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α-Amylases are the oldest and versatile starch hydrolysing enzymes which can replace chemical hydrolysis of starch in industries. It cleaves the α-(1,4)-D-glucosidic linkage of starch and other related polysaccharides to yield simple sugars like glucose, maltose and limit dextrin. α-Amylase covers about 30% shares of the total enzyme market. On account of their superior features, α-amylase is the most widely used among all the existing amylases for hydrolysis of polysaccharides. Endo-acting α-amylase of glycoside hydrolase family 13 is an extensively used biocatalyst and has various biotechnological applications like in starch processing, detergent, textile, paper and pharmaceutical industries. Apart from these, it has some novel applications including polymeric material for drug delivery, bioremediating agent, biodemulsifier and biofilm inhibitor. The present review will accomplish the research gap by providing the unexplored aspects of microbial α-amylase. It will allow the readers to know about the works that have already been done and the latest trends in this field. The manuscript has covered the latest immobilization techniques and the site-directed mutagenesis approaches which are readily being performed to confer the desirable property in wild-type α-amylases. Furthermore, it will state the inadequacies and the numerous obstacles coming in the way of its production during upstream and downstream steps and will also suggest some measures to obtain stable and industrial-grade α-amylase.

Nanoparticle is a miraculous material of this modern era due to their exceptional applications in various sectors (pharmaceutical, medical, cosmetics, paints, waste treatment process, etc.). In current study, zinc oxide nanoparticles (ZnO NPs) was synthesised using a green approach with Aegle marmelos (Bael) plant leaf extract as reducing agent. Characteristics of synthesised ZnO nanoparticles were examined with Fourier Transform Infrared Spectroscopy and UV-visible spectroscopy. The UV-vis spectroscopy study confirmed the formation of nanoparticles, showed a peak between 220-230 nm. FTIR spectroscopy was used to detect the specific functional groups involved in reducing and stabilizing during the biosynthesis process. Various applications were performed like; antibacterial properties and chromium metal adsorption. Antibacterial activity were analysed using well diffusion method. Nanoparticles of Zinc oxide were highly effective against gram-positive bacteria (Staphylococcus aureus and Bacillus cereus) and gram-negative bacteria (Escherichia coli and Salmonella typhi). So, they can be used as an excellent antibacterial agent for biological purposes. In metal removal, zinc oxide nanoparticle removes about 50% of the chromium from water through adsorption. Current study showed synthesis of ZnO nanoparticle through green approach will have great potential in antibacterial activity and treatment of chromium metal contaminated water.

α-Amylase is the most significant glycoside hydrolase having applications in various industries. It cleaves the α,1–4 glucosidic linkages of polysaccharides like starch, glycogen to yield a small polymer of glucose in α-anomeric configuration. α-Amylase is produced by all the three domains of life but microorganisms are preferred sources for industrial-scale production due to several advantages. Enormous studies and research have been done in this field in the past few decades. Still, it is requisite to work on enzyme stability and catalysis, as it loses its functionality in extreme. As the enzyme loses its structural and catalytic property under extreme environmental conditions, it is mandatory to confer some potential strategies for enhancing enzyme behaviour in such conditions. This limitation of an enzyme can be overcome up to some extent by extremophiles. They serve as an excellent source of α-amylase with outstanding features. This review is an attempt to encapsulate some structure-based strategies for improving enzyme behaviour thereby enabling researchers to selectively amend any of the strategies as per requirement during upstream and downstream processing for higher enzyme yield and stability. Thus, it will provide some cutting-edge strategies for tailoring α-amylase producing organism and enzyme with the help of several computational biology tools.

