Over the last several decades, concerns about climate change and pollution due to human activity has gained widespread attention. Microalgae have been proposed as a suitable biological platform to reduce carbon dioxide, a major greenhouse gas, while also creating commercial sources of high-value compounds such as medicines, cosmetics, food, feed, and biofuel. Industrialization of microalgae culture and valorization is still limited by significant challenges in scaling up the production processes due to economic constraints and productivity capacities. Therefore, a boost in resource usage efficiency is required. This enhancement not only lowers manufacturing costs but also enhancing the long-term viability of microalgae-based products. Using wastewater as a nutrient source is a great way to reduce manufacturing costs. Furthermore, water scarcity is one of the most important global challenges. In recent decades, industrialization, globalization, and population growth have all impacted freshwater resources. Moreover, high amounts of organic and inorganic toxins in the water due to the disposal of waste into rivers can have severe impacts on human and animal health. Microalgae cultures are a sustainable solution to tertiary and quaternary treatments since they have the ability to digest complex contaminants. This review presents biorefineries based on microalgae from all angles, including the potential for environmental pollution remediation as well as applications for bioenergy and value-added biomolecule production. An overview of current information about microalgae-based technology and a discussion of the associated hazards and opportunities for the bioeconomy are highlighted.
Aspergillus terreus was reported as the promising fungal strain for itaconic acid; however, the commercial production suffers from the low yield. Low production yield was claimed as the result of completing the tricarboxylic acid (TCA) cycle towards biomass synthesis while under limiting phosphate and nitrogen; TCA cycle was somewhat shunted and consequently, the metabolite fluxes move towards itaconic acid production route. By regulating enzymes in TCA cycle, it is believed that itaconic acid production can be improved. One of the key responsible enzymes involved in itaconic acid production was triggered in this study. Pyruvate carboxylase was allosterically inhibited by L-aspartate. The presence of 10 mM L-aspartate in the production medium directly repressed PC expression in the living A. terreus while the limited malate flux regulated the malate/citrate antiporters resulting in the increasing cis-aconitate decarboxylase activity to simultaneously convert cis-aconitate, citrate isomer, into itaconic acid. The transport of cis-aconitate via the antiporters induced citrate synthase and 6-phosphofructo-1-kinase activities in response to balance the fluxes of TCA intermediates. Successively, itaconic acid production yield and final concentration could be improved by 8.33 and 60.32 %, respectively, compared to those obtained from the control fermentation with the shortened lag time to produce itaconic acid during the production phase.
The objective of this study is to obtain new laccase and enzyme source with remarkable dye removal potential. Thirty isolates of white rot fungi were screened for extracellular laccase-production using 2,2azinobis (3-ethylbenzothiazoline-6-sulfonate) (ABTS) assay as indicator. Among these, Polyporus pseudobetulinus strain WR77 exhibits the highest laccase activity and its suitable enzyme production medium contains; 1% (w/v) rice chaff, 0.5 g/L di-ammonium tartrate, and 0.01 g/L peptone as the carbon; inorganic and organic nitrogen sources; respectively. The laccase was 60-fold concentrated (by ammonium sulphate precipitation, Q-sepharose anion-exchange chromatography, and Superdex G-75 gel filtration chromatography) and gave the specific activity of 617.12 U/mg. The MW of prepared enzyme is 75.2 kDa under SDS-PAGE determination. Empirical analyzing results indicate that the optimum pH and temperature of the enzyme are around 40°C and pH 4, respectively. Furthermore, this enzyme can resist to wide pH range (4.0-11.0) with more than 95% maximum activity remained. The enzyme's K m and V max , with ABTS substrate, were 447.93 M and 104.17 µmol/min/mg protein, respectively. The prepared enzyme was strongly inhibited by Hg 2+ and Fe 2+ but weakly (9.7%) stimulated by 10 mM Cu 2+ ions. The strain WR77 shows good ability in decolorizing many synthetic dyes (200 mg/L initial concentration); Ambifix Blue H3R (98% in 8 days), Ambifix Yellow H3R (24% in 10 days) and Ambifix Red HE3B (50% in 18 days). The prepared laccase alone (5 U/ml) could decolorize Ambifix Blue H3R by 65% within 15 min and Malachite Green by 80% within 24 h. It can be concluded that new enzyme and source with satisfactory dye removal potential have been successfully achieved. Further studies should be attempted to evaluate their feasibility in industrial uses.
Ethanol was found as the major by-product in lactate fermentation by Rhizopus oryzae. Several methods have been conducted in order to limit ethanol formation, thus increasing the lactate yield. The direct way to suppress ethanol production can be done by inhibition of the responsible enzymes in the related pathway. Pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) are responsible for ethanol production in R. oryzae. Shunting the ethanol production pathway by targeting at PDC was attempted in this study. Three compounds including 4-methylpyrazole, glyoxylic acid, and 3-hydroxypyruvate with the in vitro reversible inhibitory effect on PDC were selected from the literature and were used to regulate the living cell of R. oryzae during the fermentation. The results show that 0.1 mM 4-methylpyrazole of which the structure resembled a thiazolium ring in thiamine diphosphate, PDC cofactor, and 1.0 μm 3-hydroxypyruvate, pyruvate analog, effectively hampered ethanol production. Further observation on the enzyme expression indicated that these two regulators not only targeted PDC but also caused changes in ADH and lactate dehydrogenase (LDH) activities. This was perhaps due to the living cell of R. oryzae that responded to the presence of the regulators to balance the pyruvate flux and subsequently maintain its metabolic activities.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.