Crowdsourced analysis of fungal growth and branching on microfluidic platforms

Fungal hyphal growth and branching are essential traits that allow fungi to spread and proliferate in many environments. This sustained growth is essential for a myriad of applications in health, agriculture, and industry. However, comparisons between different fungi are difficult in the absence of standardized metrics. Here, we used a microfluidic device featuring four different maze patterns to compare the growth velocity and branching frequency of fourteen filamentous fungi. These measurements result from the collective work of several labs in the form of a competition named the "Fungus Olympics." The competing fungi included five ascomycete species (ten strains total), two basidiomycete species, and two zygomycete species. We found that growth velocity within a straight channel varied from 1 to 4 μm/min. We also found that the time to complete mazes when fungal hyphae branched or turned at various angles did not correlate with linear growth velocity. We discovered that fungi in our study used one of two distinct strategies to traverse mazes: high-frequency branching in which all possible paths were explored, and low-frequency branching in which only one or two paths were explored. While the high-frequency branching helped fungi escape mazes with sharp turns faster, the low-frequency turning had a significant advantage in mazes with shallower turns. Future work will more systematically examine these trends.

Advances in the biological control of phytoparasitic nematodes via the use of nematophagous fungi

Agricultural production is one of most important activities for food supply and demand, that provides a source of raw materials, and generates commercial opportunities for other industries around the world. It may be both positively and negatively affected by climatic and biological factors. Negative biological factors are those caused by viruses, bacteria, or parasites. Given the serious problems posed by phytoparasitic nematodes for farmers, causing crop losses globally every year, the agrochemical industry has developed compounds with the capacity to inhibit their development; however, they can cause the death of other beneficial organisms and their lixiviation can contaminate the water table. On the other hand, the positive biological factors are found in biotechnology, the scientific discipline that develops products, such as nematophagous fungi (of which Purpureocillium lilacinum and Pochonia chlamydosporia have the greatest potential), for the control of pests and/or diseases. The present review focuses on the importance of nematophagous fungi, particularly sedentary endoparasitic nematodes, their research on the development of biological control agents, the mass production of fungi Purpureocillium lilacinum and Pochonia chlamydosporia, and their limited commercialization due to the lack of rigorous methods that enable the anticipation of complex interactions between plant and phytopathogenic agents.

Fungal Solubilisation and Subsequent Microbial Methanation of Coal Processing Wastes

Large quantities of rejects from coal processing plants are currently disposed of as waste piles or in ponds and rivers, resulting in environmental concerns including pollution of rivers, and ground and surface water contamination. This work investigates for the first time, a two-stage microbial process for converting coal processing wastes (coal rejects) to methane, involving (1) fungal solubilisation of coal rejects and (2) microbial methanation of the solubilised products. Phanerochaete chrysosporium, Trichoderma viride and Neurospora discreta were screened for their ability to solubilise coal rejects. N. discreta was found to be the most suitable candidate based on the extent of bio-solubilisation, laccase activity and reversed-phase high-performance liquid chromatography (RP-HPLC) analysis. Bio-methanation of fungal-solubilised coal rejects was carried out in mesophilic anaerobic reactors with no additional carbon source, using inoculum from an anaerobic food digester. Coal rejects solubilised by N. discreta produced 3- to 6-fold higher methane compared to rejects solubilised by the other two fungi. No methane was produced from untreated coal rejects, demonstrating the importance of the fungal solubilisation stage. A total of 3.7 mmol of methane was generated per gram of carbon in 15 days from N. discreta-solubilised coal rejects. This process offers a timely, environment-friendly, and sustainable solution for the treatment of coal rejects and the generation of value-added products such as methane and volatile fatty acids.

