Development of whole-cell catalyst system for sulfide biotreatment based on the engineered haloalkaliphilic bacterium

AbstractMicroorganisms play an essential role in sulfide removal. Alkaline absorption solution facilitates the sulfide’s dissolution and oxidative degradation, so haloalkaliphile is a prospective source for environmental-friendly and cost-effective biodesulfurization. In this research, 484 sulfide oxidation genes were identified from the metagenomes of the soda-saline lakes and a haloalkaliphilic heterotrophic bacterium Halomonas salifodinae IM328 (=CGMCC 22183) was isolated from the same habitat as the host for expression of a representative sequence. The genetic manipulation was successfully achieved through the conjugation transformation method, and sulfide: quinone oxidoreductase gene (sqr) was expressed via pBBR1MCS derivative plasmid. Furthermore, a whole-cell catalyst system was developed by using the engineered strain that exhibited a higher rate of sulfide oxidation under the optimal alkaline pH of 9.0. The whole-cell catalyst could be recycled six times to maintain the sulfide oxidation rates from 41.451 to 80.216 µmol·min−1·g−1 dry cell mass. To summarize, a whole-cell catalyst system based on the engineered haloalkaliphilic bacterium is potentiated to be applied in the sulfide treatment at a reduced cost.

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Kinetic Study of the Thermo-Oxidative Degradation of Squalane (C30H62) Modelling the Base Oil of Engine Lubricants

ASME 2009 Internal Combustion Engine Division Spring Technical Conference ◽

10.1115/ices2009-76033 ◽

2009 ◽

Author(s):

Moussa Diaby ◽

Michel Sablier ◽

Anthony Le Negrate ◽

Mehdi El Fassi

Keyword(s):

Oxidative Degradation ◽

Engine Oil ◽

Ongoing Research ◽

Base Oil ◽

Rate Law ◽

Tert Butyl ◽

Oxidation Rates ◽

Base Oils ◽

Wide Range ◽

Thermo Oxidative Degradation

On the basis of ongoing research conducted on the clarification of processes responsible for lubricant degradation in the environment of piston grooves in EGR diesel engines, an experimental investigation was aimed to develop a kinetic model which can be used for the prediction of lubricant oxidative degradation correlated to endurance test conducted on engines. Knowing that base oils are a complex blend of paraffins and naphtenes with a wide range of sizes and structures, their chemistry analysis during the oxidation process can be highly convoluted. In the present work, investigations were carried out with the squalane (C30H62) chosen for its physical and chemical similarities with the lubricant base oils used during the investigations. Thermo-oxidative degradation of this hydrocarbon was conducted at atmospheric pressure in a tubular furnace, while varying temperature and duration of the tests in order to establish an oxidation reaction rate law. The same experimental procedures was applied to squalane doped with two different phenolic antioxidants usually present in engine oil composition: 2,6-di-tert-butyl-4-methylphenol (BHT), and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (OBHP). Thus, the effect of both antioxidants on the oxidation rate law was investigated. Data analysis of the oxidized samples (FTIR spectroscopy, gas chromatography/mass spectrometry GC/MS) allowed to rationalize the thermo-oxidative degradation of squalane. The resulting kinetic modelling provides a practical analytical tool to follow the thermal degradation processes, which can be used for prediction of base oil hydrocarbon ageing. If experiments confirmed the role of phenolic additives as an affective agent to lower oxidation rates, the main results lay in the observation of a threshold temperature where a reversed activity of these additives was observed.

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A deep-sea sulfate reducing bacterium directs the formation of zero-valent sulfur via sulfide oxidation

10.1101/2021.03.23.436689 ◽

2021 ◽

Author(s):

Rui Liu ◽

Yeqi Shan ◽

Shichuan Xi ◽

Xin Zhang ◽

Chaomin Sun

Keyword(s):

