Complexes of humic acid with cationic surfactants support the supramolecular view of extracted humic matter

Chaaban, Abdul Amir; Lartiges, Bruno; Hayek, Eliane El; Kazpard, Véronique; Plisson‐Chastang, Célia; Vicendo, Patricia; Caillet, Céline

doi:10.1071/en21031

Cited by 4 publications

(3 citation statements)

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“…Due to their amphiphilic supramolecular structures with hydrophobic pockets [ 19 ], humic acids could influence the bioavailability of the chemical exo-signals used for communication inside the microalgae microenvironment: microalgae to microalgae, microalgae to associated bacteria, bacteria to bacteria. Such exo-signals are, in general, hydrophobic compounds, e.g., acyl-homoserine-lactone (AHL), used for inter-specific quorum sensing (QS, detecting bacterial density from the same ecotype) in Gram-negative bacteria [ 162 ].…”

Section: Humic Substances As Microalgae Biostimulantsmentioning

confidence: 99%

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Humic Substances as Microalgal Biostimulants—Implications for Microalgal Biotechnology

Popa

Lupu

Constantinescu-Aruxandei

et al. 2022

Marine Drugs

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Humic substances (HS) act as biostimulants for terrestrial photosynthetic organisms. Their effects on plants are related to specific HS features: pH and redox buffering activities, (pseudo)emulsifying and surfactant characteristics, capacity to bind metallic ions and to encapsulate labile hydrophobic molecules, ability to adsorb to the wall structures of cells. The specific properties of HS result from the complexity of their supramolecular structure. This structure is more dynamic in aqueous solutions/suspensions than in soil, which enhances the specific characteristics of HS. Therefore, HS effects on microalgae are more pronounced than on terrestrial plants. The reported HS effects on microalgae include increased ionic nutrient availability, improved protection against abiotic stress, including against various chemical pollutants and ionic species of potentially toxic elements, higher accumulation of value-added ingredients, and enhanced bio-flocculation. These HS effects are similar to those on terrestrial plants and could be considered microalgal biostimulant effects. Such biostimulant effects are underutilized in current microalgal biotechnology. This review presents knowledge related to interactions between microalgae and humic substances and analyzes the potential of HS to enhance the productivity and profitability of microalgal biotechnology.

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Section: Humic Substances As Microalgae Biostimulantsmentioning

confidence: 99%

“…Humic acids have a more pronounced amphiphilic structure than FA [ 18 ]. Such structures promote aggregation in the supramolecular structures stabilized by hydrophobic interactions [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

Humic Substances as Microalgal Biostimulants—Implications for Microalgal Biotechnology

Popa

Lupu

Constantinescu-Aruxandei

et al. 2022

Marine Drugs

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“…It has been accepted for many years that humic substances tend to form self-assembled aggregates in water solution depending on some experimental variables such as pH, ionic strength, or the presence of polyvalent cations, mainly metals ( Stevenson, 1994 ). In some cases these humic super-aggregates have been considered supramolecules ( Piccolo, 2002 ; Baigorri et al., 2007 ; Karpiouk et al., 2012 ; Chaaban et al., 2021 ; Gerzabek et al., 2022 ). Supramolecular chemistry involves concepts such as inter-molecular self-assembly and non-covalent attractive forces but are included in specific frameworks involving order, design, molecular recognition, emerging new properties, and functions; synergy versus additive ( Menger, 2002 ; Lehn, 2005 ).…”

Section: Introductionmentioning

confidence: 99%

The molecular conformation, but not disaggregation, of humic acid in water solution plays a crucial role in promoting plant development in the natural environment

et al. 2023

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Many studies have shown the capacity of soil humic substances (HS) to improve plant growth in natural ecosystems. This effect involves the activation of different processes within the plant at different coordinated molecular, biochemical, and physiological levels. However, the first event triggered by plant root-HS interaction remains unclear. Some studies suggest the hypothesis that the interaction of HS with root exudates involves relevant modification of the molecular conformation of humic self-assembled aggregates, including disaggregation, which might be directly involved in the activation of root responses. To investigate this hypothesis, we have prepared two humic acids. A natural humic acid (HA) and a transformed humic acid obtained from the treatment of HA with fungal laccase (HA enz). We have tested the capacity of the two humic acids to affect plant growth (cucumber and Arabidopsis) and complex Cu. Laccase-treatment did not change the molecular size but increased hydrophobicity, molecular compactness and stability, and rigidity of HA enz. Laccase-treatment avoided the ability of HA to promote shoot- and root-growth in cucumber and Arabidopsis. However, it does not modify Cu complexation features. There is no molecular disaggregation upon the interaction of HA and HA enz with plant roots. The results indicate that the interaction with plant roots induced in both HA and laccase-treated HA (HA enz), changes in their structural features that showed higher compactness and rigidity. These events might result from the interaction of HA and HA enz with specific root exudates that can promote intermolecular crosslinking. In summary, the results indicate that the weakly bond stabilized aggregated conformation (supramolecular-like) of HA plays a crucial role in its ability to promote root and shoot growth. The results also indicate the presence of two main types of HS in the rhizosphere corresponding to those non-interacting with plant roots (forming aggregated molecular assemblies) and those produced after interacting with plant root exudates (forming stable macromolecules).

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The supramolecular structure of the soil humeome and the significance of humification

Piccolo,

Drosos

2024

Advances in Agronomy

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Complexes of humic acid with cationic surfactants support the supramolecular view of extracted humic matter

Cited by 4 publications

References 71 publications

Humic Substances as Microalgal Biostimulants—Implications for Microalgal Biotechnology

Humic Substances as Microalgal Biostimulants—Implications for Microalgal Biotechnology

The molecular conformation, but not disaggregation, of humic acid in water solution plays a crucial role in promoting plant development in the natural environment

The supramolecular structure of the soil humeome and the significance of humification

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