Dynamics of humus forms and soil characteristics along a forest altitudinal gradient in Hyrcanian forest

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Harnessing the potential of ligninolytic enzymes for lignocellulosic biomass pretreatment

Abundant lignocellulosic biomass from various industries provides a great potential feedstock for the production of value-added products such as biofuel, animal feed, and paper pulping. However, low yield of sugar obtained from lignocellulosic hydrolysate is usually due to the presence of lignin that acts as a protective barrier for cellulose and thus restricts the accessibility of the enzyme to work on the cellulosic component. This review focuses on the significance of biological pretreatment specifically using ligninolytic enzymes as an alternative method apart from the conventional physical and chemical pretreatment. Different modes of biological pretreatment are discussed in this paper which is based on (i) fungal pretreatment where fungi mycelia colonise and directly attack the substrate by releasing ligninolytic enzymes and (ii) enzymatic pretreatment using ligninolytic enzymes to counter the drawbacks of fungal pretreatment. This review also discusses the important factors of biological pretreatment using ligninolytic enzymes such as nature of the lignocellulosic biomass, pH, temperature, presence of mediator, oxygen, and surfactant during the biodelignification process

Dynamics of humus forms and soil characteristics along a forest altitudinal gradient in hyrcanian forest

Humus forms are good indicators of environmental conditions and thus important in forest ecological processes. Altitudinal gradients are considered as natural laboratory for evaluating soil ecological processes and humus form distribution. The objective of this study was to evaluate the macromorphology of humus forms along an altitudinal gradient (0-2000 m a.s.l.) covered with plain forest, mixed and pure forests and forest-grassland ecotone, in Alborz Mountains in northern Iran. In total, 225 humus profiles were evaluated. Forest stand variables including tree density, basal area, crown density, and height, forest floor and soil physico-chemical properties along with biological features were measured. We found that altitudinal gradients influence both humus forms distribution and soil properties but with different mechanisms. While soil properties (i.e., temperature, pH, CaCO3, soil N content, soil C/N and microbial biomass N) were significantly correlated with altitude, the forest floor properties were more influenced by tree species composition. Particularly, the abundance of Mull was decreased in plain mixed forests compared to mountain pure forests, whereas the frequency of Amphi was increased. Moreover, Oligomull and Leptoamphi were abundant in mixed beech forests, while Eumacroamphi, Eumesoamphi and Pachyamphi were only observed in pure beech forests. Such a distribution influenced soil fertility where higher values of nitrogen (N), microbial biomass nitrogen (MBN) and pH were observed at lower altitudes under mixed forests compared to pure forests at higher altitudes

Supplementary Material for: Comparative Analyses of Transport Proteins Encoded within the Genomes of Bdellovibrio bacteriovorus HD100 and Bdellovibrio exovorus JSS

<p><i>Bdellovibrio</i>, δ-proteobacteria, including <i>B. bacteriovorus</i> (Bba) and <i>B. exovorus</i> (Bex), are obligate predators of other Gram-negative bacteria. While Bba grows in the periplasm of the prey cell, Bex grows externally. We have analyzed and compared the transport proteins of these 2 organisms based on the current contents of the Transporter Classification Database (TCDB; www.tcdb.org). Bba has 103 transporters more than Bex, 50% more secondary carriers, and 3 times as many MFS carriers. Bba has far more metabolite transporters than Bex as expected from its larger genome, but there are 2 times more carbohydrate uptake and drug efflux systems, and 3 times more lipid transporters. Bba also has polyamine and carboxylate transporters lacking in Bex. Bba has more than twice as many members of the Mot-Exb family of energizers, but both may have energizers for gliding motility. They use entirely different types of systems for iron acquisition. Both contain unexpectedly large numbers of pseudogenes and incomplete systems, suggesting that they are undergoing genome size reduction. Interestingly, all 5 outer-membrane receptors in Bba are lacking in Bex. The 2 organisms have similar numbers and types of peptide and amino acid uptake systems as well as protein and carbohydrate secretion systems. The differences observed correlate with and may account, in part, for the different lifestyles of these 2 bacterial predators.</p

Nanotechnology applications in biodiesel processing and production:A comprehensive review

