scholarly journals Facultative methanotrophs – diversity, genetics, molecular ecology and biotechnological potential: a mini-review

Microbiology ◽  
2020 ◽  
Vol 166 (10) ◽  
pp. 894-908
Author(s):  
Muhammad Farhan Ul Haque ◽  
Hui-Juan Xu ◽  
J. Colin Murrell ◽  
Andrew Crombie
Keyword(s):  
Molecular Ecology ◽  
Significant Proportion ◽  
Vital Role ◽  
Short Chain ◽  
Atmospheric Methane ◽  
Biotechnological Potential ◽  
Content Type ◽  
Methane Oxidizing Bacteria ◽  
Metabolic Versatility ◽  
Carbon Compounds

Methane-oxidizing bacteria (methanotrophs) play a vital role in reducing atmospheric methane emissions, and hence mitigating their potent global warming effects. A significant proportion of the methane released is thermogenic natural gas, containing associated short-chain alkanes as well as methane. It was one hundred years following the description of methanotrophs that facultative strains were discovered and validly described. These can use some multi-carbon compounds in addition to methane, often small organic acids, such as acetate, or ethanol, although Methylocella strains can also use short-chain alkanes, presumably deriving a competitive advantage from this metabolic versatility. Here, we review the diversity and molecular ecology of facultative methanotrophs. We discuss the genetic potential of the known strains and outline the consequent benefits they may obtain. Finally, we review the biotechnological promise of these fascinating microbes.

scholarly journals Unexpected metabolic versatility among type II methanotrophs in the Alphaproteobacteria

2020 ◽  
Vol 401 (12) ◽  
pp. 1469-1477
Author(s):  
Anna Hakobyan ◽  
Werner Liesack
Keyword(s):  
Global Climate Change ◽  
Global Climate ◽  
Type Ii ◽  
Mixotrophic Growth ◽  
Methane Cycle ◽  
Oxidation Activity ◽  
Methane Oxidizing Bacteria ◽  
Metabolic Versatility ◽  
Carbon Compounds ◽  
Growth Requirement

AbstractAerobic methane-oxidizing bacteria, or methanotrophs, play a crucial role in the global methane cycle. Their methane oxidation activity in various environmental settings has a great mitigation effect on global climate change. Alphaproteobacterial methanotrophs were among the first to be taxonomically characterized, nowadays unified in the Methylocystaceae and Beijerinckiaceae families. Originally thought to have an obligate growth requirement for methane and related one-carbon compounds as a source of carbon and energy, it was later shown that various alphaproteobacterial methanotrophs are facultative, able to grow on multi-carbon compounds such as acetate. Most recently, we expanded our knowledge of the metabolic versatility of alphaproteobacterial methanotrophs. We showed that Methylocystis sp. strain SC2 has the capacity for mixotrophic growth on H2 and CH4. This mini-review will summarize the change in perception from the long-held paradigm of obligate methanotrophy to today’s recognition of alphaproteobacterial methanotrophs as having both facultative and mixotrophic capabilities.

scholarly journals Genomic and Physiological Properties of a Facultative Methane-Oxidizing Bacterial Strain of Methylocystis sp. from a Wetland

2020 ◽  
Vol 8 (11) ◽  
pp. 1719
Author(s):  
Gi-Yong Jung ◽  
Sung-Keun Rhee ◽  
Young-Soo Han ◽  
So-Jeong Kim
Keyword(s):  
Methane Oxidation ◽  
Carbon Sources ◽  
Heavy Metal Resistance ◽  
Metal Resistance ◽  
Phylogenomic Analysis ◽  
Atmospheric Methane ◽  
Methane Oxidizing Bacteria ◽  
Metabolic Versatility ◽  
Physiological Properties ◽  
Ph Range

Methane-oxidizing bacteria are crucial players in controlling methane emissions. This study aimed to isolate and characterize a novel wetland methanotroph to reveal its role in the wetland environment based on genomic information. Based on phylogenomic analysis, the isolated strain, designated as B8, is a novel species in the genus Methylocystis. Strain B8 grew in a temperature range of 15 °C to 37 °C (optimum 30–35 °C) and a pH range of 6.5 to 10 (optimum 8.5–9). Methane, methanol, and acetate were used as carbon sources. Hydrogen was produced under oxygen-limited conditions. The assembled genome comprised of 3.39 Mbp and 59.9 mol% G + C content. The genome contained two types of particulate methane monooxygenases (pMMO) for low-affinity methane oxidation (pMMO1) and high-affinity methane oxidation (pMMO2). It was revealed that strain B8 might survive atmospheric methane concentration. Furthermore, the genome had various genes for hydrogenase, nitrogen fixation, polyhydroxybutyrate synthesis, and heavy metal resistance. This metabolic versatility of strain B8 might enable its survival in wetland environments.

