scholarly journals Fungal Mineral Weathering Mechanisms Revealed Through Direct Molecular Visualization

2021 ◽  
Author(s):  
Arunima Bhattacharjee ◽  
Odeta Qafoku ◽  
Jocelyn A Richardson ◽  
Lindsey N Anderson ◽  
Kaitlyn Schwarz ◽  
...  
Keyword(s):  
Soil Fungi ◽  
Molecular Mechanisms ◽  
Fungal Growth ◽  
Mineral Weathering ◽  
Small Molecular Weight ◽  
Membrane Transport Proteins ◽  
Fungal Biology ◽  
Fusarium Sp ◽  
Mineral Interfaces ◽  
Nutrient Hotspots

Soil fungi facilitate the translocation of inorganic nutrients from soil minerals to other microorganisms and plants. This ability is particularly advantageous in impoverished soils, because fungal mycelial networks can bridge otherwise spatially disconnected and inaccessible nutrient hotspots. However, the molecular mechanisms underlying fungal mineral weathering and transport through soil remains poorly understood. Here, we addressed this knowledge gap by directly visualizing nutrient acquisition and transport through fungal hyphae in a mineral doped soil micromodel using a multimodal imaging approach. We observed that Fusarium sp. DS 682, a representative of common saprotrophic soil fungi, exhibited a mechanosensory response (thigmotropism) around obstacles and through pore spaces (~12 μm) in the presence of minerals. The fungus incorporated and translocated potassium (K) from K-rich mineral interfaces, as evidenced by visualization of mineral derived nutrient transport and unique K chemical moieties following fungal induced mineral weathering. Specific membrane transport proteins were expressed in the presence of minerals, including those involved in oxidative phosphorylation pathways and transmembrane transport of small molecular weight organic acids. This study establishes the significance of fungal biology and nutrient translocation mechanisms in maintaining fungal growth under water and nutrient limitations in a soil-like microenvironment.

scholarly journals Fatty Acids and Oxylipins as Antifungal and Anti-Mycotoxin Agents in Food: A Review

Toxins ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 852
Author(s):  
Mei Qiu ◽  
Yaling Wang ◽  
Lijun Sun ◽  
Qi Deng ◽  
Jian Zhao
Keyword(s):  
Fatty Acids ◽  
Control Systems ◽  
Molecular Mechanisms ◽  
Antifungal Agents ◽  
Recent Literature ◽  
Fungal Growth ◽  
Food Control ◽  
Fungal Contamination ◽  
Mycotoxigenic Fungi

Fungal contamination of food, especially by mycotoxigenic fungi, not only reduces the quality of the food, but can also cause serious diseases, thus posing a major food safety challenge to humans. Apart from sound food control systems, there is also a continual need to explore antifungal agents that can inhibit fungal growth and mycotoxin production in food. Many types of fatty acids (FAs) and their oxidized derivatives, oxylipins, have been found to exhibit such effects. In this review, we provide an update on the most recent literature on the occurrence and formation of FAs and oxylipins in food, their effects on fungal growth and mycotoxin synthesis, as well as the genetic and molecular mechanisms of actions. Research gaps in the field and needs for further studies in order to realizing the potential of FAs and oxylipins as natural antifungal preservatives in food are also discussed.

scholarly journals Competitive Exclusion Is a Major Bioprotective Mechanism of Lactobacilli against Fungal Spoilage in Fermented Milk Products

2020 ◽  
Vol 86 (7) ◽  
Author(s):  
Solvej Siedler ◽  
Martin Holm Rau ◽  
Susanne Bidstrup ◽  
Justin M. Vento ◽  
Stina Dissing Aunsbjerg ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Dairy Products ◽  
Molecular Mechanisms ◽  
Competitive Exclusion ◽  
Defense Mechanism ◽  
Fungal Growth ◽  
Fermented Milk ◽  
Attractive Alternative ◽  
Spoilage Yeast ◽  
Fungal Growth Inhibition

