Aspergillus Terreus Isolates Research Articles

Investigation of antifungal susceptibility of Aspergillus species isolated from systemic clinical specimens by different methods

PurposeDue to the potential for Aspergillus species to cause lethal infections and the rising rates of antifungal resistance, the significance of antifungal susceptibility tests has increased. We aimed to assess the sensitivities of Aspergillus species to amphotericin B (AMB), voriconazole (VOR), itraconazole (ITZ), and caspofungin (CAS) using disk diffusion (DD) and gradient diffusion (GD) methods and compare them with broth microdilution (BMD) as the reference susceptibility method. MethodsThe study involved 62 Aspergillus fumigatus, 28 Aspergillus flavus, and 16 Aspergillus terreus isolates, totaling 106 Aspergillus isolates. BMD and DD methods were performed in accordance with CLSI M38-A2 and CLSI M51-A documents, respectively. The GD method utilized nonsupplemented Mueller Hinton agar (MHA) as the medium. ResultsIn the BMD method, the lowest minimal inhibitory concentration (MIC)90 or minimal effective concentration (MEC)90 values were observed for VOR and CAS (0.5 μg/mL and 0.06 μg/mL, respectively). AMB and ITZ MIC90 values were both 2 μg/mL. In our comparison of the GD method with the BMD method at ±2 dilution, we observed essential agreement rates of 91.6%, 99.1%, 100%, and 38.6% for AMB, VOR, ITZ, and CAS, respectively. When comparing DD and BMD methods, we found categorical agreement rates of 65.1%, 99.1%, 77.3%, and 100% for AMB, VOR, ITZ, and CAS, respectively. For GD and BMD methods, these rates were 79.2%, 99.1%, 87.8%, and 100%. ConclusionsGiven the high essential and categorical agreement rates, we posit that the GD method is a viable alternative to the BMD method for AMB, ITZ and VOR but not for CAS. In addition, the use of nonsupplemented MHA in the GD method proves advantageous due to its cost-effectiveness and widespread availability compared to other growth media.

Deciphering Molecular Aspects of Potential α-Glucosidase Inhibitors within Aspergillus terreus: A Computational Odyssey of Molecular Docking-Coupled Dynamics Simulations and Pharmacokinetic Profiling.

Hyperglycemia, as a hallmark of the metabolic malady diabetes mellitus, has been an overwhelming healthcare burden owing to its high rates of comorbidity and mortality, as well as prospective complications affecting different body organs. Available therapeutic agents, with α-glucosidase inhibitors as one of their cornerstone arsenal, control stages of broad glycemia while showing definitive characteristics related to their low clinical efficiency and off-target complications. This has propelled the academia and industrial section into discovering novel and safer candidates. Herein, we provided a thorough computational exploration of identifying candidates from the marine-derived Aspergillus terreus isolates. Combined structural- and ligand-based approaches using a chemical library of 275 metabolites were adopted for pinpointing promising α-glucosidase inhibitors, as well as providing guiding insights for further lead optimization and development. Structure-based virtual screening through escalating precision molecular docking protocol at the α-glucosidase canonical pocket identified 11 promising top-docked hits, with several being superior to the market drug reference, acarbose. Comprehensive ligand-based investigations of these hits' pharmacokinetics ADME profiles, physiochemical characterizations, and obedience to the gold standard Lipinski's rule of five, as well as toxicity and mutagenicity profiling, proceeded. Under explicit conditions, a molecular dynamics simulation identified the top-stable metabolites: butyrolactone VI (SK-44), aspulvinone E (SK-55), butyrolactone I 4''''-sulfate (SK-72), and terrelumamide B (SK-173). They depicted the highest free binding energies and steadiest thermodynamic behavior. Moreover, great structural insights have been revealed, including the advent of an aromatic scaffold-based interaction for ligand-target complex stability. The significance of introducing balanced hydrophobic/polar moieties, like triazole and other bioisosteres of carboxylic acid, has been highlighted across docking, ADME/Tox profiling, and molecular dynamics studies for maximizing binding interactions while assuring safety and optimal pharmacokinetics for targeting the intestinal-localized α-glucosidase enzyme. Overall, this study provided valuable starting points for developing new α-glucosidase inhibitors based on nature-derived unique scaffolds, as well as guidance for prospective lead optimization and development within future pre-clinical and clinical investigations.