Antifungal features and properties of chitosan/sandalwood oil Pickering emulsion coating stabilized by appropriate cellulose nanofiber dosage for fresh fruit application

A novel composite edible coating film was developed from 0.8% chitosan (CS) and 0.5% sandalwood oil (SEO). Cellulose nanofibers (CNFs) were used as a stabilizer agent of oil-in-water Pickering emulsion. We found four typical groups of CNF level-dependent emulsion stabilization, including (1) unstable emulsion in the absence of CNFs; (2) unstable emulsion (0.006-0.21% CNFs); (3) stable emulsion (0.24-0.31% CNFs); and (4) regular emulsion with the addition of surfactant. Confocal laser scanning microscopy was performed to reveal the characteristics of droplet diameter and morphology. Antifungal tests against Botrytis cinerea and Penicillium digitatum, between emulsion coating stabilized with CNFs (CS-SEOpick) and CS or CS-SEO was tested. The effective concentration of CNFs (0.24%) may improve the performance of CS coating and maintain CS-SEO antifungal activity synergistically confirmed with a series of assays (in vitro, in vivo, and membrane integrity changes). The incorporation of CNFs contributed to improve the functional properties of CS and SEO-loaded CS including light transmission at UV and visible light wavelengths and tensile strength. Atomic force microscopy and scanning electron microscopy were employed to characterize the biocompatibility of each coating film formulation. Emulsion-CNF stabilized coating may have potential applications for active coating for fresh fruit commodities.

Aridity-driven shift in biodiversity-soil multifunctionality relationships

Relationships between biodiversity and multiple ecosystem functions (that is, ecosystem multifunctionality) are context-dependent. Both plant and soil microbial diversity have been reported to regulate ecosystem multifunctionality, but how their relative importance varies along environmental gradients remains poorly understood. Here, we relate plant and microbial diversity to soil multifunctionality across 130 dryland sites along a 4,000 km aridity gradient in northern China. Our results show a strong positive association between plant species richness and soil multifunctionality in less arid regions, whereas microbial diversity, in particular of fungi, is positively associated with multifunctionality in more arid regions. This shift in the relationships between plant or microbial diversity and soil multifunctionality occur at an aridity level of ∼0.8, the boundary between semiarid and arid climates, which is predicted to advance geographically ∼28% by the end of the current century. Our study highlights that biodiversity loss of plants and soil microorganisms may have especially strong consequences under low and high aridity conditions, respectively, which calls for climate-specific biodiversity conservation strategies to mitigate the effects of aridification.

Recovery and Its Dynamics of Filamentous Fungi from Clinical Specimen Cultures: An Extensive Study

The culture method remains vital in diagnosing fungal infections, but extensive data-based evaluation of the method, especially for filamentous fungi (molds), is minimal. The purpose of this study was to characterize mold recoveries from fungal cultures and the impact of media and incubation duration. Clinical specimens for fungal cultures were submitted primarily from the eastern and central United States, and mold isolation data were prospectively collected and analyzed. A total of 1,821 molds in 59 genera were isolated from 1,687 positive specimens, accounting for approximately 5.6% of our cohort of 30,000 fungal cultures. Within 2 weeks, nearly 90% of molds and 97.3% of Aspergillus fumigatus complex were recovered (>95% confidence interval [CI]). All Mucorales fungi were recovered within 11 days of incubation. The recovery peak time was day 3 for Mucorales fungi, day 4 for hyaline molds, day 5 for dematiaceous molds, and day 7 for Onygenales fungi. The recovery of Histoplasma capsulatum and Trichophyton species in the fourth week of incubation reveals that a 3-week incubation time is insufficient. Inhibitory mold agar was the best medium for recovering all mold types among all tested specimen types, yielding nearly 78% of mold growth overall, indicating the necessity of selective medium for fungal cultures. IMPORTANCE Fungal culture is the gold standard method of diagnosing fungal infections, but important information, such as the impact of media and incubation times on fungal recovery, is not well documented. This study addressed these gaps using extensive data-based evaluation focused on molds. We identified the best medium types and incubation times for better fungal culture practice. We analyzed 1,821 molds from 1,687 positive specimens in our cohort of approximately 30,000 fungal cultures. Mold recovery peaked between 3 and 7 days of incubation, dependent upon the type of mold. Some well-defined fungal pathogens, such as Histoplasma capsulatum and Trichophyton species, were isolated in the fourth week of incubation. Inhibitory mold agar was identified as the best medium for recovering all mold types among all tested specimen sources. As we are aware, this is the largest study of fungal culture methods and supports 4 weeks of incubation for optimal mold recovery.