Deep Sea ◽

Sulfide Oxidation ◽

Sulfur Cycle ◽

Cold Seep ◽

Cold Seeps ◽

Protein Activity ◽

Quinone Oxidoreductase ◽

Sulfate Reducing ◽

Thiosulfate Reductase ◽

Reducing Bacteria

Zero-valent sulfur (ZVS) is a critical intermediate in the biogeochemical sulfur cycle. Up to date, sulfur oxidizing bacteria have been demonstrated to dominate the formation of ZVS. In contrast, formation of ZVS mediated by sulfate reducing bacteria (SRB) has been rarely reported. Here, we report for the first time that a typical sulfate reducing bacterium Desulfovibrio marinus CS1 directs the formation of ZVS via sulfide oxidation. In combination with proteomic analysis and protein activity assays, thiosulfate reductase (PhsA) and sulfide: quinone oxidoreductase (SQR) were demonstrated to play key roles in driving ZVS formation. In this process, PhsA catalyzed thiosulfate to form sulfide, which was then oxidized by SQR to form ZVS. Consistently, the expressions of PhsA and SQR were significantly up-regulated in strain CS1 when cultured in the deep-sea cold seep, strongly indicating strain CS1 might form ZVS in its real inhabiting niches. Notably, homologs of phsA and sqr widely distributed in the metagenomes of deep-sea SRB. Given the high abundance of SRB in cold seeps, it is reasonable to propose that SRB might greatly contribute to the formation of ZVS in the deep-sea environments. Our findings add a new aspect to the current understanding of the source of ZVS.

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A Profibrotic Phenotype in Naïve and in Fibrotic Lung Myofibroblasts Is Governed by Modulations in Thy-1 Expression and Activation

Mediators of Inflammation ◽

10.1155/2018/4638437 ◽

2018 ◽

Vol 2018 ◽

pp. 1-14 ◽

Cited By ~ 5

Author(s):

Pazit Y. Cohen ◽

Raphael Breuer ◽

Shulamit B. Wallach-Dayan

Keyword(s):

Cell Proliferation ◽

Genetic Manipulation ◽

Cell Mass ◽

Angiotensin Receptors ◽

Cross Linking ◽

Collagen Deposition ◽

Wild Type ◽

Abnormal Accumulation ◽

Free Environment ◽

Deficient Mice

Lung fibrosis is characterized by abnormal accumulation of Thy-deficient fibroblasts in the interstitium of the alveolar space. We have previously shown in bleomycin-treated chimeric Thy1-deficient mice with wild-type lymphocytes that Thy1-deficient fibroblasts accumulate and promote fibrosis and an “inflammation-free” environment. Here, we aimed to identify the critical effects of Thy1, or the absence of Thy1, in lung myofibroblast profibrotic functions, particularly proliferation and collagen deposition. Using specific Thy1 siRNA in Thy1-positive cells, Thy1 knockout cells, Thy1 cDNA expression vector in Thy1-deficient cells, and Thy1 cross-linking, we evaluated cell proliferation (assessed by cell mass and BrdU uptake), differentiation (using immunofluorescence), and collagen deposition (using Sircol assay). We found that myofibroblast Thy1 cross-linking and genetic manipulation modulate cell proliferation and expression of Fgf (fibroblast growth factor) and Angtl (angiotensin) receptors (using qPCR) that are involved in myofibroblast proliferation, differentiation, and collagen deposition. In conclusion, lung myofibroblast downregulation of Thy1 expression is critical to increase proliferation, differentiation, and collagen deposition.

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Biological sulfide removal under alkaline and aerobic conditions in a packed recycling reactor

Water Science & Technology ◽

10.2166/wst.2009.121 ◽

2009 ◽

Vol 59 (7) ◽

pp. 1415-1421 ◽

Cited By ~ 8

Author(s):

A. González-Sánchez ◽

S. Revah

Keyword(s):

Oxidation Rate ◽

Sulfide Oxidation ◽

Specific Area ◽

Alkaline Condition ◽

Lower Growth ◽

Oxidation Rates ◽

Sulfide Removal ◽

Nylon Fiber ◽

Biofilm Development ◽

Recycling Reactor

The biological sulfide removal from wastewater caustic streams can be achieved without significant dilution by alkaliphilic microorganisms which usually show lower growth and oxidation rates as compared with acidic and neutral bacteria. To improve volumetric removal rates under alkaline condition (pH 10), an Alkaliphilic Sulfide-oxidizing Bacteria Consortium (ASBC) was studied in a Packed Recycling Reactor (PRR). A commercial Nylon fiber resulted to be a convenient packing support for biofilm development as it has high specific area and similar hydrophobic propertie. The PRR reached a maximum sulfide oxidation rate of 100 mmol L−1 d−1 with efficiency close to 100%, representing an enhancement of 56% from the maximum sulfide oxidation rate reached for a free cell continuous culture. Higher sulfide loading rates induced oxygen limiting conditions reducing the biological activity despite the considerable biofilm attached on the nylon fiber.