ABSTRACT A prominent feature of lactic acid bacteria (LAB) is their ability to inhibit growth of spoilage organisms in food, but hitherto research efforts to establish the mechanisms underlying bioactivity focused on the production of antimicrobial compounds by LAB. We show, in this study, that competitive exclusion, i.e., competition for a limited resource by different organisms, is a major mechanism of fungal growth inhibition by lactobacilli in fermented dairy products. The depletion of the essential trace element manganese by two Lactobacillus species was uncovered as the main mechanism for growth inhibition of dairy spoilage yeast and molds. A manganese transporter (MntH1), representing one of the highest expressed gene products in both lactobacilli, facilitates the exhaustive manganese scavenging. Expression of the mntH1 gene was found to be strain dependent, affected by species coculturing and the growth phase. Further, deletion of the mntH1 gene in one of the strains resulted in a loss of bioactivity, proving this gene to be important for manganese depletion. The presence of an mntH gene displayed a distinct phylogenetic pattern within the Lactobacillus genus. Moreover, assaying the bioprotective ability in fermented milk of selected lactobacilli from 10 major phylogenetic groups identified a correlation between the presence of mntH and bioprotective activity. Thus, manganese scavenging emerges as a common trait within the Lactobacillus genus, but differences in expression result in some strains showing more bioprotective effect than others. In summary, competitive exclusion through ion depletion is herein reported as a novel mechanism in LAB to delay the growth of spoilage contaminants in dairy products. IMPORTANCE In societies that have food choices, conscious consumers demand natural solutions to keep their food healthy and fresh during storage, simultaneously reducing food waste. The use of “good bacteria” to protect food against spoilage organisms has a long, successful history, even though the molecular mechanisms are not fully understood. In this study, we show that the depletion of free manganese is a major bioprotective mechanism of lactobacilli in dairy products. High manganese uptake and intracellular storage provide a link to the distinct, nonenzymatic, manganese-catalyzed oxidative stress defense mechanism, previously described for certain lactobacilli. The evaluation of representative Lactobacillus species in our study identifies multiple relevant species groups for fungal growth inhibition via manganese depletion. Hence, through the natural mechanism of nutrient depletion, the use of dedicated bioprotective lactobacilli constitutes an attractive alternative to artificial preservation.

scholarly journals Hop Polyphenols in Relation to Verticillium Wilt Resistance and Their Antifungal Activity

Plants ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 1318
Author(s):  
Sabina Berne ◽  
Nataša Kovačević ◽  
Damijana Kastelec ◽  
Branka Javornik ◽  
Sebastjan Radišek
Keyword(s):  
Phenolic Compounds ◽  
Antifungal Activity ◽  
Verticillium Wilt ◽  
Molecular Mechanisms ◽  
Induced Defense ◽  
Fungal Growth ◽  
Defense Responses ◽  
Resistant Variety ◽  
Phenological Stages ◽  
Total Polyphenols

(1) Background: Verticillium wilt (VW) of hop is a devastating disease caused by the soil-borne fungi Verticillium nonalfalfae and Verticillium dahliae. As suggested by quantitative trait locus (QTL) mapping and RNA-Seq analyses, the underlying molecular mechanisms of resistance in hop are complex, consisting of preformed and induced defense responses, including the synthesis of various phenolic compounds. (2) Methods: We determined the total polyphenolic content at two phenological stages in roots and stems of 14 hop varieties differing in VW resistance, examined the changes in the total polyphenols of VW resistant variety Wye Target (WT) and susceptible Celeia (CE) on infection with V. nonalfalfae, and assessed the antifungal activity of six commercial phenolic compounds and total polyphenolic extracts from roots and stems of VW resistant WT and susceptible CE on the growth of two different V. nonalfalfae hop pathotypes. (3) Results: Generally, total polyphenols were higher in roots than stems and increased with maturation of the hop. Before flowering, the majority of VW resistant varieties had a significantly higher content of total polyphenols in stems than susceptible varieties. At the symptomatic stage of VW disease, total polyphenols decreased in VW resistant WT and susceptible CE plants in both roots and stems. The antifungal activity of total polyphenolic extracts against V. nonalfalfae was higher in hop extracts from stems than those from roots. Among the tested phenolic compounds, only p-coumaric acid and tyrosol markedly restricted fungal growth. (4) Conclusions: Although the correlation between VW resistance and total polyphenols content is not straightforward, higher levels of total polyphenols in the stems of the majority of VW resistant hop varieties at early phenological stages probably contribute to fast and efficient activation of signaling pathways, leading to successful defense against V. nonalfalfae infection.