Essential oils and their nanoformulations as green preservatives to boost food safety against mycotoxin contamination of food commodities: a review

Postharvest food spoilage due to fungal and mycotoxin contamination is a major challenge in tropical countries, leading to severe adverse effects on human health. Because of the negative effects of synthetic preservatives on both human health and the environment, it has been recommended that chemicals that have a botanical origin, with an eco-friendly nature and a favorable safety profile, should be used as green preservatives. Recently, the food industry and consumers have been shifting drastically towards green consumerism because of their increased concerns about health and the environment. Among different plant-based products, essential oils (EOs) and their bioactive components are strongly preferred as antimicrobial food preservatives. Despite having potent antimicrobial efficacy and preservation potential against fungal and mycotoxin contamination, essential oils and their bioactive components have limited practical applicability caused by their high volatility and their instability, implying the development of techniques to overcome the challenges associated with EO application. Essential oils and their bioactive components are promising alternatives to synthetic preservatives. To overcome challenges associated with EOs, nanotechnology has emerged as a novel technology in the food industries. Nanoencapsulation may boost the preservative potential of different essential oils by improving their solubility, stability, and targeted sustainable release. Nanoencapsulation of EOs is therefore currently being practiced to improve the stability and bioactivity of natural products. The present review has dealt extensively with the application of EOs and their nanoformulated products encapsulated in suitable polymeric matrices, so as to recommend them as novel green preservatives against foodborne molds and mycotoxin-induced deterioration of stored food commodities. © 2021 Society of Chemical Industry.

Primary research on sampling scheme for analyzing mycotoxin distribution in wheat and rice fields

BACKGROUND

Mycotoxins are among the most severe food contaminants. Deoxynivalenol and aflatoxin contamination are predominant in wheat and rice, respectively. Nowadays, there are no standardized and approved grain-sampling schemes worldwide. This study aimed to develop a scientific grain-sampling scheme to investigate the regularity of mycotoxin distributed in wheat and rice fields. The data were analyzed with analysis of variance and cluster analysis to select a better sampling scheme.

RESULTS

Considering the influences of the weather before harvest (temperature, humidity, wind direction, and other conditions), we sampled grains from different places in different farmlands and detected the mycotoxin content of the sampled grains. The mycotoxin content had extremely significant differences in the area of rice fields (P<0.01) and significant differences in the area of wheat fields (P<0.05). The filtering effect existed peripheral the field areas, especially peripheral the humid areas, where the fungi were filtered and the toxin were easily produced. Furthermore, the upwind direction peripheral the field areas cause more filterature effect than other wind direction. Although 97% of mycotoxins in wheat can be removed through the shelling process, the toxin content were not obviously affected by rice lodging in the field. According to the cluster analysis, the peripheral and middle areas were divided into the same group with higher mycotoxin content.

CONCLUSION

This paper developed a sampling scheme to detect the mycotoxin content of wheat and rice in the field, considering the temperature and humidity of the weather, locations, and other grain contamination conditions before harvest. Meanwhile, the sampling rule of lodging and wind direction in the field was also assayed. © 2021 Society of Chemical Industry.

Effects of in-package atmospheric cold plasma treatment on the qualitative, metabolic and microbial stability of fresh-cut pears

BACKGROUND

The greatest hurdle to commercial marketing of fresh-cut fruits and vegetables is limited shelf life due to microbial hazards and quality deterioration. Atmospheric cold plasma (ACP) is an emerging non-thermal technology with significant potential to improve the safety and storability of fresh products. The objective of this study was to evaluate the effects of ACP, generated in sealed packaging, on the qualitative, metabolic and microbial stability of fresh-cut pears during simulated cold storage.

RESULTS

ACP treatments were effective in inhibiting the growth of mesophilic aerobic bacteria, yeast and mold, particularly CP3 (65 kV, 1 min), which could prolong shelf life to the greatest extent. While decontamination was not always associated with an increase in plasma intensity. Moreover, at 65 kV for 1 min, ACP treatment had the potential to retard respiration, and maintain organoleptic properties and other quality attributes. Additionally, peroxidase and pectin methylesterase (PME) activities were reduced immediately after treatments. These effects were dependent on treatment voltage and time, while a subsequent recovery in activity was only observed for PME.

CONCLUSION

The results obtained from this study will contribute to an understanding of the effects of in-package ACP treatments on the storability and microbial safety of fresh-cut pears. This knowledge could be beneficial in reducing quality losses for fresh-cut pears and the preservation of other products. © 2021 Society of Chemical Industry.

