Comparison of Chemical Sensitivity of Fresh and Long-Stored Heat Resistant Neosartorya fischeri Environmental Isolates Using BIOLOG Phenotype MicroArray System

Optical Density Assay to Determine the Sensitivity of Globisporangium and Pythium Isolates to Mefenoxam

Several species of Globisporangium and Pythium cause cavity spot of carrot. Disease management in conventional production relies primarily on application of the fungicide mefenoxam. Growers’ reports in Ontario, Canada, of severe cavity spot, even when using mefenoxam applications, suggest that mefenoxam resistance may be prevalent in pathogen populations in this region. The objectives of the study were to develop a rapid and accurate optical density (OD) assay to assess mefenoxam sensitivity of 188 isolates of Globisporangium and Pythium species collected from 13 carrot fields in Ontario from 2020 to 2023. The isolates belonged to seven species: G. intermedium, G. irregulare, G. rostratifingens, G. sylvaticum, G. ultimum, G. violae, and P. sulcatum. The OD was measured at 600 nm in broth amended with different concentrations of mefenoxam, with OD readings at nine positions per well in a 96-well plate. The OD assay was validated by comparing half maximal effective concentration values with a standard fungicide-amended agar medium assay using 20 representative isolates. There was a significant linear relationship ( R2 = 0.97, P < 0.0001) between the two assays. Of the 188 isolates tested, 24% exhibited <60% inhibition of mycelial growth at 5 μg ml–1 mefenoxam, 50% were inhibited by >60% at 5 μg ml–1, 19% were inhibited by >60% at 1 μg ml–1, and 7% were inhibited by >60% even at 0.1 μg ml–1. The OD assay proved to be efficient, rapid, and accurate for monitoring the mefenoxam sensitivity of these oomycetes.

[Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

The role of food preservatives in shaping metabolic profile and chemical sensitivity of fungi - an extensive study on crucial mycological food contaminants from the genus Neosartorya (Aspergillus spp.)

Food preservatives are crucial in fruit production, but fungal resistance is a challenge. The main objective was to compare the sensitivity of Neosartorya spp. isolates to preservatives used in food security applications and to assess the role of metabolic properties in shaping Neosartorya spp. resistance. Sodium metabisulfite, potassium sorbate, sodium bisulfite and sorbic acid showed inhibitory effects, with sodium metabisulfite the most effective. Tested metabolic profiles included fungal growth intensity and utilization of amines and amides, amino acids, polymers, carbohydrates and carboxylic acids. Significant decreases in the utilization of all tested organic compound guilds were observed after fungal exposure to food preservatives compared to the control. Although the current investigation was limited in the number of predominately carbohydrate substrates and the breadth of metabolic responses, extensive sensitivity panels are logical step in establishing a course of action against spoilage agents in food production being important approach for innovative food chemistry.

Comprehensive antifungal investigation of natural plant extracts against Neosartorya spp. (Aspergillus spp.) of agriculturally significant microbiological contaminants and shaping their metabolic profile

Fungi belonging to the genus Neosartorya (teleomorph of Aspergillus spp.) are of great concern in the production and storage of berries and fruit-based products, mainly due to the production of thermoresistant ascospores that cause food spoilage and possible secretion of mycotoxins. We initially tested the antifungal effect of six natural extracts against 20 isolates of Neosartorya spp. using a traditional inhibition test on Petri dishes. Tested isolates did not respond uniformly, creating 5 groups of descending sensitivity. Ten isolates best representing of the established sensitivity clusters were chosen for further investigation using a Biolog™ MT2 microplate assay with the same 6 natural extracts. Additionally, to test for metabolic profile changes, we used a Biolog™ FF microplate assay after pre-incubation with marigold extract. All natural extracts had an inhibitory effect on Neosartorya spp. growth and impacted its metabolism. Lavender and tea tree oil extracts at a concentration of 1000 µg mL-1 presented the strongest antifungal effect during the inhibition test, however all extracts exhibited inhibitory properties at even the lowest dose (5 µg mL-1). The fungal stress response in the presence of marigold extract was characterized by a decrease of amino acids and carbohydrates consumption and an uptake of carboxylic acids on the FF microplates, where the 10 studied isolates also presented differences in their innate resilience, creating 3 distinctive sensitivity groups of high, average and low sensitivity. The results confirm that natural plant extracts and essential oils inhibit and alter the growth and metabolism of Neosartorya spp. suggesting a possible future use in sustainable agriculture as an alternative to chemical fungicides used in traditional crop protection.

