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Dark bioH2 fermentation from microalgae is a propitious technology to reduce the global CO2 emission and environmental pollution problems. This review provides the wide varieties of microalgal biomass available in the environment and also analyses the relevant studies focused on the microalgal biomass to bioH2 fermentation pathway. In this review, major enzymes and metabolic pathways involved in the dark fermentative hydrogen production has been reported. Major enzymes involved in the process are hydrogenases (Fe Fe and Ni Fe), besides, their thermo-tolerance and other aspects have been discussed. Metabolic and mechanistic pathway like acetate, butyrate (hydrogen accelerating reactions) and propionate (hydrogen consuming reactions) were highlighted. Recently microalgal biofuels along with bio refinery approach has been put forth as propitious technology for the future to solve the looming energy crisis. Major drawback in the extraction of sugars and other organic constituents from the microalgal cells are limiting their applications in various fields including bioenergy. A wide range of pretreatment methods has been applied so far and every treatment has their unique features. This report analyzes a comparative assessment of the pretreatment technologies and provides the key insights.

Biohydrogen production from lignocellulosic biomass (LCB) is an active research area. Several workers have tested a number of substrates under different operational conditions and brought forward the many positive process performance features and identified the main sources of inhibition. This review analyzes selected fermentative biohydrogen production processes by revisiting the core biohydrogen production performances in terms of gas production rates and yields and equally addresses the options for process enhancement by the application of through pretreatment methods and detoxification of process inhibitors. In addition, the issues related to continuous biohydrogen operation in different reactor configurations are highlighted. Lastly, future avenues of research which may be engendered and engineered to enhance the biohydrogen generation and process biokinetics are discussed. This review intends to provide the fundamental understanding of biohydrogen production and provides a perspective on future developments in this area of applied research.

Nanotechnology is a rapidly growing scientific field and has attracted a great interest over the last few years because of its abundant applications. Green nanotechnology is a multidisciplinary field that has emerged as a rapidly developing research area, serving as an important technique that emphasize on making the procedure which are clean, non-hazardous, and especially environmentally friendly, in contrast with chemical and physical methods currently employed for nanosynthesis. The biogenic routes could be termed green as these do not involve the use of highly toxic chemicals or elevated energy inputs during the synthesis. Differences in the bio-reducing agents employed for nanosynthesis can lead to the production of nanoparticles (NPs) having distinct shapes, sizes, and bioactivity. The exquitiveness of the green fabricated NPs have capacitated their potential applications in various sectors such as biomedicine, pharmacology, food science, agriculture, and environmental engineering. The present review summarizes current knowledge on various biogenic synthesis methods, relying on plants, waste biomass, and biopolymers and their reducing and stabilizing agents to fabricate nanomaterials. The main emphasis has been given on the current status and future challenges related to the wide-scale fabrication of nanoparticles for environmental remediation, pathogenicity, and agricultural applications.

This work evaluates lignocellulolytic enzymes production by a selected strain Streptomyces sp. MDS cultivated in various agricultural wastes under solid-state fermentation (SSF). Maximum activities (U/gds) of endoglucanase (132.6 ± 1.15), exoglucanase (14.6 ± 0.62), cellobiase (125.6 ± 1.75), filter paperase (19.7 ± 0.42), amylase (278.5 ± 3.53), and xylanase (342.5 ± 3.36) were produced with rice waste biomass (RWB). Operational parameters and supplementation of nitrogen sources, metal additives, and surfactants were systematically optimized with a view to maximizing enzyme production. The harvested enzyme exhibited good stability at high pH (5 to 8) and temperature (50 to 80 °C) and showed robust nature in the presence of organic solvents, surfactants, and commercial detergents. The potential of crude enzyme mixture for hydrolysis of mild alkaline pretreated RWB was demonstrated, resulting in equivalent saccharification (64.85 ± 1.11%) relative to commercial enzymes (69.41 ± 1.15%). Yeast co-culture of Saccharomyces cerevisiae and Kluyveromyces marxianus resulted in higher ethanol production (21.12 ± 0.82 g/L) and sugar consumption (88%) from enzymatic RWB hydrolysates (50 g/L) than monoculture. Finally, the leftover spent slurry from SSF effectively decolorized individual dyes and the actual textile wastewater, which increases the practical applicability of the developed bioprocess.

Microbial fuel cells (MFCs) are biocatalyzed systems which can drive electrical energy by directly converting chemical energy using microbial biocatalyst and are considered as one of the important propitious technologies for sustainable energy production. Much research on MFCs experiments is under way with great potential to become an alternative to produce clean energy from renewable waste. MFCs have been one of the most promising technologies for generating clean energy industry in the future. This article summarizes the important findings in electro-active biofilm formation and the role of exo-electrogens in electron transfer in MFCs. This study provides and brings special attention on the effects of various operating and biological parameters on the biofilm formation in MFCs. In addition, it also highlights the significance of different molecular techniques used in the microbial community analysis of electro-active biofilm. It reviews the challenges as well as the emerging opportunities required to develop MFCs at commercial level, electro-active biofilms and to understand potential application of microbiological niches are also depicted. Thus, this review is believed to widen the efforts towards the development of electro-active biofilm and will provide the research directions to overcome energy and environmental challenges.

Excess consumption of energy by humans is compounded by environmental pollution, the greenhouse effect and climate change impacts. Current developments in the use of algae for bioenergy production offer several advantages. Algal biomass is hence considered a new bio-material which holds the promise to fulfil the rising demand for energy. Microalgae are used in effluents treatment, bioenergy production, high value added products synthesis and CO2 capture. This review summarizes the potential applications of algae in bioelectrochemically mediated oxidation reactions in fully biotic microbial fuel cells for power generation and removal of unwanted nutrients. In addition, this review highlights the recent developments directed towards developing different types of microalgae MFCs. The different process factors affecting the performance of microalgae MFC system and some technological bottlenecks are also addressed.

Process byproducts from the fruit industry may represent a cheap and reliable source of green reducing agents to be used in current bio-nanosynthesis. This study reports the use of orange (Citrus × clementina) peel aqueous extract (OPE) for one-pot green synthesis of silver nanoparticles (AgNPs) with high effectiveness against various microbial pathogens as well as rat glial tumor C6 cells. The effects of various operational parameters on the synthesis of AgNPs were systematically investigated. The morphology, particle size, and properties of synthesized AgNPs were characterized using UV–visible spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, and Fourier transform infrared spectroscopy. High-resolution transmission electron microscopy shows that the nanoparticles are mostly spherical in shape and monodispersed, with an average particle size of 15–20 nm. Notably, the OPE-synthesized AgNPs were stable up to 6 months without change in their properties. Low doses of OPE-AgNPs inhibited the growth of human pathogens Escherichia coli, Bacillus cereus, and Staphylococcus aureus. The minimum inhibitory concentration and minimum bactericidal concentration of AgNPs against selected pathogenic bacteria were determined. OPE-AgNPs exhibited strong antioxidant activity in terms of ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) radical scavenging (IC50 49.6 μg/mL) and DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging (IC50 63.4 μg/mL). OPE-AgNPs showed dose-dependent response against rat glial tumor C6 cells (LD50 60 μg/mL) showing a promising potential as anticancer agents. Overall, the current investigation highlighted a cheap green technology route to synthesize AgNPs using OPE byproducts and could potentially be utilized in biomedical, cosmetic, and pharmaceutical industry.

