Influence of sediment biofilm on the behaviour of aluminum and its bioavailability to the snail Lymnaea stagnalis in neutral freshwater

2001 ◽  
Vol 58 (9) ◽  
pp. 1708-1715 ◽  
Author(s):  
S Ballance ◽  
P J Phillips ◽  
C R McCrohan ◽  
J J Powell ◽  
R Jugdaohsingh ◽  
...  
Keyword(s):  
Water Column ◽  
Humic Substances ◽  
Humic Acids ◽  
Organic Material ◽  
Extracellular Polymeric Substances ◽  
Lymnaea Stagnalis ◽  
Bacterial Biofilm ◽  
Important Influence ◽  
Running Waters ◽  
Sediment Biofilm

An important influence on the behaviour, bioavailability, and toxicity of Al in neutral freshwater is its ability to form complexes with organic material such as humic acids and extracellular polymeric substances (EPS). This paper examines the influence of EPS, secreted by a natural bacterial biofilm associated with a pebble substrate ("sediment biofilm") and by the snail Lymnaea stagnalis, on the behaviour of Al in the water column and its bioavailability to the snail. Both sediment biofilm and snails were a significant source of aqueous EPS. Added Al stimulated the production of EPS by the snail but not by bacterial biofilm. Repeated elevation of the concentration of Al in the water by 500 µg Al·L–1 but not 100 µg Al·L–1 over 10 days resulted in a progressive rise of Al in the water column in the absence but not in the presence of sediment biofilm. Up to 150 µg Al·cm–2 was associated with the sediment biofilm, and we suggest that sediment is a significant "sink" for aqueous Al. EPS avidly binds colloidal Al, and we propose that the sediment biofilm is an important influence on the behaviour and bioavailability of Al in running waters when amounts of humic substances are low.

Antibiotics Application Strategies to Control Biofilm Formation in Pathogenic Bacteria

2020 ◽  
Vol 21 (4) ◽  
pp. 270-286 ◽  
Author(s):  
Fazlurrahman Khan ◽  
Dung T.N. Pham ◽  
Sandra F. Oloketuyi ◽  
Young-Mog Kim
Keyword(s):  
Biofilm Formation ◽  
Pathogenic Bacteria ◽  
Extracellular Polymeric Substances ◽  
Quorum Quenching ◽  
Resistance Mechanisms ◽  
Bacterial Biofilm ◽  
Bacterial Cells ◽  
High Concentration ◽  
Biofilm Inhibition ◽  
Abiotic Surfaces

Background: The establishment of a biofilm by most pathogenic bacteria has been known as one of the resistance mechanisms against antibiotics. A biofilm is a structural component where the bacterial community adheres to the biotic or abiotic surfaces by the help of Extracellular Polymeric Substances (EPS) produced by bacterial cells. The biofilm matrix possesses the ability to resist several adverse environmental factors, including the effect of antibiotics. Therefore, the resistance of bacterial biofilm-forming cells could be increased up to 1000 times than the planktonic cells, hence requiring a significantly high concentration of antibiotics for treatment. Methods: Up to the present, several methodologies employing antibiotics as an anti-biofilm, antivirulence or quorum quenching agent have been developed for biofilm inhibition and eradication of a pre-formed mature biofilm. Results: Among the anti-biofilm strategies being tested, the sub-minimal inhibitory concentration of several antibiotics either alone or in combination has been shown to inhibit biofilm formation and down-regulate the production of virulence factors. The combinatorial strategies include (1) combination of multiple antibiotics, (2) combination of antibiotics with non-antibiotic agents and (3) loading of antibiotics onto a carrier. Conclusion: The present review paper describes the role of several antibiotics as biofilm inhibitors and also the alternative strategies adopted for applications in eradicating and inhibiting the formation of biofilm by pathogenic bacteria.

scholarly journals Characterization of Soil Organic Matter Individual Fractions (Fulvic Acids, Humic Acids, and Humins) by Spectroscopic and Electrochemical Techniques in Agricultural Soils

