Fungus Aspergillus Flavus Research Articles

Investigation of fungi accompanying wheat grains at wheat cultivation areas in Iraq and the possibility of diagnosing it

The aim of this study was isolating and diagnosing the fungi accompanying the harvested wheat grains for the 2021 agricultural season, at some Iraqi provinces: Erbil, Sulaymaniyah, Mosul, Najaf, Karbala, Qadisiyah, Muthanna, ThiQar and Basra. The results of the field survey showed the accompanying fungi Alternaria sp, Aspergillus flavus, Aspergillus niger, Fusarium sp, Mucor, Penicillium sp, Rhizopus sp and other fungi. The results confirmed that the two genus, A. flavus and Alternaria sp, were the most prominent in all Iraqi provinces, with mean of 35.84 % for A. flavus and 25.36 % for Alternaria sp, followed by A. niger, and then both the fungi Fusarium sp, Rhizopus sp, Penicillium sp and Mucor, with mean 20.008, 5.20, 4.61, 2.20 and 0.63%, respectively. The incidence of other undiagnosed fungi was 6.09%, the genus A. niger recorded the highest occurrence in the provinces of ThiQar and Mosul with 45 and 40%, respectively, it was less visible in Erbil by 2.73%. It was also noted that the genus Fusarium sp recorded its highest occurrence in the provinces of Erbil and ThiQar with a percentage of 10.95 and 10%, while it was not recorded in the holy province of Karbala, the percentage of its occurrence varied in the rest of the provinces. The fungus Mucor sp recorded 2.94, 2.5, 1.4 and 1.35% at the provinces of Qadisiyah, ThiQar, Sulaymaniyah and Muthanna, respectively, while it was not recorded in the rest of the provinces. The genus Penicillium sp recorded occurrences in some Iraqi provinces by 5.47% in Erbil province and 4.83 and 4.41% in Karbala and Qadisiyah provinces, respectively, the percentage of his occurrence was 1.4% in Sulaymaniyah province and 1.26 in Najaf. The rest of the provinces did not record his occurrence. As for the genus Rhizopus sp, it appeared on wheat grains in most of the Iraqi provinces in different proportions, the highest percentage of its occurrence was in Basra Province, with 11.11%, did not record his occurrence in the province of Qadisiyah, while the results showed that A. flavus was the most frequent fungus at the level of the provinces under study, with a frequency of 22.77%. The fungus Alternaria sp ranked second with a frequency of 16.22%, where it was observed that the highest frequency was for A. flavus in the provinces of Muthanna and Najaf Al-Ashraf by 43% and 34%, respectively.The process of molecular diagnosis using polymerase chain reaction (PCR) technology for the most frequent isolate showed that it belongs to the genus Aspergillus flavus, it showed a 90% concordance with global isolates. The nucleotide sequence of the isolate has been deposited in GenBank under accession number ON932490.

Aspergillus flavus genetic structure at a turkey farm.

The ubiquitous environmental fungus Aspergillus flavus is also a life-threatening avian pathogen. This study aimed to assess the genetic diversity and population structure of A. flavus isolated from turkey lung biopsy or environmental samples collected in a poultry farm. A. flavus isolates were identified using both morphological and ITS sequence features. Multilocus microsatellite genotyping was performed by using a panel of six microsatellite markers. Population genetic indices were computed using FSTAT and STRUCTURE. A minimum-spanning tree (MST) and UPGMA dendrogram were drawn using BioNumerics and NTSYS-PC, respectively. The 63 environmental (air, surfaces, eggshells and food) A. flavus isolates clustered in 36 genotypes (genotypic diversity=0.57), and the 19 turkey lung biopsies isolates clustered in 17 genotypes (genotypic diversity=0.89). The genetic structure of environmental and avian A. flavus populations were clearly differentiated, according to both F-statistics and Bayesian model-based analysis' results. The Bayesian approach indicated gene flow between both A. flavus populations. The MST illustrated the genetic structure of this A. flavus population split in nine clusters, including six singletons. Our results highlight the distinct genetic structure of environmental and avian A. flavus populations, indicative of a genome-based adaptation of isolates involved in avian aspergillosis.

