Enhanced surface colonisation and competition during bacterial adaptation to a fungus.

Bacterial-fungal interactions influence microbial community performance of most ecosystems and elicit specific microbial behaviours, including stimulating specialised metabolite production. Here, we use a co-culture experimental evolution approach to investigate bacterial adaptation to the presence of a fungus, using a simple model of bacterial-fungal interactions encompassing the bacterium Bacillus subtilis and the fungus Aspergillus niger. We find in one evolving population that B. subtilis was selected for enhanced production of the lipopeptide surfactin and accelerated surface spreading ability, leading to inhibition of fungal expansion and acidification of the environment. These phenotypes were explained by specific mutations in the DegS-DegU two-component system. In the presence of surfactin, fungal hyphae exhibited bulging cells with delocalised secretory vesicles possibly provoking an RlmA-dependent cell wall stress. Thus, our results indicate that the presence of the fungus selects for increased surfactin production, which inhibits fungal growth and facilitates the competitive success of the bacterium.

Evaluation of antidiabetic, antioxidant, and cytotoxic potential of maize (zea mays l.) husk leaf extracts.

In current study, Maize (Zea mays L.) husk leave extracts were appraised for biological activities such as cytotoxicity, antidiabetic, antioxidant and antimicrobial. Maceration was performed to collect various fractions of husk leave extracts using a pool of solvents i.e., n-hexane, chloroform, ethyl acetate, butanol and methanol. Antioxidant potential was measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging, reducing power and linoleic acid oxidation assay, using butylated hydroxy toluene (BHT) as a positive control. Total phenolic and flavonoid contents were found to be 18.47-425.11 mg/100 g GAE and 5.83-16.72 mg/100 g CE, respectively. The DPPH scavenging assay was exhibited in the range of 76.36 to 88.53%. The percentage inhibition in linoleic acid oxidation was found from 10.16 to 79.51%. Significant antimicrobial activity was demonstrated by husk leaf extracts against bacterial strains and fungal strains using disc diffusion and minimum inhibitory concentration (MIC) method. Amylase alpha assay was employed to analyze the antidiabetic activity which ranged between 9.52-24.81%. Cytotoxicity was evaluated by % age lysis (0.35-9.54%), while thrombolytic activity ranged between 7.67 to 31.27%. The results presented in this study revealed that maize (Zea mays L.) husk leaf extracts can be a valuable source of biologically active compounds and may be consumed as a source of potent herbal medicine in pharmaceuticals.

On electrical gates on fungal colony.

Mycelium networks are promising substrates for designing unconventional computing devices providing rich topologies and geometries where signals propagate and interact. Fulfilling our long-term objectives of prototyping electrical analog computers from living mycelium networks, including networks hybridised with nanoparticles, we explore the possibility of implementing Boolean logical gates based on electrical properties of fungal colonies. We converted a 3D image-data stack of Aspergillus niger fungal colony to an Euclidean graph and modelled the colony as resistive and capacitive (RC) networks, where electrical parameters of edges were functions of the edges' lengths. We found that and, or and and-not gates are implementable in RC networks derived from the geometrical structure of the real fungal colony.

Phytochemical screening and biological activities of Bromus pectinatus Thunb.

The present research study investigates the phytochemical and pharmacological importance of Bromus pectinatus. Qualitative phytochemical analysis of this plant was carried out to use standard method for the presence of various bioactive constituents. Results showed the ethanolic extract contain natural product such as steroids, alkaloids, tannins, coumarin, saponins, flavonoids and phenols. These compounds play a key role to reducing various disease and microbial inhibition. The ethanolic extract also showed the antimicrobial and antifugal activity against different pathogenic bacterial strains e.g Escherichia coli, Micrococus leutus, Protus vulgarus, and Kelebsela pneumona and three fungal strains Aspergillus fumigatus, Aspergillus flavous, Aspergillus niger. The antioxidant assay was performed as % inhibition of DPPH (1, 1-diphenyl-2-picryl-hydrazyl) free radicals. The plant extract has more antioxidant activity as compared to ascorbic acid. The maximum concentration (800µg/ml) is the most effective of all. The plant extract showed the high cytotoxicity activity against Brine shrimp. Moreover, the plant extract exhibited allelopathic effect on different growth parameters of wheat plant mostly at higher concentration. These results indicate that the BPEE have a potential broad-spectrum antimicrobial, cytotoxic, antioxidant and phytotoxic activity due to the presence of bioactive compounds.

