Low-Temperature Biosurfactants from Polar Microbes

Surfactants, both synthetic and natural, are used in a wide range of industrial applications, including the degradation of petroleum hydrocarbons. Organisms from extreme environments are well-adapted to the harsh conditions and represent an exciting avenue of discovery of naturally occurring biosurfactants, yet microorganisms from cold environments have been largely overlooked for their biotechnological potential as biosurfactant producers. In this study, four cold-adapted bacterial isolates from Antarctica are investigated for their ability to produce biosurfactants. Here we report on the physical properties and chemical structure of biosurfactants from the genera Janthinobacterium, Psychrobacter, and Serratia. These organisms were able to grow on diesel, motor oil, and crude oil at 4 °C. Putative identification showed the presence of sophorolipids and rhamnolipids. Emulsion index test (E24) activity ranged from 36.4–66.7%. Oil displacement tests were comparable to 0.1–1.0% sodium dodecyl sulfate (SDS) solutions. Data presented herein are the first report of organisms of the genus Janthinobacterium to produce biosurfactants and their metabolic capabilities to degrade diverse petroleum hydrocarbons. The organisms’ ability to produce biosurfactants and grow on different hydrocarbons as their sole carbon and energy source at low temperatures (4 °C) makes them suitable candidates for the exploration of hydrocarbon bioremediation in low-temperature environments.

Download Full-text

Biocontrol of wood-rotting fungi withStreptomyces violaceusnigerXL-2

Canadian Journal of Microbiology ◽

10.1139/w06-035 ◽

2006 ◽

Vol 52 (9) ◽

pp. 805-808 ◽

Cited By ~ 48

Author(s):

Nilanshu Shekhar ◽

Debaditya Bhattacharya ◽

Dishant Kumar ◽

Rajinder K Gupta

Keyword(s):

Biocontrol Agent ◽

Sodium Dodecyl ◽

Deae Cellulose ◽

Industrial Applications ◽

Stress Factors ◽

Antihypertensive Activity ◽

Growth Media ◽

Fungal Cell ◽

Wide Range ◽

Streptomyces Violaceusniger

During the previous decade, chitinases have received increased attention because of their wide range of applications. Chito-oligomers produced by enzymatic hydrolysis of chitin have been of interest in recent years because of their broad applications in medical, agricultural, and industrial applications, such as antibacterial, antifungal, hypo cholesterolemic, and antihypertensive activity, and as food quality enhancer. Fungal cell walls being rich in chitin also enable the use of chitinases in biocontrol of fungal pathogens, as bio-fungicides. An actinomycete was isolated from the bark of trees of Dehradun in India and was later identified as Streptomyces violaceusniger. This strain exhibits strong antagonism towards various wood-rotting fungi, such as Phanerochaete chrysosporium, Postia placenta, Coriolus versicolor, and Gloeophyllum trabeum. Further, studies showed an extracellular bioactive compound was responsible for the antagonism. The conditions for the production of this biocontrol agent were optimized, and the effects of various stress factors (like nitrogen-deficient media, carbon-deficient media, etc.) were studied. The presence of chitin in the growth media was found to be an essential factor for the active production of the biocontrol agent. The pH and temperature optima for the biocontrol agent were determined. Purification and characterization of this specific biocontrol agent was performed through anion exchange chromatography using a DEAE–cellulose column, and a single protein band was obtained on a 10% sodium dodecyl sulfate – polyacrylamide gel. The protein was later identified as a 28 kDa endo chitinase by MALDI–TOF (matrix-assisted laser desorption ionization – time of flight) and by a chitobiose activity assay.Key words: actinomycetes, biocontrol agents, Streptomyces violaceusniger, chitinase.

Download Full-text

The aqueous geochemistry of thallium: speciation and solubility of thallium in low temperature systems

Environmental Chemistry ◽

10.1071/en08086 ◽

2009 ◽

Vol 6 (5) ◽

pp. 441 ◽

Cited By ~ 26

Author(s):

Yongliang Xiong

Keyword(s):

