Neha Srivastava

A Review on Fuel Ethanol Production From Lignocellulosic Biomass

The review deals with fuel ethanol production from plant-based lignocellulosic biomass as raw materials. In this article, the technologies for producing fuel ethanol with the main research prospects for improving them are discussed. The complexity in the biomass processing is identified by the analysis of various stages involved in the conversion of lignocellulosic biomass into fermentable sugars. Further, the fermentation processes with its important features are explained based on biomass conversion. Comparative index for different types of biomass for fuel ethanol production is listed. Finally, some concluding remarks on current research regarding the pre-treatment along with biological conversion of biomass into ethanol are presented.

Improved production of reducing sugars from rice straw using crude cellulase activated with Fe3O4/alginate nanocomposite.

Effect of Fe3O4 nanoparticles (NPs) and Fe3O4/Alginate nanocomposites (NCs) have been investigated on production and thermostability of crude cellulase enzyme system obtained by newly isolated thermotolerant Aspergillus fumigatus AA001. Fe3O4 NPs and Fe3O4/Alginate NCs have been synthesized by co-precipitation method and characterized through various techniques. In presence of Fe3O4 NPs and Fe3O4/Alginate NCs, filter paper activity of crude cellulase was increased about 35% and 40%, respectively in 72 h as compared to control. Fe3O4/Alginate NCs treated crude enzyme was thermally stable up to 8h at 70°C and retained 56% of its relative activity whereas; control samples could retain only 19%. Further, the hydrolysis of 1.0% alkali treated rice straw using Fe3O4/Alginate NCs treated cellulase gave much higher sugar productivity than control at optimal condition. These findings may be utilized in the area of biofuels and biowaste management.

Application of ZnO Nanoparticles for Improving the Thermal and pH Stability of Crude Cellulase Obtained from Aspergillus fumigatus AA001

Cellulases are the enzymes which are responsible for the hydrolysis of cellulosic biomass. In this study thermal and pH stability of crude cellulase has been investigated in the presence of zinc oxide (ZnO) nanoparticles. We synthesized ZnO nanoparticle by sol-gel method and characterized through various techniques including, X-ray Diffraction, ultraviolet-visible spectroscope, field emission scanning electron microscope and high resolution scanning electron microscope. The crude thermostable cellulase has been obtained from the Aspergillus fumigatus AA001 and treated with ZnO nanoparticle which shows thermal stability at 65°C up to 10 h whereas it showed pH stability in the alkaline pH range and retained its 53% of relative activity at pH 10.5. These findings may be promising in the area of biofuels production.

Efficient dark fermentative hydrogen production from enzyme hydrolyzed rice straw by Clostridium pasteurianum (MTCC116)

In the present work, production of hydrogen via dark fermentation has been carried out using the hydrolyzed rice straw and Clostridium pasteurianum (MTCC116). The hydrolysis reaction of 1.0% alkali pretreated rice straw was performed at 70°C and 10% substrate loading via Fe3O4/Alginate nanocomposite (Fe3O4/Alginate NCs) treated thermostable crude cellulase enzyme following the previously established method. It is noticed that under the optimized conditions, at 70°C the Fe3O4/Alginate NCs treated cellulase has produced around 54.18g/L sugars as the rice straw hydrolyzate. Moreover, the efficiency of the process illustrates that using this hydrolyzate, Clostridium pasteurianum (MTCC116) could produce cumulative hydrogen of 2580ml/L in 144h with the maximum production rate of 23.96ml/L/h in 96h. In addition, maximum dry bacterial biomass of 1.02g/L and 1.51g/L was recorded after 96h and 144h, respectively with corresponding initial pH of 6.6 and 3.8, suggesting higher hydrogen production.

Current and emerging trends in bioremediation of petrochemical waste: A review

ABSTRACT Various industries release harmful petrochemical contaminants into the environment. To treat these petrochemical contaminants at source, different physical, chemical, and biological methods have been proposed and applied worldwide. However, physical and chemical methods have their own advantages and limitations; in this review, we majorly focused on the biodegradation of petrochemical wastes. First, a background study on the literature available in this field is presented. Second is a review of the toxic effects of petrochemical waste and various physical and chemical processes, followed by elaborate biological processes available for petrochemical waste degradation. Further, different aspects of bioremediation, such as modes, factors, limitations, and future perspectives are critically reviewed and presented. It was found that most of the studies performed on bioremediation of petrochemical waste employed bacteria for the degradation purpose. Some studies also made use of algae, fungi, yeast, genetically modified organisms, biosurfactants, or a consortium of these microbes. Moreover, use of bioremediation is still limited at field scale due to certain limitations, which have been elaborated in this article. Overall, we strongly believe that with bioremediation capturing the attention of environmentalists worldwide, there is still a prevailing need to scale up from lab to land level applications and adaptations.

