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Bio(nano)cleaning: Bio(nano)purification and Bio(nano)remediation
Published in Naveen Dwivedi, Shubha Dwivedi, Bionanotechnology Towards Sustainable Management of Environmental Pollution, 2023
With silver nitrate and aqueous extracts of cyanobacteria Synechococcus elongatus and Microcystis aeruginosa and microalgae, the chlorophytes Coelastrum astroideum and Desmodesmus armatus, and the charophytes Cosmarium punctulatum and Klebsormidium flaccidum were synthesized silver nanoparticles. In all syntheses, nanoparticles were of well dispersed, crystalline, spherical shape with a size range of 1.8 to 5.4 nm and with no agglomerate formed. The presence of hydroxyl groups of peptidoglycan nature, acting as stabilizing agents in the surface of the nanoparticles, determines the formation of nanoparticles with a rather narrow size dispersity and prevents agglomeration (Moraes et al., 2021).
Rapidly Changing Environment and Role of Microbiome in Restoring and Creating Sustainable Approaches
Published in Suhaib A. Bandh, Javid A. Parray, Nowsheen Shameem, Climate Change and Microbial Diversity, 2023
Manishankar Chakraborty, Udaya Kumar Vandana, Debayan Nandi, Lakkakula Satish, P.B. Mazumder
Cyanobacteria have high energy densities compatibility to present full processing plants and application in food industries, alcohols are mostly produced and studied chemical produced by the strains Synechococcus elongatus 7942 and Synechocystis spp. 6803. Ethanol has been produced in high titters and improved productivity at 212 mg/L/day and 5.5 g/L in Synechocystis 6803.
Exploring the Potential of Cyanobacterial Biomass for Bioethanol Production
Published in Jitendra Kumar Saini, Surender Singh, Lata Nain, Sustainable Microbial Technologies for Valorization of Agro-Industrial Wastes, 2023
Nirmal Renuka, Sachitra Kumar Ratha, Virthie Bhola, V. Kokila, Lata Nain, Faizal Bux, Radha Prasanna
Investigations undertaken in this context have led to the development of a number of mutants which do not store photosynthate in the form of glycogen or polyhydroxybutyrate, such as those having a deletion of glgC (glucose-1-phosphate adenylyl transferase) (Xu et al. 2012). The glgC mutant of Synechocystis sp. PCC 6803 is able to grow photoautotrophically in continuous light, with no decrease in growth rate, but exhibit unusual physiology under mixotrophic growth, light/dark cycles, high light intensities, and nitrogen deprivation than wild type (WT) (Carrieri et al. 2012). Accumulation of polyhydroxy butyrate is also observed in some cyanobacteria (Beck et al. 2012). Huang et al. (2016) targeted the rewiring of metabolic networks in cyanobacteria by using CRISPR interference (CRISPRi), by suppressing the transcript levels of genes essential for the accumulation of glycogen (glgC) and the conversion of succinate to fumarate (sdhA and sdhB) in Synechococcus elongatus (PCC 7942). More importantly, cyanobacteria can be efficient as cell factories for ethanol production. The stoichiometric energy yield for ethanol was found comparable with other potential fuel metabolites, paving the way for focused research on utilizing these feedstocks for bioethanol production (Kamarainen et al. 2012).
Current status and future prospects of biological routes to bio-based products using raw materials, wastes, and residues as renewable resources
Published in Critical Reviews in Environmental Science and Technology, 2022
Ji-Young Lee, Sung-Eun Lee, Dong-Woo Lee
Advanced biofuel production has been aided by metabolic engineering of microbial pathways in bacteria, yeast, and green algae (Liao et al., 2016; Zhang et al., 2011). The four major pathways targeted to date are (1) fermentative pathways, (2) 2-keto-acid pathways for short- and medium-chain alcohols, (3) isoprenoid pathways, and (4) fatty acid pathways (Figure 5). In the case of S. cerevisiae, expression of glycerol utilization genes, heterologous overexpression of key enzymes for fatty acid ester biosynthesis (wax ester synthase/acyl-coenzyme A:diacylglycerol acyltransferase), and deletion of genes involved in glycerol production enhanced the production of fatty acid ethyl esters (FAEEs) from glycerol, with a high FAEE yield and productivity (Yu et al., 2012). Moreover, heterologous expression of a 2-keto acid decarboxylase and an alcohol dehydrogenase (ADH) enabled E. coli cells to produce various short-chain alcohols (isobutanol, 3-methyl-1-butanol, 1-propanol, 1-butanol, and others) by diverting flux into amino acid bio-synthetic pathways (Atsumi et al., 2008). Similarly, an engineered Clostridium cellulolyticum strain could directly convert crystalline cellulose to isobutanol using its indigenous cellulases and amino acid biosynthesis pathway (Gaida et al., 2016; Higashide et al., 2011). Upon addition of ADH genes from E. coli and Lactococcus lactis, the pathway from 2-keto acid intermediates was diverted toward alcohol synthesis (Higashide et al., 2011). Using the same approach, a genetically-engineered Synechococcus elongatus strain could directly convert CO2 to isobutanol through photosynthesis, resulting in increased productivity due to overexpression of ribulose-1,5-bisphosphate carboxylase/oxygenase (Atsumi et al., 2009).