Combination of supercritical CO2 and high-power ultrasound for the inactivation of fungal and bacterial spores in lipid emulsions.

For the first time, this study addresses the intensification of supercritical carbon dioxide (SC-CO2) treatments using high-power ultrasound (HPU) for the inactivation of fungal (Aspergillus niger) and bacterial (Clostridium butyricum) spores in oil-in-water emulsions. The inactivation kinetics were analyzed at different pressures (100, 350 and 550 bar) and temperatures (50, 60, 70, 80, 85 °C), depending on the microorganism, and compared to the conventional thermal treatment. The inactivation kinetics were satisfactorily described using the Weibull model. Experimental results showed that SC-CO2 enhanced the inactivation level of both spores when compared to thermal treatments. Bacterial spores (C.butyricum) were found to be more resistant to SC-CO2 + HPU, than fungal (A.niger) ones, as also observed in the thermal and SC-CO2 treatments. The application of HPU intensified the SC-CO2 inactivation of C.butyricum spores, e.g. shortening the total inactivation time from 10 to 3 min at 85 °C. However, HPU did not affect the SC-CO2 inactivation of A.niger spores. The study into the effect of a combined SC-CO2 + HPU treatment has to be necessarily extended to other fungal and bacterial spores, and future studies should elucidate the impact of HPU application on the emulsion's stability.

Integrated proteomics and metabolomics analysis of tea leaves fermented by Aspergillus niger, Aspergillus tamarii and Aspergillus fumigatus.

Post-fermented Pu-erh tea (PFPT) is a microbially-fermented tea with distinct sensory qualities and multiple health benefits. Aspergillus are the dominant fungi in the fermentation and the main contributors to the characteristics of PFPT, so their underlying functions warrant detailed study. Here, tea leaves were fermented by Aspergillus niger, Aspergillus tamarii and Aspergillus fumigatus, and resulting samples (designated as Asn, Ast and Asf, respectively) were analyzed by proteomic and metabolomic methods. Changes to the composition of flavonoids, glycerophospholipids, organo-oxygen compounds and fatty acids resulting from Aspergillus fermentation were observed. Carbohydrate-active enzymes, e.g., endoglucanases and cellulases, for degradation of cellulose, starch, lignin, pectin, xylan and xyloglucan were identified. Glycoside hydrolase, glycosyltransferases, tannase, laccases, vanillyl-alcohol oxidases and benzoquinone reductase were identified and hypothesized to catalyze hydrolysis, oxidation, polymerization and degradation of phenolic compounds. Together, functions of Aspergillius were demonstrated as production of enzymes to change concentrations and compositions of metabolites in tea leaves.

Biomanagement of rice root-knot nematode Meloidogyne graminicola using five indigenous microbial isolates under pot and field trials.

AIMS: To ascertain the effectiveness of Aspergillus niger, Trichoderma harzianum, Pochonia chlamydosporia, Bacillus subtilis and Pseudomonas fluorescens against rice root-knot nematode, Meloidogyne graminicola, and to optimize their application methods. METHODS AND RESULTS: The relative effectiveness of five indigenous biocontrol agents (BCA) against M. graminicola on rice cv. PS-5 was tested initially in pot culture. The BCAs, A. niger, P. chlamydosporia and P. fluorescens proved more effective, and significantly reduced the nematode disease. It is hypothesized that success of a biocontrol module may vary with the BCA and application methods. Hence, the effectiveness of the above three BCAs as well as seven different treatment schemes were evaluated in naturally infested farmer's fields during 2 consecutive years. In nematode-infested plots without any BCA treatments, terminal galls formed on the roots, and plants suffered a 19-31% decrease in the growth and yield. The treatments with P. chlamydosporia or A. niger through root-dip (RD) plus one soil application (SA) at 15 days after planting were found to be highly effective against the nematode. CONCLUSIONS: Relatively greater nematode control was achieved with RD plus two SAs (15 + 30 DAP) but statistically the effect was on par with RD + one SA at 15 DAP. These treatments significantly reduced galling (22-25%), egg mass production (21-29%) and reproduction factor (63-70%) of M. graminicola, and subsequently increased the grain yield (11-21%). SIGNIFICANCE AND IMPACT OF THE STUDY: Application methods enhanced the effectiveness of BCAs against M. graminicola. The RD plus one SA at 15 DAP proved to be most effective treatment to control root-knot disease in rice. Use of multiple treatments (root dip and SA) appears cumbersome, but in view of effectiveness and limitation of chemical control in rice paddies, farmers may adopt the above module that may lead to 11-21% yield improvement.

