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Plant Growth and Development Regulators and their Effect on the Functional State of Mitochondria
Published in Alexander V. Kutchin, Lyudmila N. Shishkina, Larissa I. Weisfeld, Gennady E. Zaikov, Ilya N. Kurochkin, Alexander N. Goloshchapov, Chemistry and Technology of Plant Substances, 2017
Irina V. Zhigacheva, Elena B. Burlakova
This allows realize a “potassium cycle” which provide the return of H+ to the mitochondrial matrix, that is, decrease of Ay. The decrease Ay during activation mitoK+ATP has no effect on the synthesis of ATP by oxidative phosphorylation, indicating a possible involvement of the channel in adaptation of plants to stress factors [16]. Note that in mammalian cells, potassium cycle “does not significantly contribute to uncoupling of mitochondrial respiration, as the maximum activity of this cycle is 20% of the total pool of protons generated by the respiratory chain [17].” In plant cells, the activity of this cycle is comparable to the activity of proton pumps of the respiratory chain of mitochondria. In plant cells, the activity of this cycle is comparable to the activity of proton pumps mitochondrial respiratory chain. It is noteworthy that ATP inhibits this channel in the mitochondria of plants with an efficiency of 10 times less than in mammals, and Mg2+, which inhibits this channel in a mammal, is not effective for durum wheat. Possibly, this channel can act as an antioxidant system in response to stress factors, preventing damage to plants by reducing the formation of the mitochondrial ROS. Indeed, experiments on mitochondria isolated from seedlings of durum wheat, which subjected to salt stress, show the possibility of participation PmitoK+ATP channel for reducing the generation of ROS by the respiratory chain [15, 19]. In plant organisms, protection from oxidative stress is carried out by antioxidant system cells. Reducing of the generation of ROS by mitochondria is achieved thanks to the activation of the alternative pathway oxidation involving alternative oxidase (AOX), which branches off from the main respiratory chain at the level of ubiquinone and transfers electrons directly to oxygen to form water (Fig. 12.3).
Key Microbes and Metabolic Potentials Contributing to Cyanide Biodegradation in Stirred-Tank Bioreactors Treating Gold Mining Effluent
Published in Mineral Processing and Extractive Metallurgy Review, 2020
Doyun Shin, Jeonghyun Park, Hyunsik Park, Jae-Chun Lee, Min-Seuk Kim, Jaeheon Lee
Using PiCRUSt, the relative abundances of cyanide- and alkaline-shock-related genes in the reactors was identified as shown in Figure 5. There are three categories of cyanide-related genes, involved in either cyanide degradation, resistance, or production. Cyanide biodegradation involves hydrolytic, oxidative, reductive, and substitution/transfer pathways (Ebbs, 2004; Raybuck 1992). Each pathway has its own enzymes: cyanide hydratase (formamide hydrolyase, EC 4.2.1.66) and cyanidase (cyanate amidohydrolyase, EC 3.5.5.3) (hydrolytic); cyanide monooxygenase and dioxygenase (oxidative); nitrogenase (reductive); and rhodanese (thiosulfate: cyanide sulfur transferase, EC 2.8.1.1), mercaptopyruvate sulfurtransferase (EC 2.8.1.2), and pyridoxal phosphate enzymes (substitution/transfer). The cyanide resistance-related gene is cyanide-insensitive cytochrome bd quinol oxidase, because some facultative Proteobacteria (Comolli and Donohue 2002; McDonald 2008) use cyanide-insensitive alternative oxidase as an alternative respiratory route (Voggu et al. 2006). A cyanide-producing enzyme, hydrogen cyanide synthase (hcnABC), is also found in Proteobacteria, including C. violaceum, fluorescent pseudomonads, and the genus Rhizobium (Blumer and Haas 2000). Other cyanide-related genes have been reported, but they are not included in the Greengenes database. Due to the limited database availability, PiCRUSt cannot replace whole metagenome profiling. However, it is still useful to provide supplemental data on the functional potential of genes based on 16S rRNA analyses. As shown in Figure 5a, on day 0, all the reactors inoculated only with sludge or with C. violaceum and activated sludge had some level of cyanide-degrading and cyanide-resistance potential. With cyanide addition and time, the cyanide-degradation potential decreased, except in the S-50 reactor, in which a small portion of hydrolytic cyanide degradation activity was observed. In the CS-200 and S-200 reactors, almost all the cyanide degradation potential disappeared but the cyanide-resistance potential was maintained with cyanide addition and time. In the reactors inoculated only with the cyanide-degrading bacterial mixture or the bacterial mixture and sludge (Figure 5b), cyanide production potential was observed at an early stage, but disappeared after 7 days. Thus, the first possibility which the cyanide production may contribute the low decrease of cyanide concentration in the effluent was refuted.