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1.
Shining New Light on the Kinetics of Water Uptake by Organic Aerosol Particles.
Diveky, ME, Gleichweit, MJ, Roy, S, Signorell, R
The journal of physical chemistry. A. 2021;(17):3528-3548
Abstract
The uptake of water vapor by various organic aerosols is important in a number of applications ranging from medical delivery of pharmaceutical aerosols to cloud formation in the atmosphere. The coefficient that describes the probability that the impinging gas-phase molecule sticks to the surface of interest is called the mass accommodation coefficient, αM. Despite the importance of this coefficient for the description of water uptake kinetics, accurate values are still lacking for many systems. In this Feature Article, we present various experimental techniques that have been evoked in the literature to study the interfacial transport of water and discuss the corresponding strengths and limitations. This includes our recently developed technique called photothermal single-particle spectroscopy (PSPS). The PSPS technique allows for a retrieval of αM values from three independent, yet simultaneous measurements operating close to equilibrium, providing a robust assessment of interfacial mass transport. We review the currently available data for αM for water on various organics and discuss the few studies that address the temperature and relative humidity dependence of αM for water on organics. The knowledge of the latter, for example, is crucial to assess the water uptake kinetics of organic aerosols in the Earth's atmosphere. Finally, we argue that PSPS might also be a viable method to better restrict the αM value for water on liquid water.
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2.
Metabolic engineering of microorganisms for production of aromatic compounds.
Huccetogullari, D, Luo, ZW, Lee, SY
Microbial cell factories. 2019;(1):41
Abstract
Metabolic engineering has been enabling development of high performance microbial strains for the efficient production of natural and non-natural compounds from renewable non-food biomass. Even though microbial production of various chemicals has successfully been conducted and commercialized, there are still numerous chemicals and materials that await their efficient bio-based production. Aromatic chemicals, which are typically derived from benzene, toluene and xylene in petroleum industry, have been used in large amounts in various industries. Over the last three decades, many metabolically engineered microorganisms have been developed for the bio-based production of aromatic chemicals, many of which are derived from aromatic amino acid pathways. This review highlights the latest metabolic engineering strategies and tools applied to the biosynthesis of aromatic chemicals, many derived from shikimate and aromatic amino acids, including L-phenylalanine, L-tyrosine and L-tryptophan. It is expected that more and more engineered microorganisms capable of efficiently producing aromatic chemicals will be developed toward their industrial-scale production from renewable biomass.
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3.
Effect of Organic Solvents on Microalgae Growth, Metabolism and Industrial Bioproduct Extraction: A Review.
Miazek, K, Kratky, L, Sulc, R, Jirout, T, Aguedo, M, Richel, A, Goffin, D
International journal of molecular sciences. 2017;(7)
Abstract
In this review, the effect of organic solvents on microalgae cultures from molecular to industrial scale is presented. Traditional organic solvents and solvents of new generation-ionic liquids (ILs), are considered. Alterations in microalgal cell metabolism and synthesis of target products (pigments, proteins, lipids), as a result of exposure to organic solvents, are summarized. Applications of organic solvents as a carbon source for microalgal growth and production of target molecules are discussed. Possible implementation of various industrial effluents containing organic solvents into microalgal cultivation media, is evaluated. The effect of organic solvents on extraction of target compounds from microalgae is also considered. Techniques for lipid and carotenoid extraction from viable microalgal biomass (milking methods) and dead microalgal biomass (classical methods) are depicted. Moreover, the economic survey of lipid and carotenoid extraction from microalgae biomass, by means of different techniques and solvents, is conducted.
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4.
Ectomycorrhizal fungi - potential organic matter decomposers, yet not saprotrophs.
Lindahl, BD, Tunlid, A
The New phytologist. 2015;(4):1443-1447
Abstract
Although hypothesized for many years, the involvement of ectomycorrhizal fungi in decomposition of soil organic matter remains controversial and has not yet been fully acknowledged as an important factor in the regulation of soil carbon (C) storage. Here, we review recent findings, which support the view that some ectomycorrhizal fungi have the capacity to oxidize organic matter, either by 'brown-rot' Fenton chemistry or using 'white-rot' peroxidases. We propose that ectomycorrhizal fungi benefit from organic matter decomposition primarily through increased nitrogen mobilization rather than through release of metabolic C and question the view that ectomycorrhizal fungi may act as facultative saprotrophs. Finally, we discuss how mycorrhizal decomposition may influence organic matter storage in soils and mediate responses of ecosystem C sequestration to environmental changes.
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5.
Diversity, distribution and roles of osmoprotective compounds accumulated in halophytes under abiotic stress.