Microbial Synthesis and Evaluation of Fungistatic Activity of 3-Butyl-3-hydroxyphthalide, the Mammalian Metabolite of 3-n-Butylidenephthalide

Phthalides are bioactive compounds that naturally occur in the family Apiaceae. Considering their potentially versatile applications, it is desirable to determine their physical properties, activity and metabolic pathways. This study aimed to examine the utility of whole-cell biocatalysts for obtaining 3-butyl-3-hydroxyphthalide, which is the metabolite formulated during mammalian metabolism of 3-n-butylidenephthalide. We performed transformations using 10 strains of fungi, five of which efficiently produced 3-butyl-3-hydroxyphthalide. The product yield, determined by high-performance liquid chromatography, reached 97.6% when Aspergillus candidus AM 386 was used as the biocatalyst. Increasing the scale of the process resulted in isolation yields of 29–45% after purification via reversed-phase thin layer chromatography, depending on the strain of the microorganism used. We proposed different mechanisms for product formation; however, hydration of 3-n-butylidenephthalide seems to be the most probable. Additionally, all phthalides were tested against clinical strains of Candida albicans using the microdilution method. Two phthalides showed a minimum inhibitory concentration, required to inhibit the growth of 50% of organisms, below 50 µg/mL. The 3-n-butylidenephthalide metabolite was generally inactive, and this feature in combination with its low lipophilicity suggests its involvement in the detoxification pathway. The log P value of tested compounds was in the range of 2.09–3.38.

A coumarin exudation pathway mitigates arbuscular mycorrhizal incompatibility in Arabidopsis thaliana

Overexpression of genes involved in coumarin production and secretion can mitigate mycorrhizal incompatibility in nonhost Arabidopsis plants. The coumarin scopoletin, in particular, stimulates pre-penetration development and metabolism in mycorrhizal fungi. Although most plants can benefit from mutualistic associations with arbuscular mycorrhizal (AM) fungi, nonhost plant species such as the model Arabidopsis thaliana have acquired incompatibility. The transcriptional response of Arabidopsis to colonization by host-supported AM fungi switches from initial AM recognition to defense activation and plant growth antagonism. However, detailed functional information on incompatibility in nonhost-AM fungus interactions is largely missing. We studied interactions between host-sustained AM fungal networks of Rhizophagus irregularis and 18 Arabidopsis genotypes affected in nonhost penetration resistance, coumarin production and secretion, and defense (salicylic acid, jasmonic acid, and ethylene) and growth hormones (auxin, brassinosteroid, cytokinin, and gibberellin). We demonstrated that root-secreted coumarins can mitigate incompatibility by stimulating fungal metabolism and promoting initial steps of AM colonization. Moreover, we provide evidence that major molecular defenses in Arabidopsis do not operate as primary mechanisms of AM incompatibility nor of growth antagonism. Our study reveals that, although incompatible, nonhost plants can harbor hidden tools that promote initial steps of AM colonization. Moreover, it uncovered the coumarin scopoletin as a novel signal in the pre-penetration dialogue, with possible implications for the chemical communication in plant-mycorrhizal fungi associations.

Combined laser and ozone therapy for onychomycosis in an in vitro and ex vivo model

In order to develop a fast combined method for onychomycosis treatment using an in vitro and an ex vivo models, a combination of two dual-diode lasers at 405 nm and 639 nm wavelengths, in a continuous manner, together with different ozone concentrations (until 80 ppm), was used for performing the experiments on fungal strains growing on PDA agar medium or on pig’s hooves samples. In the in vitro model experiments, with 30 min combined treatment, all species are inhibited at 40 ppm ozone concentration, except S. brevicaulis, which didn’t show an inhibition in comparison with only ozone treatment. In the ex vivo model experiments, with the same duration and ozone concentration, A. chrysogenum and E. floccosum showed total inhibition; T. mentagrophytes and T. rubrum showed a 75% growth inhibition; M. canis showed a delay in sporulation; and S. brevicaulis and A. terreus did not show growth inhibition. This combined laser and ozone treatment may be developed as a fast therapy for human onychomycosis, as a potential alternative to the use of antifungal drugs with potential side effects and long duration treatments.