Highlights • Eloquent biosynthesis of AgNPs using green seaweed Enteromorpha compressa. • Characterization of AgNPs was done by UV–vis, XRD, FTIR, HRTEM, SAED pattern and EDX. • Effective antibacterial activity against different clinical bacterial and fungal pathogens and cytotoxic assay on EAC cells., Green synthesis of nanoparticles using seaweeds are fascinating high research attention nowadays and also gaining center of attention in biomedical applications. In this work, we have synthesized biocompatible and functionalized silver nanoparticles using an aqueous extract of seaweed Enteromorpha compressa as a reducing as well as stabilizing agent and their efficient antimicrobial and anticancer activity are reported here. The UV–vis spectra of AgNPs showed the characteristics SPR absorption band at 421 nm. The chemical interaction and crystalline nature of the AgNPs were evaluated by FT-IR and XRD studies. The XRD result of AgNPs shows typical Ag reflection peaks at 38.1°, 44.2°, 64.4° and 77.1° corresponding to (111), (200), (220) and (311) Bragg’s planes. The surface morphology and composition of the samples were observed by HRTEM, EDS and SAED pattern analyses. Spherical shaped Ag nano structures were observed in the size ranges between 4 and 24 nm with clear lattice fringes in the HRTEM image. This report reveals that seaweed mediated synthesis of AgNPs and sustained delivery of Ag ions to the bacterial and fungal surface have been reducing their growth rate which was evaluated by well diffusion assay. The synthesized AgNPs showed favorable cytotoxicity against Ehlrich Ascites Carcinoma (EAC) cells with IC50 value was recorded at 95.35 μg mL−1. This study showed cost effective silver nanoparticles synthesis with excellent biocompatibility and thus could potentially be utilized in biomedical and pharmaceutical applications.

The current investigation highlighted a novel cost-effective green synthesis of silver nanoparticles (AgNPs) using Argyreia nervosa leaves extract (ANE) as a potential reducing and capping agent. Surface plasmon resonance confirmed the formation of AgNPs with maximum absorbance at λ max = 435 nm. FTIR revealed the involvement of biological macromolecules of ANE in the synthesis and stabilization of AgNPs. HRTEM images showed that the size of the spherical AgNPs ranged between 5 and 40 nm with average particle size of about 15 nm. The ANE-AgNPs showed inhibition activity against carbohydrate digestive enzymes α-amylase and α-glucosidase, with EC50 of 55.5 and 51.7 µg/mL, respectively, indicating its antidiabetic potential. The in vitro antioxidant activity of ANE-AgNPs was evaluated in terms of ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) and DPPH (1,1-diphenyl-2-picrylhydrazyl) free radicals scavenging assays with IC50 value of 44.3 and 55.9 µg/mL, respectively. The AgNPs displayed strong antibacterial activity against foodborne bacteria with zone of inhibition 16.0 and 12.5 mm for Escherichia coli and Staphylococcus aureus, respectively, and also exhibited strong synergistic antibacterial activity together with standard antibiotics. The biological activity in terms of antioxidant, antidiabetic and antibacterial potential could be useful in various bio-applications such as cosmetics, food, and biomedical industry.

Coffee is the second largest traded commodity after petroleum and the second most popular beverage after water. This big industry is believed to generate huge amount of waste with spent coffee grounds (SCGs) represents one of the main by-products. Recycling of such waste to fuels and value-added products through bio-refineries is a promising way to solve the problem of many countries that face daily challenges and heavy cost in waste disposal. This review aims to shadow the light on SCGs recycling potential in which over 230 published papers on SCGs recycling topic were gathered and discussed. Various opportunities to produce biofuels such as biodiesel, biogas, bioethanol, bio-oil and fuel pellets besides value-added products such as bioactive compounds, adsorbents, polymers, nanocomposites, and compost were discussed. Moreover, the potential of membrane technology related to various processes of biorefining, separation and purification in the proposed SCG-integrated biorefinery are presented. Based on the presented review, it is obvious that recycling of SCGs offers many worthwhile options to policymakers that can contribute towards huge financial saving on taxpayers of running and maintaining landfills besides saving the environment from harmful emissions. In conclusion, this review emphasizes that SCG-integrated biorefineries to produce different types of biofuels and value-added products are a very promising approach that shall be economically more scrutinized in the foreseen future.

Background The low cost of aminoglycoside (AMG) antibiotics facilitates their excessive use in animal husbandry and the agriculture sector. This scenario has led to the occurrence of residues in the food chain. After several years of AMG use in antibacterial therapy, resistance to streptomycin has begun to appear. Most of the detection methods developed for AMG antibiotics lacks specificity. A broad target specific nanoprobe would be ideal for detecting the entire class of AMGs. A rapid and sensitive method for the detection of AMGs is urgently needed. Results Gallic acid-coated silver nanoparticles (AgNPs) were demonstrated as a nanoprobe for the colorimetric detection of AMGs (yellow to orange / red). A linear dynamic range of 50-650 pmol L-1 was achieved readily by ratiometric spectrophotometry (A560 /A400 ) with a limit of detection (LOD) as low as 36 pmol L-1 . The amine-groups of the AMGs function as molecular linkers, so that electrostatic coupling interactions between neighboring particles drive the formation of AgNP aggregates. The assay can also be applied for the determination of streptomycin residues in serum and milk samples. Conclusion This study revealed the potential of an AgNP probe for the rapid and cost-effective detection of low-molecular-weight target analytes, such as the AMGs. A ligand-induced aggregation of AgNPs coated with gallic acid was reported to be a rapid and sensitive assay for AMGs. Analysis of streptomycin was demonstrated with excellent picomolar-level sensitivity. Thus, the validated method can find practical applications in the ultrasensitive detection of AMGs in complex and diagnostic settings. © 2019 Society of Chemical Industry.