Lipid-Like Biofilm from a Clinical Brain Isolate of Aspergillus terreus: Quantification, Structural Characterization and Stages of the Formation Cycle.

Invasive infections caused by filamentous fungi have increased considerably due to the alteration of the host's immune response. Aspergillus terreus is considered an emerging pathogen and has shown resistance to amphotericin B treatment, resulting in high mortality. The development of fungal biofilm is a virulence factor, and it has been described in some cases of invasive aspergillosis. In addition, although the general composition of fungal biofilms is known, findings related to biofilms of a lipid nature are rarely reported. In this study, we present the identification of a clinical strain of A. terreus by microbiological and molecular tools, also its in vitro biofilm development capacity: (i) Biofilm formation was quantified by Crystal Violet and reduction of tetrazolium salts assays, and simultaneously the stages of biofilm development were described by Scanning Electron Microscopy in High Resolution (SEM-HR). (ii) Characterization of the organizational structure of the biofilm was performed by SEM-HR. The hyphal networks developed on the surface, the abundant air channels created between the ECM (extracellular matrix) and the hyphae fused in anastomosis were described. Also, the presence of microhyphae is reported. (iii) The chemical composition of the ECM was analyzed by SEM-HR and CLSM (Confocal Laser Scanning Microscopy). Proteins, carbohydrates, nucleic acids and a relevant presence of lipid components were identified. Some structures of apparent waxy appearance were highlighted by SEM-HR and backscatter-electron diffraction, for which CLSM was previously performed. To our knowledge, this work is the first description of a lipid-type biofilm in filamentous fungi, specifically of the species A. terreus from a clinical isolate.

Possibility of controlling on Aspergillus terreus produciny Aflatoxine isolation from some Chips local and imporet pleurotus ostereatus plauate and Sodium bicarbonate

After study HPLC technique showed that the highest concentration of Aflatoxin B1 toxin was due to the filterate of Aspergillus terreus isolate of the chips sample, which amounted to 193.9 ppb, and this isolate was phenotypically diagnosed using taxonomic keys as well as molecularly diagnosed by polymerase chain reaction (PCR) technique in addition to base sequence analysis phylogenetic tree analysis for the purpose of comparing the isolate of the contaminated fungus A.terreus with the isolates previously registered in the National Center for Biotechnology Information (NCBI). P.ostreatus filtrate and sodium bicarbonate proved their inhibitory ability for both radial growth and dry weight of the contaminated fungus, This study show effect toxin inside histo pathology of liver and kidney in mice.

In Vitro Susceptibilities of Worldwide Isolates of Intrapulmonary Aspergillus Species and Important Candida Species in Sterile Body Sites against Important Antifungals: Data from the Antimicrobial Testing Leadership and Surveillance Program, 2017-2020.

To understand the changes of resistance in clinically commonly encountered fungi, we used the Antimicrobial Testing Leadership and Surveillance (ATLAS) database to explore in vitro antifungal susceptibilities against clinically important isolates of Aspergillus and Candida species (collected from intrapulmonary and sterile body areas, respectively). We applied the CLSI antifungal 2020 and the EUCAST antifungal 2020 guidelines. From 2017 to 2020, isolates of intrapulmonary Aspergillus fumigatus (n = 660), Aspergillus niger (n = 107), Aspergillus flavus (n = 96), Aspergillus terreus (n = 40), and Aspergillus nidulans species complex (n = 26) and sterile site-originated isolates of Candida albicans (n = 1,810), Candida glabrata (n = 894), Candida krusei (n = 120), Candida dubliniensis (n = 107), Candida lusitaniae (n = 82), Candida guilliermondii (n = 28), and Candida auris (n = 7) were enrolled in this study. Using the EUCAST 2020 breakpoints, it was demonstrated that amphotericin B and posaconazole displayed poor in vitro susceptibility rates against A. fumigatus isolates (<50% and 18.9%, respectively). In contrast, isavuconazole and itraconazole showed high in vitro potency against most Aspergillus isolates (>92%). Most intrapulmonary Aspergillus isolates exhibited MICs of ≤0.06 μg/mL to anidulafungin. Furthermore, intrapulmonary A. fumigatus isolates collected from Italy and the United Kingdom exhibited lower in vitro susceptibility to isavuconazole (72.2% and 69%, respectively) than those in the remaining ATLAS participant countries (>85%). Higher isavuconazole MIC90s against C. auris and C. guilliermondii (1 and 4 μg/mL, respectively) were observed compared to the other five Candida species. Despite the aforementioned MICs and susceptibilities against fungi, research needs to consider the pharmacokinetic (PK) profiles, pharmacodynamic (PD) parameters, and clinical treatment experience with antifungals against specific Aspergillus species. IMPORTANCE In addition to monitoring the antifungal susceptibilities of clinically important fungi, reviewing the PK/PD indices and the clinical therapy experience of antifungals under evaluation are important to guide an appropriate antifungal prescription. The efficacies of liposomal amphotericin B complex and anidulafungin for the treatment of pulmonary aspergillosis caused by different Aspergillus species need to be periodically evaluated in the future.

