scholarly journals Proteomics reveals synergy in biomass conversion between fungal enzymes and inorganic Fenton chemistry in leaf-cutting ant colonies

2020 ◽  
Author(s):  
Morten Schiøtt ◽  
Jacobus J. Boomsma
Keyword(s):  
Hydrogen Peroxide ◽  
Oxygen Radicals ◽  
Enzymatic Degradation ◽  
Biomass Conversion ◽  
Fungal Enzymes ◽  
Ant Colonies ◽  
Fenton Chemistry ◽  
Biochemical Assays ◽  
Oxidized Iron ◽  
Leaf Cutting

AbstractThe herbivorous symbiosis between leaf-cutting ants and fungal cultivars processes biomass via ant fecal fluid mixed with munched plant substrate before fungal degradation. Here we present a full proteome of the fecal fluid of Acromyrmex leaf-cutting ants, showing that most proteins function as biomass degrading enzymes and that ca. 80% are produced by the fungal cultivar and ingested, but not digested, by the ants. Hydrogen peroxide producing oxidoreductases were remarkably common in the fecal proteome, inspiring us to test a scenario in which hydrogen peroxide reacts with iron in the fecal fluid to form reactive oxygen radicals after which oxidized iron is reduced by other fecal-fluid enzymes. Our biochemical assays confirmed that these cyclical Fenton reactions do indeed take place in special substrate pellets, presumably to degrade recalcitrant lignocellulose. This implies that the symbiosis manages a combination of chemical and enzymatic degradation, an achievement that surpasses current human bioconversion technology.

scholarly journals Proteomics reveals synergy between biomass degrading enzymes and inorganic Fenton chemistry in leaf-cutting ant colonies

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Morten Schiøtt ◽  
Jacobus J Boomsma
Keyword(s):  
Hydrogen Peroxide ◽  
Plant Cell Wall ◽  
Plant Biomass ◽  
Biomass Degradation ◽  
Ant Colonies ◽  
Fenton Chemistry ◽  
Degrading Enzymes ◽  
Biochemical Assays ◽  
Oxidized Iron ◽  
Leaf Cutting

The symbiotic partnership between leaf-cutting ants and fungal cultivars processes plant biomass via ant fecal fluid mixed with chewed plant substrate before fungal degradation. Here we present a full proteome of the fecal fluid of Acromyrmex leaf-cutting ants, showing that most proteins function as biomass degrading enzymes and that ca. 85% are produced by the fungus and ingested, but not digested, by the ants. Hydrogen peroxide producing oxidoreductases were remarkably common in the proteome, inspiring us to test a scenario in which hydrogen peroxide reacts with iron to form reactive oxygen radicals after which oxidized iron is reduced by other fecal-fluid enzymes. Our biochemical assays confirmed that these so-called Fenton reactions do indeed take place in special substrate pellets, presumably to degrade plant cell wall polymers. This implies that the symbiotic partnership manages a combination of oxidative and enzymatic biomass degradation, an achievement that surpasses current human bioconversion technology.

scholarly journals Ammonia Production by Streptomyces Symbionts of Acromyrmex Leaf-Cutting Ants Strongly Inhibits the Fungal Pathogen Escovopsis

2021 ◽  
Vol 9 (8) ◽  
pp. 1622
Author(s):  
Basanta Dhodary ◽  
Dieter Spiteller
Keyword(s):  
Fungal Pathogen ◽  
Closed Loop ◽  
Pathogenic Fungus ◽  
Ant Colonies ◽  
Strong Activity ◽  
Streptomyces Sp ◽  
Mutualistic Symbiosis ◽  
Leaf Cutting ◽  
Leucoagaricus Gongylophorus ◽  
Production Of Ammonia

Leaf-cutting ants live in mutualistic symbiosis with their garden fungus Leucoagaricus gongylophorus that can be attacked by the specialized pathogenic fungus Escovopsis. Actinomyces symbionts from Acromyrmex leaf-cutting ants contribute to protect L. gongylophorus against pathogens. The symbiont Streptomyces sp. Av25_4 exhibited strong activity against Escovopsis weberi in co-cultivation assays. Experiments physically separating E. weberi and Streptomyces sp. Av25_4 allowing only exchange of volatiles revealed that Streptomyces sp. Av25_4 produces a volatile antifungal. Volatile compounds from Streptomyces sp. Av25_4 were collected by closed loop stripping. Analysis by NMR revealed that Streptomyces sp. Av25_4 overproduces ammonia (up to 8 mM) which completely inhibited the growth of E. weberi due to its strong basic pH. Additionally, other symbionts from different Acromyrmex ants inhibited E. weberi by production of ammonia. The waste of ca. one third of Acomyrmex and Atta leaf-cutting ant colonies was strongly basic due to ammonia (up to ca. 8 mM) suggesting its role in nest hygiene. Not only complex and metabolically costly secondary metabolites, such as polyketides, but simple ammonia released by symbionts of leaf-cutting ants can contribute to control the growth of Escovopsis that is sensitive to ammonia in contrast to the garden fungus L. gongylophorus.