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Sulfide removal from industrial wastewaters by lithotrophic denitrification using nitrate as an electron acceptor

Water Science & Technology ◽

10.2166/wst.2010.545 ◽

2010 ◽

Vol 62 (10) ◽

pp. 2286-2293 ◽

Cited By ~ 16

Author(s):

Esra Can-Dogan ◽

Mustafa Turker ◽

Levent Dagasan ◽

Ayla Arslan

Keyword(s):

Electron Acceptor ◽

Wastewater Treatment Plants ◽

Sulfide Oxidation ◽

Sulfide Concentration ◽

Loading Rates ◽

Oxidation Rates ◽

Yield Values ◽

Experimental Yield ◽

Biotechnological Processes ◽

Volumetric Loading

Sulfide is present in wastewaters as well as in biogas and can be removed by several physicochemical and biotechnological processes. Nitrate is a potential electron acceptor, readily available in most wastewater treatment plants and it can replace oxygen under anoxic conditions. A lab-scale reactor was operated for treatment of sulfide containing wastewater with nitrate as an electron acceptor and is used to evaluate the effects of volumetric loading rates, hydraulic retention time (HRT) and substrate concentrations on the performance of the lithotrophic denitrification process for treating industrial fermentation wastewaters. Sulfide is removed more than 90% at the loading rates between 0.055 and 2.004 kg S−2/m3 d, when the influent sulfide concentration is kept around 0.163 kg/m3 and the HRT decreased from 86.4 to 2 h. Nitrogen removal differed between 23 and 99% with different influent NO3−-N concentration and loading rates of NO3−/S−2 ratio. The stoichiometry of sulfide oxidation with nitrate is calculated assuming different end-products based on thermodynamic approach and compared with experimental yield values. The calculated maximum volumetric and specific sulfide oxidation rates reached 0.076 kg S−2/m3 h and 0.11 kg S−2/kg VSS h, respectively. The results are obtained at industrially relevant conditions and can be easily adapted to either biogas cleaning process or to sulfide containing effluent streams.

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Sulfur globule oxidation in green sulfur bacteria is dependent on the dissimilatory sulfite reductase system

Microbiology ◽

10.1099/mic.0.044669-0 ◽

2011 ◽

Vol 157 (4) ◽

pp. 1229-1239 ◽

Cited By ~ 53

Author(s):

Carina Holkenbrink ◽

Santiago Ocón Barbas ◽

Anders Mellerup ◽

Hiroyo Otaki ◽

Niels-Ulrik Frigaard

Keyword(s):

Sulfide Oxidation ◽

Green Sulfur Bacteria ◽

Substrate Oxidation ◽

Sulfite Reductase ◽

Wild Type ◽

Oxidation Rates ◽

Dissimilatory Sulfite Reductase ◽

Sulfur Bacteria ◽

Sulfur Globules ◽

Green Sulfur

Green sulfur bacteria (GSB) oxidize sulfide and thiosulfate to sulfate, with extracellular globules of elemental sulfur as an intermediate. Here we investigated which genes are involved in the formation and consumption of these sulfur globules in the green sulfur bacterium Chlorobaculum tepidum. We show that sulfur globule oxidation is strictly dependent on the dissimilatory sulfite reductase (DSR) system. Deletion of dsrM/CT2244 or dsrT/CT2245, or the two dsrCABL clusters (CT0851–CT0854, CT2247–2250), abolished sulfur globule oxidation and prevented formation of sulfate from sulfide, whereas deletion of dsrU/CT2246 had no effect. The DSR system also seems to be involved in the formation of thiosulfate, because thiosulfate was released from wild-type cells during sulfide oxidation, but not from the dsr mutants. The dsr mutants incapable of complete substrate oxidation oxidized sulfide and thiosulfate about twice as fast as the wild-type, while having only slightly lower growth rates (70–80 % of wild-type). The increased oxidation rates seem to compensate for the incomplete substrate oxidation to satisfy the requirement for reducing equivalents during growth. A mutant in which two sulfide : quinone oxidoreductases (sqrD/CT0117 and sqrF/CT1087) were deleted exhibited a decreased sulfide oxidation rate (∼50 % of wild-type), yet formation and consumption of sulfur globules were not affected. The observation that mutants lacking the DSR system maintain efficient growth suggests that the DSR system is dispensable in environments with sufficiently high sulfide concentrations. Thus, the DSR system in GSB may have been acquired by horizontal gene transfer as a response to a need for enhanced substrate utilization in sulfide-limiting habitats.