scholarly journals Synthesis of Short-Chain Diols and Unsaturated Alcohols from Secondary Alcohol Substrates by the Rieske Nonheme Mononuclear Iron Oxygenase MdpJ

2012 ◽  
Vol 78 (17) ◽  
pp. 6280-6284 ◽  
Author(s):  
Franziska Schäfer ◽  
Judith Schuster ◽  
Birgit Würz ◽  
Claus Härtig ◽  
Hauke Harms ◽  
...  
Keyword(s):  
Secondary Alcohol ◽  
Enantiomeric Excess ◽  
Short Chain ◽  
Wild Type ◽  
Knockout Mutant ◽  
Biotechnological Potential ◽  
Content Type ◽  
Mononuclear Iron ◽  
Tertiary Alcohols ◽  
Fuel Oxygenate

ABSTRACTThe Rieske nonheme mononuclear iron oxygenase MdpJ of the fuel oxygenate-degrading bacterial strainAquincola tertiaricarbonisL108 has been described to attack short-chain tertiary alcohols via hydroxylation and desaturation reactions. Here, we demonstrate that also short-chain secondary alcohols can be transformed by MdpJ. Wild-type cells of strain L108 converted 2-propanol and 2-butanol to 1,2-propanediol and 3-buten-2-ol, respectively, whereas anmdpJknockout mutant did not show such activity. In addition, wild-type cells converted 3-methyl-2-butanol and 3-pentanol to the corresponding desaturation products 3-methyl-3-buten-2-ol and 1-penten-3-ol, respectively. The enzymatic hydroxylation of 2-propanol resulted in an enantiomeric excess of about 70% for the (R)-enantiomer, indicating that this reaction was favored. Likewise, desaturation of (R)-2-butanol to 3-buten-2-ol was about 2.3-fold faster than conversion of the (S)-enantiomer. The biotechnological potential of MdpJ for the synthesis of enantiopure short-chain alcohols and diols as building block chemicals is discussed.

scholarly journals Sustaining Rice Production through Biofertilization with N2-Fixing Cyanobacteria

2021 ◽  
Vol 11 (10) ◽  
pp. 4628
Author(s):  
Macarena Iniesta-Pallarés ◽  
Consolación Álvarez ◽  
Francisco M. Gordillo-Cantón ◽  
Carmen Ramírez-Moncayo ◽  
Pilar Alves-Martínez ◽  
...  
Keyword(s):  
Agricultural Practices ◽  
Vital Role ◽  
Rice Production ◽  
Point Of View ◽  
Paddy Fields ◽  
Nitrogen Fertilizers ◽  
Trophic Chain ◽  
Agricultural Practice ◽  
Biotechnological Potential

Current agricultural productivity depends on an exogenous nutrient supply to crops. This is of special relevance in cereal production, a fundamental part of the trophic chain that plays a vital role in the human diet. However, our agricultural practices entail highly detrimental side-effects from an environmental point of view. Long-term nitrogen fertilization in croplands results in degradation of soil, water, and air quality, producing eutrophication and subsequently contributing to global warming. In accordance with this, there is a biotechnological interest in using nitrogen-fixing microorganisms to enhance crop growth without adding chemically synthesized nitrogen fertilizers. This is particularly beneficial in paddy fields, where about 60% of the synthetic fertilizer that has been applied is dissolved in the water and washed away. In these agricultural systems, N2-fixing cyanobacteria show a promising biotechnological potential as biofertilizers, improving soil fertility while reducing the environmental impact of the agricultural practice. In the current study, Andalusian paddy fields have been explored to isolate N2-fixing cyanobacteria. These endogenous microorganisms have been subsequently re-introduced in a field trial in order to enhance rice production. Our results provide valuable insights regarding the use of an alternative natural source of nitrogen for rice production.

Tribological behaviors of some novel dimercaptothiadiazole derivatives containing hydroxyl as multifunctional lubricant additives in biodegradable lithium grease

2014 ◽  
Vol 66 (1) ◽  
pp. 51-61 ◽  
Author(s):  
Huan Chen ◽  
Junhui Jiang ◽  
Tianhui Ren ◽  
Lei Zheng ◽  
Yidong Zhao
Keyword(s):  
Lubricant Additives ◽  
Short Chain ◽  
Lithium Grease ◽  
Edge Structure ◽  
Content Type ◽  
Organic Sulfide ◽  
Ferrous Sulfide ◽  
Heterocyclic Derivatives ◽  
Main Component ◽  
Thermal Films