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1067
Author(s):  
Aleksandra Ukalska-Jaruga ◽  
Romualda Bejger ◽  
Guillaume Debaene ◽  
Bożena Smreczak
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Humic Substances ◽  
Humic Acids ◽  
Agricultural Soils ◽  
Fulvic Acids ◽  
Sorption Properties ◽  
Aliphatic Chains

The objective of this paper was to investigate the molecular characterization of soil organic matter fractions (humic substances (HS): fulvic acids-FAs, humic acids-HAs, and humins-HNs), which are the most reactive soil components. A wide spectrum of spectroscopic (UV–VIS and VIS–nearIR), as well as electrochemical (zeta potential, particle size diameter, and polydispersity index), methods were applied to find the relevant differences in the behavior, formation, composition, and sorption properties of HS fractions derived from various soils. Soil material (n = 30) used for the study were sampled from the surface layer (0–30 cm) of agricultural soils. FAs and HAs were isolated by sequential extraction in alkaline and acidic solutions, according to the International Humic Substances Society method, while HNs was determined in the soil residue (after FAs and HAs extraction) by mineral fraction digestion using a 0.1M HCL/0.3M HF mixture and DMSO. Our study showed that significant differences in the molecular structures of FAs, Has, and HNs occurred. Optical analysis confirmed the lower molecular weight of FAs with high amount of lignin-like compounds and the higher weighted aliphatic–aromatic structure of HAs. The HNs were characterized by a very pronounced and strong condensed structure associated with the highest molecular weight. HAs and HNs molecules exhibited an abundance of acidic, phenolic, and amine functional groups at the aromatic ring and aliphatic chains, while FAs mainly showed the presence of methyl, methylene, ethenyl, and carboxyl reactive groups. HS was characterized by high polydispersity related with their structure. FAs were characterized by ellipsoidal shape as being associated to the long aliphatic chains, while HAs and HNs revealed a smaller particle diameter and a more spherical shape caused by the higher intermolecular forcing between the particles. The observed trends directly indicate that individual HS fractions differ in behavior, formation, composition, and sorption properties, which reflects their binding potential to other molecules depending on soil properties resulting from their type. The determined properties of individual HS fractions are presented as averaged characteristics over the examined soils with different physico-chemical properties.

scholarly journals Effect of different levels of humic acids on the nutrient content, plant growth, and soil properties under conditions of salinity

2011 ◽  
Vol 6 (No. 1) ◽  
pp. 21-29 ◽  
Author(s):  
H. Khaled ◽  
H.A. Fawy
Keyword(s):  
Plant Growth ◽  
Humic Substances ◽  
Humic Acids ◽  
Foliar Application ◽  
N Uptake ◽  
Seedling Emergence ◽  
Dry Weight ◽  
Nutrient Content ◽  
Nutrient Elements ◽  
A Minor

In this study, the effects were investigated of salinity, foliar and soil applications of humic substances on the growth and mineral nutrients uptake of Corn (Hagein, Fardy10), and the comparison was carried out of the soil and foliar applications of humic acid treatments at different NaCl levels. Soil organic contents are one of the most important parts that they directly affect the soil fertility and textures with their complex and heterogenous structures although they occupy a minor percentage of the soil weight. Humic acids are an important soil component that can improve nutrient availability and impact on other important chemical, biological, and physical properties of soils. The effects of foliar and soil applications of humic substances on the plant growth and some nutrient elements uptake of Corn (Hagein, Fardy10) grown at various salt concentrations were examined. Sodium chloride was added to the soil to obtain 20 and 60mM saline conditions. Solid humus was applied to the soil one month before planting and liquid humic acids were sprayed on the leaves twice on 20<sup>th</sup> and 40<sup>th</sup> day after seedling emergence. The application doses of solid humus were 0, 2 and 4 g/kg and those of liquid humic acids were 0, 0.1 and 0.2%. Salinity negatively affected the growth of corn; it also decreased the dry weight and the uptake of nutrient elements except for Na and Mn. Soil application of humus increased the N uptake of corn while foliar application of humic acids increased the uptake of P, K, Mg,Na,Cu and Zn. Although the effect of interaction between salt and soil humus application was found statistically significant, the interaction effect between salt and foliar humic acids treatment was not found significant. Under salt stress, the first doses of both soil and foliar application of humic substances increased the uptake of nutrients.