Low Temperature ◽

Solubility Product ◽

Formation Constants ◽

Industrial Applications ◽

Thermodynamic Database ◽

Aqueous Geochemistry ◽

The Earth ◽

Soil Solutions ◽

Wide Range ◽

Cadmium And Lead

Environmental context. The aqueous geochemistry of thallium is not well known in comparison with cadmium and lead, although it is more highly toxic, and at the same time has a wide range of industrial applications. A database allowing us to reliably predict the speciation and solubility of thallium in various environments in low temperature systems would be invaluable in providing some understanding of thallium’s mobilisation and mitigation. We propose here such a thermodynamic database based on critical reviews. Abstract. Thallium is a highly toxic element, and at the same time it has a wide range of applications in industry. Therefore, it is important to know its speciation and solubility under low temperature conditions. This study expands the thermodynamic database of the first paper of this series on the aqueous geochemistry of thallium by providing the formation constants of some important thallium complexes, including TlEDTA3–, TlOx– (Ox: oxalate), TlSuc– (Suc: succinate), TlMal– (Mal: malonate) and TlHPO4–. This study also recommends the solubility product constant of TlCl(s) as 10–3.65. The combined database allows us to model reliably the speciation and solubility of thallium in the Earth surface environments. As an example, the speciation and solubility of thallium in soil solutions are presented based on thermodynamic calculations.

Download Full-text

Microbial Ecology from the Himalayan Cryosphere Perspective

Microorganisms ◽

10.3390/microorganisms8020257 ◽

2020 ◽

Vol 8 (2) ◽

pp. 257 ◽

Cited By ~ 3

Author(s):

Kusum Dhakar ◽

Anita Pandey

Keyword(s):

Low Temperature ◽

Microbial Ecology ◽

Higher Plants ◽

Biological Activities ◽

Large Fraction ◽

Polar Regions ◽

Cold Environments ◽

Wide Range ◽

Extreme Cold ◽

Ecological Importance

Cold-adapted microorganisms represent a large fraction of biomass on Earth because of the dominance of low-temperature environments. Extreme cold environments are mainly dependent on microbial activities because this climate restricts higher plants and animals. Himalaya is one of the most important cold environments on Earth as it shares climatic similarities with the polar regions. It includes a wide range of ecosystems, from temperate to extreme cold, distributed along the higher altitudes. These regions are characterized as stressful environments because of the heavy exposure to harmful rays, scarcity of nutrition, and freezing conditions. The microorganisms that colonize these regions are recognized as cold-tolerant (psychrotolerants) or/and cold-loving (psychrophiles) microorganisms. These microorganisms possess several structural and functional adaptations in order to perform normal life processes under the stressful low-temperature environments. Their biological activities maintain the nutrient flux in the environment and contribute to the global biogeochemical cycles. Limited culture-dependent and culture-independent studies have revealed their diversity in community structure and functional potential. Apart from the ecological importance, these microorganisms have been recognized as source of cold-active enzymes and novel bioactive compounds of industrial and biotechnological importance. Being an important part of the cryosphere, Himalaya needs to be explored at different dimensions related to the life of the inhabiting extremophiles. The present review discusses the distinct facts associated with microbial ecology from the Himalayan cryosphere perspective.

Download Full-text

The typA Gene is Required for Stress Adaptation as Well as for Symbiosis of Sinorhizobium meliloti 1021 with Certain Medicago truncatula Lines

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi.2004.17.3.235 ◽

2004 ◽

Vol 17 (3) ◽

pp. 235-244 ◽

Cited By ~ 48

Author(s):

Ernö Kiss ◽

Thierry Huguet ◽

Véréna Poinsot ◽

Jacques Batut

Keyword(s):

Escherichia Coli ◽

Low Temperature ◽

Medicago Truncatula ◽

Sinorhizobium Meliloti ◽

Sodium Dodecyl ◽

Low Ph ◽

Stress Adaptation ◽

Symbiotic Interaction ◽

Wide Range ◽

Cold Sensitive

In this article, we describe the typA gene of Sinorhizobium meliloti, the orthologue of typA/bipA genes found in a wide range of bacteria. We found that typA was required for survival of S. meliloti under certain stress conditions, such as growth at low temperature or low pH and in the presence of sodium dodecyl sulfate (SDS). The cold-sensitive phenotype of both Escherichia coli bipA and S. meliloti typA mutants were cross-complemented, indicating that the two genes are functionally equivalent. typA was indispensable for symbiosis on Medicago truncatula Jemalong and F83005.5 and contributes to the full efficiency of symbiosis on other host plant lines such as DZA315.16 or several cultivars of M. sativa. Hence, the symbiotic requirement for typA is host dependent. Interestingly, the symbiotic defect was different on Jemalong and F83005.5 plants, thus indicating that typA is required at a different stage of the symbiotic interaction.