Soil-Borne Neosartorya spp.: A Heat-Resistant Fungal Threat to Horticulture and Food Production-An Important Component of the Root-Associated Microbial Community

Soil-borne Neosartorya spp. are the highly resilient sexual reproductive stage (teleomorph) of Aspergillus spp. Fungi of this genus are relevant components of root-associated microbial community, but they can also excrete mycotoxins and exhibit great resistance to high temperatures. Their ascospores easily transfer between soil and crops; thus, Neosartorya poses a danger to horticulture and food production, especially to the postharvest quality of fruits and vegetables. The spores are known to cause spoilage, mainly in raw fruit produce, juices, and pulps, despite undergoing pasteurization. However, these fungi can also participate in carbon transformation and sequestration, as well as plant protection in drought conditions. Many species have been identified and included in the genus, and yet some of them create taxonomical controversy due to their high similarity. This also contributes to Neosartorya spp. being easily mistaken for its anamorph, resulting in uncertain data within many studies. The review discusses also the factors shaping Neosartorya spp.'s resistance to temperature, preservatives, chemicals, and natural plant extracts, as well as presenting novel solutions to problems created by its resilient nature.

A rapid and accurate method for the detection of four aminoglycoside modifying enzyme drug resistance gene in clinical strains of Escherichia coli by a multiplex polymerase chain reaction

BACKGROUND

Antibiotics are highly effective drugs used in the treatment of infectious diseases. Aminoglycoside antibiotics are one of the most common antibiotics in the treatment of bacterial infections. However, the development of drug resistance against those medicines is becoming a serious concern.

AIM

This study aimed to develop an efficient, rapid, accurate, and sensitive detection method that is applicable for routine clinical use.

METHODS

Escherichia coli was used as a model organism to develop a rapid, accurate, and reliable multiplex polymerase chain reaction (M-PCR) for the detection of four aminoglycoside modifying enzyme (AME) resistance genes Aac(6')-Ib, Aac(3)-II, Ant(3″)-Ia, and Aph(3')-Ia. M-PCR was used to detect the distribution of AME resistance genes in 237 clinical strains of E. coli. The results were verified by simplex polymerase chain reaction (S-PCR).

RESULTS

Results of M-PCR and S-PCR showed that the detection rates of Aac(6')-Ib, Aac(3)-II, Ant(3″)-Ia, and Aph(3')-Ia were 32.7%, 59.2%, 23.5%, and 16.8%, respectively, in 237 clinical strains of E. coli. Compared with the traditional methods for detection and identification, the rapid and accurate M-PCR detection method was established to detect AME drug resistance genes. This technique can be used for the clinical detection as well as the surveillance and monitoring of the spread of those specific antibiotic resistance genes.

Loop-mediated isothermal amplification (LAMP) approach for detection of heat-resistant Talaromyces flavus species

Talaromyces flavus is a soilborne fungus that can contaminate fruits. It constitutes serious influence on heat-processed food spoilage, as T. flavus belongs to the heat-resistant fungi group, which are able to survive the pasteurization process. Moreover T. flavus has been reported to be capable of mycotoxigenicity, therefore they have a serious threat to human health. To maintain the safety of food production, sensitive method for T. flavus detection was developed. The loop mediated amplification, abbreviated LAMP, reactions were designed as specific for detection of DNA replication licensing factor gene of T. flavus. The specificity of assay was confirmed by use of 5 T. flavus strains and 35 other fungal isolates. The achieved limit of detection was 1fg of T. flavus genomic DNA and 64 ascospores in 1 g of strawberry fruits or soil samples.

Alternative Molecular-Based Diagnostic Methods of Plant Pathogenic Fungi Affecting Berry Crops-A Review

Increasing consumer awareness of potentially harmful pesticides used in conventional agriculture has prompted organic farming to become notably more prevalent in recent decades. Central European countries are some of the most important producers of blueberries, raspberries and strawberries in the world and organic cultivation methods for these fruits have a significant market share. Fungal pathogens are considered to be the most significant threat to organic crops of berries, causing serious economic losses and reducing yields. In order to ameliorate the harmful effects of pathogenic fungi on cultivations, the application of rapid and effective identification methods is essential. At present, various molecular methods are applied for fungal species recognition, such as PCR, qPCR, LAMP and NGS.