Glutamine Synthetase Contributes to the Regulation of Growth, Conidiation, Sclerotia Development, and Resistance to Oxidative Stress in the Fungus Aspergillus flavus.

The basic biological function of glutamine synthetase (Gs) is to catalyze the conversion of ammonium and glutamate to glutamine. This synthetase also performs other biological functions. However, the roles of Gs in fungi, especially in filamentous fungi, are not fully understood. Here, we found that conditional disruption of glutamine synthetase (AflGsA) gene expression in Aspergillus flavus by using a xylose promoter leads to a complete glutamine deficiency. Supplementation of glutamine could restore the nutritional deficiency caused by AflGsA expression deficiency. Additionally, by using the xylose promoter for the downregulation of AflgsA expression, we found that AflGsA regulates spore and sclerotic development by regulating the transcriptional levels of sporulation genes abaA and brlA and the sclerotic generation genes nsdC and nsdD, respectively. In addition, AflGsA was found to maintain the balance of reactive oxygen species (ROS) and to aid in resisting oxidative stress. AflGsA is also involved in the regulation of light signals through the production of glutamine. The results also showed that the recombinant AflGsA had glutamine synthetase activity in vitro and required the assistance of metal ions. The inhibitor molecule L-α-aminoadipic acid suppressed the activity of rAflGsA in vitro and disrupted the morphogenesis of spores, sclerotia, and colonies in A. flavus. These results provide a mechanistic link between nutrition metabolism and glutamine synthetase in A. flavus and suggest a strategy for the prevention of fungal infection.

Synthesis, Spectroscopic, Computational, Biological and Molecular docking studies on 3‐allyl 2,6‐diaryl piperidin‐4‐ones

AbstractA series of 3‐allyl‐2,6‐diarylpiperidin‐4‐one derivatives were designed and synthesized as antimicrobial agents with good yields. The target compounds were characterized by Mass, NMR, FT‐IR and FT‐Raman spectral techniques. The optimization had been performed on the title compound using the B3LYP method with 6‐311++G(d,p) basis set. The optimized bond parameter of the title molecule was calculated by DFT method. To study the intramolecular charge transfer within the molecule, the Lewis (bonding) and Non‐Lewis (anti‐bonding) structural calculation was performed. The Non‐linear optical behaviour of the title compound was measured using first order hyperpolarizability calculation. Mulliken atomic charges and thermodynamic properties were also calculated and analyzed. In vitro antibacterial and antifungal screening for all the synthesized 3‐allyl 2,6‐diaryl piperidin‐4‐ones was evaluated for two Gram‐positive bacteria (Staphylococcus aurous, Enterococcus faecalis), three Gram‐negative bacteria Pseudomonas aeruginosa, Escherichia coliand K. pneumonia) and five fungi (Candida albicans, Aspergillus niger, Aspergillus flavus, Rhizopus sp and Mucor sp). All the compounds showed good antibacterial and antifungal activities. Molecular docking study is to demonstrate that piperidine derivatives bind to Ribonucleotide reductases (RNRs) enzymes and to evaluate whether these molecules can be used as potential drugs.

The Characteristic, Occurrence of Aflatoxin and Associated Risk with Human Health

Aflatoxins are toxins produced by the fungus Aspergillus parasiticus and Aspergillus flavus. They are colorless, cannot be detected under normal light, odorless and contaminated foods most often do not have any special or bad smell. Environmental factors such as the temperature, and vectors causing grain damage have an important effect on favoring the colonization of fungus and the production of aflatoxins. They contaminate agriculture products worldwide affecting their quality, safety & security. The effects on safety & security cause health threats among people and animals on their long-term exposure through consumption because they are mutagenic, teratogenic, genotoxic, and carcinogenic. Humans and animals can develop the disease known as aflatoxicosis as a result of aflatoxins known as Acute and Chronic primary aflatoxicosis. Aflatoxins' long-term effects have been shown to decrease normal immune response also it can cause growth retardation in babies and affect nutritional deficiency. It can disrupt such enzymes that can affect hormones, endocrine glands, and neurotransmitters which may influence a person's cognitive abilities, memory, and learning, restlessness, muscular tremors, seizures, absentmindedness, tremors, uncoordinated movement of muscles, and aberrant agitation are caused by deficiencies in the neurotransmitters. Aflatoxin toxicity in humans can range from acute or chronic conditions to liver damage such as liver carcinoma, internal bleeding, edema, and instant death. Acute toxicosis can cause gastrointestinal dysfunctions in humans and animals. Aflatoxins have been shown to have detrimental negative impacts on vascular fragility and cardiovascular health, tissue bleeding, and teratogenic consequences. According to reports, aflatoxins have severe and detrimental impacts mostly on the respiratory systems it can also cause lung cancer.