A Whole Genome Sequencing-Based Approach to Track down Genomic Variants in Itraconazole-Resistant Species of Aspergillus from Iran.

The antifungal resistance in non-fumigatus Aspergillus spp., as well as Aspergillus fumigatus, poses a major therapeutic challenge which affects the entire healthcare community. Mutation occurrence of cyp51 gene paralogs is the major cause of azole resistance in Aspergillus spp. To obtain a full map of genomic changes, an accurate scan of the entire length of the Aspergillus genome is necessary. In this study, using whole genome sequencing (WGS) technique, we evaluated the mutation in cyp51A, cyp51B, Cdr1B, AtrR, Hmg1, HapE and FfmA genes in different clinical isolates of Aspergillus fumigatus, Aspergillus niger, Aspergillus tubingensis, Aspergillus welwitschiae and Aspergillus terreus which responded to minimum inhibitory concentrations of itraconazole above 16 µg mL−1. We found different nonsynonymous mutations in the cyp51A, cyp51B, Cdr1B, AtrR, Hmg1, HapE and FfmA gene loci. According to our findings, Aspergillus species isolated from different parts of the world may represent different pattern of resistance mechanisms which may be revealed by WGS.

Isolation and identification of fungi contaminated with some local and imported chips and the possibility of controlling one of the toxin-producing fungi by using pleurotus ostreatusFiltrate and Sodiumbicarbonate treatments

Samples of chips were collected from the markets and shops of the center and districts of Al-Diwaniyah Governorate for the period from (October - November 2021) and several types of fungi were isolated, Aspergillus niger , A.flavus, A.parasiticus, Aspergillus sp1,Aspergillus sp2,Aspergillus terreus,Mucor, Penicillium natatum and Rhizopus stolanifer. The results of the HPLC technique showed that the highest concentration of Aflatoxin B1 toxin was due to the filterate of Aspergillus terreus isolate of the chips sample, which amounted to 193.9 ppb, and this isolate was phenotypically diagnosed using taxonomic keys as well as molecularly diagnosed by polymerase chain reaction (PCR) technique in addition to base sequence analysis phylogenetic tree analysis for the purpose of comparing the isolate of the contaminated fungus A.terreus with the isolates previously registered in the National Center for Biotechnology Information (NCBI). Pleurotus.ostreatus filtrate and sodium bicarbonate proved their inhibitory ability for both radial growth and dry weight of the contaminated fungus isolate, where the highest inhibition rate reached64.44% for radial growth at 30% concentration to treat the interaction between P.ostreatus filtrate and sodium bicarbonate, while the highest inhibition rate was 57.03% for dry weight at 30% for same treat.

Performance and microbiota of the digestive tract of Nellore calves supplemented with fungi isolated from bovine rumen