Physical Properties, Chemical Analysis, and Evaluation of Antimicrobial Response of New Polylactide/Alginate/Copper Composite Materials.

In recent years, due to an expansion of antibiotic-resistant microorganisms, there has been growing interest in biodegradable and antibacterial polymers that can be used in selected biomedical applications. The present work describes the synthesis of antimicrobial polylactide-copper alginate (PLA-ALG-Cu2+) composite fibers and their characterization. The composites were prepared by immersing PLA fibers in aqueous solution of sodium alginate, followed by ionic cross-linking of alginate chains within the polylactide fibers with Cu(II) ions to yield PLA-ALG-Cu2+ composite fibers. The composites, so prepared, were characterized by scanning electron microscopy (SEM), UV/VIS transmittance and attenuated total reflection Fourier-transform infrared spectroscopy ATR-FTIR, and by determination of their specific surface area (SSA), total/average pore volumes (through application of the 5-point Brunauer-Emmett-Teller method (BET)), and ability to block UV radiation (determination of the ultraviolet protection factor (UPF) of samples). The composites were also subjected to in vitro antimicrobial activity evaluation tests against colonies of Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria and antifungal susceptibility tests against Aspergillus niger and Chaetomium globosum fungal mold species. All the results obtained in this work showed that the obtained composites were promising materials to be used as an antimicrobial wound dressing.

Aspergillus niger α-1,3-glucan acts as a virulence factor by inhibiting the insect phenoloxidase system.

Phenoloxidase (PO) is a key enzyme in the melanization process involved in elimination of pathogens in insects. The PO system is rapidly activated in response to pathogen recognition. Inhibition of PO activity can be a way to avoid immune response and increase infection effectiveness. In this study, the effects of inoculation of Galleria mellonella larvae with Aspergillus niger α-1,3-glucan and conidia on PO activity in hemolymph are analyzed in comparison with the effects of ß-1,3/1,6-glucan inoculation. Our results indicate that α-1,3-glucan, a fungal cell wall polysaccharide, can play a role of a virulence factor involved in inhibition of the insect PO system.

Apical but not sub-apical hyphal compartments are self-sustaining in growth.

It was recently demonstrated that apical compartments of Aspergillus niger hyphae are self-sustaining in growth. This was shown by assessing the growth rate of individual hyphae before and after dissection of the second compartment. Using the same methodology, it is here demonstrated that single apical compartments of the septate fungi Penicillium chrysogenum and Schizophyllum commune as well as the 500-µm-apical region of the non-septate fungus Rhizopus stolonifer are also self-sustaining in growth. In contrast, single 2nd compartments (obtained by dissection of the first and third compartment) of the septate fungi or the region between 500 and 1000 µm from tips of R. stolonifer were severely impacted in their growth rate. In addition, it is shown that existing or newly formed branches originating from the 2nd compartments function as a backup system for hyphal growth when the apical part of the hypha of the three studied fungi is damaged. Together, it is concluded that the apical compartments/zones of the studied fungi are self-sustaining in growth. In contrast, the subapical region is not self-sustaining but functions as a backup once the apical zone is damaged. This back up system is relevant in nature because the apices of hyphae are the first to be exposed to (a)biotic stress conditions when entering an unexplored substrate.

Developmental stages of biofilm and characterization of extracellular matrix of manglicolous fungus Aspergillus niger BSC-1.