In Vitro Sprouted Plantlets of Citrullus colocynthis (L.) Schrad Shown to Possess Interesting Levels of Cucurbitacins and Other Bioactives against Pathogenic Fungi.

Cucurbitacins, structurally different triterpenes mainly found in the members of Cucurbitaceae, possess a vast pharmacological potential. Genus Cucurbita, Cucumis, and Citrullus are affluent in these bioactive compounds, and, amongst them, Citrullus colocynthis (L.) Schrad. is widely exploited in folk medicine, since a huge number of diseases are successfully treated with organic and aqueous extracts obtained from different organs and tissues of the plant. The well-known pharmacological activities of such species have been attributed to its peculiar composition, which includes cucurbitacins and other bioactive molecules; thus, owing to its high importance as a valuable natural resource for pharmaceuticals and nutraceuticals, C. colocynthis propagation and multiplication protocols are considered significant, but the exploitation of its phytochemical potential is limited by the restricted cultivation conditions and the low rate of seed germination in the natural environment; in fact, the assessment of accumulation rate of specific phytochemicals under controlled conditions is still missing. Axenically sprouted plantlets obtained without the use of culture media or the addition of hormones have been evaluated here for the production of bioactive compounds and relevant bioactive features. Our results proved that derived organic extracts contain cucurbitacins and other bioactives, show antioxidant potential, and exert activity against some pathogenic fungi (Candida krusei, C. albicans, C. parapsilosis, C. glabrata, and Aspergillus flavus), supporting the feasibility of a methodology intended to scale-up cultivation of this species as a source of pharmaceutically interesting compounds, achievable from plantlets cultivated under laboratory conditions.

Temperature mediated influence of mycotoxigenic fungi on the life cycle attributes of Callosobruchus maculatus F. in stored chickpea

Environmental factors (biotic and abiotic) are major depletion reasons in granaries. Fungi and insect pests act synergistically in deterioration of grains in storages which results in nutritional damage to the stored food which becomes unpalatable for the consumer. There is a need to establish a timeline for synergistic damage caused by insect pests and mycotoxigenic fungi for better management. For this purpose, interaction of mycotoxigenic fungi (Aspergillus flavus, Aspergillus niger, Penicillium digitatum and Alternaria alternata) with Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) was studied at different temperatures. Development of C. maculatus was observed on fungus inoculated and uninoculated C. arietinum seeds. In fungus inoculated grains the development (Fecundity, larval emergence, pupation rate and adult emergence) of C. maculatus was found more better as compared on uninoculated grain. The population of C. maculatus was decreased by increase in temperature but high temperatures favours more fungi developments. More egg laying was observed at 27 °C and 33 °C. At tested temperatures, larval emergence was high as compared to other observed life attributes. Infestation of A. flavus and A. niger was also increased with increase of temperatures. Penicillium digitatum and A. alternata infestation were increased in the C. arietinum at 27 °C and 30 °C respectively. This study will help in measuring the control practices of fungi and insect pest infestations in stored C. arietinum (chickpea) in Pakistan.