The growing consumption of fossil fuels like coal, petroleum, and diesel releases greenhouse gases that ultimately deteriorate the air quality. Moreover, fossil fuels pose serious threats like global warming, ocean acidification, unusual climate change and ecosystem fluctuation to the environment and human health. Biofuel is a feasible and sustainable alternative to overcome the limitations of fossil fuels. Among all the biofuels, bioethanol is currently in trend. The industrial-scale bioethanol production is a time-consuming process due to the non-availability of potential techniques and instrumentation. The pretreatment of rigid and recalcitrant lignocellulosic biomass to release fermentable sugars is crucial in the bioethanol production process. Conventionally it was done through physical, chemical and biological methods that demand high energy input, temperature, pressure, efficient organisms, expensive chemicals and solvents to loosen the compact structure of the raw materials. All these methods are sophisticated and expensive which results in the formation of harmful and inhibitory compounds and may also cause equipment corrosion. In this context, the introduction of nanotechnology in bioethanol production has shown improvement on a large scale. The small size, sturdiness and high surface to volume ratio of nanoparticles make them suitable for application in bioethanol production. Thus, the current review provides an insight into the role of nanotechnology in the various steps of the bioethanol production process. The paper will focus on the application of various nanomaterials and nanobiocatalyst in boosting the conversion of rigid lignocellulosic feedstock into fermentable sugar and facilitating the extent of reaction during fermentation for higher bioethanol yield. Graphical Abstract

The demand for an alternative source of energy is an imperative requirement of the current time. Second-generation biofuel (bioethanol) is capable of overcoming the problem of energy crises soon. Bioethanol production from agricultural by-products is an effective and sustainable approach. Bioethanol from agro-waste residues fulfil the energy demand and also reduce the pollution load of the environment. The present study was based on bioethanol production from cheap lignocellulosic agro-waste ‘rice husk’ by using  Klebsiella oxytoca  ATCC 13182 and standardization of production parameters and determining proficient pretreatment strategies. The present investigation reveals that bioethanol production can be enhanced significantly up to 32.61 ± 0.45 g/L at pH 7, 36 °C after 48–72 h of incubation. The nitrogen supplementation like ammonium chloride, peptone, and beef extract increased bioethanol production up to 38.95 ± 0.65 g/L, 42.29 ± 0.01 g/L, 43.23 ± 0.71 g/L respectively. Among the trace metals and ions analyzed, the highest bioethanol production (44.60 ± 0.11 g/L) and (35.13 ± 0.01 g/L) was obtained in Zn 2+ and MgCl 2 supplementation respectively. Out of all the pretreatment approaches analyzed, the acid and biological pretreatment (particularly with  Aspergillus niger ) had enhanced the bioethanol production (47.98 ± 1.25 g/L) up to 1.47 fold. Therefore, the current study will provide complete standardized parameters with an effective pretreatment strategy for utilizing lignocellulosic agro-wastes as an efficient and economical substrate for bioethanol production. Graphical Abstract

BackgroundTandem occlusions of the extracranial carotid and intracranial carotid or middle cerebral artery have a particularly poor prognosis without treatment. Several management strategies have been used with no clear consensus recommendations. We examined subjects with tandem occlusions enrolled in the ESCAPE trial and their outcomes.MethodsData are from the ESCAPE trial. Additional data were sought on interventions for each subject.ResultsThere were 54 (17%) subjects with tandem extracranial and intracranial occlusions. Patients in the endovascular treatment arm (n=30) were more likely to be younger (median age 66 years, p<0.01), male (66.7%, p=0.03), diabetic, and without atrial fibrillation. Subjects with tandem occlusions were more likely to have intracranial internal carotid artery occlusions than M1 occlusions (p<0.01). Of the 30 intervention-arm subjects, 17 (57%) underwent emergency endovascular treatment of the extracranial disease, 10 subjects before and seven subjects after intracranial thrombectomy. Of the remaining 13 subjects, only four required staged carotid revascularization due to persistent severe carotid stenosis; four had cervical pseudo-occlusions with no residual stenosis after large distal carotid thrombus burden aspiration/retrieval. Outcomes were similar between subjects with and without tandem lesions. The use of antithrombotic agents after acute carotid artery stenting was variable but no symptomatic intracerebral hemorrhage was seen in subjects who underwent emergency endovascular treatment of extracranial carotid artery.ConclusionsTandem occlusions occurred in one-sixth of patients and were treated highly variably within the ESCAPE trial. While outcomes were similar, the best method to treat the carotid artery in patients with tandem occlusion awaits further randomized data.Trial registration numberNCT01778335.