Background and Aim:In tropical semiarid regions, supplementation with fungi could contribute to rumen modulation, promoting greater production of fibrolytic enzymes and degradation of forage. The objective of this study was to analyze the effect of supplementation with fungi, isolated from the bovine rumen, on the performance and microbiota of the digestive tract of Nellore calves.Materials and Methods:The experiment was conducted in randomized blocks evaluating eight Nellore calves that were daily supplemented with isolates of Aspergillus terreus and Trichoderma longibrachiatum, along with eight calves that were not supplemented. After 55 days, the animals were weighed, and samples of rumen fluid and feces were collected for analysis. The characteristics that showed normal distribution were subjected to analysis of variance and compared using Tukey’s test. Whereas, the variables that did not show normal distribution were subjected to the Kruskal–Wallis test, and the frequencies of the bacterial and fungal genera were compared using the Chi-square test.Results:Supplementation with fungi promoted the reduction in ruminal pH (p<0.05). However, the final live weight; average daily weight gain; total weight gain; rumen protozoa; and the count of Enterobacteriaceae, mycelial fungi, and yeasts of ruminal fluid and feces were not influenced by supplementation (p>0.05). Moreover, the protozoa Eodinium spp. was identified only in supplemented calves (p<0.05).Conclusion:Supplementation with the fungi presented the potential for use as possible additives because it did not alter the physiological parameters of the facultative anaerobic microbiota composition in the rumen and feces. In addition, it favored the presence of the ciliate genus Eodinium. However, further studies should be performed to better define suitable dosages for supplementation.

Evaluation of crude oil biodegradation using mixed fungal cultures.

The use of potent fungal mixed cultures is a promising technique for the biodegradation of crude oil. Four isolates of fungi, namely, Alternaria alternata (AA-1), Aspergillus flavus (AF-3), Aspergillus terreus (AT-7), and Trichoderma harzianum (TH-5), were isolated from date palm soil in Saudi Arabia. The mixed fungal of the four isolates have a powerful tool for biodegradation up to 73.6% of crude oil (1%, w/v) in 14 days. The fungal consortium no. 15 containing the four isolates (1:1:1:1) performed significantly better as a biodegradation agent than other consortium in a variety of environmental factors containing crude oil concentration, incubation temperature, initial pH, biodegradation time and the salinity of the medium. The fungal consortium showed better performance in the biodegradation of normal alkanes (n-alkanes) than that of the polycyclic aromatic hydrocarbons (PAHs); the biodegradation efficiency of normal alkanes of the fungal consortium (67.1%) was clearly high than that of the PAHs (56.8%).

Aspergillus spp. isolates from bovine rumen can increase the digestibility and degradability of forages

The bovine production on pastures is a sustainable activity, responsible to generating income and employments in many tropical regions. However, in this system a major obstacle occurs during long dry periods, when the forages show low nutritional quality. In this research we evaluated the in vitro digestibility and degradability of Urochloa decumbens and Cynodon dactylons var Tiffton 85 inoculated with isolates of Aspergillus spp. from the gastrointestinal tract cattle. Four cows with rumen fistula were used as rumen contents donors to determine the in vitro digestibility of dry matter (IVDMD). The treatments were, as follows: control - No fungal inoculum, AT13 – (with Aspergillus terreus isolate), AF69 – (with Asperillus fumigates isolate, MIX (with mix of fungi AT13 and AF69). The analyses were performed in rumen simulator with four replications. The gas production was determined by semi-automatic method for both gas and the mechanics ability to fiber colonization of these fungi isolates were evaluated by scanning electron microscopy. The inclusion of AF69 and MIX promoted significant increase of IVDMD of U. decumbens (41.4 - 42.1%). The dry matter degradability were not influenced by the inoculums types using the by semi-automatic gas production method However, they linearly increased with fermentation time. The two isolates of Aspergillus spp. were able to colonize the U. decumbens fiber showing production of mycelium and reproductive structures in electronic microscopic analyses. The addition these Aspergillus isolates promotes significant increase of IVDMD to U. decumbens, indicating promising potential for development of microbial or probiotic additive to cattle raised on lignified tropical pasture.

Biosynthesis of Lovastatin by Gamma Irradiated Aspergillus terreus

Lovastatin (C24H36O5, Mevinolin, Monacolin K and Mevacor®) is the first compound of its kind to become available for treatment of hypercholesterolemia. This fungal secondary metabolite is produced by Aspergillus, Monascus and Penicillium species, via the polyketide synthase (PKSs). The role of hypercholesterolemia as a risk factor for atherosclerosis, and ischemic heart disease was indicated by the clinical, epidemiologic and pathologic studies. In the present study, gamma irradiated of selected highly lovastatin producer Aspergillus terreus isolate (A. terreus S3γ8) was employed for lovastatin production in submerged fermentation (SmF) conditions. Different fermentation parameters including: incubation period, initial pH of the medium, temperature, different carbon and nitrogen sources, type of inoculum and agitation; were carried out under SmF conditions to enhance the lovastatin production. The maximum lovastatin production (547.33 mg/l) was achieved at initial pH 6, incubation temperature 30 °C, agitation rate 150 rpm, 4% soluble starch and 0.3% yeast extract as carbon and nitrogen sources, respectively, after 8 days when the production medium (which containing bio-elements: KH2PO4, MgSO4 and MnSO4) was inoculated with 48 h age from seed culture inoculum.

Comparative evaluation of protease production from okara, broken wheat, chickpea and black gram by the soil isolate of Aspergillus terreus

Comparative evaluation of protease production from okara, broken wheat, chickpea and black gram by the soil isolate of Aspergillus terreus

Phenotypic and Genotypic Identification and Antifungal Susceptibility of Some Fungi Isolated from Tympanotonus fuscatus var. radula

Aim: This study aimed to identify fungi isolated from Tympanotonus fuscatus var. radula and evaluate its level of susceptibility to known antifungal compounds.&#x0D; Place and Duration of Study: Biotechnology Advanced Research Centre, Sheda Science and Technology Complex, Abuja between September and December 2019.&#x0D; Methods: Tympanotonus fuscatus var. radula samples were purchased from the Keffi, Masaka, and Orange markets in Nasarawa State, Nigeria. Fungal isolation was achieved using Sabouraud dextrose agar supplemented with chloramphenicol and incubated at 28ᵒC for 5 days. ITS-1 and ITS-4 primers were used at 94°C for 2 min, 52°C for 1 min, and 72°C for 2 min for the polymerase chain reaction before sequencing at Inqaba Biotech South Africa. Disk diffusion technique was employed for antifungal susceptibility testing.&#x0D; Results: Data obtained revealed that the suspected fungal species exhibited a generally higher level of resistance (19-40 mm) to 1 µg voriconazole in addition to a 20-35.5 mm zone of inhibition against 10 µg ketoconazole. Blast sequence analysis of the isolated samples revealed a 99.65% sequence homology to Meyerozyma guilliermondii, 99.38% to Fusarium oxysporium isolate E-225 1 and 96.23% to Aspergillus terreus isolate A2S4. &#x0D; Conclusion: Food safety involves isolating and accurately identifying disease causing pathogens such as fungi in food. Based on the fungal load obtained from this study, proper cooking and handling of sea-food which would otherwise cause disease, is highly recommended.

Biosynthesis and Bio-sensing Applications of Silver and Gold Metal Nanoparticles

Biogenic nanoparticles have gained major interest because of their eco-friendly approach, as non-toxic chemicals are involved in the biosynthesis, and the preparation process carried out at ambient pressure and temperature. In the present study, two fungal strains (MM1and MM2) showed the ability to biosynthesize silver and gold nanoparticles, respectively, were isolated from local Egyptian soil samples. These two fungi were identified by the molecular technique 18srRNA as Aspergillus terreus isolate MM1-EGY and Aspergillus flavus isolate MM2-EGY. The biosynthesized silver nanoparticles by Aspergillus terreus isolate MM1-EGY exhibited UV absorbance around 420 nm and particle size range of 15-35 nm as measured by transmission electron microscopy (TEM). On the other hand, gold nanoparticles biosynthesized by Aspergillus flavus isolate MM2-EGY showed maximum UV/Vis absorbance around 550 nm and size range of 20-50 nm. The XRD of both AgNPs and AuNPS was constructed. The green synthesized gold nanoparticles were tested for sensitive and selective simultaneous voltammetric determination of neurotransmitter metabolite, vanillylmandelic acid (VMA) and homovanillic acids (HVA), while silver nanoparticles were applied for the fabrication of disposable screen-printed Ag/AgCl planner reference electrode.