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Kinetic Study of the Thermo-Oxidative Degradation of Squalane (C30H62) Modeling the Base Oil of Engine Lubricants

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.3155797 ◽

2009 ◽

Vol 132 (3) ◽

Cited By ~ 5

Author(s):

Moussa Diaby ◽

Michel Sablier ◽

Anthony Le Negrate ◽

Mehdi El Fassi

Keyword(s):

Oxidative Degradation ◽

Engine Oil ◽

Ongoing Research ◽

Base Oil ◽

Rate Law ◽

Tert Butyl ◽

Oxidation Rates ◽

Base Oils ◽

Wide Range ◽

Thermo Oxidative Degradation

On the basis of ongoing research conducted on the clarification of processes responsible for lubricant degradation in the environment of piston grooves in exhaust gas recirculation (EGR) diesel engines, an experimental investigation was aimed to develop a kinetic model, which can be used for the prediction of lubricant oxidative degradation correlated with endurance test conducted on engines. Knowing that base oils are a complex blend of paraffins and naphthenes with a wide range of sizes and structures, their chemistry analysis during the oxidation process can be highly convoluted. In the present work, investigations were carried out with the squalane (C30H62) chosen for its physical and chemical similarities with the lubricant base oils used during the investigations. Thermo-oxidative degradation of this hydrocarbon was conducted at atmospheric pressure in a tubular furnace, while varying temperature and duration of the tests in order to establish an oxidation reaction rate law. The same experimental procedures were applied to squalane doped with two different phenolic antioxidants usually present in engine oil composition: 2,6-di-tert-butyl-4-methylphenol and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. Thus, the effect of both antioxidants on the oxidation rate law was investigated. Data analysis of the oxidized samples (Fourier transform infrared spectroscopy and gas chromatography/mass spectrometry) allowed rationalization of the thermo-oxidative degradation of squalane. The resulting kinetic modeling provides a practical analytical tool to follow the thermal degradation processes, which can be used for prediction of base oil hydrocarbon aging. If experiments confirmed the role of phenolic additives as an effective agent to lower oxidation rates, the main results lie in the observation of a threshold temperature where a reversed activity of these additives was observed.

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Isolation and Molecular Identification of Auxotrophic Mutants to Develop a Genetic Manipulation System for the HaloarchaeonNatrinemasp. J7-2

Archaea ◽

10.1155/2015/483194 ◽

2015 ◽

Vol 2015 ◽

pp. 1-16 ◽

Cited By ~ 5

Author(s):

Jie Lv ◽

Shuai Wang ◽

Yuchen Wang ◽

Yuping Huang ◽

Xiangdong Chen

Keyword(s):

Genomic Dna ◽

Genetic Manipulation ◽

Gene Mutations ◽

Transformation Method ◽

Wild Type ◽

Auxotrophic Mutants ◽

Archaeal Species ◽

Manipulation System ◽

Exogenous Genes ◽

Mutant Phenotypes

Our understanding of the genusNatrinemais presently limited due to the lack of available genetic tools. Auxotrophic markers have been widely used to construct genetic systems in bacteria and eukaryotes and in some archaeal species. Here, we isolated four auxotrophic mutants ofNatrinemasp. J7-2, via 1-methyl-3-nitro-1-nitroso-guanidin mutagenesis, and designated them as J7-2-1, J7-2-22, J7-2-26, and J7-2-52, respectively. The mutant phenotypes were determined to be auxotrophic for leucine (J7-2-1), arginine (J7-2-22 and J7-2-52), and lysine (J7-2-26). The complete genome and the biosynthetic pathways of amino acids in J7-2 identified that the auxotrophic phenotype of three mutants was due to gene mutations inleuB(J7-2-1),dapD(J7-2-26), andargC(J7-2-52). These auxotrophic phenotypes were employed as selectable makers to establish a transformation method. The transformation efficiencies were determined to be approximately 103transformants perµg DNA. And strains J7-2-1 and J7-2-26 were transformed into prototrophic strains with the wild type genomic DNA, amplified fragments of the corresponding genes, or the integrative plasmids carrying the corresponding genes. Additionally, exogenous genes,bgaHoramyHgene, were expressed successfully in J7-2-1. Thus, we have developed a genetic manipulation system for theNatrinemagenus based on the isolated auxotrophic mutants ofNatrinemasp. J7-2.

