Strains Of Aspergillus Species Research Articles

In-Vitro Efficacy of Botanical extracts for the Management of Aspergillus flavus growth in Tanzania

Maize is one of the most important food and commercial crops in Tanzania but is vulnerable to pre-and postharvest contamination with aflatoxins produced mostly by Aspergillus flavus. This study evaluated the in-vitro antifungal efficacy of five locally available botanicals (Azadirachta indica, Calotropis procera, Euphorbia hirta, Jatropha curcas, and Ricinus communis) against the growth of A. flavus. The botanical leaves were collected mainly from the Kongwa district, while strains of Aspergillus species were isolated from maize grain from Kongwa and Morogoro rural districts during the cropping season 2021/2022. The effect of botanicals on the radial mycelium growth of A. flavus was tested at concentrations of 0.2 0.25, 0.3, and 0.35 g/mL. The inhibitory effect was proportional to the concentration of botanicals. The highest radial growth inhibition of A. flavus was exhibited by extracts of J. curcas (69.7%), R. communis (62.8%), A. indica (61.8%), and E. hirta (52.4%). The least mean inhibition was found in C. procera (45.7%) at a concentration of 0.35 g/ml. The antifungal effect of botanicals demonstrated in this study warrants further evaluation for pre-harvest management of Aspergillus species contamination under field conditions.

Ribosomal subunit protein typing using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification and discrimination of Aspergillus species

BackgroundAccurate identification of Aspergillus species is a very important subject. Mass spectral fingerprinting using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is generally employed for the rapid identification of fungal isolates. However, the results are based on simple mass spectral pattern-matching, with no peak assignment and no taxonomic input. We propose here a ribosomal subunit protein (RSP) typing technique using MALDI-TOF MS for the identification and discrimination of Aspergillus species. The results are concluded to be phylogenetic in that they reflect the molecular evolution of housekeeping RSPs.ResultsThe amino acid sequences of RSPs of genome-sequenced strains of Aspergillus species were first verified and compared to compile a reliable biomarker list for the identification of Aspergillus species. In this process, we revealed that many amino acid sequences of RSPs (about 10–60%, depending on strain) registered in the public protein databases needed to be corrected or newly added. The verified RSPs were allocated to RSP types based on their mass. Peak assignments of RSPs of each sample strain as observed by MALDI-TOF MS were then performed to set RSP type profiles, which were then further processed by means of cluster analysis. The resulting dendrogram based on RSP types showed a relatively good concordance with the tree based on β-tubulin gene sequences. RSP typing was able to further discriminate the strains belonging to Aspergillus section Fumigati.ConclusionsThe RSP typing method could be applied to identify Aspergillus species, even for species within section Fumigati. The discrimination power of RSP typing appears to be comparable to conventional β-tubulin gene analysis. This method would therefore be suitable for species identification and discrimination at the strain to species level. Because RSP typing can characterize the strains within section Fumigati, this method has potential as a powerful and reliable tool in the field of clinical microbiology.

In vitro Activity of Natural Antimicrobial Compounds against Aspergillus Strains

The current trend to use natural preservatives in food industry had led to the use of essential oils which are natural compounds already known for their antimicrobial and antioxidant activity. The aim of this study is to investigate the in vitro antifungal activity of rosemary essential oil and of some terpenes like eugenol, nerol, limonene (+), limonene (-) and pinene against three strains of Aspergillus species. The method used to evaluate the in vitro antifungal activity of the essential oils and terpenes tested is disk diffusion method. A suspension of the tested filamentous fungi was spread on the agar surface and 6 mm diameter sterile filter paper disks were impregnated with the essential oils and placed in the middle of the inoculated agar plates. Control samples were realized using the same procedure but without using essential oils. The samples were incubated at 25 °C under aerobic conditions for 7 days. Antifungal activity was evaluated by measuring the inhibition zone against the tested fungi and by determining the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC). The results showed the effectiveness of eugenol and nerol as antifungal compounds, these ones having the highest inhibitory effect against the tested strains of Aspergillus. Essential oils can be an alternative to synthetic antimicrobial compounds for controlling food spoilage and for assuring microbiological safety of products.

Chemical composition and in vitro antifungal activity of the essential oil from Cuminum cyminum against various Aspergillus strains

Antifungal activity of the essential oil obtained from Cuminum cyminum (C. cyminum) was investigated against different Aspergillus strains. Gas chromatography/mass spectrometry (GC/MS) analysis of the chemical composition of the oil was performed to determine their different components. The minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) of C. cyminum essential oil and amphotericin B for seven strains ofAspergillus species, comprising Aspergillus fumigatus (A. fumigatus) PTCC 5009,Aspergillus flavus PTCC 5006, Aspergillus niger PTCC 5011, Aspergillus terreus PTCC 5267, Aspergillus ochraceus PTCC 5017, Aspergillus nidulans PTCC 5014 and A. fumigatus AIR13, were determined by a broth macro dilution method. C. cyminum oil contained α-pinene (30%), limonene (21%) and 1, 8-cineole (18.5%), as the major components. The MIC values of the oil were ranged from 0.3 to 74 mg/ml and C. cyminum oil demonstrated strong antifungal activity on A. nidulans (P 2 µg/ml. Data showed that C. cyminum oil was more effective in comparison with amphotericin B. Furthermore, the study suggests that this essential oil can be used as an antifungal agent for the treatment of aspergillosis. Key words: Fungitoxicity, Aspergillus, Cuminum cyminum, essential oil, amphotericin B.