Slama, I, Abdelly, C, Bouchereau, A, Flowers, T, Savouré, A
Annals of botany. 2015;(3):433-47
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Abstract
BACKGROUND AND AIMS Osmolytes are low-molecular-weight organic solutes, a broad group that encompasses a variety of compounds such as amino acids, tertiary sulphonium and quaternary ammonium compounds, sugars and polyhydric alcohols. Osmolytes are accumulated in the cytoplasm of halophytic species in order to balance the osmotic potential of the Na(+) and Cl(-) accumulated in the vacuole. The advantages of the accumulation of osmolytes are that they keep the main physiological functions of the cell active, the induction of their biosynthesis is controlled by environmental cues, and they can be synthesized at all developmental stages. In addition to their role in osmoregulation, osmolytes have crucial functions in protecting subcellular structures and in scavenging reactive oxygen species. SCOPE This review discusses the diversity of osmolytes among halophytes and their distribution within taxonomic groups, the intrinsic and extrinsic factors that influence their accumulation, and their role in osmoregulation and osmoprotection. Increasing the osmolyte content in plants is an interesting strategy to improve the growth and yield of crops upon exposure to salinity. Examples of transgenic plants as well as exogenous applications of some osmolytes are also discussed. Finally, the potential use of osmolytes in protein stabilization and solvation in biotechnology, including the pharmaceutical industry and medicine, are considered.
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6.
Nutrient and chemical sensing by intestinal pathogens.
Hernandez-Doria, JD, Sperandio, V
Microbes and infection. 2013;(12):759-64
Abstract
Pathogenic gut bacteria, such as those comprising the Enterobacteriaceae family, have evolved sophisticated virulence mechanisms, including nutrient and chemical sensing, to escape host defense strategies and produce disease. In this review we describe the mechanisms utilized by the enteric pathogen enterohemorrhagic Escherichia coli (EHEC) O157:H7 to achieve successful colonization of its mammalian host.
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7.
Bio-based production of organic acids with Corynebacterium glutamicum.
Wieschalka, S, Blombach, B, Bott, M, Eikmanns, BJ
Microbial biotechnology. 2013;(2):87-102
Abstract
The shortage of oil resources, the steadily rising oil prices and the impact of its use on the environment evokes an increasing political, industrial and technical interest for development of safe and efficient processes for the production of chemicals from renewable biomass. Thus, microbial fermentation of renewable feedstocks found its way in white biotechnology, complementing more and more traditional crude oil-based chemical processes. Rational strain design of appropriate microorganisms has become possible due to steadily increasing knowledge on metabolism and pathway regulation of industrially relevant organisms and, aside from process engineering and optimization, has an outstanding impact on improving the performance of such hosts. Corynebacterium glutamicum is well known as workhorse for the industrial production of numerous amino acids. However, recent studies also explored the usefulness of this organism for the production of several organic acids and great efforts have been made for improvement of the performance. This review summarizes the current knowledge and recent achievements on metabolic engineering approaches to tailor C. glutamicum for the bio-based production of organic acids. We focus here on the fermentative production of pyruvate, L- and D-lactate, 2-ketoisovalerate, 2-ketoglutarate, and succinate. These organic acids represent a class of compounds with manifold application ranges, e.g. in pharmaceutical and cosmetics industry, as food additives, and economically very interesting, as precursors for a variety of bulk chemicals and commercially important polymers.
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Laccase-catalysed oxidations of naturally occurring phenols: from in vivo biosynthetic pathways to green synthetic applications.
Jeon, JR, Baldrian, P, Murugesan, K, Chang, YS
Microbial biotechnology. 2012;(3):318-32
Abstract
Laccases are oxidases that contain several copper atoms, and catalyse single-electron oxidations of phenolic compounds with concomitant reduction of oxygen to water. The enzymes are particularly widespread in ligninolytic basidiomycetes, but also occur in certain prokaryotes, insects and plants. Depending on the species, laccases are involved in various biosynthetic processes contributing to carbon recycling in land ecosystems and the morphogenesis of biomatrices, wherein low-molecular-weight naturally occurring phenols serve as key enzyme substrates. Studies of these in vivo synthetic pathways have afforded new insights into fungal laccase applicability in green synthetic chemistry. Thus, we here review fungal laccase-catalysed oxidations of naturally occurring phenols that are particularly relevant to the synthesis of fine organic chemicals, and we discuss how the discovered synthetic strategies mimic laccase-involved in vivo pathways, thus enhancing the green nature of such reactions. Laccase-catalysed in vivo processes yield several types of biopolymers, including those of cuticles, lignin, polyflavonoids, humus and the melanin pigments, using natural mono- or poly-phenols as building blocks. The in vivo synthetic pathways involve either phenoxyl radical-mediated coupling or cross-linking reactions, and can be adapted to the design of in vitro oxidative processes involving fungal laccases in organic synthesis; the laccase substrates and the synthetic mechanisms reflect in vivo processes. Notably, such in vitro synthetic pathways can also reproduce physicochemical properties (e.g. those of chromophores, and radical-scavenging, hydration and antimicrobial activities) found in natural biomaterials. Careful study of laccase-associated in vivo metabolic pathways has been rewarded by the discovery of novel green applications for fungal laccases. This review comprehensively summarizes the available data on laccase-catalysed biosynthetic pathways and associated applications in fine chemical syntheses.
