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The bioprocessing of lignocellulosic biomass to produce bio-based products under biorefinery setup is gaining global attention. The economic viability of this biorefinery would be inclined by the efficient bioconversion of all three major constituents of lignocellulosic biomass i.e. cellulose, hemicellulose, and lignin for value-added biochemicals and biofuels production. Although the lignocellulosic biorefinery setup has a clear value proposition, the commercial success at the industrial scale is still inadequate. This can be attributed mainly to irregular biomass supply chain, market uncertainties, and scale-up challenges. Global research efforts are underway by public and private sectors to get deeper market penetration. A comprehensive account of important factors, limitations, and propositions are worth consideration for the commercial success of lignocellulosic biorefineries. In this article, the importance of integration of lignocellulosic biorefineries with existing petrochemical refineries, the technical challenges of industrialization, SWOT analysis, and future directions have been reviewed., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The production of bioethanol was studied by the cultivation of Clostridium thermocellum ATCC 31924 in MTC medium including crystalline cellulose as the sole substrate. The effects of key operational parameters that affect bioethanol production from microcrystalline cellulose were optimized. Under optimum conditions (pH 8.0, temperature 55 °C, inoculum size 4% (v/v) and 0.5% (w/v) substrate concentration), a maximum ethanol yield of 0.30 g ethanol/g cellulose consumed and 95.32% cellulose conversion was obtained. An inclusion of modest acetate concentration in the medium showed that carbon flux shifted away from lactate accompanied by 20% increase in ethanol production. It suggests that strain ATCC 31924 differed in its cellulose conversion efficacy and optimum pH requirements compared to the other reported strains of Clostridium thermocellum. The purified cellulosome of strain ATCC 31924 found to be rich in both cellulase and xylanase enzymes emphasizing the importance of this strain for the degradation of lignocellulosic biomass., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Marine microalgae present a renewable alternative source for sustainable production of omega-3 fatty acids, as compared to conventional sources such as krill oil and fish oil. In this study, we optimised a method for lipid extraction from marine thraustochytrids using a bead mill and enzymatic concentration of omega-3 fatty acids from the thraustochytrid oil. The optimised lipid extraction conditions were, bead size 0.4-0.6μm, 4500rpm, 4min of processing time at 5g biomass concentration. The maximum lipid yield (% dry weight basis) achieved at optimum conditions were 40.5% for Schizochytrium sp. S31 (ATCC) and 49.4% for Schizochytrium sp. DT3 (in-house isolate). DT3 oil contained 39.8% docosahexaenoic acid (DHA) as a percentage of lipid, a higher DHA percentage than S31. Partial hydrolysis of DT3 oil using Candida rugosa lipase was performed to enrich omega-3 polyunsaturated fatty acids (PUFAs) in the glyceride portion. Total omega-3 fatty acid content was increased to 88.7%., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

In this work, a newly isolated marine thraustochytrid strain, Schizochytrium sp. DT3, was used for omega-3 fatty acid production by growing on lignocellulose biomass obtained from local hemp hurd (Cannabis sativa) biomass. Prior to enzymatic hydrolysis, hemp was pretreated with sodium hydroxide to open the biomass structure for the production of sugar hydrolysate. The thraustochytrid strain was able to grow on the sugar hydrolysate and accumulated polyunsaturated fatty acids (PUFAs). At the lowest carbon concentration of 2%, the PUFAs productivity was 71% in glucose and 59% in the sugars hydrolysate, as a percentage of total fatty acids. Saturated fatty acids (SFAs) levels were highest at about 49% of TFA using 6% glucose as the carbon source. SFAs of 41% were produced using 2% of SH. This study demonstrates that SH produced from lignocellulose biomass is a potentially useful carbon source for the production of omega-3 fatty acids in thraustochytrids, as demonstrated using the new strain, Schizochytrium sp. DT3., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The suitability of optimised ultrafine Eri silk microparticles as novel enzyme supports was studied for potential application in biofuel production. β-glucosidase (BGL) from Aspergillus niger was immobilised on Eri silk fibrion particles via an adsorption method resulting in a 62% immobilisation yield. Soluble and immobilised enzymes exhibited pH-optima at pH 4.0 and 5.0, respectively with optimum activity at 60°C. The Michaelis constant (K(M)) was 0.16 and 0.27 mM for soluble and immobilised BGL respectively. The immobilisation support has a protective effect on the enzyme by increasing rigidity; this is reflected by an increase in stability under thermal denaturation at 70°C. Immobilised enzyme retained more than 50% of initial activity for up to eight cycles. Maximum cellobiose hydrolysis by immobilised BGL was achieved at 20 h. Crystalline ultrafine Eri silk particles were found to be a promising viable, environmentally sound and stable matrix for binding BGL for cellobiose hydrolysis., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

A fast growing strain of Chlorella saccharophila was isolated from the marine water of New Zealand and grown in heterotrophic conditions using glucose or glycerol as a carbon source. Biomass production was found to be higher in culture fed with glucose (2.14±0.08 g L(-1)) as compared to glycerol (0.378±0.04 g L(-1)). Lipid accumulation was similar for both carbon sources, at approximately 22% of dry cell weight. However, carotenoid yield was higher with glycerol (0.406±0.0125 mg g(-1)) than with glucose (0.21±0.034 mg g(-1)). Further optimization of the growth of the isolate gave maximal carotenoid production of 16.39±1.19 mg g(-1) total carotenoid, containing 11.32±0.64 mg g(-1) zeaxanthin and 5.07±0.55 mg g(-1) β-carotene. Comparison of various chemical and physical carotenoid extraction methods showed that ultrasonication was required for maximum extraction yields. The new strain has potential for biofuel, with carotenoid co-production., (Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.)

The objective of the present work was to develop a thermostable β-glucosidase through immobilization on a nanoscale carrier for potential application in biofuel production. β-Glucosidase (BGL) from Aspergillus niger was immobilized to functionalized magnetic nanoparticles by covalent binding. Immobilized nanoparticles showed 93% immobilization binding. Immobilized and free BGL were characterized using Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) techniques. Free and immobilized enzyme exhibited different pH-optima at pH 4.0 and 6.0, respectively, but had the same temperature optima at 60 °C. Michaelis constant (KM) was 3.5 and 4.3mM for free and immobilized BGL. Thermal stability of the immobilized enzyme was enhanced at 70 °C. The immobilized nanoparticle-enzyme conjugate retained more than 50% enzyme activity up to the 16th cycle. Maximum glucose synthesis from cellobiose hydrolysis by immobilized BGL was achieved at 16 h., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Metagenomics provides culture-independent access to gene pool of the whole microbial communities. To identify genes responsible for salt tolerance in unculturable bacteria, Escherichia coli clones were enriched with an ability to grow at inhibitory NaCl concentrations (750mM) from a pond water metagenomic library. From two unique clones, genes encoding for proteins with similarity to a putative general stress protein (GspM) harbouring GsiB domain and a putative enoyl-CoA hydratase (EchM) were identified to be responsible for salt tolerance. The gspM was expressed by its native promoter whereas the echM was expressed from the lacZ promoter of the plasmid. EchM was overexpressed with a hexahistidyl tag. Purified EchM showed crotonyl-CoA hydratase activity. These genes have potential application in generating salt tolerant recombinant bacteria or transgenic plants., (Copyright 2010 Elsevier Ltd. All rights reserved.)