Alkaline extract of the seaweed Ascophyllum nodosum stimulates arbuscular mycorrhizal fungi and their endomycorrhization of plant roots

Ascophyllum nodosum extracts (ANE) are well-established plant biostimulants that improve stress tolerance and crop vigour, while also having been shown to stimulate soil microbes. The intersection of these two stimulatory activities, and how they combine to enhance plant health, however, remains poorly understood. In the present study, we aimed to evaluate: (1) the direct effect of ANE on the arbuscular mycorrhizal fungus Rhizophagus irregularis, and (2) whether ANE influences endomycorrhization in plants. ANE enhanced development of R. irregularis in vitro, showing greater spore germination, germ tube length, and hyphal branching. Greenhouse-grown Medicago truncatula drench-treated with ANE formed mycorrhizal associations faster (3.1-fold higher mycorrhization at week 4) and grew larger (29% greater leaf area by week 8) than control plants. Foliar applications of ANE also increased root colonization and arbuscular maturity, but did not appear to enhance plant growth. Nonetheless, following either foliar or drench application, M. truncatula genes associated with establishment of mycorrhizae were expressed at significantly higher levels compared to controls. These results suggest that ANE enhances mycorrhization through both direct stimulation of arbuscular mycorrhizal fungus growth and through stimulation of the plant's accommodation of the symbiont, together promoting the establishment of this agriculturally vital plant-microbe symbiosis.

Rubesanolides F and G: Two Novel Lactone-Type Norditerpenoids from Isodon rubescens

A phytochemical investigation of the leaves of the medicinal plant Isodon rubescens led to the isolation of the two new degraded abietane lactone diterpenoids rubesanolides F (1) and G (2). Their structures were elucidated based on the analyses of the HRESIMS and 1D/2D NMR spectral data, and their absolute configurations were determined by ECD spectrum calculations and X-ray single crystal diffraction methods. Compounds 1 and 2, with a unique γ-lactone subgroup between C-8 and C-20, were found to form a carbonyl carbon at C-13 by removal of the isopropyl group in an abietane diterpene skeleton. Rubesanolide G (2) is a rare case of abietane that possesses a cis-fused configuration between rings B and C. The two isolates were evaluated for their biological activities against two cancer cell lines (A549 and HL60), three fungal strains (Candida alba, Aspergillus niger and Rhizopus nigricans) and three bacterial strains (Escherichia coli, Staphylococcus aureus and Bacillus subtilis).

Assessment of Biotechnologically Important Filamentous Fungal Biomass by Fourier Transform Raman Spectroscopy

Oleaginous filamentous fungi can accumulate large amount of cellular lipids and biopolymers and pigments and potentially serve as a major source of biochemicals for food, feed, chemical, pharmaceutical, and transport industries. We assessed suitability of Fourier transform (FT) Raman spectroscopy for screening and process monitoring of filamentous fungi in biotechnology. Six Mucoromycota strains were cultivated in microbioreactors under six growth conditions (three phosphate concentrations in the presence and absence of calcium). FT-Raman and FT-infrared (FTIR) spectroscopic data was assessed in respect to reference analyses of lipids, phosphorus, and carotenoids by using principal component analysis (PCA), multiblock or consensus PCA, partial least square regression (PLSR), and analysis of spectral variation due to different design factors by an ANOVA model. All main chemical biomass constituents were detected by FT-Raman spectroscopy, including lipids, proteins, cell wall carbohydrates, and polyphosphates, and carotenoids. FT-Raman spectra clearly show the effect of growth conditions on fungal biomass. PLSR models with high coefficients of determination (0.83-0.94) and low error (approximately 8%) for quantitative determination of total lipids, phosphates, and carotenoids were established. FT-Raman spectroscopy showed great potential for chemical analysis of biomass of oleaginous filamentous fungi. The study demonstrates that FT-Raman and FTIR spectroscopies provide complementary information on main fungal biomass constituents.