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9.
Biomonitoring in Greenland: human biomarkers of exposure and effects - a short review.
Bonefeld-Jorgensen, EC
Rural and remote health. 2010;(2):1362
Abstract
CONTEXT Since 1997 the Arctic Monitoring and Assessment Programme (AMAP) has produced integrated assessment reports on the status of and trends in environmental persistent organic pollutants (POPs) in the Arctic ecosystem. Three reports on biomonitoring POPs and their health risks for Arctic populations were published in 1998, 2002, and 2009. ISSUE The present review summarizes data from Greenland on human monitoring of biomarkers of POP exposure and bioaccumulation and the determination of biomarkers for POP effects. The review focuses on hormone disruptive potentials and some genetic sensitivity biomarkers. The overview covers Greenlandic studies from 2000 to 2006. LESSONS LEARNED The Greenland biomonitoring studies showed general geographical and gender differences of bioaccumulated serum POP levels, which were primarily related to diet and lifestyle. A high intake of traditional Greenlandic diet (eg seal, whale, polar bear, and seabirds) together with smoking caused higher blood concentrations of POPs. The highest POP values were found on the east coast of Greenland. The receptor effect studies showed a general inverse relationship between high serum POP concentration and estrogen receptor (ER) and Ah-receptor (AhR) transactivity; in addition for men in the two West Greenlandic districts, Nuuk and Sisimiut, a trend towards increased induced AR activity was found. An observed trend to an opposite direction between the dioxin-like AhR and ER activity supports the perception of that dioxins exert an antiestrogen effect. In conclusion, the actual mixtures of serum POPs in Greenlandic Inuit have an endocrine disrupting potential. Comparisons between European and Greenlandic male serum POP levels showed significantly higher levels in Inuit; however, in the same study Inuit had significantly lower sperm DNA damage. Further studies are required to elucidate whether the serum POP related effects on hormone receptors and/or AhR are explanatory factors. 'The Arctic dilemma' is that along with the intake of the Greenlandic traditional diet that contains POPs, there are also a number of important nutrients, such as trace elements/antioxidants and marine unsaturated fatty acids which have favorable effects on health. However, a number of studies suggest that an increase in Western food items in the diet can lead to other health risks, such as the metabolic syndrome and its sequels increase in weight, hypertension, diabetes type 2, cardiovascular disease, and cancer, including breast cancer. To elucidate these aspects further studies are required, including those into biomarkers for exposure and effects, epigenetic contexts and the determination of relevant genetic polymorphisms, case-control as well as generation studies. Finally, there is a need for the development of new biomarkers to study the potential POP effects that inhibit the immune system and affect the development of the central nervous system.
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10.
Uptake of organic nitrogen by plants.
Näsholm, T, Kielland, K, Ganeteg, U
The New phytologist. 2009;(1):31-48
Abstract
Languishing for many years in the shadow of plant inorganic nitrogen (N) nutrition research, studies of organic N uptake have attracted increased attention during the last decade. The capacity of plants to acquire organic N, demonstrated in laboratory and field settings, has thereby been well established. Even so, the ecological significance of organic N uptake for plant N nutrition is still a matter of discussion. Several lines of evidence suggest that plants growing in various ecosystems may access organic N species. Many soils display amino acid concentrations similar to, or higher than, those of inorganic N, mainly as a result of rapid hydrolysis of soil proteins. Transporters mediating amino acid uptake have been identified both in mycorrhizal fungi and in plant roots. Studies of endogenous metabolism of absorbed amino acids suggest that L- but not D-enantiomers are efficiently utilized. Dual labelled amino acids supplied to soil have provided strong evidence for plant uptake of organic N in the field but have failed to provide information on the quantitative importance of this process. Thus, direct evidence that organic N contributes significantly to plant N nutrition is still lacking. Recent progress in our understanding of the mechanisms underlying plant organic N uptake may open new avenues for the exploration of this subject.