Download Full-text

Untapped Resources: Biotechnological Potential of Peptides and Secondary Metabolites in Archaea

Archaea ◽

10.1155/2015/282035 ◽

2015 ◽

Vol 2015 ◽

pp. 1-7 ◽

Cited By ~ 27

Author(s):

James C. Charlesworth ◽

Brendan P. Burns

Keyword(s):

Secondary Metabolites ◽

Small Molecules ◽

Food Industry ◽

Extreme Environments ◽

Cell Communication ◽

Biotechnological Applications ◽

Small Peptide ◽

Biotechnological Potential ◽

Homoserine Lactones ◽

Wide Range

Archaea are an understudied domain of life often found in “extreme” environments in terms of temperature, salinity, and a range of other factors. Archaeal proteins, such as a wide range of enzymes, have adapted to function under these extreme conditions, providing biotechnology with interesting activities to exploit. In addition to producing structural and enzymatic proteins, archaea also produce a range of small peptide molecules (such as archaeocins) and other novel secondary metabolites such as those putatively involved in cell communication (acyl homoserine lactones), which can be exploited for biotechnological purposes. Due to the wide array of metabolites produced there is a great deal of biotechnological potential from antimicrobials such as diketopiperazines and archaeocins, as well as roles in the cosmetics and food industry. In this review we will discuss the diversity of small molecules, both peptide and nonpeptide, produced by archaea and their potential biotechnological applications.

Download Full-text

Adaptation and Acclimation of Photosynthetic Microorganisms to Permanently Cold Environments

Microbiology and Molecular Biology Reviews ◽

10.1128/mmbr.70.1.222-252.2006 ◽

2006 ◽

Vol 70 (1) ◽

pp. 222-252 ◽

Cited By ~ 301

Author(s):

Rachael M. Morgan-Kiss ◽

John C. Priscu ◽

Tessa Pocock ◽

Loreta Gudynaite-Savitch ◽

Norman P. A. Huner

Keyword(s):

Low Temperature ◽

Low Temperatures ◽

Extreme Environments ◽

Energy Sources ◽

Temperature Dependent ◽

Low Light ◽

Cold Environments ◽

Phototrophic Microorganisms ◽

Energy Products ◽

Dependent Processes

SUMMARY Persistently cold environments constitute one of our world's largest ecosystems, and microorganisms dominate the biomass and metabolic activity in these extreme environments. The stress of low temperatures on life is exacerbated in organisms that rely on photoautrophic production of organic carbon and energy sources. Phototrophic organisms must coordinate temperature-independent reactions of light absorption and photochemistry with temperature-dependent processes of electron transport and utilization of energy sources through growth and metabolism. Despite this conundrum, phototrophic microorganisms thrive in all cold ecosystems described and (together with chemoautrophs) provide the base of autotrophic production in low-temperature food webs. Psychrophilic (organisms with a requirement for low growth temperatures) and psychrotolerant (organisms tolerant of low growth temperatures) photoautotrophs rely on low-temperature acclimative and adaptive strategies that have been described for other low-temperature-adapted heterotrophic organisms, such as cold-active proteins and maintenance of membrane fluidity. In addition, photoautrophic organisms possess other strategies to balance the absorption of light and the transduction of light energy to stored chemical energy products (NADPH and ATP) with downstream consumption of photosynthetically derived energy products at low temperatures. Lastly, differential adaptive and acclimative mechanisms exist in phototrophic microorganisms residing in low-temperature environments that are exposed to constant low-light environments versus high-light- and high-UV-exposed phototrophic assemblages.

Download Full-text

Pt-Pd Nanoalloy for the Unprecedented Activation of Carbon-Fluorine Bond at Low Temperature

10.26434/chemrxiv.11145098 ◽

2019 ◽

Author(s):

Raghu Nath Dhital ◽

keigo nomura ◽

Yoshinori Sato ◽

Setsiri Haesuwannakij ◽

Masahiro Ehara ◽

...

Keyword(s):

Activation Energy ◽

Low Temperature ◽

Dft Calculations ◽

Bond Activation ◽

Mild Conditions ◽

Selective Transformation ◽

Rate Determining Step ◽

Highly Active ◽

Harsh Conditions ◽

Reaction Profile

Carbon-Fluorine (C-F) bonds are considered the most inert organic functionality and their selective transformation under mild conditions remains challenging. Herein, we report a highly active Pt-Pd nanoalloy as a robust catalyst for the transformation of C-F bonds into C-H bonds at low temperature, a reaction that often required harsh conditions. The alloying of Pt with Pd is crucial to activate C-F bond. The reaction profile kinetics revealed that the major source of hydrogen in the defluorinated product is the alcoholic proton of 2-propanol, and the rate-determining step is the reduction of the metal upon transfer of the beta-H from 2-propanol. DFT calculations elucidated that the key step is the selective oxidative addition of the O-H bond of 2-propanol to a Pd center prior to C-F bond activation at a Pt site, which crucially reduces the activation energy of the C-F bond. Therefore, both Pt and Pd work independently but synergistically to promote the overall reaction

Download Full-text

Substituent Effects on the Thermal Decomposition of Phosphate Esters on Ferrous Surfaces

10.26434/chemrxiv.11418978.v1 ◽

2019 ◽

Author(s):

James Ewen ◽

Carlos Ayestaran Latorre ◽

Arash Khajeh ◽

Joshua Moore ◽

Joseph Remias ◽

...