Purpose – In order to meet the requests of exploring environmental-friendly and multifunctional lubricant additives, some novel dimercaptothiadiazole derivatives containing hydroxyl are prepared and used as antiwear (AW) and extreme-pressure (EP) additives in biodegradable lithium grease. The paper aims to discuss these issues. Design/methodology/approach – The tribological performances of the grease samples containing these derivatives are evaluated by using a four-ball tester. X-ray absorption near edge structure (XANES) spectroscopy is used to analyze the chemistry of tribofilms under AW/EP regime, and thermal films are also considered for comparison. Findings – The tribological tests show that these derivatives are all effective in reducing wear, especially at lower additive concentrations, but they are basically failed in reducing friction. They are also helpful in improving the EP characteristic of the base grease. The thermal films generated by these derivatives are composed of adsorbed organic sulfide and ferrous sulfate, though for short-chain derivatives, organic sulfide is the only component at 5.0 wt.%. Ferrous sulfide is the main component of the tribofilms formed by these derivatives at various additive concentrations. But for short-chain derivatives, these tribofilms consist of ferrous sulfide and ferrous disulfide at 5.0 wt.%, and the appearance of disulfide suggests that the interfacial temperature between the upper ball and three lower balls under these conditions is considerably low. The EP films generated by short-chain derivatives are all composed of organic sulfide and ferrous sulfide, while for long-chain derivatives, ferrous sulfide is the main component. Originality/value – These low-toxic and oil-soluble dimercaptothiadiazole derivatives are effective in improving the tribological characteristic of the biodegradable lithium grease, and these heterocyclic derivatives may be good substitutes for some harmful traditional additives.

Is this mine? Psychological ownership and the social media follower

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Caroline S.L. Tan
Keyword(s):  
Social Media ◽  
Design Methodology ◽  
Vital Role ◽  
Psychological Ownership ◽  
Structured Interviews ◽  
Content Type ◽  
Face To Face ◽  
The Social ◽  
Social Currency ◽  
Different Levels

Purpose The purpose of this study is to examine psychological ownership (PO) experienced by followers of social media influencers toward both influencer and the product. Design/methodology/approach Data were collected using face-to-face semi-structured interviews that were conducted with 30 respondents and analyzed using thematic analysis. Findings The study demonstrated that the PO experienced by the follower changes under different conditions resulting from perceived value, social currency and follower activity. Social currency plays a vital role in determining the target of PO, often affecting the narrative by the follower. Originality/value To the best of the author’s knowledge, this is the first paper to examine the transference of PO between product and influencer as experienced by the follower. It provides an understanding on PO that is experienced in different levels of intensity and changes depending on the motive of the follower; hence, transference of PO occurs and it is not a static.

The role of academic conferences in the [re]production of gender inequality in business disciplines: not just a STEM problem

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Trudie Walters ◽  
Najmeh Hassanli ◽  
Wiebke Finkler
Keyword(s):  
Gender Inequality ◽  
Significant Proportion ◽  
Content Type ◽  
Discipline Area ◽  
Gendered Patterns ◽  
Underlying Processes ◽  
Patterns Of Interaction ◽  
Practical Implications ◽  
Academic Conferences

PurposeIn this paper the authors seek to understand how academic conferences [re]produce deeply embedded gendered patterns of interaction and informal norms within the business disciplines.Design/methodology/approachDrawing on Acker's (2012) established and updated theory of gendered organisations, the authors focus on the role of academic conferences in the reproduction of gendered practices in the business disciplines. The authors surveyed academics at top universities in Australia and New Zealand who had attended international conferences in their discipline area.FindingsAcademic conferences in the business disciplines communicate organisational logic and act as gendered substructures that [re]produce gendered practices, through the hierarchy of conference participation. Even in disciplinary conferences with a significant proportion of women delegates, the entrenched organisational logic is manifest in the bodies that perform keynote and visible expert roles, perpetuating the notion of the “ideal academic” as male.Practical implicationsThe authors call for disciplinary associations to formulate an equality policy, which covers all facets of conference delivery, to which institutions must then respond in their bid to host the conference and which then forms part of the selection criteria; explicitly communicate why equality is important and what decisions the association and hosts took to address it; and develop databases of women experts to remove the most common excuse for the lack of women keynote speakers. Men, question conference hosts when asked to be a keynote speaker or panelist: Are half of the speakers women and is there diversity in the line-up? If not, provide the names of women to take your place.Originality/valueThe contribution of this study is twofold. First is the focus on revealing the underlying processes that contribute to the [re]production of gender inequality at academic conferences: the “how” rather than the “what”. Second, the authors believe it to be the first study to investigate academic conferences across the spectrum of business disciplines.