A novel Cu catalyst was developed using water-washed coal fly ash (WFA) as a support material for catalytic reduction of p-nitrophenol (p-NP) in the presence of NaBH4. Cu/WFA showed ~ × 105 times higher estimated rate constant kobs-p-NP/CCu (L min−1 gCu−1) compared with Cu/SiO2, Cu/Al2O3, and other Cu catalysts previously reported. Surprisingly, we obtained a significant lower price value (Price’/K) (0.027–0.068 USD/L min−1) for Cu/WFA in comparison with other Cu catalysts and precious metallic catalysts (Pd, Au, Ag, and Pt). Various surface analyses and additional experiments using Fe/SiO2, Cu/Fe2O3/SiO2, and Cu/HCl-treated WFA demonstrated that Cu(0) nanoparticles were well loaded on the surface of WFA, where Fe elements were abundant, resulting in a dramatic enhancement of the Cu/WFA catalytic activity. Particularly, X-ray photoelectron spectroscopy revealed the abundance of Cu(0)/Fe(III) and Cu(0)/Fe(II) in the WFA surface. This indicates that Cu(0) was the main driving force for the activation of Had molecule, and that the reduction of Fe(III) to Fe(II) by NaBH4 can accelerate the reduction of Cu(II) to Cu(0). Recycling and phytotoxicity tests showed that Cu/WFA can be applied as a reusable catalyst with low environmental impact, revealing the remarkable potential of non-precious metal/WFA catalyst in the field of environmental remediation.

In the past few decades, rapid industrialization led to increasing the demand for textile products which leads to increase in water pollution. Effluent released by the textile industry pose a threat to environmental safety throughout the world. Bioremediation approaches could be considered as an efficient and effective way to treat textile effluent relative to existing physical and chemical methods. This book chapter describes various methods used to treat textile industry wastewater. Bioremediation approaches using live cells system, enzymes, and phytoremediation approaches and their detailed mechanisms have also been discussed. Further discussion on the various types of the bioreactors employed to treat textile industry wastewater at large scale is summarized. The performance of the system and their key challenges and future technological aspects are also briefly discussed. The aim of this chapter is to provide an overview of bioremediation approaches to resolve issues related to textile industry wastewater and to minimize pollution and control their associated effects on the environment.

The presence of hazardous, radioactive, and rare earth metal such as yttrium (Y

The leather industry is a major source of environmental pollution in India. The wastewater generated by leather industries contains very high pollution parameters due to the presence of a complex mixture of organic and inorganic pollutants even after the treatment at a Common Effluent Treatment Plant (CETP) and disturbs the ecological flora and fauna. The nature, characteristics and toxicity of CETP treated wastewater is yet to be fully elucidated. Thus, this study aims to characterize and evaluate the toxicity of CETP treated tannery wastewater collected from the Unnao district of Uttar Pradesh, India. In addition to measuring the physico-chemical parameters, the residual organic pollutants was identified by GC-MS analysis and phytotoxicity, cytotoxicity and genotoxicity of the treated wastewater was evaluated using Vigna radiata L. and Allium cepa L. Results showed that the treated wastewater contained very high pollution parameters (TDS 3850 mg/L, BOD 680 mg/L, COD-1300 mg/L). GC-MS analysis revealed the presence of various types of residual organic pollutants including benzoic acid, 3-[4,-(T-butyl) Phenyl] furan-2-5-dione, benzeneacetamide, resorcinol, dibutyl phthalate, and benzene-1,2,4-triol. Further, toxicological studies showed the phytotoxic nature of the wastewater as it inhibited seed germination in V. radiata L. and root growth of A. cepa. Genotoxicity was evidenced in the root tip cell of A. cepa where chromosomal aberrations (stickiness, chromosome loss, C-mitosis, and vagrant chromosome) and nuclear abnormalities like micronucleated and binucleated cells were observed. Thus, results suggested that it is not safe to discharge these wastewater into the environment.

Silver nanoparticles (AgNPs) coated with whey peptides are shown to be a useful optical nanoprobe for the highly sensitive determination of Pd(II). The peptidic surface of the AgNPs works as a molecular receptor for the rapid detection of Pd(II) via a color change from dark yellow to orange/red along with a spectral red-shift with a gap about 120 nm. The effect is caused by the formation of a coordination complex between Pd(II) and the peptide ligands. This results in the aggregation of AgNPs and an absorbance spectral shift from 410 to 530 nm. The absorbance response is linear in the range 0.1 to 1.3 μM Pd(II) with a low detection limit of 115 nM. The nanoprobe responds within a few minutes and is not interfered by other metal ions except for Mg(II). The probe potentially can be applied to the determination of Pd(II) contamination in the products of Pd(II)-catalyzed organic reactions and in pharmaceutical settings. Graphical abstractSchematic representation of the nanoprobe for Pd(II). (a) Synthesis of whey peptide-coated silver nanoparticles (AgNPs), (b) the nanoprobe design for Pd(II) detection, (c) HR-TEM imaging and elemental mapping, (d) quantitative determination of Pd(II) (Inset shows colorimetric results).

Increasing environmental contamination with highly toxic chemicals is warning us to find sustainable technologies to protect the environment and human health, which is a key challenge of the current scenario. A variety of physicochemical technologies are currently being applied presently to decontaminate the environment to safeguard the environment and human health. However, these technologies are costly and chemical-consuming, thus causing secondary pollution and, hence, are not environmental-friendly. As an alternative approach, bioremediation technologies using microbes and plants and their enzymes are currently viewed as eco-friendly and most sustainable technologies due to their self-sustainable and low-cost nature. But sometimes bioremediation technologies are get limited by low degradability/accumulability of microbes and plants, respectively. To overcome these limitations, genetic engineering approaches are highly decisive to design the transgenic microbes and plants for the enhanced biodegradation and biodetoxification of environmental pollutants for sustainable development. Genetically modified organisms (GMOs) offer great potential for environmental remediation, and hence, in this chapter, we focused on the applications of GMOs in the environmental management with risks involved, constraints, and challenges faced by researchers in the release of GMOs for field applications.

This study reports the degradation and decolourization capability of a manganese peroxidase enzyme producing bacterium isolated from pulp and paper mill wastewater. The isolate was identified as Bacillus aryabhattai based on biochemical analysis and 16S rRNA gene sequencing. The strain was designated MG966493. This bacterium was able to reduce 67% and 54% colour and lignin, respectively from the pulp and paper mill wastewater after 144 h of treatment at 32 °C, pH 7.6 and 120 rpm. Further, FT-IR analysis showed that during the lignin degradation process a number of metabolites were produced comprising different functional groups such as carbonyl (C = C), carboxyl (-COOH), alkene (C=C), amines (-NH2), sulphonic (-SO3) and nitro (-NO2). In addition, the SEM analysis showed that the bacterial cells exposed to pulp and paper mill wastewater have rough surfaces with reduced size as compared to the unexposed cells with smooth surfaces. This study concluded that the isolated bacterium B. aryabhattai has significant potential for the bioremediation of pulp and paper mill wastewater and thus, can be applied for their treatment at an industrial scale.