Keyword(s):

Thermal Decomposition ◽

Film Formation ◽

Substituent Effects ◽

Vapour Phase ◽

Industrial Applications ◽

Phosphate Esters ◽

Antiwear Additives ◽

Formation Mechanisms ◽

Phosphate Ester ◽

Wide Range

Phosphate esters have a wide range of industrial applications, for example in tribology where they are used as vapour phase lubricants and antiwear additives. To rationally design phosphate esters with improved tribological performance, an atomic-level understanding of their film formation mechanisms is required. One important aspect is the thermal decomposition of phosphate esters on steel surfaces, since this initiates film formation. In this study, ReaxFF molecular dynamics simulations are used to study the thermal decomposition of phosphate esters with different substituents on several ferrous surfaces. On Fe3O4(001) and α-Fe(110), chemisorption interactions between the phosphate esters and the surfaces occur even at room temperature, and the number of molecule-surface bonds increases as the temperature is increased from 300 to 1000 K. Conversely, on hydroxylated, amorphous Fe3O4, most of the molecules are physisorbed, even at high temperature. Thermal decomposition rates were much higher on Fe3O4(001) and particularly α-Fe(110) compared to hydroxylated, amorphous Fe3O4. This suggests that water passivates ferrous surfaces and inhibits phosphate ester chemisorption, decomposition, and ultimately film formation. On Fe3O4(001), thermal decomposition proceeds mainly through C-O cleavage (to form surface alkyl and aryl groups) and C-H cleavage (to form surface hydroxyls). The onset temperature for C-O cleavage on Fe3O4(001) increases in the order: tertiary alkyl < secondary alkyl < primary linear alkyl ≈ primary branched alkyl < aryl. This order is in agreement with experimental observations for the thermal stability of antiwear additives with similar substituents. The results highlight surface and substituent effects on the thermal decomposition of phosphate esters which should be helpful for the design of new molecules with improved performance.

Download Full-text

PLATINUM

Alloy Digest ◽

10.31399/asm.ad.pt0001 ◽

1970 ◽

Vol 19 (11) ◽

Keyword(s):

Corrosion Resistance ◽

High Temperature ◽

Heat Treating ◽

Industrial Applications ◽

High Melting ◽

High Melting Point ◽

White Metal ◽

Temperature Performance ◽

Wide Range ◽

Corrosion And Oxidation

Abstract PLATINUM is a soft, ductile, white metal which can be readily worked either hot or cold. It has a wide range of industrial applications because of its excellent corrosion and oxidation resistance and its high melting point. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Pt-1. Producer or source: Matthey Bishop Inc..

Download Full-text

Antimicrobial Peptides - Small but Mighty Weapons for Plants to Fight Phytopathogens

Protein and Peptide Letters ◽

10.2174/0929866526666190619112438 ◽

2019 ◽

Vol 26 (10) ◽

pp. 720-742 ◽

Cited By ~ 8

Author(s):

Kaushik Das ◽

Karabi Datta ◽

Subhasis Karmakar ◽

Swapan K. Datta

Keyword(s):

Antimicrobial Peptides ◽

Durable Resistance ◽

Defense Responses ◽

Defense System ◽

Biotechnological Potential ◽

Functional Aspects ◽

Low Concentrations ◽

Wide Range ◽

Vital Component ◽

Pathogen Entry

Antimicrobial Peptides (AMPs) have diverse structures, varied modes of actions, and can inhibit the growth of a wide range of pathogens at low concentrations. Plants are constantly under attack by a wide range of phytopathogens causing massive yield losses worldwide. To combat these pathogens, nature has armed plants with a battery of defense responses including Antimicrobial Peptides (AMPs). These peptides form a vital component of the two-tier plant defense system. They are constitutively expressed as part of the pre-existing first line of defense against pathogen entry. When a pathogen overcomes this barrier, it faces the inducible defense system, which responds to specific molecular or effector patterns by launching an arsenal of defense responses including the production of AMPs. This review emphasizes the structural and functional aspects of different plant-derived AMPs, their homology with AMPs from other organisms, and how their biotechnological potential could generate durable resistance in a wide range of crops against different classes of phytopathogens in an environmentally friendly way without phenotypic cost.

Download Full-text