Development of two dosimetry systems based on basic violet dye for possible use as radiation dosimeters

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Nehad Magdy ◽  
Sameh Gafar
Keyword(s):  
Gamma Ray ◽  
Raw Materials ◽  
Absorbed Dose ◽  
Chemical Yield ◽  
Radiation Sensitivity ◽  
Vital Role ◽  
Radiation Chemical ◽  
Content Type ◽  
Before And After

Purpose The purpose of this research paper is to study a comparison between two dosimetry systems, both of them based on basic violet dye (BV). Design/methodology/approach The first system depends on (BV) (incorporating polyvinyl alcohol) as a thin-film dosimeter. The second system also relies on (BV) as a solution dosimeter, which is more sensitive to gamma rays. The two prepared film/solutions have a considerable signal that decreases upon irradiation and the strength of the signal decreases with increasing radiation dose. Findings The gamma ray absorbed dose for these dosimeters was found to be up to 35 kGy for films and 1 kGy for the liquid phase. All dosimetric characteristics as radiation chemical yield, additive substance, dose-response function, radiation sensitivity, also before and after-irradiation stability under various conditions were considered. Practical implications It is expected the vital role of gamma radiation on this dye in its two forms or two media. This reveals their wide applications in the field of gamma irradiation processing. Originality/value These two dosimetry systems which depend upon the same dye are safe to handle, inexpensive, available raw materials and can be applied in various dosimetry applications as mentioned above.

The relationship between performance appraisal system and employees' voice behavior through the mediation-moderation mechanism

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Khalid Rasheed Memon ◽  
Bilqees Ghani
Keyword(s):  
Performance Appraisal ◽  
Psychological Empowerment ◽  
Vital Role ◽  
Voice Behavior ◽  
Perceived Fairness ◽  
Appraisal System ◽  
Empowering Leadership ◽  
Content Type ◽  
Performance Appraisal System ◽  
The Relationship

PurposeThe purpose of this study is to investigate and articulate the performance appraisal process as a tool, used for the development of voice behavior through the fostering of trustworthiness and empowering culture in the organization.Design/methodology/approachData has been collected through survey instruments, filled by employees and their coworkers. The study proposes and tests a new model based on the relationship between performance appraisal and voice behavior through the moderation-mediation mechanism. Data analysis has been performed using SEM through SMART PLS 3.FindingsResults show that a strong and positive relationship exists between performance appraisal and voice behavior through the mediating variable of psychological empowerment. The moderators, empowering leadership and perceived fairness have played vital role in boosting psychological empowerment and strengthening the relationship with performance appraisal.Research limitations/implicationsThe study presents the performance appraisal system as one of the antecedents of employees' voice behavior generated through psychological empowerment (mediator) and perceived fairness and empowering leadership (moderators) since the appraisal system is to be implemented through the leader.Originality/valueThe study presents a unique and innovative idea while it tries to explore and measure the different effects/impacts of the relationship between performance appraisal and voice behavior.

Investigating the citation advantage of author-pays charges model in computer science research: a case study of Elsevier and Springer

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tehmina Amjad ◽  
Mehwish Sabir ◽  
Azra Shamim ◽  
Masooma Amjad ◽  
Ali Daud
Keyword(s):  
Open Access ◽  
Computer Science ◽  
Science Research ◽  
Vital Role ◽  
The Body ◽  
Content Type ◽  
Body Of Knowledge ◽  
Computer Science Research ◽  
Science Domain ◽  
Citation Advantage

PurposeCitation is an important measure of quality, and it plays a vital role in evaluating scientific research. However, citation advantage varies from discipline to discipline, subject to subject and topic to topic. This study aims to compare the citation advantage of open access and toll access articles from four subfields of computer science.Design/methodology/approachThis research studies the articles published by two prestigious publishers: Springer and Elsevier in the author-pays charges model from 2011 to 2015. For experimentation, four sub-domains of computer science are selected including (a) artificial intelligence, (b) human–computer interaction, (c) computer vision and graphics, and (d) software engineering. The open-access and toll-based citation advantage is studied and analyzed at the micro level within the computer science domain by performing independent sample t-tests.FindingsThe results of the study highlight that open access articles have a higher citation advantage as compared to toll access articles across years and sub-domains. Further, an increase in open access articles has been observed from 2011 to 2015. The findings of the study show that the citation advantage of open access articles varies among different sub-domains of a subject. The study contributed to the body of knowledge by validating the positive movement toward open access articles in the field of computer science and its sub-domains. Further, this work added the success of the author-pays charges model in terms of citation advantage to the literature of open access.Originality/valueTo the best of the authors’ knowledge, this is the first study to examine the citation advantage of the author-pays charges model at a subject level (computer science) along with four sub-domains of computer science.

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