Effects of various soil fungi and insecticides on the capacity of Mucor alternans to degrade DDT

1972 ◽  
Vol 18 (5) ◽  
pp. 553-560 ◽  
Author(s):  
J. P. E. Anderson ◽  
E. P. Lichtenstein
Keyword(s):  
Contaminated Soils ◽  
Soil Fungi ◽  
Fungal Spores ◽  
Fungal Growth ◽  
Fungal Species ◽  
Water Soluble ◽  
Metabolite Formation ◽  
Pure Cultures ◽  
Free Media ◽  
Related Compounds

Pure cultures of the fungus Mucor alternans, isolated from DDT-contaminated soils, were able to degrade DDT to water-soluble metabolites. After the addition of fungal spores to DDT-contaminated soils, however, the insecticide-degrading capacity of the fungus was no longer evident. Since under field conditions many species of fungi are simultaneously exposed to mixed residues of pesticidal chemicals, the effects of various species of soil fungi and of various insecticides on DDT degradation by M. alternans were investigated. Experiments were conducted to study the effect of nine fungal species, their stale cell-free media, and various insecticides and related compounds on the capacity of M. alternans to degrade 14C-DDT to water-soluble metabolites. It was found that several pure fungal cultures or some cell-free media, in which mycelia had grown, could also degrade the insecticide. In most cases, however, addition of one of the various fungi to 14C-DDT-treated M. alternans cultures resulted in a total depression of the appearance of water-soluble metabolites in the media. This was due to an accumulation of the metabolites in the mycelium of the other fungus or in an inhibition of metabolite formation. Addition of stale media from various fungi to 14C-DDT-treated M. alternans cultures had various effects on fungal growth and on the capacity of the fungus to degrade the insecticide. Among the insecticides and related compounds tested only lindane, parathion, and Dyfonate caused a reduction in DDT degradation by M. alternans, without severely reducing its vegetative growth.

scholarly journals Genetic underpinnings of host manipulation by Ophiocordyceps as revealed by comparative transcriptomics

2020 ◽  
Author(s):  
Ian Will ◽  
Biplabendu Das ◽  
Thienthanh Trinh ◽  
Andreas Brachmann ◽  
Robin Ohm ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Fungal Growth ◽  
Behavioral Changes ◽  
Host Manipulation ◽  
Hybrid Assembly ◽  
Apparent Increase ◽  
Similar Work ◽  
A Site ◽  
Globally Distributed ◽  
Biting Behavior

AbstractThe ant-infecting Ophiocordyceps fungi are globally distributed, host manipulating, specialist parasites that drive aberrant behaviors in infected ants, at a lethal cost to the host. An apparent increase in activity and wandering behaviors precedes a final summiting and biting behavior on to vegetation, positioning the manipulated ant in a site beneficial for fungal growth and transmission. Notably, across Ophiocordyceps species and other known host manipulators, the molecular mechanisms underlying behavioral changes remain largely unclear. We explored possible genetic underpinnings of host manipulation by: (i) producing a hybrid assembly of the Ophiocordyceps camponoti-floridani genome, (ii) conducting laboratory infections coupled with RNAseq of both O. camponoti-floridani and its host, Campontous floridanus, and (iii) using these data for a comparative analysis to similar work performed in Ophiocordyceps kimflemingiae and Camponotus castaneus. We propose differentially expressed genes tied to ant neurobiology, odor response, circadian rhythms, and foraging behavior may be the result of putative fungal effectors such as enterotoxins, aflatrem, and mechanisms disrupting nutrition-sensing or caste-identity pathways.

scholarly journals A Mycovirus Mediates the Virulence of an Insect-Killing Fungus against the Malaria Mosquito Vector