Fungal biofilm is ubiquitous in natural environment. The major constituent of fungal biofilm other than biomass is the extracellular matrix (ECM), in which fungal hyphae are embedded. Physical properties of biofilms such as attachment, mechanical strength, and antibiotic resistance can be attributed to ECM. The present work probes various stages of biofilm formation by filamentous manglicolous fungus Aspergillus niger BSC-1. The spectroscopic analysis revealed that with an increase in incubation time the biofilm formation was significantly increased (p < .0001) up to 36 h. Scanning electron micrograph and confocal micrograph depicted the development of fungal biofilm comprising of six stages, that is, (a) adsorption, (b) active attachment, (c) germling and monolayer formation, (d) hyphal development and formation of ECM, (e) maturation of ECM, and (f) dispersal of spores. At maturation stage, thickness of biofilm was observed upto approximately 15 µm. Approximately, 8.1 mg of ECM materials were extracted from 20 ml of broth culture using ethanol precipitation method. Furthermore, attenuated total reflectance Fourier-transformed infrared spectroscopic analysis exhibited peaks at 3,398, 2,930, 1,571, 1,391, 1,092, 977 cm-1 which confirmed the presence of protein, carbohydrate, and lipid in the biofilm-associated matrix.

Aspergillus fumigatus establishes infection in zebrafish by germination of phagocytized conidia, while Aspergillus niger relies on extracellular germination.

Among opportunistically pathogenic filamentous fungi of the Aspergillus genus, Aspergillus fumigatus stands out as a drastically more prevalent cause of infection than others. Utilizing the zebrafish embryo model, we applied a combination of non-invasive real-time imaging and genetic approaches to compare the infectious development of A. fumigatus with that of the less pathogenic A. niger. We found that both species evoke similar immune cell migratory responses, but A. fumigatus is more efficiently phagocytized than A. niger. Though efficiently phagocytized, A. fumigatus conidia retains the ability to germinate and form hyphae from inside macrophages leading to serious infection even at relatively low infectious burdens. By contrast, A. niger appears to rely on extracellular germination, and rapid hyphal growth to establish infection. Despite these differences in the mechanism of infection between the species, galactofuranose mutant strains of both A. fumigatus and A. niger display attenuated pathogenesis. However, deficiency in this cell wall component has a stronger impact on A. niger, which is dependent on rapid extracellular hyphal growth. In conclusion, we uncover differences in the interaction of the two fungal species with innate immune cells, noticeable from very early stages of infection, which drive a divergence in their route to establishing infections.

Inhibition of growth and ochratoxin A production in Aspergillus species by fungi isolated from coffee beans.

Ochratoxin A (OTA) is a mycotoxin found in several agricultural commodities. Produced by Aspergillus spp., it is nephrotoxic and hepatotoxic and can be carcinogenic. Preventive measures are preventing fungal growth and OTA production. In this study, fungal strains (Rhizopus oryzae, Lichtheimia ramosa, Aspergillus westerdijkiae, Aspergillus niger, Aspergillus tamarii, Aspergillus sp., and Aspergillus fumigatus) isolated from coffee beans were identified for their abilities to inhibit the growth of Aspergillus ochraceus, Aspergillus westerdijkiae, Aspergillus carbonarius, and Aspergillus niger, and OTA production. All fungi strains tested were able to inhibit growth of the four Aspergillus species and OTA production, where A. niger showed the best results in both tests. L. ramosa showed the lowest growth-reducing potential, while the other fungal strains had a growth-reducing potential higher than 70% against all Aspergillus species tested. Regarding OTA production, L. ramosa and Aspergillus sp. completely inhibited the mycotoxin production by A. ochraceus and non-toxigenic strain A. niger completely inhibited OTA production by A. niger. Our findings indicate that the strains tested can be used as an alternative means to control growth of OTA-producing fungi and production of the mycotoxin in coffee beans.

Signal pattern plot: a simple tool for time-dependent metabolomics studies by 1H NMR spectroscopy.

