scholarly journals Light-absorbing secondary organic material formed by glyoxal in aqueous aerosol mimics

2009 ◽  
Vol 9 (1) ◽  
pp. 59-80 ◽  
Author(s):  
E. L. Shapiro ◽  
J. Szprengiel ◽  
N. Sareen ◽  
C. N. Jen ◽  
M. R. Giordano ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Inorganic Salt ◽  
Aldol Condensation ◽  
Aerosol Particles ◽  
Pi Conjugated ◽  
Tropospheric Aerosol ◽  
Surface Active ◽  
Visible Wavelengths ◽  
Seed Aerosol

Abstract. Light-absorbing and high-molecular-weight secondary organic products were observed to result from the reaction of glyoxal in mildly acidic (pH=4) aqueous inorganic salt solutions mimicking aqueous tropospheric aerosol particles. High-molecular-weight (500–600 amu) products were observed when ammonium sulfate ((NH4)2SO4) or sodium chloride (NaCl) was present in the aqueous phase. The products formed in the (NH4)2SO4 solutions absorb light at UV and visible wavelengths. Substantial absorption at 300–400 nm develops within two hours, and absorption between 400–600 nm develops within days. Pendant drop tensiometry measurements show that the products are not surface-active. The experimental results along with ab initio predictions of the UV/Vis absorption of potential products suggest that an aldol condensation mechanism is active in the glyoxal-(NH4)2SO4system, resulting in the formation of pi-conjugated products. If similar products are formed in atmospheric aerosol particles, they could change the optical properties of the seed aerosol over its lifetime.

scholarly journals Light-absorbing secondary organic material formed by glyoxal in aqueous aerosol mimics

2009 ◽  
Vol 9 (7) ◽  
pp. 2289-2300 ◽  
Author(s):  
E. L. Shapiro ◽  
J. Szprengiel ◽  
N. Sareen ◽  
C. N. Jen ◽  
M. R. Giordano ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Inorganic Salt ◽  
Aerosol Particles ◽  
Ammonium Ion ◽  
Pendant Drop ◽  
Tropospheric Aerosol ◽  
Surface Active ◽  
Visible Wavelengths ◽  
Seed Aerosol

Abstract. Light-absorbing and high-molecular-weight secondary organic products were observed to result from the reaction of glyoxal in mildly acidic (pH=4) aqueous inorganic salt solutions mimicking aqueous tropospheric aerosol particles. High-molecular-weight (500–600 amu) products were observed when ammonium sulfate ((NH4)2SO4) or sodium chloride (NaCl) was present in the aqueous phase. The products formed in (NH4)2SO4 or ammonium nitrate (NH4NO3) solutions absorb light at UV and visible wavelengths. Substantial absorption at 300–400 nm develops within two hours, and absorption between 400–600 nm develops within days. Pendant drop tensiometry measurements show that the products are not surface-active. The experimental results along with ab initio predictions of the UV/Vis absorption of potential products suggest a mechanism involving the participation of the ammonium ion. If similar products are formed in atmospheric aerosol particles, they could change the optical properties of the seed aerosol over its lifetime.

scholarly journals Secondary organic material formed by methylglyoxal in aqueous aerosol mimics – Part 1: Surface tension depression and light-absorbing products

2009 ◽  
Vol 9 (4) ◽  
pp. 15541-15565 ◽  
Author(s):  
A. N. Schwier ◽  
E. L. Shapiro ◽  
N. Sareen ◽  
V. F. McNeill
Keyword(s):  
Surface Tension ◽  
Organic Material ◽  
Aldol Condensation ◽  
Aerosol Particles ◽  
Ammonium Ion ◽  
Inorganic Salts ◽  
Solution Composition ◽  
Tropospheric Aerosol ◽  
Seed Aerosol ◽  
Nitrate Solutions

Abstract. We show that methylglyoxal forms light-absorbing secondary organic material in aqueous ammonium sulfate and ammonium nitrate solutions mimicking tropospheric aerosol particles. The light-absorbing products form on the order of minutes, and solution composition continues to change over several days. The results suggest an aldol condensation pathway involving the participation of the ammonium ion. Aqueous solutions of methylglyoxal, with and without inorganic salts, exhibit surface tension depression. Methylglyoxal uptake could potentially change the optical properties, climate effects, and heterogeneous chemistry of the seed aerosol over its lifetime.

scholarly journals Bacterial surfactants as agents with antibiofilm activity

2021 ◽  
Vol 16 (1) ◽  
pp. 94-104
Author(s):  
А.Е. Abaturov
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Low Molecular Weight ◽  
Antibiofilm Activity ◽  
Antibiotic Resistant ◽  
Biological Surface ◽  
The Matrix ◽  
Surface Active ◽  
Bacteria And Fungi ◽  
Surface Active Compounds