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An inducible CRISPR-ON system for controllable gene activation in human pluripotent stem cells

10.1101/106112 ◽

2017 ◽

Cited By ~ 2

Author(s):

Jianying Guo ◽

Dacheng Ma ◽

Rujin Huang ◽

Jia Ming ◽

Min Ye ◽

...

Keyword(s):

Gene Expression ◽

Stem Cells ◽

Pluripotent Stem Cells ◽

Genetic Manipulation ◽

Inner Cell Mass ◽

Cell Mass ◽

Human Pluripotent Stem Cells ◽

Hesc Line ◽

Transcription Activator

AbstractHuman pluripotent stem cells (hPSCs) are an important system to study early human development, model human diseases, and develop cell replacement therapies. However, genetic manipulation of hPSCs is challenging and a method to simultaneously activate multiple genomic sites in a controllable manner is sorely needed. Here, we constructed a CRISPR-ON system to efficiently upregulate endogenous genes in hPSCs. A doxycycline (Dox) inducible dCas9-VP64-p65-Rta (dCas9-VPR) transcription activator and a reverse Tet transactivator (rtTA) expression cassette were knocked into the two alleles of the AAVS1 locus to generate an iVPR hESC line. We showed that the dCas9-VPR level could be precisely and reversibly controlled by addition and withdrawal of Dox. Upon transfection of multiplexed gRNA plasmid targeting the NANOG promoter and Dox induction, we were able to control NANOG gene expression from its endogenous locus. Interestingly, an elevated NANOG level did not only promote naïve pluripotent gene expression but also enhanced cell survival and clonogenicity, and it enabled integration of hESCs with the inner cell mass (ICM) of mouse blastocysts in vitro. Thus, iVPR cells provide a convenient platform for gene function studies as well as high-throughput screens in hPSCs.

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Comparison of the benzyl viologen and bimane HPLC assays for the determination of sulfide-oxidizing capability in the tissues of hydrothermal vent and non-vent polychaetes

Canadian Journal of Zoology ◽

10.1139/z97-788 ◽

1997 ◽

Vol 75 (10) ◽

pp. 1618-1627 ◽

Cited By ~ 3

Author(s):

Pascale Martineu ◽

S. Kim Juniper

Keyword(s):

Hydrothermal Vent ◽

High Performance ◽

Sulfide Oxidation ◽

Sulfur Oxidation ◽

Tissue Level ◽

Hplc Assay ◽

Protein Ratio ◽

Benzyl Viologen ◽

Oxidation Rates

Two commonly used methods for in vitro measurement of tissue-level sulfide oxidation in animals were compared using homogenates of hydrothermal vent (Paralvinella sulfincola and P. palmiformis) and non-vent (Nereis virens and Nephtys caeca) polychaetes. All examined worms showed heat-labile sulfide-oxidizing ability and rates were slightly higher in the two vent species. A previously observed discrepancy between the results of the spectrophotometric benzyl viologen (BV) and bimane high-performance liquid chromatography (HPLC) assays was confirmed. We explain this discrepancy firstly by the fact that H2S removal measured by the bimane HPLC assay is only the first step in a cascade of several possible sulfur-oxidation steps recorded by BV. Secondly, we show that the low H2S/protein ratio used in the bimane HPLC assay can result in undersaturation of the catalyst responsible for H2S oxidation. The latter can lead to underestimation of potential oxidation rates and may be as important as the nonspecificity of BV in explaining differences between assay results. Tissue-level sulfide oxidation is clearly widespread in marine invertebrates, but the catalyst(s) responsible remain(s) unidentified. The fact that sulfide-oxidation rates in vent polychaete tissues are similar to rates in non-vent species and appear to reflect a common basal level of sulfide-oxidizing activity in many animal tissues suggests that other defense mechanisms may be more important in the adaptation of these worms to the hydrothermal milieu.

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