Impact of certain endophytic fungi as biocontrol agents against sesame wilt disease

This study was conducted to evaluate the ability of some endophytic fungi, as biocontrol agents against sesame wilt caused by Fusarium oxysporum f. sp. sesame. Eleven fungal species belong to genus Fusarium was isolated from different localities in Sohag and Assiut governorates. All isolated species proved to be pathogenic on Giza-32 sesame cultivar. Twelve endophytic fungi isolates were isolated from some parts of various plants. The endophytic fungi isolates were tested for antagonistic activity by the dual culture and culture filtrate techniques. All endophytic fungal isolates were showed antagonistic activity againstthe causal pathogen in vitro. The endophytic Aspergillus niger was more antagonistic than other tested isolates toward the causal pathogenfollowed by A. clavatus, Penicillium chrysogenum and P. crustosum. All the tested fungal culture filtrates (FCF) were significantly affected the growth of the causal pathogen. FCF of Aspergillus terreusisolate at 20 % concentration displayed the greatest inhibitory action to the pathogen mycelia growth. Single application with endophytic fungi or combined with Trichoderma sp. were significantly deceased the disease severity (%) and increased the plant growth parameters such as shoot length, shoot weight, root weight and number of pods.

Aspergillus terreus Inhibits Growth and Induces Morphological Abnormalities in Pythium aphanidermatum and Suppresses Pythium-Induced Damping-Off of Cucumber.

The study investigated the efficacy of two isolates of Aspergillus terreus (65P and 9F) on the growth, morphology and pathogenicity of Pythium aphanidermatum on cucumber. In vitro tests showed that the two isolates inhibited the growth of P. aphanidermatum in culture. Investigating P. aphanidermatum hyphae close to the inhibition zone showed that the hyphae showed abnormal growth and loss of internal content. Treating P. aphanidermatum with the culture filtrate (CF) of A. terreus resulted in significant rise in cellular leakage of P. aphanidermatum mycelium. Testing glucanase enzyme activity by both A. terreus isolates showed a significant increase in glucanase activity. This suggests that the cell walls of Pythium, which consist of glucan, are affected by the glucanase enzyme produced by A. terreus. In addition, Aspergillus isolates produced siderephore, which is suggested to be involved in inhibition of Pythium growth. Also, the CFs of 65P and 9F isolates significantly reduced spore production by P. aphanidermatum compared to the control (P < 0.05). In bioassay tests, the two isolates of A. terreus increased the survival rate of cucumber seedlings from 10 to 20% in the control seedlings treated with P. aphanidermatum to 38–39% when the biocontrol agents were used. No disease symptoms were observed on cucumber seedlings only treated with the isolates 65P and 9F of A. terreus. In addition, the A. terreus isolates did not have any negative effects on the growth of cucumber seedlings. This study shows that isolates of A. terreus can help suppress Pythium-induced damping-off of cucumber, which is suggested to be through the effect of A. terreus and its glucanase enzyme on P. aphanidermatum mycelium.

Diversity of clinical isolates of Aspergillus terreus in antifungal susceptibilities, genotypes and virulence in Galleria mellonella model: Comparison between respiratory and ear isolates.

We analyzed the antifungal susceptibility profiles, genotypes, and virulence of clinical Aspergillus terreus isolates from six university hospitals in South Korea. Thirty one isolates of A. terreus, comprising 15 respiratory and 16 ear isolates were assessed. Microsatellite genotyping was performed, and genetic similarity was assessed by calculating the Jaccard index. Virulence was evaluated by Galleria mellonella survival assay. All 31 isolates were susceptible to itraconazole, posaconazole, and voriconazole, while 23 (74.2%) and 6 (19.4%) showed amphotericin B (AMB) minimum inhibitory concentrations (MICs) of ≤ 1 mg/L and > 4 mg/L, respectively. Notably, respiratory isolates showed significantly higher geometric mean MICs than ear isolates to AMB (2.41 vs. 0.48 mg/L), itraconazole (0.40 vs. 0.19 mg/L), posaconazole (0.16 vs. 0.08 mg/L), and voriconazole (0.76 vs. 0.31 mg/L) (all, P <0.05). Microsatellite genotyping separated the 31 isolates into 27 types, but the dendrogram demonstrated a closer genotypic relatedness among isolates from the same body site (ear or respiratory tract); in particular, the majority of ear isolates clustered together. Individual isolates varied markedly in their ability to kill infected G. mellonella after 72 h, but virulence did not show significant differences according to source (ear or respiratory tract), genotype, or antifungal susceptibility. The current study shows the marked diversity of clinical isolates of A. terreus in terms of antifungal susceptibilities, genotypes and virulence in the G. mellonella model, and ear isolates from Korean hospitals may have lower AMB or triazole MICs than respiratory isolates.