Proceedings ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 148
Author(s):  
Andre N. Pitaluga ◽  
Charalampos Filippou ◽  
Josephine Blakiston ◽  
Robert H.A. Coutts ◽  
George K. Christophides ◽  
...  
Keyword(s):  
Immune System ◽  
Gut Microbiota ◽  
Beauveria Bassiana ◽  
Molecular Mechanisms ◽  
Pathogenic Fungus ◽  
Fungal Growth ◽  
Protozoan Parasite ◽  
Rnai Pathway ◽  
Mosquito Vector ◽  
Fungal Host

The cosmopolitan insect-pathogenic fungus and popular biocontrol agent Beauveria bassiana can be used to control Anopheles mosquito populations and restrict the spread of malaria, the deadliest vector-borne infectious disease in the world caused by the protozoan parasite Plasmodium. Here, we establish that infection with a double-stranded (ds)RNA mycovirus, Beauveria bassiana polymycovirus (BbPmV)-1, significantly reduces B. bassiana virulence against A. coluzzii, the main vector of malaria. The BbPmV-1-mediated hypovirulence can be at least partially attributed to slow fungal growth on the mosquitos. Analysis of the dual next-generation sequencing of the B. bassiana and A. coluzzii transcriptomes provided insight into the molecular mechanisms of the BbPmV-1-mediated effects. BbPmV-1-free B. bassiana has a wide impact on the A. coluzzii transcriptome, affecting immunity and metabolism, and led to the identification of novel immune response proteins. BbPmV-1 regulates the gene expression profile of its fungal host, directing the use of available resources towards sporulation and suppressing the mosquito immune system. Additionally, BbPmV-1-infected and -free B. bassiana strains differentially modulate mosquito gut microbiota; the former reduces the bacterial genus Elizabethkingia and the latter Serratia. Co-transfection of mosquitos with B. bassiana and P. berghei revealed a reduction of ookinetes in the presence of BbPmV-1, potentially due to the upregulation of a mycotoxin. Finally, BbPmV-1-mediated hypovirulence is at least partially dependent on the A. coluzzii RNAi pathway, and silencing of the dicer-2 gene restores virulence. Taken together, our data clearly demonstrate the crucial role of mycovirus infection in mediating B. bassiana virulence against A. coluzzii and suggest that BbPmV-1 protects A. coluzzii from B. bassiana, the mosquito’s own immune system, potentially harmful gut microbiota, and Plasmodium parasites.

scholarly journals Protein Expression Profile and Transcriptome Characterization of Penicillium expansum Induced by Meyerozyma guilliermondii

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Qiya Yang ◽  
Dhanasekaran Solairaj ◽  
Maurice Tibiru Apaliya ◽  
Mandour Abdelhai ◽  
Marui Zhu ◽  
...  
Keyword(s):  
Protein Expression ◽  
Expression Profile ◽  
Molecular Mechanisms ◽  
Polyketide Synthase ◽  
Fungal Growth ◽  
Differentially Expressed ◽  
Penicillium Expansum ◽  
Protein Expression Profile ◽  
Meyerozyma Guilliermondii

Antagonistic yeasts can inhibit fungal growth. In our previous research, Meyerozyma guilliermondii, one of the antagonistic yeasts, exhibited antagonistic activity against Penicillium expansum. However, the mechanisms, especially the molecular mechanisms of inhibiting activity of M. guilliermondii, are not clear. In this study, the protein expression profile and transcriptome characterization of P. expansum induced by M. guilliermondii were investigated. In P. expansum induced by M. guilliermondii, 66 proteins were identified as differentially expressed, among them six proteins were upregulated and 60 proteins were downregulated, which were associated with oxidative phosphorylation, ATP synthesis, basal metabolism, and response regulation. Simultaneously, a transcriptomic approach based on RNA-Seq was applied to annotate the genome of P. expansum and then studied the changes of gene expression in P. expansum treated with M. guilliermondii. The results showed that differentially expressed genes such as HEAT, Phosphoesterase, Polyketide synthase, ATPase, and Ras-association were significantly downregulated, in contrast to Cytochromes P450, Phosphatidate cytidylyltransferase, and Glutathione S-transferase, which were significantly upregulated. Interestingly, the downregulated differentially expressed proteins and genes have a corresponding relationship; these results revealed that these proteins and genes were important in the growth of P. expansum treated with M. guilliermondii.