The wide application of diesel engines globally and the resulting exhaust emissions have been the driving force behind producing eco-friendly alternatives to fossil diesel. Biodiesel derived from triglycerides is a promising replacement for fossil diesel due to less contribution to greenhouse gases and other harmful emissions. Transesterification is a widely adopted production method for converting triglycerides into alkyl esters, primarily owing to its superior conversion efficiency. Both homogeneous and heterogeneous catalysts, as well as enzymes, can be utilized to catalyze this process. However, commonly used catalysts often exhibit significant technical, economic, and environmental challenges, which can compromise the sustainability aspects of biodiesel production. Consequently, efforts are being directed towards developing sustainable catalysts in alignment with the United Nations Sustainable Development Goals. Among the proposed solutions, the application of nanomaterials has emerged as a promising avenue to address the limitations of conventional catalysts in the transesterification reaction. Compared with conventional catalysts, nanocatalysts have a substantially higher surface-to-volume ratio, amplifying the catalytic activity and eliminating many intrinsic limitations. In addition to their increased surface-to-volume ratio, nanocatalysts provide enhanced activity, stability, and reusability, along with greater resistance to saponification. Moreover, nanomaterials can enhance lipid extraction from feedstocks, especially from third-generation resources, due to the lack of toxicity and, subsequently, less environmental concern. While achieving promising outcomes, advancing nanotechnology as an environmentally friendly and economical approach to processing feedstocks and biodiesel production necessitates continued scrutiny. This issue is due to the potential for nanomaterials to infiltrate living systems, giving rise to various safety concerns. Thus, this review summarizes the opportunities and limitations of the mainstream applications of nanotechnology in biodiesel research.</p

Applications of nanotechnology in biodiesel combustion and post-combustion stages

Diesel fuel exhibits high efficiency, durability, and profitability for combustion engines but remains a major source of airborne pollutants, including particulate matter and nitrogen oxides. To address the urgent need for alternative energy sources and reduce greenhouse gas emissions, biodiesel has been developed as a potential replacement for petrodiesel. However, biodiesel combustion has its drawbacks, especially the emission of nitrogen oxides, which hinder its ability to replace petrodiesel sustainably. Nanotechnology has been proposed as a promising solution to improve biodiesel combustion and enhance its competitiveness against petrodiesel. Various studies have shown that both metallic and non-metallic nanoparticles can potentially enhance biodiesel performance during combustion, improving fuel combustion efficiency by 11.7% and 13.4% while reducing air pollutants such as carbon monoxide by 24.2% and 24.8% and unburned hydrocarbons by 11.5% and 25.3%, respectively. While both types of nanoparticles can potentially reduce greenhouse gas and particulate matter emissions, their impact on nitrogen oxide emissions varies. Non-metallic nanoparticles are more successful in reducing nitrogen oxide emissions, achieving reductions of up to 13.0%, while metallic nanoparticles have been shown to increase nitrogen oxides by 0.8% on average. In the post-combustion phase, nanoparticles can filter pollution from diesel engines with more than 99% efficiency, reducing friction, enhancing engine durability, preventing deposit formation, and reducing maintenance costs. However, using nanoparticles in biodiesel has several drawbacks, including toxicity to humans and ecosystems, high prices, lack of standardization, and limited understanding of their long-term effects. Further research is needed to address these constraints and ensure the safe and effective use of nanoparticles in biodiesel combustion. The potential benefits of nanotechnology for improving biodiesel combustion and reducing emissions can make this research field an exciting avenue for future research and development

Comparative study of biorefinery processes for the valorization of fast-growing Paulownia wood

In this work, valorization of Paulownia wood (PW) was proposed following several process configurations for biofuels and value-added compounds production. Firstly, autohydrolysis and ethanol-organosolv strategies were assessed separately for the fractionation of PW to enhance the enzymatic digestibility of cellulose. A third strategy focused on a sequential process (autohydrolysis and organosolv) was explored. Two temperatures were selected for the first stage of the combined process. High concentration of oligosaccharides (26.29 g/L) and high concentration of degradation products (17.21 g/L) were obtained at 210 and 230 °C, respectively. The solids obtained from both pretreatments were subjected to organosolv delignification (200 °C, 3 h and 50% ethanol) achieving delignification of 58 and 30% for the autohydrolyzed biomass at 210 °C and 230 °C, respectively. The combined process resulted in susceptible biomass able to produce 64 g/L of ethanol. Therefore, the strategies explored in this work open the possibility to build a refinery around Paulownia wood.Authors are grateful to MINECO (Spain) for thefinancial support ofthis work in the framework of the projects “Multistage processes for theintegral benefit of macroalgal and vegetal biomass” with referenceCTM2015-68503-R, and “Cutting-edge strategies for a sustainablebiorefinery based on valorization of invasive species” with reference PID2019-110031RB-I00, to Consellería de Cultura, Educación e Ordenación Universitaria (Xunta de Galicia) through the contract ED431C 2017/62-GRC to Competitive Reference Group BV1, and to the CITACA Strategic Partnership ED431E 2018/07, programs partiallyfunded by European Regional Development Fund (FEDER). Pablo G. delRío and Beatriz Gullón would like to express their gratitude to theMinistry of Science, Innovation and Universities of Spain for his FPUresearch grant (FPU16/04077) and her RYC grant (RYC2018-026177-I), respectively.info:eu-repo/semantics/publishedVersio