Amperometric glucose biosensor utilizing FAD-dependent glucose dehydrogenase immobilized on nanocomposite electrode

Amperometric glucose biosensors utilizing commercially available FAD-dependent glucose dehydrogenases from two strains of Aspergillus species are described. Enzymes were immobilized on nanocomposite electrode consisting of multi-walled carbon nanotubes by entrapment between chitosan layers. Unlike the common glucose oxidase based biosensor, the presented biosensors appeared to be O2-independent. The optimal amount of enzymes, working potential and pH value of working media of the glucose biosensors were determined. The biosensor utilizing enzyme isolated from Aspergillus sp. showed linearity over the range from 50 to 960μM and from 70 to 620μM for enzyme from Aspergillus oryzae. The detection limits were 4.45μM and 4.15μM, respectively. The time of response was found to be 60s. The biosensors showed excellent operational stability – no loss of sensitivity after 100 consecutive measurements and after the storage for 4 weeks at 4°C in phosphate buffer solution. When biosensors were held in a dessicator at room temperature without use, they kept the same response ability at least after 6 months. Finally, the results obtained from measurements of beverages and wine samples were compared with those obtained with the enzymatic-spectrophotometric and standard HPLC methods, respectively. Good correlation between results in case of analysis of real samples and good analytical performance of presented glucose biosensor allows to use presented concept for mass production and commercial use.

Evaluation of new method for diagnosis of opportunistic fungal infection

New methods for the possible presence DNA specific for Aspergillus or Trichosporon species were developed. In aspergillus PCR, Aspergillus l8S rRNA encoding gene was amplified from five strains of Aspergillus species by the nested PCR but not from other microorganisms. Results of preliminary investigation of this method demonstrated efficient detections of Aspergillus species in serum samples of rats model of aspergillosis and 29 patients with invasive aspergillosis. In trichosporon PCR, Trichosporon 26S rRNA encoding gene was amplified from two strains of Trichosporon species, and detected by the nested PCR in 64 % of serum samples of patients with trichosporonosis, while glucuronoxylomannan antigen was detected in 55 % of samples. The high sensitivity and specificity of the nested PCR indicate that the assay can provide early diagnosis with sufficient accuracy to be clinically useful for patients with opportunistic fungal infection.

PCR detection of DNA specific for Aspergillus species in serum of patients with invasive aspergillosis.

We investigated the possible presence of DNA specific for Aspergillus species in serum samples of patients with invasive aspergillosis (IA) by the nested PCR method. Fourteen strains of fungi including 5 strains of Aspergillus species and 10 strains of common bacteria were used for examination of specificity and sensitivity of the nested PCR. Two sets of oligonucleotide primers were derived from the sequence of the variable regions V7 to V9 of the 18S rRNA genes of Aspergillus fumigatus. The specific fragment was amplified from five strains of Aspergillus species in the single and nested PCR but not from other microorganisms. Target DNA was detected by the nested PCR with as little as 50 fg of the extracted DNA of A. fumigatus. We investigated the detection of DNA specific for Aspergillus species in serum samples of a murine model of aspergillosis and 20 patients with IA. The specific fragment was detected by the nested PCR in 71% of serum samples of infected mice and 70% of serum samples of patients with IA, while galactomannan antigen was detected in 43 and 60% of samples, respectively. The high sensitivity and specificity of the nested PCR indicate that the assay can provide early diagnosis with sufficient accuracy to be clinically useful for immunocompromised patients with IA.

Reducing aflatoxin contamination in peanut genotypes by selection and breeding

AbstractThe potential for developing agronomically suitable cultivais using peanut genotypes that exhibit resistance to seed colonization by aflatoxin‐producing strains ofAspergillus species is explored. Some factors found to be associated with the nature of resistance to seed colonization by the toxin‐producing fungi are cell structure, cell arrangement, permeability, waxy surface, tannin content and amino acid components of the seed testae. The practical implications of developing resistant cultivars are presented in data for yield, value and seed quality for 6 advanced peanut lines that were developed by breeding and selection from crosses.

Developing Groundnut Lines with Resistance to Seed Colonisation by Toxin-producing Strains of Aspergillus Species

Abstract Evidence for the possible development of groundnut (Arachis hypogaea L.) cultivars with favourable agronomic characteristics and resistance to aflatoxinproducing strains of Aspergillus species is presented. In studies of F2 and F3 progenies from crosses of resistant and susceptible genotypes data on the frequency distribution and least square estimates of genetic effects showed the possibility of selecting for resistance to seed colonisation by the fungus. Yield, value and seed quality data for seven advanced lines developed by using pedigree selection from crosses showed that potential favourable groundnut cultivars may be developed.