China 
Africa 
Explore chapters and articles related to this topic
Mortierella Isabellina
Published in Mark R. Servos, Kelly R. Munkittrick, John H. Carey, Glen J. Van Der Kraak, and PAPER MILL EFFLUENTS, 2020
A.G. Werker, P.A. Bicho, J.N. Saddler, E.R. Hall
Biological growth as marked by the depression in pH and the increase in optical density is paralleled by the consumption of TOC (Fig. 5). An offset is maintained between the TOC for the culture with DHA versus the one without DHA. Based on previous reports (Kutney 1981a), this offset, deemed to be related to the additional organic carbon added as DHA, was taken as an indication that the resin acid was not mineralized but only transformed by the fungus. M. isabellina is known to detoxify DHA through membrane bound (Servizi et al. 1986) hydroxylation reactions at C-2 with subsequent hydroxylation at C-15 or C-16 (Fig. 6). Secondary hydroxylation occurs only for resting cell cultures. Hydroxylation will increase the polarity of the diterpene molecule and thereby increase its water solubility. The improved water solubility is likely linked to the corresponding decrease in toxicity.
Environmental Fate and Transport of Solvent-Stabilizer Compounds
Published in Thomas K.G. Mohr, William H. DiGuiseppi, Janet K. Anderson, James W. Hatton, Jeremy Bishop, Barrie Selcoe, William B. Kappleman, Environmental Investigation and Remediation, 2020
Thomas K.G. Mohr, James Hatton
The pathway for aerobic degradation of 1,4-dioxane parallels that of THF, which involves oxygenase-mediated hydroxylation of the carbon present in the no. 2 position on the dioxane ring and its subsequent dehydrogenation to form the lactone ring. Hydroxylation is any process that introduces one or more hydroxyl groups (-OH) into a compound (or radical), thereby oxidizing it. In biochemistry, hydroxylation reactions are often facilitated by enzymes called hydroxylases. A lactone is a cyclic ester. After opening the lactone ring, intermediary metabolism pathways may begin (Zenker, 2006).
Heavy Metals, Hydrocarbons, Radioactive Materials, Xenobiotics, Pesticides, Hazardous Chemicals, Explosives, Pharmaceutical Waste and Dyes Bioremediation
Published in Vivek Kumar, Rhizomicrobiome Dynamics in Bioremediation, 2021
Elżbieta Wołejko, Agata Jabłońska-Trypuć, Andrzej Butarewicz, Urszula Wydro
Biotransformation of xenobiotics involving microorganisms can occur both in the absence or presence of oxygen (Cao et al. 2009). In most cases, oxygen is involved in the first reactions of xenobiotic transformations, regardless of whether their chemical structure is aromatic or aliphatic (Sinha et al. 2009). However, as suggested by Cao et al. (2009), hydroxylation reactions of these compounds seem to be of key importance in their transformation processes, and sometimes can be the limiting stage for xenobiotics metabolism by microorganisms. The major hydroxylation reactions involve oxygenase enzymes, mainly dioxygenase or monooxygenase (Ullrich and Hofrichter 2007). Moreover, through oxidation of aliphatic xenobiotics, carboxylic acids are formed, which may be the central indirect metabolite participating in the fatty acid transformation cycle in the microbial cell. In turn, the distribution of xenobiotics with an aromatic structure involves the transformation of the xenobiotic to one of the key indirect metabolites, such as procatechuic acid, catechol, hydroquinone or gentisic acid (Cao et al. 2009). Their common feature is the presence of two hydroxyl groups located either in the para or ortho position. If the hydroxyl group is in the structure of the compound which undergoes microbiological biodegradation, monooxygenase involved in the transformation of this compound introduces one of the oxygen atoms into the aromatic ring, which reduces other to water (Ullrich and Hofrichter 2007). Vaillancourt et al. (2006) report that the situation is different when the structure of the aromatic compound has no hydroxyl substituents. Then, it is required to introduce two hydroxyl groups into the ring and this transition is catalysed by hydroxylating dioxygenase.
New oxovanadium and dioxomolybdenum complexes as catalysts for sulfoxidation: experimental and theoretical investigations of E and Z isomers of ONO tridentate Schiff base ligand
Published in Journal of Sulfur Chemistry, 2022
Hadi Kargar, Atefeh Moghimi, Mehdi Fallah-Mehrjardi, Reza Behjatmanesh-Ardakani, Hadi Amiri Rudbari, Khurram Shahzad Munawar
The current work is based on the synthesis of an ONO-donor tridentate Schiff base and its oxovanadium and dioxomolybdenum complexes, and their characterization by using elemental and various spectroscopic techniques. Only ligand was isolated in the form of single crystal; hence, its theoretical calculations were performed by employing DFT method with the B3LYP/Def2-TZVP level of theory. The computational data for four possible configurations of the ligand including Z and E stereoisomers were also calculated. The exact molecular structure of H2L ligand determined by single-crystal X-ray crystallography is in agreement with the theoretical results for the keto form of E stereoisomer. Moreover, after preparation and characterization of the VOL and MoO2L complexes, their catalytic activities were investigated for the oxidation of sulfides by using H2O2 in ethanol under reflux conditions. The metal centers of the catalysts are attacked by the hydrogen peroxide to form intermediates which are further ambushed by the sulfur to give sulfoxides by breaking O–O bond. The results showed that oxovanadium catalyst has higher selectivity for the sulfoxide formation over the sulfone. In the future, these catalysts can be employed industrially for hydroxylation, epoxidation and selective oxidation of benzylic alcohols.