Neptunium Speciation in Humic Acid-rich Clay Water upon Interaction With Radioactive Waste Glass Samples

2002 ◽  
Vol 757 ◽  
Author(s):  
V. Pirlet ◽  
P. Van Iseghem
Keyword(s):  
Humic Substances ◽  
Humic Acids ◽  
Specific Interaction ◽  
Waste Glass ◽  
High Level Waste ◽  
Boom Clay ◽  
Dissolution Tests ◽  
Vis Spectroscopy ◽  
Doped Glasses ◽  
High Level

ABSTRACTOrganic complexes of actinides are known to occur upon interaction of high level waste glass and Boom Clay which is a potential host rock formation for disposal of high level waste in Belgium. The solubility and mobility of 237Np, one of the most critical radionuclides, can be affected by the high dissolved organic carbon content of the Boom Clay porewater through complexation with the humic substances. The influence of humic substances on the Np behaviour is considered through dissolution tests of Np-doped glasses in Boom Clay water and through fundamental study of the specific interaction between Np(IV) and the humic acids using spectroscopic techniques. High Np(IV) concentrations are found in the glass dissolution tests. These concentrations are higher than what we should expect from the solubility of Np(OH)4, the solubility limiting solid phase predicted under the reducing conditions and pH prevailing in Boom Clay. Studying the specific interaction of Np(IV) with humic acids in Boom Clay porewater, high soluble Np concentrations are also measured and two main tetravalent Np-humate species are observed by UV-Vis spectroscopy. The two species are interpreted in terms of mixed hydroxo-humate complexes, Np(OH)xHA with x = 3 or 4. These species are the most likely species that can form according to the pH working conditions. Using thermodynamic simplified approaches, high complexation constants, i.e. log β131 and log β141 respectively equal to 46 and 51.6, are calculated for these species under the Boom Clay conditions.Comparing the spectroscopic results of the dissolution tests with the study of the interaction of Np(IV) with humic substances, we can conclude that the complexation of Np(IV) with the humic acids may occur and increases the solubility of Np(OH)4 upon interaction of a Np-doped glass and the Boom Clay porewater.

scholarly journals Infeksi Biofilm Bakterial

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Heriyannis . Homenta
Keyword(s):  
Cystic Fibrosis ◽  
Antibiotic Resistance ◽  
Cell Surface ◽  
Medical Devices ◽  
Extracellular Polymeric Substances ◽  
Bacterial Endocarditis ◽  
Bacterial Biofilm ◽  
Microbial Cell ◽  
Space And Time

Abstract: Biofilm is the unity of microbial cell surface surrounded by a matrix of extracellular polymeric substances (EPS). Bacteria composing the biofilm are heterogeneous in space and time. This biofilm continues to grow influenced by internal and external processes. Moreover, biofilm can be found on the surface of medical devices, as well as in bacterial endocarditis and cystic fibrosis. Biofilm that is already formed can lead to antibiotic resistance.Keywords: infections, bacterial biofilm, antibiotic resistance Abstrak: Biofilm merupakan kesatuan dari permukaan sel mikroba yang dilingkupi oleh matriks substansi polimerik ekstraseluler. Bakteri yag menyusun biofilm bersifat heterogen dalam ruang dan waktu. Biofilm terus berkembang yang dipengaruhi oleh proses internal dan eksternal. Biofilm dapat ditemukan pada permukaan alat-alat medis, endokarditis bakterial, dan kistik fibrosis. Biofilm yang telah terbentuk dapat menyebabkan resistensi antibiotik. Kata kunci: infeksi, biofilm bakterial, resistensi antibiotik

scholarly journals THE USE OF HUMIC ACIDS FOR MODIFICATION OF BIODEGRADABLE FILMS MANUFACTURED ON THE BASIS OF POLYVINYL ALCOHOL AND HYDROXYPROPYLMETHYL CELLULOSE