scholarly journals Mathematical Modelling on Avoidance-to- Acceptance Transition in Leaf Cutting Ant Colonies

2016 ◽  
Vol 9 (11) ◽  
Author(s):  
J. Amudhavel ◽  
C. Kodeeswari ◽  
S. Jarina ◽  
S. Jaiganesh ◽  
B. Bhuvaneswari
Keyword(s):  
Mathematical Modelling ◽  
Ant Colonies ◽  
Leaf Cutting

A solar-to-chemical conversion efficiency up to 0.26% achieved in ambient conditions

2021 ◽  
Vol 118 (46) ◽  
pp. e2115666118
Author(s):  
Yu-Xin Ye ◽  
Jinhui Pan ◽  
Yong Shen ◽  
Minhui Shen ◽  
Huijie Yan ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Charge Carrier ◽  
Separation Efficiency ◽  
Biomass Conversion ◽  
Chemical Conversion ◽  
Electron Acceptors ◽  
Ambient Conditions ◽  
Reduction Efficiency ◽  
Earth Abundant ◽  
Carrier Separation

Artificial photosynthesis in ambient conditions is much less efficient than the solar-to-biomass conversion (SBC) processes in nature. Here, we successfully mimic the NADP-mediated photosynthetic processes in green plants by introducing redox moieties as the electron acceptors in the present conjugated polymeric photocatalyst. The current artificial process substantially promotes the charge carrier separation efficiency and the oxygen reduction efficiency, achieving a photosynthesis rate for converting Earth-abundant water and oxygen in air into hydrogen peroxide as high as 909 μmol⋅g−1⋅h−1 and a solar-to-chemical conversion (SCC) efficiency up to 0.26%. The SCC efficiency is more than two times higher than the average SBC efficiency in nature (0.1%) and the highest value under ambient conditions. This study presents a strategy for efficient SCC in the future.

Hydroxyl radical formation from bacteria-assisted Fenton chemistry at neutral pH under environmentally relevant conditions

2016 ◽  
Vol 13 (4) ◽  
pp. 757 ◽  
Author(s):  
Jarod N. Grossman ◽  
Tara F. Kahan
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Natural Waters ◽  
Shewanella Oneidensis ◽  
Radical Formation ◽  
Production Rates ◽  
Fenton Chemistry ◽  
Iron Reducing Bacteria ◽  
Neutral Ph ◽  
Reducing Bacteria

Environmental contextReactions in natural waters such as lakes and streams are thought to be extremely slow in the absence of sunlight (e.g. at night). We demonstrate that in the presence of iron, hydrogen peroxide and certain bacteria (all of which are common in natural waters), certain reactions may occur surprisingly quickly. These findings will help us predict the fate of many compounds, including pollutants, in natural waters at night. AbstractDark Fenton chemistry is an important source of hydroxyl radicals (OH•) in natural waters in the absence of sunlight. Hydroxyl radical production by this process is very slow in many bodies of water, owing to slow reduction and low solubility of FeIII at neutral and near-neutral pH. We have investigated the effects of the iron-reducing bacteria Shewanella oneidensis (SO) on OH• production rates from Fenton chemistry at environmentally relevant hydrogen peroxide (H2O2) and iron concentrations at neutral pH. In the presence of 2.0 × 10–4M H2O2, OH• production rates increased from 1.3 × 10–10 to 2.0 × 10–10Ms–1 in the presence of 7.0 × 106cellsmL–1 SO when iron (at a concentration of 100μM) was in the form of FeII, and from 3.6 × 10–11 to 2.2 × 10–10Ms–1 when iron was in the form of FeIII. This represents rate increases of factors of 1.5 and 6 respectively. We measured OH• production rates at a range of H2O2 concentrations and SO cell densities. Production rates depended linearly on both variables. We also demonstrate that bacteria-assisted Fenton chemistry can result in rapid degradation of aromatic pollutants such as anthracene. Our results suggest that iron-reducing bacteria such as SO may be important contributors to radical formation in dark natural waters.

