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Genomics of PHA Synthesizing Bacteria
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Parveen K. Sharma, Jilagamazhi Fu, Nisha Mohanan, David B. Levin
The enzymes involved in mcl-PHA polymer synthesis are encoded by six genes that are organized into a PHA synthesis operon, which is identical in all the Pseudomonas strains analyzed. The six genes are phaC1, phaZ, phaC2, phaD, phaF, and phaI. The mcl-PHA biosynthesis cluster forms two putative transcriptional units: phaC1-phaZ-phaC2-phaD and phaF-phaI, which are under the regulation of a transcriptional regulator, PhaD [54]. The regulator was thought to be activated by an intermediate from the fatty acid β-oxidation pathway, resulting in higher transcriptional levels of mcl-PHA synthesis genes when the cell is grown -on fatty acid substrates (such as octanoic acid) versus glucose (Figure 3.3). The phaZ encodes a PHA depolymerase, which hydrolyzes the PHA monomers when they are required as a carbon source and are catabolized via a central metabolism for growth [55,56]. PhaF and phaI encode phasin proteins involved in PHA granule structure and size [57].
Physical Properties of Individual Groundwater Chemicals
Published in John H. Montgomery, Thomas Roy Crompton, Environmental Chemicals Desk Reference, 2017
John H. Montgomery, Thomas Roy Crompton
Biological. n-Octane may biodegrade in two ways. This first is the formation of octyl hydroperoxide, which decomposes to 1-octanol followed by oxidation to octanoic acid. The other pathway involves dehydrogenation to 1-octene, which may react with water giving 1-octanol (Dugan, 1972). 1-Octanol was reported as the biodegradation product of octane by a Pseudomonas sp. (Riser-Roberts, 1992). Microorganisms can oxidize alkanes under aerobic conditions (Singer and Finnerty, 1984). The most common degradative pathway involves the oxidation of the terminal methyl group, forming the corresponding alcohol (1-octanol). The alcohol may undergo a series of dehydrogenation steps, forming an aldehyde (octanal) then a fatty acid (octanoic acid). The fatty acid may then be metabolized by β-oxidation to form the mineralization products, carbon dioxide and water (Singer and Finnerty, 1984).
Hydrothermal And Thermochemical Synthesis of Bio-Oil from Lignocellulosic Biomass: Composition, Engineering and Catalytic Upgrading
Published in Devarajan Thangadurai, Jeyabalan Sangeetha, Industrial Biotechnology, 2017
Sonil Nanda, Pravakar Mohanty, Janusz A. Kozinski, Ajay K. Dalai
Hydrothermal conversion of several model components, microalgae and cyanobacteria were studied at various concentrations of HCOOH and Na2CO3 (Biller and Ross, 2011). The microalgae used in the study were Chlorella vulgaris, Nannochloropsis occulata and Porphyridium cruentum, and the cyanobacteria used was Spirulina. The study on model compound was used to predict the liquid yield from microalgae. The bio-crude from Chlorella with Na2CO3 contained phenols and piperdine-derived compounds and alkanes. Water and HCOOH processing resulted in aliphatic amides such as dimethyldecanamide, dodecamine and fatty acid octanoic acid. Nannochloropsis, which had high lipid content, resulted in the bio-crude containing large amounts of fatty acids and heterocycles such as indole. The HCOOH processing resulted in the formation of aliphatic amide hexadacamide and fatty acid tetradecanoic acid. The higher fraction of nitrogen heterocycles, pyrroles and indoles in the biocrude was observed with hydrolysis of algal feedstock and Na2CO3. The use of Na2CO3 increased the formation of phenolic compounds and stimulated the breakdown of lipids to alkanes, while water and HCOOH resulted in the lipids breakdown to fatty acids. Table 12.3 lists a few waste biomasses and their hot compressed water conversion.
Synthesis and modelling of the mechanical properties of Ag, Au and Cu nanowires
Published in Science and Technology of Advanced Materials, 2019
Nurul Akmal Che Lah, Sonia Trigueros
A new type of 1D Ag nanostructures, that is Ag nanocables (with larger aspect ratios and smaller line widths) has been synthesised using a combination of hard and soft templates growth methods (Figure 3(b)) [113]. The hybrid nanocable structure of Ag- polymer involve a complex process with hybrid organic reagents, where the system requires more than one different blocks or topologies [114]. The anodic membrane (e.g. anodic alumina membrane (AAM)) is the type of hard template used in the process to assist the uniform and ordered pores structure. For example, Ag nanocables wrapped in nanosheath polystyrene involves the channelling of metal solution into the void channels was through the self-assembly of Pluronic F127 and EG. F127 acted not only as the soft template but also as the guiding agent and reductant to the precursor used in the solution. The system is indeed highly conductive compared to other nanocables reported before. In the case of Ag nanotubes, the first hollow nanotube was created through the assistance of fatty acid (e.g. octanoic acid) [115].