Enhance the inactivation of fungi by the sequential use of cold atmospheric plasma and plasma-activated water: Synergistic effect and mechanism study

Cold atmospheric plasma (CAP) has been widely applied for microbe inactivation. Previous studies revealed that the inactivation efficiency could be improved with the sequential use of plasma-activated water (PAW) after the direct CAP treatment, while the mechanism requires further exploration. In this work, we employed a CAP jet device and investigated the inactivation effect of CAP combined with PAW treatment on two kinds of fungi (Saccharomyces cerevisiae and Aspergillus flavus), and particularly, we examined the synergistic effect by scrutinizing the roles of varied reactive species. Our experimental results showed that short-term CAP treatment combined with the continued long-term (e.g., 120 min) PAW treatment led to significant reduction of Saccharomyces cerevisiae/Aspergillus flavus, with the disinfection effect equivalentto the single CAP approach with much longer treatment time. The comparative analysis revealed that the inactivation of fungi was induced by different reactive oxygen and nitrogen species (RONS) during the combination of CAP and PAW treatments, which had different influences on the fungal morphology, membrane permeability, intracellular RONS and energy metabolism. In the first stage of CAP treatment, the plasma produced ·OH and 1O2, could directly destroy the structure of fungal wall and membrane, leading to cell death. While in the subsequent PAW treatment, the reactive nitrogen species (RNS) could enter cell and influence metabolic activities, leading inactivation of more fungi. The synergistic effect was attributed to the increasing of intracellular 1O2 and ONOO– induced membrane damage, causing the irreparable oxidative damage to mitochondria and energy metabolic system. This mechanistic study may thus provide a new guidance for the optimal application of low-temperature plasma technology in the application of fungal disinfection with high efficiency.

Intraspecific Growth and Aflatoxin Inhibition Responses to Atoxigenic Aspergillus flavus: Evidence of Secreted, Inhibitory Substances in Biocontrol.

The fungus Aspergillus flavus infects corn, peanut, and cottonseed, and contaminates seeds with acutely poisonous and carcinogenic aflatoxin. Aflatoxin contamination is a perennial threat in tropical and subtropical climates. Nonaflatoxin-producing isolates (atoxigenic) are deployed in fields to mitigate aflatoxin contamination. The biocontrol competitively excludes toxigenic A. flavus via direct replacement and thigmoregulated (touch) toxin inhibition mechanisms. To understand the broad-spectrum toxin inhibition, toxigenic isolates representing different mating types and sclerotia sizes were individually cocultured with different atoxigenic biocontrol isolates. To determine whether more inhibitory isolates had a competitive advantage to displace or touch inhibit toxigenic isolates, biomass accumulation rates were determined for each isolate. Finally, to determine whether atoxigenic isolates could inhibit aflatoxin production without touch, atoxigenic isolates were grown separated from a single toxigenic isolate by a membrane. Atoxigenic isolates 17, Af36, and K49 had superior abilities to inhibit toxin production. Small (<400 µm) sclerotial, Mat1-1 isolates were not as completely inhibited as others by most atoxigenic isolates. As expected for both direct replacement and touch inhibition, the fastest-growing atoxigenic isolates inhibited aflatoxin production the most, except for atoxigenic Af36 and K49. Aflatoxin production was inhibited when toxigenic and atoxigenic isolates were grown separately, especially by slow-growing atoxigenic Af36 and K49. Additionally, fungus-free filtrates from atoxigenic cultures inhibited aflatoxin production. Toxin production inhibition without direct contact revealed secretion of diffusible chemicals as an additional biocontrol mechanism. Biocontrol formulations should be improved by identifying isolates with broad-spectrum, high-inhibition capabilities and production of secreted inhibitory chemicals.

Antifungal, Repellency, and Insecticidal Activities of Cymbopogon distans and Ruta graveolens Essential Oils and Their Main Chemical Constituents.

Essential oils produced by Cymbopogon distans and Ruta graveolens with a similar Chinese name could be explained as book fragrance in the Chinese idiom 'shu xiang men di', namely, a wealthy intellectual family according to ancient Chinese. Therefore, volatile oils from these two plants and their main compounds were tested to explore their antifungal, repellent, and insecticide actions. In this study, the essential olis (EO) of C. distans exhibited significant antifungal activity against Rhizopus stolonifera (97 %), