EFFECT OF HETEROTROPHIC BACTERIA ON DIFFERENT HUMIC SUBSTANCES IN MIXED BATCH CULTURES

1990 ◽  
Vol 70 (1) ◽  
pp. 51-59 ◽  
Author(s):  
C. YANZE KONTCHOU ◽  
R. BLONDEAU

Humic substances extracted from different soil samples and synthetic humic compounds (two melanoidins and one synthetic polymer) were used as the sole carbon source in liquid media inoculated with a mixed bacterial community selected by adaptation culture technique, and incubated for 90 or 100 d. The results show a high resistance to degradation of humic compounds by heterotrophic bacteria. Only a slight decrease in carbohydrate content and some modifications in carboxyl content were observed with the natural compounds. This resistance to biodegradation does not seem to be related to sample origin (e.g., forest humic substances compared to cultivated soil humic substances), or extraction procedure (sodium pyrophosphate compared to sodium hydroxide). Fulvic acids were as refractory as humic acids. The action of heterotrophic bacteria on incubated humic substances was similar under anaerobic (with nitrate reducing conditions) and aerobic conditions. Key words: Fulvic acids, humic acids, humus recalcitrance, melanoidins

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1067
Author(s):  
Aleksandra Ukalska-Jaruga ◽  
Romualda Bejger ◽  
Guillaume Debaene ◽  
Bożena Smreczak

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.


2021 ◽  
Vol 11 (18) ◽  
pp. 8466
Author(s):  
Christian Millo ◽  
Carlo Bravo ◽  
Stefano Covelli ◽  
Elena Pavoni ◽  
Elisa Petranich ◽  
...  

The Cananéia-Iguape estuarine–lagoon complex (São Paulo state, Brazil) is a natural laboratory to study metal binding by humic substances (HS) in subtropical settings. This transitional environment is evolving into a freshwater environment due to water input from the Ribeira River, funneled through the Valo Grande Canal (Iguape). Past mining activities in the Ribeira River basin and maritime traffic are suspected to be potential sources of trace metals in the system. In this study, the trace metal contents of Free Humic Acids (FHA), Bound Humic Acids (BHA), and Fulvic Acids (FA) extracted from sedimentary organic matter were investigated. Moreover, the sources of HS were traced using their stable carbon isotope compositions and C/N ratios. The results suggested a mixed marine–terrestrial source of FHA, BHA, and FA. Copper and Cr were the most abundant trace metals bound to HS. On average, Cu showed concentrations of 176, 115, and 37.9 μg g−1 in FHA, BHA, and FA, respectively, whereas Cr showed average concentrations of 47.4, 86.3, and 43.9 μg g−1 in FHA, BHA, and FA, respectively. Marine FHA showed the highest binding capacity for trace metals, whereas terrestrial FA derived from the decay of mangrove organic matter showed the lowest binding capacity.


2014 ◽  
Vol 2 ◽  
Author(s):  
Carolina Vázquez ◽  
Laura Noe ◽  
Adriana Abril ◽  
Carolina Merlo ◽  
Carlos Romero ◽  
...  

This short communication presents a novel approach to determining the soil sustainability of productive practices in an Argentinean arid region, using the resilience degree of soil organic matter components. The study was conducted in four sites of the Arid Chaco region of the Cordoba province: one undisturbed site, two sites with livestock (with total and with selective clearing) and one site with agriculture. In each site three soil samples were taken and total soil organic matter, fulvic and humic acids, and non-humic substances were analyzed. Variations of each component (%) between each productive practice and the undisturbed site were calculated in order to establish the resilience degree. The livestock soils showed: a) moderate resilience for non-humic substances, b) low resilience for organic matter and humic acids, and c) no resilience for fulvic acids. The agricultural soils showed: a) low resilience for total organic matter and non-humic substances, and b) no resilience for fulvic and humic acids. We conclude that this approach is a powerful tool for establishing management practices according to each particular situation, allowing improved productivity in arid regions.


2011 ◽  
Vol 35 (5) ◽  
pp. 1597-1608 ◽  
Author(s):  
Gislane M. de Moraes ◽  
Francisco Alisson da Silva Xavier ◽  
Eduardo de Sá Mendonça ◽  
João Ambrósio de Araújo Filho ◽  
Teógenes Senna de Oliveira

Studies have proven that the agroforestry systems in the semi-arid region of the State of Ceará, Brazil, induce an increase in soil organic C levels. Notwithstanding, there is no information if this increase also results in qualitative changes in different pools of soil organic matter. The objective of this study was to verify the possible chemical and structural alterations in fulvic and humic acids of a Luvisol in areas adopting agroforestry, traditional intensive cultivation and native forest in a long-term experiment conducted in the semi-arid region of Ceará State, Brazil. The study was conducted in an experimental area of the National Goat Research Center (Embrapa) in Sobral, CE. The following treatments were evaluated: agrosilvopasture (AGP), silvopasture (SILV), intensive cultivation under fallow (ICF), and areas with native forest (NF). Soil fulvic and humic acids fractions were extracted from the 0-6 and 6-12 cm layers and characterized by elemental composition, thermogravimetry and infrared spectroscopy analyses. The elemental composition analysis of humic acids confirmed the data found for fulvic acids, showing reduction in the C, H and N levels, followed by an increase in O contents in the AGP and ICF treatments over SILV and NF. In all treatments, except to SILV in the 0-6 cm layer, the percentage of mass loss was highest (300-600 °C) for humic acids in the thermally most stable region. Despite the similarity between infrared spectra, soil fulvic acids in the SILV treatment extracted from 6-12 cm depth decrease the absorption bands at 1708 and 1408 cm-1 followed by an increase in the absorption band at 1608 cm-1 attributed to aromatic C=C groups. This behavior suggests an increase in the aromatic character of the structure. The AGP and ICF treatments, which increase the soil tilling, favored the maintenance of humic substances with a more aromatic character in the soil than SILV and NF. The less aromatic humic substances in the SILV treatment resulted in an increase of exchange sites of soil organic matter, indicating improved nutrient cycling and maintenance of productivity in the system.