Quantitative structure–activity and quantitative structure–property relationship approaches as alternative skin sensitization risk assessment methods
Published in Journal of Toxicology and Environmental Health, Part A, 2019
Ji Yun Kim, Min Kook Kim, Kyu-Bong Kim, Hyung Sik Kim, Byung-Mu Lee
The following 38 non-skin sensitizers were selected: 2-hydroxypropyl 2-methylacrylate (2H2M); diethyl phthalate (DEPL); dextran (DEX); kanamycin (KNMC); streptomycin sulfate (SMCS); allyl acetate (AACT); 1-chloro-3-iodopropane (1C3I); cyclooctanol (CCO); nonanoic acid (NNA); 2-butoxyethyl acetate (2BTE); vinylidene dichloride (VDC); citralva (CTV); 1-iodohexane (1IDH); isopentyl alcohol (ISAC) octanenitrile (OCTT); dibutyl phthalate (DBP); dimethyl formamide (DMFA); 2-methyl-2-butenal (2M2B); zinc sulfate (ZSFT); benzalkonium chloride (BKC); 2,4,6-trimethylcyclohex-3-ene-1-methanol (TRCM); hexane (HE); isopropanol (IPP); methyl salicylate (MS); sodium lauryl sulfate (SLS); 2-acetylcyclohexane (2-AC); benzaldehyde (BZ); cyclopentanepropanol (CYCP); 1-bromobutane (1-BR); 1-butanol (1-BT); chlorobenzene (CBZ); 1-chlorononane (1-CR); coumarin (CM); benzoylactate (EBA); diethyltoluamide (DETA); 3-bromopropanoic acid methyl ester (3BAME); octanoic acid (OA); and propylene glycol (PG). The EC3 values of all materials were obtained from reported LLNA data (Basketter, Gerberick, and Kimber 2007; Basketter and Kimber 2001; Basketter, Smith Pease, and Patlewicz 2003; Gerberick et al. 2007a, 2007b; Kimber et al. 1998; Nepal et al. 2018; National Institutes of Health 2009; Takenouchi et al. 2013) and classified by skin sensitization potency (Table 1; European Centre for Ecotoxicology and Toxicology of Chemicals 2003a; 2003b).
Rhamnolipid production using Shewanella seohaensis BS18 and evaluation of its efficiency along with phytoremediation and bioaugmentation for bioremediation of hydrocarbon contaminated soils
Published in International Journal of Phytoremediation, 2019
Gomathi Ram, Manoharan Melvin Joe, Shalini Devraj, Abitha Benson
TLC analysis revealed the presence of di- and mono-rhamnolipids based on the spots at Rf value of 0.38 and 0.86 (Figure S1b). The occurrence of these two bands confirmed the presence of di- and mono-rhamnolipid type BSs. The di-rhamnolipid fraction could only be separated and this fraction was used for further study. FTIR analysis confirmed the presence of a rhamnolipid type BS based on the peaks located at 2929, 1641, and 1401 cm−1, which correspond to the presence of C=H, C=O, and CH/OH stretching vibrations (Figure 3a). GC–MS analysis was done to identify the major fatty acids in the rhamnolipid and the results are provided in Figure 3b. GC–MS analysis shows the predominance of hexanedioic acid bis (2-ethylhexyl) ester and octadecanoic acid methyl ester as the major fatty acids in the rhamnolipid. These results on the mono- and di-rhamnolipid bands in TLC and the visibility of CH2/CH3 and COO stretching vibrations for the separated rhamnolipid type BS go well with the earlier reports of Nalini et al. (2016) and Sakthipriya et al. (2015). Leitermann et al. (2008), reported that peaks at 2921/2855 describe the C=H stretching vibrations of aliphatic groups, which represent the hydroxydecanoic acid chain for the rhamnolipid type BS. Furthermore, the vibrations in the fingerprint region of 1200–1460 cm−1, represent the CH/OH deformation, which are typical for carbohydrates. Results on GC–MS analysis of fatty acids in the rhamnolipid goes well with the previous study of Sakthipriya et al. (2015), who reported the presence of hexadecanoic acid and methyl ester of octanoic acid in the isolated rhamnolipid indicating the presence of Rha-C10 and Rha-C8 components.