Strategies to Increase the Production of Biosynthetic Riboflavin

Riboflavin is widely regarded as an essential nutrient that is involved in biological oxidation in vivo. In addition to preventing and treating acyl-CoA dehydrogenase deficiency in patients with keratitis, stomatitis, and glossitis, riboflavin is also closely related to the treatment of radiation mucositis and cardiovascular disease. Chemical synthesis has been the dominant method for producing riboflavin for approximately 50 years. Nevertheless, due to the intricate synthesis process, relatively high cost, and high risk of pollution, alternative methods of chemical syntheses, such as the fermentation method, began to develop and eventually became the main methods for producing riboflavin. At present, there are three types of strains used in industrial riboflavin production: Ashbya gossypii, Candida famata, and Bacillus subtilis. Additionally, many recent studies have been conducted on Escherichia coli and Lactobacillus. Fermentation increases the yield of riboflavin using genetic engineering technology to modify and induce riboflavin production in the strain, as well as to regulate the metabolic flux of the purine pathway and pentose phosphate pathway (PP pathway), thereby optimizing the culture process. This article briefly introduces recent progress in the fermentation of riboflavin.

Bio-Preservative Potential of Microorganisms Isolated from Red Grape against Food Contaminant Fungi

Fungal spoilage is one of the main reasons of economic losses in the food industry, especially in the wine sector. Consequently, the search for safer and new preservation techniques has gained importance in recent years. The objective of this study was to investigate the antifungal and anti-mycotoxigenic activity from 28 microorganisms (MO) isolated from red grape. The antifungal activity of a cell free supernatant of fermented medium by the isolated MO (CFS) was tested with the agar diffusion method and the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) assay. Additionally, different antifungal compounds from the CFS were identified and quantified (organic acids, phenolic compounds, and volatile organic compounds). Finally, the most active CFS were tested as red grape bio-preservative agents. Results evidenced that CFS fermented by the strain UTA 6 had the highest antifungal activity, above all isolates, and produced a wide pool of antifungal compounds. The use of UTA 6 CFS as bio-preservative agent showed a reduction of 0.4 and 0.6 log₁₀ spores per gram of fruit in grapes contaminated by A. flavus and B. cinerea, respectively. Moreover, UTA 6 CFS treatment reduced the occurrence of aflatoxin B₁ and fumonisin (B₂, B₃, and B₄) production in grapes contaminated by 28-100%.

High hydrostatic pressure shapes the development and production of secondary metabolites of Mariana Trench sediment fungi

The hadal biosphere is one of the least understood ecosystems on our planet. Recent studies have revealed diverse and active communities of prokaryotes in hadal sediment. However, there have been few studies on fungi in hadal sediment. Here we report the first isolation and cultivation of 8 fungi from the Mariana Trench sediment. The individual colonies were isolated and identified as Stemphylium sp., Cladosporium sp., Arthrinium sp., Fusarium sp., Alternaria sp., and Aspergillus sp. High hydrostatic pressure (HHP) test was carried out to identify the piezophily of these hadal fungi. Among them, 7 out of the 8 fungal isolates exhibited the ability of germination after incubation under 40 MPa for 7 days. Vegetative growth of the isolates was also affected by HHP. Characterization of secondary metabolites under different pressure conditions was also performed. The production of secondary metabolites was affected by the HHP treatment, improving the potential of discovering novel natural products from hadal fungi. The antibacterial assay revealed the potential of discovering novel natural products. Our results suggest that fungal growth pressure plays an important role in the development and production of secondary metabolites of these hadal fungi under the extreme environment in the Mariana Trench.

Novel (+)-Neoisopulegol-Based O-Benzyl Derivatives as Antimicrobial Agents

Discovery of novel antibacterial agents with new structures, which combat pathogens is an urgent task. In this study, a new library of (+)-neoisopulegol-based O-benzyl derivatives of aminodiols and aminotriols was designed and synthesized, and their antimicrobial activity against different bacterial and fungal strains were evaluated. The results showed that this new series of synthetic O-benzyl compounds exhibit potent antimicrobial activity. Di-O-benzyl derivatives showed high activity against Gram-positive bacteria and fungi, but moderate activity against Gram-negative bacteria. Therefore, these compounds may serve a good basis for antibacterial and antifungal drug discovery. Structure-activity relationships were also studied from the aspects of stereochemistry of the O-benzyl group on cyclohexane ring and the substituent effects on the ring system.