Environmental contamination due to heavy metals (HMs) is of serious ecotoxicological concern worldwide because of their increasing use at industries. Due to non-biodegradable and persistent nature, HMs cause serious soil/water pollution and severe health hazards in living beings upon exposure. HMs can be genotoxic, carcinogenic, mutagenic, and teratogenic in nature even at low concentration. They may also act as endocrine disruptors and induce developmental as well as neurological disorders, and thus, their removal from our natural environment is crucial for the rehabilitation of contaminated sites. To cope with HM pollution, phytoremediation has emerged as a low-cost and eco-sustainable solution to conventional physicochemical cleanup methods that require high capital investment and labor alter soil properties and disturb soil microflora. Phytoremediation is a green technology wherein plants and associated microbes are used to remediate HM-contaminated sites to safeguard the environment and protect public health. Hence, in view of the above, the present paper aims to examine the feasibility of phytoremediation as a sustainable remediation technology for the management of metal-contaminated sites. Therefore, this paper provides an in-depth review on both the conventional and novel phytoremediation approaches; evaluates their efficacy to remove toxic metals from our natural environment; explores current scientific progresses, field experiences, and sustainability issues; and revises world over trends in phytoremediation research for its wider recognition and public acceptance as a sustainable remediation technology for the management of contaminated sites in the twenty-first century.

Biodegradation of phenolic compounds in wastewater can be effectively carried out in packed bed reactors (PBRs) employing immobilized microorganisms. A low-cost, reusable immobilization matrix in PBR can provide economic advantages in large scale removal of high concentration phenol. In this study, we evaluated the efficiency and reusability of sugarcane bagasse (SCB) as a low-cost immobilization support for high strength phenol removal in recirculating upflow PBR. An isolated yeast Candida tropicalis PHB5 was immobilized onto the SCB support and packed into the reactor to assess phenol biodegradation at various influent flow rates. Scanning electron microscopy exhibited substantial cell attachment within the pith and onto the fibrous strand surface of the SCB support. The PBR showed 97% removal efficiency at the initial phenol concentration of 2400 mg L−1 and 4 mL min−1 flow rate within 54 h. Biodegradation kinetic studies revealed that the phenol biodegradation rate and biodegradation rate constant were dependent on the influent flow rate. A relatively higher rate of biodegradation (64.20 mg g−1 h−1) was found at a flow rate of 8 mL min−1, indicating rapid phenol removal in the PBR. Up to six successive batches (phenol removal >94%) were successfully applied in the PBR using an initial phenol concentration of 400–2400 mg L−1 at a flow rate of 4 mL min−1 indicating the reusability of the PBR system. The SCB-immobilized C. tropicalis could be employed as a cost-effective packing material for removal of high strength phenolic compounds in real scale PBR.

Biohydrogen could be considered as a clean and attractive substitute for fossil fuels and can progress to a sustainable hydrogen-oriented economy in the years to come. In recent years, biohydrogen production from renewable waste biomass resources has attained increasing attention because of its ecofriendly and sustainable approach. Dark fermentative biohydrogen production with biomass is an ingenious solution and has major advantages relative to other biohydrogen production processes. On the other hand, this process seems to be sluggish because of rebellious biomass structure and thus various pretreatment processes are required for the deliverance of readily fermentable sugars for fermentation. The main focus of this chapter depicts an outline on the use of various potential biomass resources and also various pretreatment possibilities employed for enhanced biohydrogen production. Moreover, low biohydrogen yield is still the main drawback of dark fermentation. To overcome this, many solutions, for instance, microbial inoculum, substrate pretreatment, and optimization of process operating parameters, are essential. Nevertheless, various integrated processes, such as dark fermentation in combination with photofermentation, anaerobic digestion, and microbial electrochemical systems (Microbial fuel cells (MFC) and microbial electrolysis cell), are used to achieve industrialized biohydrogen production, and to whip up the process more competent and virtually applicable. In this chapter, we have elaborated various integrated approaches by conversing their principles, as well the current study progresses, from the literature.

Various types of medicines, including nonsteroidal antiinflammatory drugs and quinolone antibiotics, have been used to treat infections caused by microorganisms. Consequently, most of these medicines, undigested, and with their metabolic intermediates, are released through excretion into the ecosystem. In addition, hormones, especially steroid hormones, are observed in the ecosystem, which because of their long-term persistence (even at trace levels) in the environmental surroundings might pose a risk to living systems. Hence, various research groups have studied the fate of such contaminants. To avoid the high risk of micropollutants, various remediation techniques have been proposed to remove such contaminants from the environment. One of these methods is removal of the contaminant(s) by microalgae. In this book chapter, we briefly summarize the occurrence of some of these microcontaminants in the ecosystem and their detoxification as well as elimination by microalgae (alone or combination with other processes), as reported in the published literature.

Basically, nitro functional group-containing chemicals have been used to synthesize various useful products like dyes, pesticides and solvents, and also military products and so on. Hence, many nitroaromatics (including nitrophenols) have been continuously released into the environment and appear in the soil and water. Some are known to be toxic due to their great impact on living systems (especially on health). Most such chemicals (nitroaromatic compounds) are listed as priority chemicals by the Environmental Protection Agency (EPA). The vast use of such chemicals and their toxic effects had led to the study of the degradation of nitro group-containing chemicals by microbes (an easily available and cost-effective treatment). In view of this, we discuss the degradation of a few nitro group-containing compounds and herbicide(s) by microorganisms from published literature, and we consider the future perspective.

Keratin is a global class of biological material, which represents a group of cysteine-rich filament-forming proteins. They serve as a shielding layer for the epidermal appendages like nails, claws, beak, hair, wool, horns, and feathers. These proteins are further subdivided into two different class based on their secondary structure: α-keratin and β-keratin. Keratin is insoluble in hot or cold water; this unique property helps to prevent their digestion by proteolytic enzymes. Additionally, their complex hierarchical-like filament-matrix structure at nanoscale and the polypeptide chains create a robust wall for protection against heat stress, pathogen invasions (particularly through skin), mechanical damage, etc. In this review, we are trying to attempt a linear focus in the direction of structure, function, extraction of keratin, and its industrial applications.

