Biotransformation of industrial tannins by filamentous fungi

Abstract

Tannins are secondary metabolites widely distributed in the plant kingdom. They act as growth inhibitors towards many microorganisms: upon microbial attack, they are released helping to fight the infection of plant tissues. Extraction of tannins from plants is an active industrial sector with several applications from the beginning of the industrial era. Actually, tannins have many industrial applications in oenology, animal feeding, mining and chemical industry and, in particular, in the tanning industry. But tannins are also considered very recalcitrant pollutants in wastewaters of different origins. The ability to grow on plant substrates rich in tannins and on industrial tannin preparations is traditionally considered peculiar of some species of fungi that have developed mechanisms to tolerate the toxicity of tannins producing a complex enzymatic pattern active in the transformation of these substrates, mainly by hydrolysis and oxidation. Filamentous fungi capable of degrading tannins could have a strong environmental impact as bioremediation agents mostly in the treatment of tanning wastewaters.

Chemodiversity of Soil Dissolved Organic Matter and Its Association With Soil Microbial Communities Along a Chronosequence of Chinese Fir Monoculture Plantations

“…Supplementary Figure 7 also shows that Basidiomycota had a positive correlation with tannin-like DOM. As Prigione et al (2018) report, the suitability to grow on matrix rich in tannins and on industrial tannin preparations is usually a recognized characteristic of some species of fungi such as Basidiomycota . These microbes can tolerate the toxicity of tannins owing to the production of enzymes that degrade or transform these substrates, largely through oxidation and hydrolysis, and some can utilize tannins as the single carbon source ( Prigione et al, 2018 ).…”

Modification of Natural Proanthocyanidin Oligomers and Polymers Via Chemical Oxidation under Alkaline Conditions

“…Currently, the estimated annual worldwide production of PAs is several 100 kilotons. − From this, majority is extracted from a few resources only (barks and/or woods of wattle, mimosa, quebracho, oak, chestnut, mangrove, sumach, myrabolans, tara, and several species of pines and firs), mainly for the demands of leather tanning industry, wine industry, animal nutrition, and for some other industrial uses such as mineral flotation and oil drilling. − Meanwhile, a substantial part of the residues from the handling and processing of fruits, vegetables, and forest resources still comprises significant amounts of the original plant materials and accordingly, natural compounds, such as PAs, can be found in many of these leftovers. − In addition to the possible use of these resources to extract tannins for the abovementioned industrial purposes, with some additional processing steps, these residues could be transformed from low-value leftovers into attractive high-value products, for example, as feedstock for the expanding markets in the sustainable food and feed, cosmetic, and pharmaceutical industries.…”

Characterization of Natural and Alkaline-Oxidized Proanthocyanidins in Plant Extracts by Ultrahigh-Resolution UHPLC-MS/MS

“…PAs are the most commonly available subgroup of plant tannins, responsible for nearly 90% of the world's overall market for industrial tannins (>multiple 100-kilo tons annually) and are chemically and economically more appealing as a bio-polymer [2][3][4][5]. Currently, only a few resources, such as the barks or woods of wattle, mimosa, quebracho, oak, chestnut, mangrove, sumach, myrobalans and tara, are used for their production and mainly for the demands of leather tanning, wine, mineral flotation and oil drilling industries, for preparing adhesives, in addition to animal nutrition [4,6,7]. However, even waste or byproducts from handling and processing fruits, vegetables and forest resources from the above listed industrial applications could be a potential source for natural PAs [8][9][10][11].…”