Formation of Hydroxyl Radicals from Hydrogen Peroxide and Iron Salts by Superoxide- and Ascorbate-Dependent Mechanisms: Relevance to the Pathology of Rheumatoid Disease

1983 ◽  
Vol 64 (6) ◽  
pp. 649-653 ◽  
Author(s):  
D. A. Rowley ◽  
B. Halliwell
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Oxygen Radicals ◽  
Rheumatoid Disease ◽  
Iron Salts ◽  
Low Concentrations ◽  
Short Period ◽  
Generating System

1. Superoxide and hydrogen peroxide are formed by activated phagocytes and react together in the presence of iron salts to form the hydroxyl radical, which attacks hyaluronic acid. Ascorbic acid also interacts with hydrogen peroxide and iron salts to form hydroxyl radical in a reaction independent of superoxide. Since iron salts, ascorbate and activated phagocytes are present in the rheumatoid joint, experiments were designed to see whether ascorbate-dependent or superoxide-dependent formation of hydroxyl radicals would be more important in vivo. 2. in the present study, addition of ascorbate to a superoxide-generating system at concentrations of 100 μmol/l provoked a superoxide-independent formation of hydroxyl radicals for a short period. Lower concentrations of ascorbate did not do this. It is therefore suggested that the superoxide-dependent reaction is probably more important. 3. It is further suggested that destruction of ascorbate by oxygen radicals formed by activated phagocytes accounts for the previously reported low concentrations of this compound in the serum and synovial fluid of rheumatoid patients.

scholarly journals Thimerosal-Derived Ethylmercury Is a Mitochondrial Toxin in Human Astrocytes: Possible Role of Fenton Chemistry in the Oxidation and Breakage of mtDNA

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Martyn A. Sharpe ◽  
Andrew D. Livingston ◽  
David S. Baskin
Keyword(s):  
Hydrogen Peroxide ◽  
Caspase 3 ◽  
Permeability Transition ◽  
Fold Increase ◽  
Hydrogen Peroxide Production ◽  
Fenton Chemistry ◽  
Human Astrocytes ◽  
Mitochondrial Toxin ◽  
Normal Human

Thimerosal generates ethylmercury in aqueous solution and is widely used as preservative. We have investigated the toxicology of Thimerosal in normal human astrocytes, paying particular attention to mitochondrial function and the generation of specific oxidants. We find that ethylmercury not only inhibits mitochondrial respiration leading to a drop in the steady state membrane potential, but also concurrent with these phenomena increases the formation of superoxide, hydrogen peroxide, and Fenton/Haber-Weiss generated hydroxyl radical. These oxidants increase the levels of cellular aldehyde/ketones. Additionally, we find a five-fold increase in the levels of oxidant damaged mitochondrial DNA bases and increases in the levels of mtDNA nicks and blunt-ended breaks. Highly damaged mitochondria are characterized by having very low membrane potentials, increased superoxide/hydrogen peroxide production, and extensively damaged mtDNA and proteins. These mitochondria appear to have undergone a permeability transition, an observation supported by the five-fold increase in Caspase-3 activity observed after Thimerosal treatment.

scholarly journals Endophytic fungi reduce leaf-cutting ant damage to seedlings

2010 ◽  
Vol 7 (1) ◽  
pp. 30-32 ◽  
Author(s):  
L. S. Bittleston ◽  
F. Brockmann ◽  
W. Wcislo ◽  
S. A. Van Bael
Keyword(s):  
Leaf Area ◽  
Plant Communities ◽  
Endophytic Fungi ◽  
Cordia Alliodora ◽  
Neotropical Forests ◽  
Ant Colonies ◽  
Leaf Toughness ◽  
Leaf Tissues ◽  
Leaf Cutting ◽  
Atta Colombica

Our study examines how the mutualism between Atta colombica leaf-cutting ants and their cultivated fungus is influenced by the presence of diverse foliar endophytic fungi (endophytes) at high densities in tropical leaf tissues. We conducted laboratory choice trials in which ant colonies chose between Cordia alliodora seedlings with high ( E high ) or low ( E low ) densities of endophytes. The E high seedlings contained 5.5 times higher endophyte content and a greater diversity of fungal morphospecies than the E low treatment, and endophyte content was not correlated with leaf toughness or thickness. Leaf-cutting ants cut over 2.5 times the leaf area from E low relative to E high seedlings and had a tendency to recruit more ants to E low plants. Our findings suggest that leaf-cutting ants may incur costs from cutting and processing leaves with high endophyte loads, which could impact Neotropical forests by causing variable damage rates within plant communities.

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