We show an alternative way to visualize time course NMR data without the application of multivariate data analysis, based on the temporal change of the metabolome of hazelnuts after mold infestation. Fresh hazelnuts were inoculated with eight different natural mold species and the growth was studied over a period of 14 days. The data were plotted in a color-coded scheme showing metabolic changes as a function of chemical shift, which we named signal pattern plot. This plot graphically displays alteration (trend) of a respected signal over time and allows visual interpretation in a simple manner. Changes are compared with a reference sample stored under identical conditions as the infected nuts. The plot allows, at a glance, the recognition of individual landmarks specific to a sample group as well as common features of the spectra. Each sample reveals an individual signal pattern. The plot facilitates the recognition of signals that belong to biological relevant metabolites. Betaine and five signals were identified that specifically changed upon mold infestation. Graphical abstract.

The study of intracellular and secreted high-molecular-mass protease(s) of Trichoderma spp., and their responses to conidiation stimuli.

We continued our study of high-molecular-mass proteases (HMMPs) using several strains of the genus Trichoderma, and other filamentous fungi (Botrytis cinerea, Aspergillus niger, Fusarium culmorum, and Penicillium purpurogenum). We found that five Trichoderma strains secreted HMMPs into the media after induction with bovine serum albumin. Botrytis cinerea and F. culmorum secreted proteases in the absence of inducer, while A. niger or P. purpurogenum did not secrete proteolytic activity (PA). The activity of HMMPs secreted by or intracellularly located in Trichoderma spp. represents the predominant part of cellular PA, according to zymogram patterns. This observation allowed the study of HMMPs' physiological role(s) independent from the secretion. In studying conidiation, we found that illumination significantly stimulated PA in Trichoderma strains. In the T. atroviride IMI 206040 strain, we demonstrated that this stimulation is dependent on the BLR1 and BLR2 receptors. No stimulation of PA was observed when mechanical injury was used as an elicitor of conidiation. Compounds used as inhibitors or activators of conidiation exerted no congruent effects on both PA and conidiation. These results do not favour a direct role of HMMPs in conidiation. Probably, HMMP activity may be involved in the process of the activation of metabolism during vegetative growth, differentiation, and aging-related processes.

Study of the corrosion behavior of Aspergillus niger on 7075-T6 aluminum alloy in a high salinity environment.

In this study, the corrosion behavior of 7075-T6 aluminum alloy in a high salinity environment containing Aspergillus niger was investigated using high-performance liquid chromatography tandem mass spectrometry, gas chromatography, surface analysis and electrochemical measurement. Results demonstrated that uniform and localized corrosion rates of the alloy in the presence of A. niger were approximately 3.7 and 22.4 times, respectively, of that in the absence A. niger. This higher corrosion rate was attributed to accelerated anode and cathode reactions from the actions of A. niger biofilm. Additionally, organic acid corrosion caused by the presence of A. niger was confirmed to be the main cause for the corrosion of aluminum alloy.

Survival of Microorganisms on Nonwovens Used for the Construction of Filtering Facepiece Respirators.

Filtering nonwovens that constitute the base material for filtering facepiece respirators (FFRs) used for the protection of the respiratory system against bioaerosols may, in favourable conditions, promote the development of harmful microorganisms. There are no studies looking at the impact that different types of filtering nonwovens have on microorganism survival, which is an important issue for FFR producers and users. Five commercial filtering nonwovens manufactured using diverse textile technologies (i.e., needle-punching, melt-blown, spun-bonding) with different structural parameters and raw material compositions were used within our research. The survival of microorganisms on filtering nonwovens was determined for E. coli, S. aureus, B. subtilis bacteria; C. albicans yeast and A. niger mould. Samples of nonwovens were collected immediately after inoculum application (at 0 h) and after 4, 8, 24, 48, 72, and 96 h of incubation. The tests were carried out in accordance with the AATCC 100-1998 method. Survival depended strongly on microorganism species. E. coli and S. aureus bacteria grew the most on all nonwovens tested. The structural parameters of the nonwovens tested (mass per unit area and thickness) and contact angle did not significantly affect microorganism survival.

Effects of partial dietary substitution of groundnut meal by defatted, Aspergillus niger-fermented and heated Jatropha curcas kernel meal on feed intake and growth performance of broiler chicks.

