Role of Humic Acid Chemical Structure Derived from Different Biomass Feedstocks on Fe(III) Bioreduction Activity: Implication for Sustainable Use of Bioresources

Abstract

Humic acids (HAs) are redox-active components that play a crucial role in catalyzing relevant redox reactions in various ecosystems. However, it is unclear what role the different compost-derived Has play in the dissimilatory Fe(III) bioreduction and which chemical structures could accelerate Fe reduction. In this study, we compared the effect of eighteen HAs from the mesophilic phase, thermophilic phase and mature phase of protein-, lignocellulose- and lignin-rich composting on catalyzing the bioreduction of Fe(III)-citrate by Shewanella oneidensis MR-1 in temporarily anoxic laboratory systems. The chemical composition and structure of different compost-derived HAs were analyzed by UV–Vis spectroscopy, excitation-emission matrices of the fluorescence spectra, and 13C-NMR. The results showed that HAs from lignocellulose- and lignin-rich composting, especially in the thermophilic phase, promoted the bioreduction of Fe(III). They also showed that HA from protein-rich materials suppressed significantly the Fe(II) production, which was mainly affected by the amount and structures of functional groups (e.g., quinone groups) and humification degree of the HAs. This study can aid in searching sustainable HA-rich composts for wide-ranging applications to catalyze redox-mediated reactions of pollutants in soils.

Biodegradation of Different Types of Bioplastics through Composting—A Recent Trend in Green Recycling

“…Recycling or composting are generally regarded as more suitable ways of recovering plastic from solid waste. Composting occurs when microorganisms convert organic matter into CO 2 and humus by consuming it [58,77]. A number of modern techniques have been introduced to detect the presence of microorganisms, among them, polymerase chain reaction (PCR) and next-generation sequencing (NGS) are two well-known techniques that can be used to analyze and sequence in depth the specific microbial communities involved in the degradation of plastics [78,79].…”

Interactions between Humic Substances and Microorganisms and Their Implications for Nature-like Bioremediation Technologies

“…The presence of phenolic and quinonic fragments in HSs determines their redox activity. Phenolic moieties were suggested as major electron-donating structures, whereas quinones are considered to be one of the principal acceptor moieties present in HSs [ 77 , 78 ]. Phenolic moieties mainly include mono- and polyhydroxylated benzene units and have antioxidant properties [ 77 , 79 ].…”

“…A lack of quality control of humic products is of special importance as the internal variability observed among humic materials and their fractions, mainly redox properties, can change their properties entirely [ 78 , 228 , 232 , 243 ]. Reducible moieties in HSs were revealed to cover a wide range of apparent standard reduction potentials at pH 7 from +0.15 to −0.3 V [ 92 ].…”

“…Pursuing the same goal, Wei and coauthors compared the effects of 18 HAs from the mesophilic, thermophilic, and mature phases of protein-, lignocellulose-, and lignin-rich composting on catalyzing the bioreduction of Fe(III)–citrate by Shewanella oneidensis MR-1 in temporarily anoxic laboratory systems. They showed the Has from lignocellulose- and lignin-rich composting, especially in the thermophilic phase, significantly promoted the bioreduction of Fe(III), and Has from protein-rich materials significantly suppressed Fe(II) production [ 78 ].…”

Catalytic Biomass to Renewable Biofuels and Biomaterials

“…The role of humic acid's chemical structure derived from different biomass feedstocks on Fe(III) bioreduction activity was reported by Wei et al The role that the different compost-derived humic acids played in the dissimilatory Fe(III) bioreduction and chemical structures accelerating Fe reduction was discussed. This study can aid in searching sustainable humic acid-rich composts for wide-ranging applications to catalyzing redox-mediated reactions of pollutants in soils [10]. In a review, Liberato et al introduced some organisms such as Clostridium carboxidivorans, C. ragsdalei, and C. ljungdahlii used to catalyze the production of biofuels, including ethanol and butanol, and several chemical preparations, such as acetone, 1,3-propanediol, and butyric acid.…”