2019 ◽  
Vol 80 ◽  
pp. 03002
Author(s):  
Maria Elisabete Silva ◽  
Marlene Santos ◽  
Isabel Brás

This study aimed to characterize the humic substances (HS) extracted from landfills wastewater – leachates, with different ages of exploration. To reach the objective it was applied spectroscopy techniques, UV-Vis and FTIR spectra, as well as the ratio between the absorbance analysed. First, the HS were extracted, then fractionated in fulvic acids (FA) and humic acids (HA) and it was evaluated the phytotoxicity. HS content in the leachates were higher than the typical values found in the natural aquatic humic sources. It has been identified that the leachate HS, HA and FA aromatic fractions increased with the increase of the landfilling age, suggesting that the degree of humification increased with the landfilling age. All the HS showed a high aromaticity and humification degree. The HS extracts irrespective of their source presents similar structural composition. The functional groups found are in agreement with the literature: phenols, alcohols, carboxylic groups, aliphatic structures, among others. It was found that HA are mainly organic matter with a higher aromatic degree than FA. The HS and HA showed absence of phytotoxicity, testing by germination index, suggesting that may be used to produce liquid organic fertilizers.


Nukleonika ◽  
2015 ◽  
Vol 60 (3) ◽  
pp. 455-459 ◽  
Author(s):  
Barbara Pytel ◽  
Aneta Filipiak ◽  
Izabella Pisarek ◽  
Ryszard Olchawa ◽  
Dariusz Man

AbstractIn this paper, the effects of model (commercial) and natural (extracted from peat) humic substances on the membrane of liposomes formed with egg yolk lecithin (EYL) are presented. In our research, mass concentrations of fulvic and humic acids were used, which in relation to lecithin varied from 0% to 13%. To study membrane fluidity, electron spin resonance (EPR) was used with two spin probes, penetrating various regions of the lipid bilayer. The effects of model and natural humic substances (humic acids – HAs and fulvic acids – FAs) on the lipid membrane in different regions were researched: the lipid-water interphase, and in the middle of the lipid bilayer. It was shown that FA and HA impact the fluidity of liposome membranes in different ways. Increased mass concentrations of HAs decreased membrane fluidity in both acids: extracted from peat and the model. However, increased mass concentration of FAs extracted from peat, decreased membrane fluidity in the surface region, at the same time stiffening the central part of the bilayer. Increasing the concentration of FAs extracted from peat had the opposite effect when compared to model FA. This effect may be related to the complexation of xenobiotics present in the soil environment and their impact on biological membranes.


2016 ◽  
Vol 46 (6) ◽  
pp. 1094-1099 ◽  
Author(s):  
Silvio Teixeira da Costa ◽  
Fernando Jonas Sutili ◽  
Luciane Tourem Gressler ◽  
Luíza Loebens ◽  
Carine Vargas Colpo ◽  
...  

ABSTRACT: Humic substances are organic compounds that possess high molecular weight and are formed by the decomposition of plant materials. Humic substances comprise humic acids, fulvic acids and humin. Humic acids (HA) have shown to be able to provide some protection to biological membranes of fish in water with low pH, replacing the protective action of Ca2+. Thus, this studyaimed to observe growth of silver catfish ( Rhamdia quelen ) juveniles exposed to pHs 5.5 and 6.5 and to different levels of HA: 0, 10, 25 and 50mg L-1. Results showed that, irrespective of pH, HA was highly detrimental to silver catfish growth, since the higher the concentration of HA, the lower the weight gain and feed intake, resulting in lower biomass and lower specific growth rate of juveniles. Hence, HA is extremely damaging to the performance of silver catfish juveniles in the tested concentrations.


Author(s):  
Joaquín A. Chong ◽  
José A. Dumas

The distribution and chemical properties of humic substances (humic acids and fulvic acids) from a twelve-month-old static aerated compost pile of coffee pulp were studied. The compost was separated into five physical granule fractions (500, 1000, 2000, 4000 and 8000 um) in order to determine the effect of particle size on humic substances, on nutrient composition, and on distribution. The objective of this study was to understand the chemical properties and distribution of humic substances in mature coffee pulp compost. There were no significant differences across fractions for total N and available P2O5; these fractions averaged 4.9 and 0.66%, respectively. Potassium (K) increased as fraction size increased, from 3.01 to 3.94%. Readily available nitrogen, NO3 and NH4, was 7.19% of the total N. Eighty-nine percent of the total K was exchangeable K ions, and these varied within compost fractions from 2.82 to 3.33%. Approximately 50% of the total Ca and Mg were exchangeable ions; Ca ions varied from 2.13 to 3.01%, and Mg ions varied from 0.22 to 0.26% among fractions. Sequential extraction of organic carbon showed higher extractable carbon by the extraction with 0.1 N NaOH for 24 h, followed by 0.1 N NaOH for 2 h, and water for 2 h. The optical densities E4/E6 ratio ranged between 6.6 and 8.5 for humic acids (HA) extracted with NaOH for 2 h. The diversity in humic substances (HS) and exchangeable ions among compost fractions indicates that nutrient release is regulated by the size of the granules. In conclusion, these data demonstrate that smaller size particles have greater humification rates, and that N and available P are similar across particle sizes, thus providing an excellent soil compost amendment. 


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