Lignin, is the most abundant, renewable and degradable biopolymer available in the nature. The present study exploited purified lignin from wheat straw as reducing, capping and stabilizing agent for the green synthesis of silver nanoparticles (Li-AgNPs) under optimized conditions. The analytical studies revealed synthesized Li-AgNPs having a face centered cubic crystalline structure, size ranging ~15–20 nm and the biomolecules comprising majorly phenolic, hydroxyl and carboxylic group of lignin coated on the surface of AgNPs. Li-AgNPs showed significant antimicrobial efficacy against human pathogens namely; Staphylococcus aureus and Escherichia coli and also determined their minimum inhibitory and minimum bactericidal concentration (MIC and MBC). Li-AgNPs also displayed substantial antioxidant activity in terms of well-known enzyme marker viz.; ABTS and DPPH free radical scavenging assay relative to commercial AgNPs. In vitro cytotoxicity assay of Li-AgNPs demonstrated dose-dependent toxicity effects in SKOV3 ovarian cancer cell line (LD50; 150 μg/mL) indicative of promising anticancer agent. Further, H2O2 sensing ability of stabilized Li-AgNPs exhibited its vital role in determining reactive oxygen species. Synthesis of Li-AgNPs is a cheap green technology and could exhibit its commercial use in biomedical, cosmetic, and pharmaceutical industry.

Polyhydroxyalkanoates (PHA) are appealing as an important alternative to replace synthetic plastics owing to its comparable physicochemical properties to that of synthetic plastics, and biodegradable and biocompatible nature. This review gives an inclusive overview of the current research activities dealing with PHA production by utilizing different waste fluxes generated from food, milk and sugar processing industries. Valorization of these waste fluxes makes the process cost effective and practically applicable. Recent advances in the approaches adopted for waste treatment, fermentation strategies, and genetic engineering can give insights to the researchers for future direction of waste to bioplastics production. Lastly, synthesis and application of PHA-nanocomposites, research and development challenges, future perspectives for sustainable and cost-effective PHB production are also discussed. In addition, the review addresses the useful information about the opportunities and confines associated with the sustainable PHA production using different waste streams and their evaluation for commercial implementation within a biorefinery.

In this study, Lysinibacillus sp. RGS was evaluated to synthesize polyhydroxybutyrate (PHB) from a broad range of pure carbon sources and residual sugars of chemically pretreated sugarcane bagasse (SCB) hydrolysates. Effects of supplementation of nutrients and various experimental variables to enhance PHB accumulation were investigated. Results of optimized parameters were identified as 48 h, 37 °C, pH 7; inoculums concentration (2.5% v/v) and shaking condition (100 rpm). Growth kinetics and bioprocess parameters of Lysinibacillus sp. using SCB hydrolysates with corn steep liquor (2%) accounted for the maximum cell growth (8.65 g/L) and PHA accumulation (61.5%) with PHB titer of (5.31 g/L) under optimal conditions. The produced biopolymer was studied by Fourier Transform Infrared (FTIR) spectroscopy and the results revealed the obtained to be PHB. Thus Lysinibaciluus sp. exhibits high potential in industrial scale manufacture of PHB using SCB as an inexpensive substrate.

The present study deals with a gram-positive and rod-shaped bacterium SCRB 19 isolated from chromium contaminated tannery wastewater of common effluent treatment plant (CETP), Kanpur (U.P), India. Based on 16S rRNA gene sequencing investigation, the bacterium was recognized as Microbacterium paraoxydans. This bacterium exhibits relatively elevated tolerance to Cr(VI) (≤1000 mg/L). The Cr(VI) reduction potential of isolated bacterium was studied at 100, 200 300 and 500 mg/L of Cr(VI) and the results revealed that bacterium reduced 93.45, 87.28, 72.01 and 39.24 % of Cr(VI) at their respective concentrations. The bacterial cell exterior showed the morphological changes and intracellular accumulation during the reduction of Cr(VI) was evidenced by SEM and EDX analysis. The Cr (VI) reduced product was bound with membrane functional groups such as amide and carboxyl group were determined through FTIR spectroscopy. The prominent peaks determined by XRD and XPS analysis corroborate the presence of possible reduced chromium species. The suspended culture of Microbacterium paraoxydans SCRB19 also showed chromate reductase enzyme activity of 1.603 ± 0.041 U/mL. Hence, this strain can be a promising bio-agent for ecofriendly clean up strategies of toxic Cr(VI) from polluted environments.

Existing coronavirus named as a severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has speeded its spread across the globe immediately after emergence in China, Wuhan region, at the end of the year 2019. Different techniques, including genome sequencing, structural feature classification by electron microscopy, and chest imaging using computed tomography, are primarily used to diagnose and screen SARS-CoV-2 suspected individuals. Determination of the viral structure, surface proteins, and genome sequence has provided a design blueprint for the diagnostic investigations of novel SARS-CoV-2 virus and rapidly emerging diagnostic technologies, vaccine trials, and cell-entry-inhibiting drugs. Here, we describe recent understandings on the spike glycoprotein (S protein), receptor-binding domain (RBD), and angiotensin-converting enzyme 2 (ACE2) and their receptor complex. This report also aims to review recently established diagnostic technologies and developments in surveillance measures for SARS-CoV-2 as well as the characteristics and performance of emerging techniques. Smartphone apps for contact tracing can help nations to conduct surveillance measures before a vaccine and effective medicines become available. We also describe promising point-of-care (POC) diagnostic technologies that are under consideration by researchers for advancement beyond the proof-of-concept stage. Developing novel diagnostic techniques needs to be facilitated to establish automatic systems, without any personal involvement or arrangement to curb an existing SARS-CoV-2 epidemic crisis, and could also be appropriate for avoiding the emergence of a future epidemic crisis.

The performance of green liquor pretreatment using Na2CO3 and Na2SO3 and its optimization for whole rice waste biomass (RWB) was investigated. Incubation of Na2CO3-Na2SO3 at a 1:1 ratio (chemical charge 10%) for 12% RWB at 100°C for 6h resulted in maximum delignification (58.2%) with significant glucan yield (88%) and total sugar recovery (545mg/g of RWB) after enzymatic hydrolysis. Recovery and reusability of the resulting chemical spent wash were evaluated to treat RWB along with its compatibility for enzymatic digestibility. Significant hydrolysis and lignin removal were observed for up to three cycles; however, further reuse of Na2CO3 and Na2SO3 lowered their performance. Significant 2,3-butanediol (BDO) was produced by Klebsiella pneumoniae KMK-05 with the RWB enzymatic hydrolysate from each pretreatment cycle. BDO yield achieved using RWB-derived sugars was similar to those using laboratory-grade sugars. This pretreatment strategy constitutes an ecofriendly, cost-effective, and practical method for utilizing lignocellulosic biomass.