DyP-Type Peroxidases: Recent Advances and Perspectives

In this review, we chart the major milestones in the research progress on the DyP-type peroxidase family over the past decade. Though mainly distributed among bacteria and fungi, this family actually exhibits more widespread diversity. Advanced tertiary structural analyses have revealed common and different features among members of this family. Notably, the catalytic cycle for the peroxidase activity of DyP-type peroxidases appears to be different from that of other ubiquitous heme peroxidases. DyP-type peroxidases have also been reported to possess activities in addition to peroxidase function, including hydrolase or oxidase activity. They also show various cellular distributions, functioning not only inside cells but also outside of cells. Some are also cargo proteins of encapsulin. Unique, noteworthy functions include a key role in life-cycle switching in Streptomyces and the operation of an iron transport system in Staphylococcus aureus, Bacillus subtilis and Escherichia coli. We also present several probable physiological roles of DyP-type peroxidases that reflect the widespread distribution and function of these enzymes. Lignin degradation is the most common function attributed to DyP-type peroxidases, but their activity is not high compared with that of standard lignin-degrading enzymes. From an environmental standpoint, degradation of natural antifungal anthraquinone compounds is a specific focus of DyP-type peroxidase research. Considered in its totality, the DyP-type peroxidase family offers a rich source of diverse and attractive materials for research scientists.

Arbuscular mycorrhizal fungi alter microbiome structure of rhizosphere soil to enhance maize tolerance to La

Rhizosphere microbes are essential partners for plant stress tolerance. Recent studies indicate that arbuscular mycorrhizal fungi (AMF) can facilitate the revegetation of soils contaminated by heavy metals though interacting with rhizosphere microbiome. However, it is unclear how AMF affect rhizosphere microbiome to improve the growth of plant under rare earth elements (REEs) stress. AMF (Claroideoglomus etunicatum) was inoculated to maize grown in soils spiked with Lanthanum (0 mg kg^-1, La0; 10 mg kg^-1, La10; 100 mg kg^-1, La100; 500 mg kg^-1, La500). Plant biomass, nutrient uptake, REE uptake and rhizosphere bacterial and fungal community were evaluated. The results indicated that La100 and La500 decreased significantly root colonization rates and nutrition uptake (K, P, Ca and Mg content). La500 decreased significantly α-diversity indexes of bacterial and fungal community. AMF enhanced significantly the shoot and root fresh and dry weight of maize in all La treatments (except for the root fresh and dry weight of La0 and La10 treatment). For La100 and La500 treatments, AMF increased significantly nutrition uptake (K, P, Ca and Mg content) in shoot of maize by 27.40-441.77%. For La500 treatment, AMF decreased significantly shoot La concentration by 51.53% in maize, but increased significantly root La concentration by 30.45%. In addition, AMF decreased bacterial and fungal Shannon index in La0 treatment, but increased bacterial Shannon index in La500 treatment. Both AMF and La500 affected significantly the bacterial and fungal community composition, and AMF led to more influence than La. AMF promoted the enrichment of bacteria, including Planomicrobium, Lysobacter, Saccharothrix, Agrococcus, Microbacterium, Streptomyces, Penicillium and other unclassified genus, and fungi (Penicillium) in La500, which showed the function for promoting plant growth and tolerance of heavy metal. The study revealed that AMF can regulate the rhizosphere bacterial and fungal composition and foster certain beneficial microbes to enhance the tolerance of maize under La stress. Phytoremediation assisted by AMF is an attractive approach to ameliorate REEs-contaminated soils.

Microbial contamination of money sorting facilities

INTRODUCTION

Money is the most common item with which we have daily contact. Circulated banknotes and coins can become microbiologically contaminated and act as both a source and a means of spreading such pollutants.

MATERIAL AND METHODS

The study was carried out in three money sorting facilities in Poland. Bioaerosol samples were collected using a 6-stage Andersen impactor, and microorganisms deposited on tabletop surfaces were sampled using the swab method. Bacterial and fungal concentrations were calculated and all isolated species were taxonomically identified.

RESULTS

The study confirmed that means of payment are active sources of microbial emission in money sorting facilities. The bioaerosol concentrations did not exceed the threshold limit values proposed for this type of office premises. It confirms that ventilation systems in these facilities worked efficiently, protecting them from the migration of microbial contaminants present in both indoor and outdoor (atmospheric) background air. On the other hand, the average concentrations of bacteria and fungi on tabletop surfaces in banknote and coin sorting rooms were above the proposed purity levels for indoor surfaces and should be treated as microbiologically contaminated. Microbiota isolated from the air and surfaces were very diverse and among those strains were bacterial and fungal pathogens that can pose a health threat to exposed individuals.