2021 ◽  
Vol 6 ◽  
pp. 22-37
Author(s):  
Zhang Siaobin ◽  
V.V Lebedev ◽  
D.V Miroshnichenko
Keyword(s):  
Polyvinyl Alcohol ◽  
Mathematical Models ◽  
Humic Substances ◽  
Structure Formation ◽  
Humic Acids ◽  
Polymer Films ◽  
Biodegradable Polymer ◽  
Hydroxypropyl Methylcellulose ◽  
Specific Effect ◽  
Low Grade

The article is devoted to the problem of obtaining packaging materials that combine a high level of gas and / or moisture resistance and strength with the ability to quickly decompose without harmful effects on the environment. The purpose of the research described in the article is to study the possibility of making such a material, which, during the period of use, will not only be resistant to the effects of various bacteria, but even prevent their appearance, and upon burial it will be biodegradable. The initial components, namely polyvinyl alcohol, hydroxypropyl methylcellulose, and humic acids of coal origin (as antibacterial additives) were reasonably selected. The modifying effect of humic substances obtained from three different samples of low-grade Ukrainian coal has been studied. In the course of the studies performed, it was found that humic acids of different origins and with different characteristics have a specific effect on the processes of structure formation in solutions of polyvinyl alcohol and hydroxypropyl methylcellulose. In particular, it was shown that in polyvinyl alcohol and methylcellulose solutions with the addition of humic acids that do not contain particles of carbon residues of various degrees of dispersion, an increase in the formation of an ordered structure is observed. Micrographs of solutions of polyvinyl alcohol and hydroxypropyl methylcellulose with humic acids are presented. The peculiarities of the influence of humic substances on the processes of structure formation of solutions of polyvinyl alcohol and hydroxypropyl methylcellulose have been investigated in order to obtain hybrid environmentally friendly biodegradable polymer films. The corresponding experimental-statistical mathematical models have been developed, they describe the dependence of the conditional viscosity and conductivity of polyvinyl alcohol and hydroxypropyl methylcellulose on the content of humic acids, the duration of preparation and one of the characteristics of the raw materials used to obtain humic acids. The corresponding equations are given. Keywords: biodegradable polymer films, coal, humic acids, polyvinyl alcohol, hydroxypropyl methylcellulose, experimental statistical mathematical models Corresponding author Zhang Siaobin, e-mail: [email protected]

Modeling ammonia removal in aerated facultative lagoons

2005 ◽  
Vol 51 (12) ◽  
pp. 139-142 ◽  
Author(s):  
C.D. Houweling ◽  
L. Kharoune ◽  
A. Escalas ◽  
Y. Comeau
Keyword(s):  
Seasonal Variation ◽  
Activated Sludge ◽  
Water Column ◽  
Bacterial Growth ◽  
Organic Material ◽  
Mechanistic Model ◽  
Ammonia Removal ◽  
Stirred Tank ◽  
Tank Reactor ◽  
Continuously Stirred Tank Reactor

A mechanistic model has been developed to model ammonia removal in aerated facultative lagoons. Flow is modeled through the water column by a continuously stirred tank reactor and exchanges between the sludge layer and the water column are simulated by a solids separator. The biological model is based on an activated sludge model with reactions added for anaerobic bacterial growth and degradation of inert organic material. Results show that the model is able to predict seasonal variation in ammonia removal as well as sludge accumulation in the lagoons.

Observations on the dispersion and aggregation of clays by humic substances, I. Dispersive effects of humic acids

Geoderma ◽  
1988 ◽  
Vol 42 (3-4) ◽  
pp. 331-337 ◽  
Author(s):  
S.A. Visser ◽  
M. Caillier
Keyword(s):  
Humic Substances ◽  
Humic Acids
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