, Cucurbita maxima, Cucurbita moschata, Cucurbita pepo, and Legenaria siceraria. We identified 103 Cucurbit HMA proteins with various members, ranging from 8 (Legenaria siceraria) to 14 (Cucurbita pepo) across species. The phylogenetic and structural analysis confirmed that the Cucurbitaceae HMA protein family could be further classified into two major clades: Zn/Co/Cd/Pb and Cu/Ag. The GO-annotation-based subcellular localization analysis predicted that all HMA gene family members were localized on membranes. Moreover, the analysis of conserved motifs and gene structure (intron/exon) revealed the functional divergence between clades. The interspecies microsynteny analysis demonstrated that maximum orthologous genes were found between species of the Citrullus genera. Finally, nine candidate HMA genes were selected, and their expression analysis was carried out via qRT-PCR in root, leaf, flower, and fruit tissues of C. pepo under arsenic stress. The expression pattern of the CpeHMA genes showed a distinct pattern of expression in root and shoot tissues, with a remarkable expression of CpeHMA6 and CpeHMA3 genes from the Cu/Ag clade. Overall, this study provides insights into the functional analysis of the HMA gene family in Cucurbitaceae species and lays down the basic knowledge to explore the role and mechanism of the HMA gene family to cope with arsenic stress conditions

Molecular Characterization of Fungal Pigments

The industrial application of pigments of biological origin has been gaining strength over time, which is mainly explained by the increased interest of the consumer for products with few synthetic additives. So, the search for biomolecules from natural origin has challenged food scientists and technologists to identify, develop efficient and less consuming strategies for extraction and characterization of biopigments. In this task, elucidation of molecular structure has become a fundamental requirement, since it is necessary to comply with compound regulatory submissions of industrial sectors such as food, pharmaceutical agrichemicals, and other new chemical entity registrations. Molecular elucidation consists of establishing the chemical structure of a molecule, which allows us to understand the interaction between the natural additive (colorant, flavor, antioxidant, etc) and its use (interaction with the rest of the mixture of compounds). Elucidation of molecular characteristics can be achieved through several techniques, the most common being infrared spectroscopy (IR), spectroscopy or ultraviolet-visible spectrophotometry (UV-VIS), nuclear-resonance spectroscopy (MAGNETIC MRI), and mass spectrometry. This review provides the details that aid for the molecular elucidation of pigments of fungal origin, for a viable and innocuous application of these biopigments by various industries

Anaerobic Biodegradation of Polyaromatic Hydrocarbons by a Sulfate Reducing Bacteria C1Fd Strain

Aromatic hydrocarbons contamination is widely prevalent in various parts of the world due to anthropogenic activities and leads to anaerobic conditions. As a result, most of its biodegradation is due to anaerobic microorganisms, and most specifically by anaerobic bacteria capable of using sulfates as final electron acceptor to degrade these compounds. Although there are reports on consortia of microorganisms that are involved in the anaerobic biodegradation of monoaromatic hydrocarbons (MAH) and polyaromatic hydrocarbons (PAH), only few reports are available using pure cultures. This paper describes an anaerobic, gram positive and spore forming bacterial strain (C1Fd), which was isolated and purified from aromatic compounds degrading consortium developed using bovine rumen fluid as inoculum. C1Fd was able to use MAH and PAH under anaerobic conditions and removed up 9.4 mM of MAH and 9.2 mM of PAH in less than 72 h. The strain was identified as Bacillus sp. and is phylogenetically related to the hydrocarbon degrading bacteria, Desulfotomaculum sp., isolated from a wastewater treatment plant

Insight into Pretreatment Methods of Lignocellulosic Biomass to Increase Biogas Yield: Current State, Challenges, and Opportunities

Lignocellulosic biomass is recalcitrant due to its heterogeneous structure, which is one of the major limitations for its use as a feedstock for methane production. Although different pretreatment methods are being used, intermediaries formed are known to show adverse effect on microorganisms involved in methane formation. This review, apart from highlighting the efficiency and limitations of the different pretreatment methods from engineering, chemical, and biochemical point of views, will discuss the strategies to increase the carbon recovery in the form of methane by way of amending pretreatments to lower inhibitory effects on microbial groups and by optimizing process conditions