Amphotericin B Resistance in Aspergillus terreus Is Overpowered by Coapplication of Pro-oxidants.

Invasive fungal infections have significantly increased over the past decades in immunocompromised individuals and high-risk patients. Amphotericin B (AmB) exerts a powerful and broad activity against a vast array of fungi and has a remarkably low rate of microbial resistance. However, most isolates of Aspergillus terreus developed an intrinsic resistance against AmB, and during this study, we characterized the mode of action of this polyene antifungal drug in more detail in resistant (ATR) and rare susceptible (ATS) clinical isolates of A. terreus. We illustrate that AmB treatment changes cellular redox status and promotes the generation of high levels of reactive oxygen species (ROS) in ATS. In contrast, ATR isolates were able to cope better with AmB-induced oxidative stress. Most importantly, we demonstrate in this study that coapplication of anti- and pro-oxidants significantly affects AmB efficacy in an antithetic manner--antioxidants and ROS-scavenging agents increase AmB tolerance in susceptible strains, while pro-oxidants render formerly resistant isolates considerably susceptible to the antifungal drug also in vivo in a Galleria animal model. Thereby, our study provides novel therapeutic options to treat formerly resistant fungal strains by a combination of AmB and pro-oxidant compounds.

Dissimilatory nitrate reduction by Aspergillus terreus isolated from the seasonal oxygen minimum zone in the Arabian Sea.

BackgroundA wealth of microbial eukaryotes is adapted to life in oxygen-deficient marine environments. Evidence is accumulating that some of these eukaryotes survive anoxia by employing dissimilatory nitrate reduction, a strategy that otherwise is widespread in prokaryotes. Here, we report on the anaerobic nitrate metabolism of the fungus Aspergillus terreus (isolate An-4) that was obtained from sediment in the seasonal oxygen minimum zone in the Arabian Sea, a globally important site of oceanic nitrogen loss and nitrous oxide emission.ResultsAxenic incubations of An-4 in the presence and absence of oxygen and nitrate revealed that this fungal isolate is capable of dissimilatory nitrate reduction to ammonium under anoxic conditions. A 15N-labeling experiment proved that An-4 produced and excreted ammonium through nitrate reduction at a rate of up to 175 nmol 15NH4+ g-1 protein h-1. The products of dissimilatory nitrate reduction were ammonium (83%), nitrous oxide (15.5%), and nitrite (1.5%), while dinitrogen production was not observed. The process led to substantial cellular ATP production and biomass growth and also occurred when ammonium was added to suppress nitrate assimilation, stressing the dissimilatory nature of nitrate reduction. Interestingly, An-4 used intracellular nitrate stores (up to 6–8 μmol NO3- g-1 protein) for dissimilatory nitrate reduction.ConclusionsOur findings expand the short list of microbial eukaryotes that store nitrate intracellularly and carry out dissimilatory nitrate reduction when oxygen is absent. In the currently spreading oxygen-deficient zones in the ocean, an as yet unexplored diversity of fungi may recycle nitrate to ammonium and nitrite, the substrates of the major nitrogen loss process anaerobic ammonium oxidation, and the potent greenhouse gas nitrous oxide.

Development of Microbial Nanofactory for Zinc, Magnesium, and Titanium Nanoparticles Production Using Soil Fungi

To access the nanoparticle production potential over a hundreds of fungi were isolated from the soil and tested with precursor salts of Zn, Mg and Ti. Initially, the nanoparticle size was calculated by using the dynamic light scattering through particle size analyzer. Only 14 fungi isolate were found suitable for nanoparticle biosynthesis. All the fourteen fungal isolate identified as molecular level, out of which six were identified as Aspergillus flavus, two each as Aspergillus terreus and Aspergillus tubingensis and one each as Aspergillus niger, Rhizoctonia bataticola, Aspergillus fumigatus, and Aspergillus oryzae. To understand the reason of variable potential of nanoparticle production, extracellular protein content was measured. The results suggested that CZR 1 isolate of Aspergillus terreus showing the maximum 1480.98 gm L −1 extracellular protein contents and have potential for nanoparticle synthesis of all the three Zn, Mg and Ti metals. The 32 kDa protein was responsible for the synthesis of Zn, Mg and Ti nanoparticles from its precursor compound ZnO, MgO and TiO2 respectively.