scholarly journals Detecting Redox Potentials Using Porous Boron Nitride/ATP-DNA Aptamer/Methylene Blue Biosensor to Monitor Microbial Activities

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 83
Author(s):  
Kai Guo ◽  
Zirui Song ◽  
Gaoxing Wang ◽  
Chengchun Tang

Microbial activity has gained attention because of its impact on the environment and the quality of people’s lives. Most of today’s methods, which include genome sequencing and electrochemistry, are costly and difficult to manage. Our group proposed a method using the redox potential change to detect microbial activity, which is rooted in the concept that metabolic activity can change the redox potential of a microbial community. The redox potential change was captured by a biosensor consisting of porous boron nitride, ATP-DNA aptamer, and methylene blue as the fluorophore. This assembly can switch on or off when there is a redox potential change, and this change leads to a fluorescence change that can be examined using a multipurpose microplate reader. The results show that this biosensor can detect microbial community changes when its composition is changed or toxic metals are ingested.

2021 ◽  
Vol 4 ◽  
Author(s):  
Carlos Rochera ◽  
Maria Peña ◽  
Antonio Picazo ◽  
Javier Miralles-Lorenzo ◽  
Daniel Morant ◽  
...  

The use of proxies for ecosystem function in biomonitoring is desirable to move towards more holistic strategies. Next-generation sequencing of environmental DNA can clearly contribute to these advances. This research is part of a project aimed to use constructed wetlands (CWs), managed by the company Global Omnium (https://www.globalomnium.com/Group/Home/) and having the University of Valencia in charge of the scientific research, in order to improve the ecological quality of already treated wastewaters before being poured into natural environments. The rationale is that, although wastewaters treated by classical methods can meet the standards required by law, transitional constructed ecosystems, as the CWs, can promote ancillary benefits that contribute to the maintenance of the ecological health of receiving natural ecosystems. We propose that some functional traits of the microbial community can be used to outline the process of water renaturation. To assess this, the prokaryotic communities of different types of CWs were profiled by the MiSeq sequencing of the V4 region of the 16S rRNA. Using the sequences obtained, a prediction of the functional capabilities of these communities was made with the bioinformatic package PICRUSt2 (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States; https://github.com/picrust/picrust2), assuming that phylogeny and function are effectively related attributes. Predictions on the occurrence of functional marker genes, particularly those involved in the biogeochemical cycling of main nutrients (C, N, S, P), were then made. The PICRUSt2 predictions were based in the annotated genes catalog of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database (https://www.genome.jp/kegg/). In general, results indicated a decline in the CWs effluents of microbial functions typical from wastewater in favor of those more suited for the receiving environment. An enhancement of aerobic metabolism was predicted to occur based on the increase of the gene encoding the cytochrome-c oxidase compared to fermentation pathways. Accordingly, both the denitrification and the dissimilatory reduction of sulfate, that are predominant in the anaerobic environments, also decreased in the effluents of the CWs to lower levels more similar to those observed in natural environments, showing a shift towards reactions at higher redox potentials. On the other hand, a development of metabolic skills for degrading plant materials (e.g., xylose, vanillin, syringate, protocatechuate) was also predicted, which was likely related to a parallel transformation of the organic matter pool in the CWs (more unreactive and natural). Additionally, increases observed in pathways for the synthesis of some cell structural compounds (e.g., mycolic acids) and coenzymes (e.g., F420 cofactor, NAD+) can be related with an enhancement of colonization and competitive potentials of the natural microbial community, as well as with changes in the actual availability of nutrients in the environment. Based on these findings, we raise the possibility of considering these functional surveys made on marker genes as a complementary strategy on the biomonitoring procedures, not only for CWs, but for the general study of freshwater ecosystem potentially affected by wastewater pollution.


2021 ◽  
Author(s):  
Xingjiang Li ◽  
Ying He ◽  
Wei Yang ◽  
Dongdong Mu ◽  
Min Zhang ◽  
...  

Author(s):  
Keisuke Saito ◽  
Minesato Nakagawa ◽  
Manoj Mandal ◽  
Hiroshi Ishikita

AbstractPhotosystem II (PSII) contains Ca2+, which is essential to the oxygen-evolving activity of the catalytic Mn4CaO5 complex. Replacement of Ca2+ with other redox-inactive metals results in a loss/decrease of oxygen-evolving activity. To investigate the role of Ca2+ in this catalytic reaction, we investigate artificial Mn3[M]O2 clusters redox-inactive metals  [M] ([M]  = Mg2+, Ca2+, Zn2+, Sr2+, and Y3+), which were synthesized by Tsui et al. (Nat Chem 5:293, 2013). The experimentally measured redox potentials (Em) of these clusters are best described by the energy of their highest occupied molecular orbitals. Quantum chemical calculations showed that the valence of metals predominantly affects Em(MnIII/IV), whereas the ionic radius of metals affects Em(MnIII/IV) only slightly.


1980 ◽  
Vol 188 (2) ◽  
pp. 535-540 ◽  
Author(s):  
A Tomoda ◽  
M Ida ◽  
A Tsuji ◽  
Y Yoneyama

The time course of methaemoglobin reduction in human erythrocytes treated with nitrite was studied at pH 7.4, 37 degrees C, in the presence or absence of Methylene Blue, and the changes in methaemoglobin, intermediate haemoglobins and oxyhaemoglobin during the reaction were analysed by isoelectric-focusing on Ampholine/polyacrylamide-gel plates. In both cases, with or without the dye, the intermediate haemoglobins were found to be present at (alpha 3+beta 2+)2 and (alpha 2+beta 3+)2 valency hybrids from their characteristic position on electrophoresis, but amounts changed consecutively with time. The amount of (alpha 3+beta 2+)2 was always greater than that of the (alpha 2+beta 3+)2 valency hybrid. This result is explained by the differences in redox potentials between alpha- and beta-chains in methaemoglobin tetramer. It was concluded that methaemoglobin was reduced in human erythrocytes through these two different pats: methaemoglobin leads to k+3 (alpha 2+beta 3+)2 leads to k+3 oxyhaemoglobin. The reaction rate constants k'+1 (= k+1+k+3) and k'+2(=k+2+k+4) were estimated from the changes in each component methaemoglobin, intermediate haemoglobins [(alpha 3+beta 2+)2+(alpha 2+beta 3+)2] and oxyhaemoglobin.


2017 ◽  
Vol 2 (2) ◽  
pp. 90 ◽  
Author(s):  
Yulius Dala Ngapa

<p>Activation is one of the processes by which are mostly done to improve the quality of natural zeolite. Activation process by zeolite will change the ratio of the Si/Al and can increase the formation of empty cavities so that the capability of zeolite as an adsorbent be optimal. In this research, natural zeolite from the district of Ende, Nusa Tenggara Timur. Activation Ende natural zeolite done chemically using HCl and NaOH solution, with variations concentrate 0,5 M; 1,5 M; and 3,0 M. Next, zeolite which has activated used to adsorb dye methylene blue. Based on the research results, chemically of activation from natural zeolite can increase the adsorption capacity to substance methylene blue. The adsorption capacity in the Ende natural and after activation is 17,289 mg/g and 19,98 mg/g respectively. The Langmuir model most closely matched the isothermal adsorption of equilibrium process.</p>


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