CONCLUSIONS

The results showed that employees in money sorting facilities were exposed to microorganisms that may contribute to the development of adverse health outcomes. To protect them, highly efficient hygienic measures should be introduced in this working environment, to prevent both unwanted pollution and subsequent secondary emission of microbial contaminants from sorted means of payment and tabletop surfaces.

Plant-mediated synthesis of nanoparticles and their antimicrobial activity against phytopathogens

Nanotechnology is an emerging science with a wide array of applications involving the synthesis and manipulation of materials with dimensions in the range of 1-100 nm. Nanotechnological applications include diverse fields such as pharmaceuticals, medicine, the environment, food processing and agriculture. Regarding the latter, applications are mainly focused on plant growth and crop protection against plagues and diseases. In recent years, the biogenic reduction of elements such as Ag, Au, Cu, Cd, Al, Se, Zn, Ce, Ti and Fe with plant extracts has become one of the most accepted techniques for obtaining nanoparticles (NPs), as it is considered an ecological and cost-effective process without the use of chemical contaminants. The objective of this work was to review NPs synthesized by green chemistry using vegetable extracts, as well as their use as antimicrobial agents against phytopathogenic fungi and bacteria. Given the need for alternatives to control and integrate management of phytopathogens, this review is relevant to agriculture, although this technology is barely exploited in this field. © 2020 Society of Chemical Industry.

Sanitizer efficacy in reducing microbial load on commercially grown hydroponic lettuce

BACKGROUND

Most hydroponic lettuce growers harvest and package their marketable-size lettuces with an intact root ball. With a high microbial load on the peat moss substrate, there is a risk of microbial transfer onto the edible portion during packaging and throughout the product's shelf life. Since the produce is believed to have no contact with the substrate, no sanitizer wash is performed before packaging and storage.

RESULTS

Aerobic plate count (APC) results suggested that reduction in count was influenced by both sanitizer application and storage time. Peroxyacetic acid significantly reduced APC count on leaves, roots, and substrate, with a 1.8 log CFU g-1 initial reduction on the leaf. Fungi and APC levels increased with storage time, with the greatest APC increase in the roots. Leaves had the lowest coliform bacteria (CB), with chlorine slightly reducing CB count. Unlike APC, CB levels decreased during storage on the substrate and root samples. No Listeria positive was confirmed by agglutination test. Further evaluation of different commercial substrates reveals that Com4, a drier-compacted plug, had the least ability to support growth/survival of all microbial populations enumerated relative to the spongy, wet black plugs.

CONCLUSION

The ability of peat moss substrates to host microorganisms is influenced by the physical properties of the product. Sanitizer wash efficacy is dependent on the initial microbial load and the length of storage. Chlorine and peroxyacetic acid are effective in reducing microbial populations on the leaves of hydroponically grown lettuce without affecting visual quality during shelf life. © 2020 Society of Chemical Industry.

The gut mycobiome of healthy mice is shaped by the environment and correlates with metabolic outcomes in response to diet

As an active interface between the host and their diet, the gut microbiota influences host metabolic adaptation; however, the contributions of fungi have been overlooked. Here, we investigate whether variations in gut mycobiome abundance and composition correlate with key features of host metabolism. We obtained animals from four commercial sources in parallel to test if differing starting mycobiomes can shape host adaptation in response to processed diets. We show that the gut mycobiome of healthy mice is shaped by the environment, including diet, and significantly correlates with metabolic outcomes. We demonstrate that exposure to processed diet leads to persistent differences in fungal communities that significantly associate with differential deposition of body mass in male mice compared to mice fed standardized diet. Fat deposition in the liver, transcriptional adaptation of metabolically active tissues and serum metabolic biomarker levels are linked with alterations in fungal community diversity and composition. Specifically, variation in fungi from the genera Thermomyces and Saccharomyces most strongly associate with metabolic disturbance and weight gain. These data suggest that host-microbe metabolic interactions may be influenced by variability in the mycobiome. This work highlights the potential significance of the gut mycobiome in health and has implications for human and experimental metabolic studies.