scholarly journals Identification of a novel type of glucose dehydrogenase involved in the mineral weathering ability of Collimonas pratensis strain PMB3(1)

2020 ◽  
Author(s):  
L Picard ◽  
M-P Turpault ◽  
P M Oger ◽  
S Uroz
Keyword(s):  
Gluconic Acid ◽  
Molecular Mechanisms ◽  
Glucose Dehydrogenase ◽  
Random Mutagenesis ◽  
Mineral Weathering ◽  
Single Type ◽  
Biotite Weathering ◽  
Genomic Regions ◽  
Oxidation Of Glucose

Abstract The exact molecular mechanisms as well as the genes involved in the mineral weathering (MW) process by bacteria remain poorly characterized. To date, a single type of glucose dehydrogenase (GDH) depending on a particular co-factor named pyrroloquinoline quinone (PQQ) is known. These enzymes allow the production of gluconic acid through the oxidation of glucose. However, it remains to be determined how bacteria missing PQQ-dependent GDH and/or the related pqq biogenesis genes weather minerals. In this study, we considered the very effective mineral weathering bacterial strain PMB3(1) of Collimonas pratensis. Genome analysis revealed that it does not possess the PQQ based system. The use of random mutagenesis, gene complementation and functional assays allowed us to identify mutants impacted in their ability to weather mineral. Among them, three mutants were strongly altered on their acidification and biotite weathering abilities (58 to 75% of reduction compared to WT) and did not produce gluconic acid. The characterization of the genomic regions allowed noticeably to the identification of a Glucose/Methanol/Choline oxidoreductase. This region appeared very conserved among collimonads and related genera. This study represents the first demonstration of the implication of a PQQ-independent GDH in the mineral weathering process and explains how Collimonas weather minerals.

scholarly journals Study of the Control of Fungus Occurring in Schizolobium amazonicum Seeds with the Use of Pyroligneous Extract

2020 ◽  
pp. 1-9
Author(s):  
D. G. Da C. Macedo ◽  
G. Q. David ◽  
O. M. Yamashita ◽  
W. M. Peres ◽  
M. A. C. de Carvalho ◽  
...  
Keyword(s):  
Plant Pathogens ◽  
Seed Quality ◽  
Fungal Growth ◽  
Phytopathogenic Fungi ◽  
Distilled Water ◽  
Seed Deterioration ◽  
Storage Fungi ◽  
Fusarium Sp ◽  
Petri Dishes ◽  
Production Losses

Fungi are the main microorganisms present in seeds, constituting the main cause of deterioration and production losses. Among the health testing methodologies for detecting fungi in seeds, incubation tests under controlled conditions facilitate fungal growth and sporulation. Therefore, this work aimed to evaluate the efficiency of pyroligneous extract in the control of phytopathogenic fungi occurring in Schizolobium amazonicum seeds. Treatments consisted of exposure of seeds to pyroligneous extract for a period of five minutes at concentrations (0%, 1%, 2.5%, 5%, 7%, 10% and 12.5%). The treated seeds were placed in Petri dishes, lined with two sheets of filter paper, moistened with sterile distilled water. The experimental design was completely randomized, consisting of 7 treatments, with 9 seeds per plate and 10 replications per treatment, totaling 630 seeds arranged in 7 Petri dishes. The evaluation was performed 8 days later, with the aid of stereoscopic and light microscopy, where the fungal growth in each seed in the plates was verified for the incidence calculation and then the identification of these. Pyroligneous extract was found to be efficient in reducing the fungal incidence of the genera Fusarium sp. and Rhizoctonia sp., fungi considered important plant pathogens that could compromise seed quality and seedling establishment in the field. It also reduced the incidence of storage fungi capable of causing seed deterioration and consequent loss of vigor, such as Aspergillus spp. occurring in seed samples of S. amazonicum. However, Penicillium sp was not controlled by treatment of S. amazonicum seeds with pyroligneous extract up to 12.5% concentration.

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