Application of TiO2 Nanoparticle in Photocatalytic Degradation of Organic Pollutants

Heavy industrialization, specifically in the developing countries, has generated several unwanted environmental pollution. A variety of toxic organic compounds is produced in chemical and petroleum industries, which have resulted in collectively hazardous effects on the environment that needs immediate attention for remediation. Degradation of these pollutants has been tried through the various mechanism, out of which photocatalytic degradation seems to be one of the most promising approaches to reduce environmental pollution specifically in waste water treatment. Photocatalytic degradation has potential for the effective decomposition of organic pollutants due to efficiency to convert light energy into chemical energy. Additionally, the photocatalytic oxidation process is an advanced technique as it offers high degradation and effective mineralization at moderate temperature and specific radiation wavelength. Among various known photocatalysts, TiO2 is regarded as the one of the potential photocatalysts because of its hydrophilic property, high reactivity, reduced toxicity, chemical stability and lower costs. Therefore, the present chapter focuses on the role of TiO2 as the photocatalyst for the degradation of organic pollutants. The general mechanism of degradation of organic pollutants along with properties of TiO2 as the photocatalyst, existing mechanism of degradation via TiO2 was explained. The possible approaches to enhance degradation via TiO2 nanoparticle along with existing bottlenecks have been also discussed.

Nanoparticles for Biofuels Production from Lignocellulosic Waste

Lignocellulosic biomass is a sustainable alternative to current biofuels. The conversion of biomass-based sugars into biofuels, which emerged in 1970, is gaining more attention due to fossil fuel issues. Biohydrogen and bioethanol from cellulosic wastes is a sustainable and solves economic issues. This chapter reviews the use of nanoparticles for the bioconversion of biomass into biofuels.

Biofuels from Protein-Rich Lignocellulosic Biomass: New Approach

Increasing consumption of fossil fuels and concern over environmental emissions has provided impetus to the development of renewable biofuels. Presently available biofuel production processes and developing approaches have focused on closing the carbon cycle by biological fixation of atmospheric carbon dioxide and conversion of biomass into biofuels. Lignocellulosic plant residues are found in abundance quantity and contain an appropriate amount of protein which is a by-product of biomass pretreatment. Besides conversion of carbohydrates into fuel, efforts towards conversion protein to fuel and ammonia may improve its value addition. Moreover, development of this technology will also realize its advantages of high carbon fixation rates, reduce consumption of synthetic fertilizer, inexpensive, and simple feedstock processing. Therefore, the present chapter provides an overview of the production process of biofuels using lignocellulosic plant residues and their protein by-products. The major hurdles to enhance the yield/production of the product and possible approaches to overcome these hindrances were also discussed.

Synthetic Biology Strategy for Microbial Cellulases

Abstract Cellulase enzymes have a significant role in the biomass derived biofuels production process. Enzyme cost is one of the major challenges currently faced by biofuels industries. The biomass to biofuels production process is an environmentally friendly and sustainable approach. For developing economically viable cellulases, various approaches have been tried. Among these, synthetic biology is one of the potential techniques and is a sustainable approach to enhance the production of cellulase enzymes. Using recombinant expression technology, highly active and stable cellulases at low cost can be produced. Serious and in-depth investigations are under process to develop sustainable recombinant technology and other glycosyl-hydrolase enzymes. This chapter presents an overview of existing recombinant technology to enhance cellulase enzyme production. The latest recombinant methods in various cellulase producing microorganisms are discussed as well as these methods’ role in biofuels production processes from lignocellulosic biomass. Viable possibilities of recombinant technology using various methods are also explained in brief.

Recent trends in biobutanol production

Abstract Finite availability of conventional fossil carbonaceous fuels coupled with increasing pollution due to their overexploitation has necessitated the quest for renewable fuels. Consequently, biomass-derived fuels are gaining importance due to their economic viability and environment-friendly nature. Among various liquid biofuels, biobutanol is being considered as a suitable and sustainable alternative to gasoline. This paper reviews the present state of the preprocessing of the feedstock, biobutanol production through fermentation and separation processes. Low butanol yield and its toxicity are the major bottlenecks. The use of metabolic engineering and integrated fermentation and product recovery techniques has the potential to overcome these challenges. The application of different nanocatalysts to overcome the existing challenges in the biobutanol field is gaining much interest. For the sustainable production of biobutanol, algae, a third-generation feedstock has also been evaluated.