Aim The aim of this study was to evaluate an isolate of Amycolatopsis sp. GDS for cellulase and xylanase production, their characterization, and its application to the preparation of biomass feedstock for ethanol production. Methods and Results A novel potent cellulolytic bacterial strain was isolated and identified as Amycolatopsis sp. GDS. The strain secreted high levels of cellulase and xylanase in the presence of agricultural waste biomass. The enzymes were thermostable and active up to 70°C. Interestingly, the enzymes were expressed well at higher NaCl (up to 2·5 mol l−1) and ionic liquid (10%) concentrations, so that they could be used during the pretreatment of biomass. Enzyme stability in the presence of organic solvents, surfactants and oxidizing agents was also noted. Crude enzymes from Amycolatopsis sp. GDS resulted in comparable saccharification (60%) of wheat straw to commercial enzymes (64%). Conclusions The cellulolytic enzymes from Amycolatopsis sp. GDS were stable, expressed well under conditions with various chemicals, and yielded significant amounts of hydrolysates from the biomass. The high bioethanol production using yeast co-cultures with enzymatic hydrolysates highlights the significance of selecting the strain and substrate for biofuel production. Significance and Impact of the Study This study demonstrates the importance of the isolate Amycolatopsis sp. GDS that secretes high levels of cellulase and hemicellulase by utilizing agricultural waste biomass and its application in the preparation of biomass feedstock and sequential ethanol fermentation.

The present study consists of the preparation of activated carbon from peach stone (PSAC) by H4P2O7 activation and its detailed characterization. The influence of different activants and various operational conditions including; soaking time, activation time, and activation temperature during PSAC preparation were systematically investigated. The chemical properties and morphology of prepared activated carbon was characterized by various analytical techniques (FTIR, SEM and EDX). TG-DTA analysis showed that the pore development of PSAC was significant at temperatures > 450°C. The prepared PSAC were utilized for the rapid removal and adsorption of Acid Red 18 (AR18) from aqueous solution that follows pseudo-second-order kinetics. The Langmuir isotherm model corresponded well with equilibrium data than the others, implying that the adsorption of AR18 onto prepared PSAC from the aqueous solutions proceeds by a monolayer formation. Thermodynamic investigations showed that the adsorption process is an exothermic and spontaneous process. During reusability studies, PSAC showed complete removal of AR18 upto seventh cycle increasing its practical applicability. Finally the prepared PSAC showed the best adsorptive capacity as compared to commercial AC for dye removal from actual industrial wastewater. This confers the possibility of applying PSAC economically viable option for the treatment of industrial wastewaters containing dye pollutants using suitable reactor.

Spent coffee grounds (SCG) are an important waste product millions of tons generated from coffee consumption and could be effectively utilized for various applications due to their high organic content. SCG can be used as a potential feedstock to develop coffee-based biorefinery towards value-added products generation through various biotechnological processes. Considerable developments have been reported on emerging SCG-based processes/products in various environmental fields such as removal of heavy metals and cationic dyes and in wastewater treatment. In addition, SCG are also utilized to produce biochar and biofuels. This review addressed the details of innovative processes used to produce polymers and catalysts from SCG. Moreover, the application of these developed products is provided and future directions of the circular economy for SCG utilization.

This study investigated a one-pot green and sustainable silver nanoparticles (AgNPs) synthesis by utilizing Portulaca oleracea leaves (PNL) aqueous extract as a reducing agent. The physical and chemical characteristics of the produced AgNPs were studied by employing numerous standard analytical techniques. The analytical outcomes suggest that PNL-AgNPs were crystalline in nature, fabricated with PNL phytochemicals, and circular in shape measuring ∼20 nm in size. Biosynthesized PNL-AgNPs exhibited a significant photocatalytic activity for degrading various reactive textile dyes without the need of any reducing agent. Particularly, of the reactive textile dyes, PNL-AgNPs exhibited higher photocatalytic degradation of Reactive Green 19A (RG19A), wherein its deterioration was studied by measuring the reduction in chemical oxygen demand (COD; 84%) and total organic carbon (TOC; 75%) within 60 min of incubation. The effects of various influencing operational factors, such as temperature, pH, light condition, photocatalyst amount, and dye concentrations, on the photocatalytic degradation of RG19A were systematically examined. The catalytic activity of PNL-AgNPs remains stable up to three repeated cycles, which upsurges the real-world applicability of PNL-AgNPs in textile wastewater treatment. PNL-AgNPs showed significant antibacterial activity and synergy with commercial antibiotics against human pathogenic bacteria. The mechanism underlying antibacterial activity was determined based on bacterial cell membrane disruption and cytoplasmic content leakage. PNL-AgNPs potentially constrain the activity of α-glucosidase and α-amylase enzymes, which are marker enzymes of diabetes. The results obtained indicate the potential application of synthesized PNL-AgNPs in environmental and nano-biomedical applications.

Development of an effective pretreatment method is a vital stage to enhance biomass-based biopolymers production. The present study aims on the pretreatment of wheat waste biomass (WS) with alkaline and in combination with ultrasound (US) treatment to enhance enzymatic saccharification of WS into monomeric sugars. Effects of chemical dosage, substrate loading, US power and US pretreatment time on the pretreatment efficiency were systematically investigated. Under optimized conditions; US + NaOH pretreatment attained maximum 70% delignification of WS, with 84.5% hydrolysis yield, 90% glucose yield and 65% xylose yield after enzymatic hydrolysis (30 FPU/g of dry WS) which is substantially higher than the individual pretreatment. Analytical studies (XRD, FTIR, and SEM) revealed that the combined US + NaOH pretreatment can effectively destroyed the ultrastructure of biomass and improved the accessibility to hydrolyzing enzymes. The resulted enzymatic hydrolysates were utilized as a possible biomass feedstock for polyhydroxybutyrate (PHB) production using Ralstonia eutropha. Effects of supplementation of nutrients, stressing agents and initial concentration of US + NaOH pretreated WS hydrolysates (20 to 40 g/L) on PHB production were evaluated. The maximum 74% PHA accumulation, PHB titer of 7.85 g/L and yield of PHB about 0.441 g/g of reducing sugar production was obtained. Analytical characterization and thermal characteristics of extracted biopolymer showed the poperies of standard PHB. The foregoing results suggested the potential of WS as an alternate renewable resource for sustainable biopolymer production and enables WS waste biomass disposal concerns.