Intraspecific functional and genetic diversity of Petriella setifera

The aim of the study was an analysis of the intraspecific genetic and functional diversity of the new isolated fungal strains of P. setifera. This is the first report concerning the genetic and metabolic diversity of Petriella setifera strains isolated from industrial compost and the first description of a protocol for AFLP fingerprinting analysis optimised for these fungal species. The results showed a significant degree of variability among the isolates, which was demonstrated by the clearly subdivision of all the isolates into two clusters with 51% and 62% similarity, respectively. For the metabolic diversity, the BIOLOG system was used and this analysis revealed clearly different patterns of carbon substrates utilization between the isolates resulting in a clear separation of the five isolates into three clusters with 0%, 42% and 54% of similarity, respectively. These results suggest that genetic diversity does not always match the level of functional diversity, which may be useful in discovering the importance of this fungus to ecosystem functioning. The results indicated that P. setifera strains were able to degrade substrates produced in the degradation of hemicellulose (D-Arabinose, L-Arabinose, D-Glucuronic Acid, Xylitol, γ-Amino-Butyric Acid, D-Mannose, D-Xylose and L-Rhamnose), cellulose (α-D-Glucose and D-Cellobiose) and the synthesis of lignin (Quinic Acid) at a high level, showing their importance in ecosystem services as a decomposer of carbon compounds and as organisms, which make a significant contribution to carbon cycling in the ecosystem.The results showed for the first time that the use of molecular biology techniques (such as AFLP and BIOLOG analyses) may allow for the identification of intraspecific diversity of as yet poorly investigated fungal species with favourable consequences for our understanding their ecosystem function.

Development of a qPCR assay for the detection of heat-resistant Talaromyces flavus

Heat-resistant fungi of the species Talaromyces flavus, which inhabits soil and can contaminate fruits, constitutes significant impact on spoilage of heat-processed food. T. flavus possess the ability to produce numerous mycotoxins and is able to survive the process of pasteurization what makes it a treat to food industry. Up to date there is no rapid and reliable method to detect and identify T. flavus. Therefore in this study, a sensitive method for detecting T. flavus was developed. The primers (Tf1_F/R) specific to detection of DNA replication licensing factor gene of T. flavus were designed. With this set of primers, a qPCR reaction with SybrGreen detection was developed. The specificity of assay with use of 5 T. flavus strains and 35 other fungal isolates was tested. The detection threshold was 200 fg of T. flavus genomic DNA. The developed method was able to detect 640 ascospores in 1 g of strawberry fruits and soil samples.

Fast and Accurate Microplate Method (Biolog MT2) for Detection of Fusarium Fungicides Resistance/Sensitivity

The need for finding fungicides against Fusarium is a key step in the chemical plant protection and using appropriate chemical agents. Existing, conventional methods of evaluation of Fusarium isolates resistance to fungicides are costly, time-consuming and potentially environmentally harmful due to usage of high amounts of potentially toxic chemicals. Therefore, the development of fast, accurate and effective detection methods for Fusarium resistance to fungicides is urgently required. MT2 microplates (Biolog(TM)) method is traditionally used for bacteria identification and the evaluation of their ability to utilize different carbon substrates. However, to the best of our knowledge, there is no reports concerning the use of this technical tool to determine fungicides resistance of the Fusarium isolates. For this reason, the objectives of this study are to develop a fast method for Fusarium resistance to fungicides detection and to validate the effectiveness approach between both traditional hole-plate and MT2 microplates assays. In presented study MT2 microplate-based assay was evaluated for potential use as an alternative resistance detection method. This was carried out using three commercially available fungicides, containing following active substances: triazoles (tebuconazole), benzimidazoles (carbendazim) and strobilurins (azoxystrobin), in six concentrations (0, 0.0005, 0.005, 0.05, 0.1, 0.2%), for nine selected Fusarium isolates. In this study, the particular concentrations of each fungicides was loaded into MT2 microplate wells. The wells were inoculated with the Fusarium mycelium suspended in PM4-IF inoculating fluid. Before inoculation the suspension was standardized for each isolates into 75% of transmittance. Traditional hole-plate method was used as a control assay. The fungicides concentrations in control method were the following: 0, 0.0005, 0.005, 0.05, 0.5, 1, 2, 5, 10, 25, and 50%. Strong relationships between MT2 microplate and traditional hole-plate methods were observed regarding to the detection of Fusarium resistance to various fungicides and their concentrations. The tebuconazole was most potent, providing increased efficiency in the growth inhibition of all tested isolates. Almost all among tested isolates were resistant to azoxystrobin-based fungicide. Overall, the MT2 microplates method was effective and timesaving, alternative method for determining Fusarium resistance/sensitivity to fungicides, compering to traditional hole-plate approach.