This study was conducted to determine intake and growth performance of broiler chicks fed with Jatropha curcas kernel meal physico-chemically and biologically processed. The feed experiment lasted for 7 days with 20-day-old Ross 308 strain unsexed broiler chicks. Two dietary treatments were given each to ten animals, according to a complete randomized design. Kernels, manually obtained from J. curcas seed, were defatted, heated, and fermented with a strain of Aspergillus niger and oven-dried, in order to obtain the treated jatropha kernel meal. This latter was used to replace one third of a groundnut meal premix which was then incorporated in a commercial diet to warrant iso-nitrogenous and iso-caloric characteristics of the diets. Data collected were analyzed according to ANOVA procedure. The results revealed that the animals that received the diet incorporating jatropha kernel meal had numerically higher live weight (156.1 vs. 152.7 g/animal) (P > 0.05) and average daily weight gain (12.3 vs. 11.7 g/day/animal) (P > 0.05) than the control ones, at the end of experiment. The average daily feed intake was the same for the two groups of animals (23.2 g/day/animal) (P > 0.05) with a similar feed conversion ratio (2.0 vs. 2.1 respectively for the jatropha group and the control group). The survival rate, at the end of the experiment, was 100% for the two groups of animals. Physico-chemically and biologically processed Jatropha curcas kernel could be an interesting by-product for poultry feeding.

Molybdenum disulfide nanosheets loaded with chitosan and silver nanoparticles effective antifungal activities: in vitro and in vivo.

A method was developed for the liquid exfoliation of molybdenum disulfide (MoS2) from its bulk materials using ultrasound in aqueous phase with the assistance of chitosan (CS) and silver nanoparticles (Ag NPs) for effective loading of a variety of therapeutic molecules. The characterization results revealed that the as-made chemically-exfoliated MoS2 nanosheets had an average thickness of ∼10 nm. The new material, CS and Ag NPs-modified MoS2 (MoS2-CS-Ag), showed highly effective antifungal activities against Saccharomyces uvarum and Aspergillus niger. The Ag NPs-loaded MoS2 nanosheets achieved outstanding antifungal effect by inhibiting fungal growth both in vitro and in vivo. Notably, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis of spore morphological changes caused by MoS2-CS-Ag treatment reveal that it may directly cause the cell death. The result of the analysis of the application of MoS2-CS-Ag as an antifungal for fruits also demonstrated the MoS2-CS-Ag protective properties against fungi. The excellent film-forming ability of CS has been shown to contribute to the effectiveness of MoS2-CS-Ag in preserving the freshness of fruits, exhibited in four chemical quality sections: Vc, total carbohydrate, weight loss, and titratable acidity in fruit preservation application assay. The present study reports a new and exciting insight in a multi-functional drug carrier for protecting postharvest fruit.

Isolation and characterization of Aspergillus niger NBC001 underlying suppression against Heterodera glycines.

Heterodera glycines is the most pervasive soybean pests worldwide. Biocontrol provides a strategy to sustainably control nematodes. In this study, 22 fungal isolates were obtained and identified from cysts of Heterodera spp. Among them, Aspergillus niger NBC001 showed high nematicidal activity against H. glycines. The 2-fold dilution of NBC001 culture filtrate caused 89% mortality of second-stage juveniles and inhibited more than 98% of egg hatching in vitro. In both pot and field experiments, the numbers of H. glycines cysts in soybean seedlings dressed with the the 5-fold concentrated culture filtrate of NBC001 were significantly reduced by 43% and 28%, respectively. In addition, application of NBC001 remarkably reduced the penetration of nematodes into the roots. Histochemical and fluorometric staining analyses indicate that application of NBC001 stimulated hydrogen peroxide activity in the roots and triggered callose deposition in the leaves and roots. Transcription of the PR1a and EREBP genes in the salicylic acid and ethylene signaling pathways was upregulated in soybean plants treated with NBC001. However, the application of concentrated culture filtrate of NBC001 had no significant impacts on the soil microbial community based on next generation DNA sequencing technology. In summary, NBC001 may be a good biocontrol agent against H. glycines via stimulation of the immunity/defense of the plant host.