Present day rising necessity for rare earth elements (REE) is of great interest for its recovery through processing various waste materials concerning both economic and environmental benefits. The present study investigates the recovery potential of yttrium from fluorescent lamp waste using a hydrometallurgical process. Leaching of metals from the waste was studied by applying acids viz. hydrochloric acid (HCl), nitric acid (HNO3) and sulfuric acid (H2SO4). Influence of various factors (solid:liquid ratio, reaction temperature, reaction time, and acid concentration) were conducted by full factorial design for the recovery of yttrium. Experimental variables such as decomposition, leaching and the oxide preparation were studied and the mechanisms responsible during the progress in each step was systematically investigated. The optimal experimental conditions attained with 40% solid/liquid ratio, at 45 °C in 0.5 h at 150 rpm, with 3N H2SO4 concentration. Whereas, HCl and HNO3 leachants showed poor performance. Leaching process conducted in this study were best suited to ‘ash diffusion control dense constant size-spherical particles model’, which means that the diffusion process through the ash is the rate regulatory step in the leaching process. With increase in the concentration of oxalic acid as precipitating agent, a reduction in the nuclear induction period resulted indicating a higher sedimentation rate and shorter equilibration time. In addition, crystal nucleation rate and crystal growth rate, showed that the reaction velocity of the crystal nucleation ‘p’ is 2.88 and the crystal growth degree and value increases with the increase in the concentration of oxalic acid (n: 0.3437–0.4872). The precipitation rate was improved with the rise in temperature (from 25 °C to 45 °C) while the sedimentation rate was found negligible above 45 °C. This detailed study methodology can be considered as a feasible process thus creating a possibility to treat fluorescent waste lamp powders for various industrial applications.

Aminoglycosides (AMGs) have been extensively used to treat infectious diseases caused by Gram-negative bacteria in livestock and humans. A selective and sensitive colorimetric probe for the determination of streptomycin and kanamycin was proposed based on chlortetracycline-coated silver nanoparticles (AgNPs&ndash, CTC) as the sensing element. Almost all of the tested aminoglycoside antibiotics can rapidly induce the aggregation of AgNPs, along with a color change from yellow to orange/red. The selective detection of aminoglycoside antibiotics, including tobramycin, streptomycin, amikacin, gentamicin, neomycin, and kanamycin, with other types of antibiotics, can be achieved by ultraviolet (UV) spectroscopy. This developed colorimetric assay has ability to detect various AMGs using in-depth surface plasmon resonance (SPR) studies. With this determination of streptomycin and kanamycin was achieved at the picomolar level (pM) by using a UV&ndash, visible spectrophotometer. Under aqueous conditions, the linear range of the colorimetric sensor for streptomycin and kanamycin was 1000&ndash, 1,1000 and 120&ndash, 480 pM, respectively. The corresponding limit of detection was 2000 pM and 120 pM, respectively. Thus, the validated dual colorimetric and ratiometric method can find various analytical applications for the ultrasensitive and rapid detection of AMG antibiotics in water samples.

This study reports the degradation and decolourization capability of a manganese peroxidase enzyme producing bacterium isolated from pulp and paper mill wastewater. The isolate was identified as Bacillus aryabhattai based on biochemical analysis and 16S rRNA gene sequencing. The strain was designated MG966493. This bacterium was able to reduce 67% and 54% colour and lignin, respectively, from the pulp and paper mill wastewater after 144 h of treatment at 32 °C, pH 7.6 and 120 rpm. Further, FT-IR analysis showed that during the lignin degradation process a number of metabolites were produced comprising different functional groups such as carbonyl (C=C), carboxyl (–COOH), alkene (C=C), amines (–NH(2)), sulphonic (–SO(3)) and nitro (–NO(2)). In addition, the SEM analysis showed that the bacterial cells exposed to pulp and paper mill wastewater have rough surfaces with reduced size as compared to the unexposed cells with smooth surfaces. This study concluded that the isolated bacterium B. aryabhattai has significant potential for the bioremediation of pulp and paper mill wastewater and thus, can be applied for their treatment at an industrial scale.

The current study presents a comprehensive comparison towards the potential of different microalgal-based materials for the removal of hexavalent chromium (Cr(VI)) from water. Among the tested materials, microalgal biochar showed the highest removal efficiency (100%) of Cr(VI). The highest monolayer estimated adsorption capacities were 23.98, 25.19 and 24.27 mg/g at 5, 22 and 35 °C, respectively. Experimental data showed good compliance with pseudo-second-order kinetic model. The results of continuous column studies showed that the column removal efficiency increased from 52.33 to 57.58% by increasing the adsorbent dose from 0.125 to 0.200 g. Desorption efficiency of Cr(VI) by 0.1 M NaOH was increased from 51.16 to 59.41% by sonication bath as compared to roller shaker. More than 97% of desorbed Cr(VI) was recovered in less than 10 min by BaCl2. This study shows that non-living microalga materials are more effective than living cells in the removal and recovery of Cr(VI) from water.

Through extracellular electron transfer (EET), bacteria are capable of transforming different insoluble materials of geochemical interest into energy-rich molecules for their growth. For this process, bacteria have been depending directly or indirectly on molecules synthesized within the cells or by various synthetics as mediators. Herein, we studied the in-situ change in electrochemistry and supporting components for EET in the extracellular polysaccharide (EPS) producing biofilm of thermophilic Geobacillus sp. The CV and DPV resultsrevealed that the intact biofilm of bacteria was not able to generate any potential at 25 °C /- ≤50 °C. However, at 55 °C (optimal condition), the potential occurred drastically after the EPS production by bacteria. HPLC and MALDI-TOF results revealed that the presence of Flavins, which can able adsorbed to the electrodes from the cell surface. Moreover, the temperature-dependent EPS production and originally conceived ability of flavins to act as electron shuttles suggest that not much complexity in bacteria with minerals. Additionally, the electrochemical potential was severely affected upon removal of EPS/flavin moiety from the intact biofilm, revealed the necessity of EPS bound flavins in transferring the electrons across its thick cell walls. This paradigm shift to electrogenic nature of Geobacillus sp. biofilm will become evident in the adaptation of other microbes during mineral respiration in extreme environments.

The presence of hazardous, radioactive, and rare earth metal such as yttrium (Y3+) in water poses a serious health concern to the public health, thus, exploring novel Y3+-binding molecules and colorimetric indicators are desired. Chlortetracycline (CTC)-functionalized silver nanoparticles (AgNPs–CTC) were synthesized, purified by centrifugation and then characterized by UV–vis spectroscopy, XPS, XRD, and HR-TEM. Functionalization of AgNPs with CTC molecules enabled the rapid and sensitive detection of trivalent yttrium ion (Y3+). A decrease in the intensity of the original surface plasmon resonance peak at 420 nm was observed within the fraction of a min, with the simultaneous appearance of a new peak at a longer wavelength (540 nm); thus, a novel colorimetric and ratiometric absorbance probe was achieved. The free-O-containing moieties of CTC on the AgNPs surface coordinate with Y3+. Thus, CTC molecules led to the bridging of the AgNPs and subsequent aggregation. A good linear relationship (R2 = 0.933) in the range of 18 to 243 nM for Y3+ was observed, and the limit of detection (LOD) for ratiometric results was approximately 57.7 nM. The AgNPs–CTC sensor exhibited better colorimetric performance in terms of excellent sensitivity, LOD, and rapid formation of the AgNPs-CTC complex towards Y3+. The Y3+ spiked water samples from different sources and fetal bovine serum suggest that the developed method is practically useful and essentially portable for on-site monitoring. The AgNPs–CTC sensor can be also applied as a common colorimetric indicator for the detection of trace levels of Y3+ and lanthanides.