Biosuragents are a heterogeneous group of biological surface-active amphiphilic compounds. The producers of biosurfactants are various microorganisms: bacteria and fungi. The class of biosurfactants consists of two groups: low molecular weight and high molecular weight compounds. Representatives of low molecular weight compounds are lipopeptides, glycolipids, fatty acids, phospholipids that reduce surface and interfacial tension, and high molecular weight compounds are polymer and dispersed biosurfactants, which are emulsion stabilizers. The most studied biosurfactants with the potential of drugs are lipopeptides and glycolipids. A subgroup of lipopeptides are polymyxins, pseudo-factins, putisolvins, surfactin, fengycin and others; and glycoli­pids — rhamnolipids, trehalose, sophorose, cellobiose, mannosileritritol lipids, and others. Biosurfactants play a key role in the life of biofilms: they regulate the adhesion of bacteria and biofilm matrix, support the functioning of the matrix channels, providing the nutrient needs of bacteria. It has also been shown that biosurfactants are involved in the formation and dispersion of formed biofilms. These substances, directly reacting with the components of the matrix, induce degradation of the biofilm. Biosurfing agents, possessing antimicrobial, antifungal and antiviral, and antitumor properties, are a promising class of compounds that, possessing a combination of antibacterial and antibiofilm action, open up new perspectives in the treatment of recurrent chronic infectious di­seases. It is believed that surface-active compounds, both representatives of lipopeptides and glycolipids, can be the molecular basis for the development of drugs that will enhance the effectiveness of antibiotic therapy for problem infections, especially those caused by antibiotic-resistant strains.

scholarly journals Production and characterisation of a marine Halomonas surface-active exopolymer

2019 ◽  
Vol 104 (3) ◽  
pp. 1063-1076
Author(s):  
Tony Gutierrez ◽  
Gordon Morris ◽  
Dave Ellis ◽  
Barbara Mulloy ◽  
Michael D. Aitken
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
High Molecular Weight ◽  
Positive Influence ◽  
Contaminated Sites ◽  
Crude Oils ◽  
Magnetic Resonance Spectroscopic Analysis ◽  
Surface Active ◽  
Low Ionic Strength ◽  
Pure Hydrocarbon

AbstractDuring screening for novel emulsifiers and surfactants, a marine gammaproteobacterium, Halomonas sp. MCTG39a, was isolated and selected for its production of an extracellular emulsifying agent, P39a. This polymer was produced by the new isolate during growth in a modified Zobell’s 2216 medium amended with 1% glucose, and was extractable by cold ethanol precipitation. Chemical, chromatographic and nuclear magnetic resonance spectroscopic analysis confirmed P39a to be a high-molecular-weight (~ 261,000 g/mol) glycoprotein composed of carbohydrate (17.2%) and protein (36.4%). The polymer exhibited high emulsifying activities against a range of oil substrates that included straight-chain aliphatics, mono- and alkyl- aromatics and cycloparaffins. In general, higher emulsification values were measured under low (0.1 M PBS) compared to high (synthetic seawater) ionic strength conditions, indicating that low ionic strength is more favourable for emulsification by the P39a polymer. However, as observed with other bacterial emulsifying agents, the polymer emulsified some aromatic hydrocarbon species, as well as refined and crude oils, more effectively under high ionic strength conditions, which we posit could be due to steric adsorption to these substrates as may be conferred by the protein fraction of the polymer. Furthermore, the polymer effected a positive influence on the degradation of phenanthrene by other marine bacteria, such as the specialist PAH-degrader Polycyclovorans algicola. Collectively, based on the ability of this Halomonas high-molecular-weight glycoprotein to emulsify a range of pure hydrocarbon species, as well as refined and crude oils, it shows promise for the bioremediation of contaminated sites.

scholarly journals Distinct high molecular weight organic compound (HMW-OC) types in aerosol particles collected at a coastal urban site

2017 ◽  
Vol 171 ◽  
pp. 118-125 ◽  
Author(s):  
M. Dall’Osto ◽  
R.M. Healy ◽  
J.C. Wenger ◽  
C. O'Dowd ◽  
J. Ovadnevaite ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Organic Compound ◽  
High Molecular Weight ◽  
Aerosol Particles ◽  
Urban Site

Involvement of a surface-active high molecular weight factor in degradation of polycyclic aromatic hydrocarbons by Pseudomonas marginalis

1996 ◽  
Vol 42 (8) ◽  
pp. 791-797 ◽  
Author(s):  
G. Burd ◽  
O. P. Ward
Keyword(s):  
Molecular Weight ◽  
Polycyclic Aromatic Hydrocarbons ◽  
High Molecular Weight ◽  
Aromatic Hydrocarbons ◽  
Aqueous Suspension ◽  
Bacterial Cells ◽  
Mineral Salts ◽  
Active Factor ◽  
Polycyclic Aromatic ◽  
Surface Active

A strain of Pseudomonas marginalis PD-14B, isolated from polycyclic aromatic hydrocarbon (PAH) contaminated soil, produced an extracellular surface-active factor of high molecular weight containing protein and lipopolysaccharide. A crude preparation of the factor, obtained from the culture broth of cells grown in mineral salts (MS) medium with succinate and yeast extract, affected the extent of PAH degradation by the bacterial cells and prevented flocculation of PAHs in an aqueous suspension. A washed suspension of P. marginalis cells also prevented flocculation of PAH suspensions and emulsified liquid hydrocarbons. Incubation of the factor and the factor-producing strain in the presence of different PAHs resulted in gradual increase of turbidity of the PAH dispersions. The factor markedly stimulated rate and extent of turbidity generation by bacterial cells. The surface-active factor may promote infection of lettuce and other plants by this known pathogen and may also have application in bioremediation.Key words: biosurfactant, polycyclic aromatic hydrocarbons, Pseudomonas marginalis, bioremediation, plant pathogenesis.

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