International audience; This review provides the alternative routes towards the valorization of dark H-2 fermentation effluents that are mainly rich in volatile fatty acids such as acetate and butyrate. Various enhancement and alternative routes such as photo fermentation, anaerobic digestion, utilization of microbial electrochemical systems, and algal system towards the generation of bioenergy and electricity and also for efficient organic matter utilization are highlighted. What is more, various integration schemes and two-stage fermentation for the possible scale up are reviewed. Moreover, recent progress for enhanced performance towards waste stabilization and overall utilization of useful and higher COD present in the organic source into value-added products are extensively discussed.

Biogas production using algal resources has been widely studied as a green and alternative renewable technology. This review provides an extended overview of recent advances in biomethane production via direct anaerobic digestion (AD) of microalgae, macroalgae and co-digestion mechanism on biomethane production and future challenges and prospects for its scaled-up applications. The effects of pretreatment in the preparation of algal feedstock for methane generation are discussed briefly. The role of different operational and environmental parameters for instance pH, temperature, nutrients, organic loading rate (OLR) and hydraulic retention time (HRT) on sustainable methane generation are also reviewed. Finally, an outlook on the possible options towards the scale up and enhancement strategies has been provided. This review could encourage further studies in this area, to intend and operate continuous mode by designing stable and reliable bioreactor systems and to analyze the possibilities and potential of co-digestion for the promotion of algal-biomethane technology.

This study focuses on development of calcium peroxide (CaO2) pretreatment that removes major part of lignin but retaining most of sugar components of kenaf core powder (KCP) biomass. In chemical pretreatment, usually higher loss of biomass occurs which was less during this pretreatment strategy. Supplementation of inorganic salts; manganese sulfate (MnSO4) and cobalt chloride (COCl2) in CaO2 pretreatment resulted in maximum delignification of KCP relative to individual CaO2 pretreatment. Maximum glucose yield (98%) and hydrolysis yield (80.5%) was achieved after enzymatic hydrolysis (30 FPU/g of KCP) under optimized conditions. Analytical results proved effective lignin removal and significant destruction of KCP with this pretreatment strategy. Finally, utilization of KCP enzymatic hydrolysates by developed strain Klebsiella pneumoniae KMK05 resulted in maximum 2,3-butanediol (BDO) production (10.42 g/L) and BDO titer (0.385 g/g of sugar). BDO titer achieved with KCP derived sugars were found comparable with the mixture of standard sugars which is notable.

The purpose of this research was to improve microbial fuel cell (MFC) performance - treating landfill-derived waste liquor - by applying effluents of various biogas fermenters as inocula. It turned out that the differences of initial microbial community profiles notably influenced the efficiency of MFCs. In fact, the adaptation time (during 3 weeks of operation) has varied significantly, depending on the source of inoculum and accordingly, the obtainable cumulative energy yields were also greatly affected (65% enhancement in case of municipal wastewater sludge inoculum compared to sugar factory waste sludge inoculum). Hence, it could be concluded that the capacity of MFCs to utilize the complex feedstock was heavily dependent on biological factors such as the origin/history of inoculum, the microbial composition as well as proper acclimation period. Therefore, these parameters should be of primary concerns for adequate process design to efficiently generate electricity with microbial fuel cells.

A novel approach to explore the impact of calcium specific chelant - Ethylene glycol tetra acetic acid (EGTA) on deflocculation followed by biomass disintegration using microwave (MW) was investigated. In the first phase of the study, the EGTA dosage of 0.012 g/g suspended solids (SS) was found to be optimal for disassociating the biomass. Subsequent disintegration of biomass in microwave (EGTA-MW) yielded a biomass lysis and solids reduction of about 39.7% and 30.5%. EGTA-MW disintegration reduces the amount of specific energy required to disintegrate the biomass from 18,900 kJ/kg TS to 13,500 kJ/kg TS, when compared to control. The impact of EGTA-MW disintegration on anaerobic digestion was also evident from its methane yield (235.3 mL/g VS) which was 36.2% higher than control. An economic assessment of this study provides a net profit of 8.48 €/ton in EGTA-MW and highly endorsed for biomass disintegration.

Alkaline pretreatment using NaOH, KOH, or NaOCl has been applied to various types of waste biomass to enhance enzymatic digestibility. Pretreatment (2% NaOH, 121 °C, 30 min) of rice paddy straw (PS) resulted in a maximum yield of 703 mg of reducing sugar per gram of PS with 84.19% hydrolysis yield after a two-step enzymatic hydrolysis process. Ralstonia eutropha ATCC 17699 was tested for its ability to synthesize poly-3-hydroxybutyrate (PHB) using PS hydrolysates as its sole carbon source. It is noteworthy that dry cell weight, polyhydroxyalkanoate (PHA) accumulation and PHB yield with the use of laboratory-grade sugars were similar to those achieved with PS-derived sugars. Under optimized conditions, we observed maximal PHA accumulation (75.45%) and PHB production (11.42 g/L) within 48 h of fermentation. After PHB recovery, the physicochemical properties of PHB were determined by various analytical techniques, showed the results were consistent with the characteristics of a standard polymer of PHB. Thus, the PS hydrolysate proved to be an excellent cheap carbon substrate for PHB production.

The potential of isolated actinomycetes and fungi were evaluated for the cellulase and xylanase production under solid state fermentation conditions. Maximal secretion of enzymes was observed with Phanerochaete chrysosporium using soybean straw. The potential of the produced crude enzyme complex was demonstrated by two-step enzymatic hydrolysis of untreated and mild acidpretreated sorghum husk (SH). A cellulase dose of 10 filter paper units (FPU) released 563.21 mg of reducing sugar (RS) per gram of SH with 84.45% hydrolysis and 53.64% glucose yields, respectively. Finally, enzymatic hydrolysates of SH were utilized for hydrogen production by Clostridium beijerinckii. Effects of temperature, pH of media, and substrate concentration on the biohydrogen production from SH hydrolysates were investigated. The optimal conditions for maximal hydrogen production using SH hydrolysate were determined to be a loading of 5.0 g RS/L, at 35°C, and controlled pH at 5.5. Under these optimal conditions, the cumulative H2 production, H2 production rate, and H2 yield were 1,117 mL/L, 46.54 mL/L/h, and 1.051 mol/mol RS, respectively. These results demonstrated a cost-effective hydrogen production is possible with sorghum husk as a lignocellulosic feedstock.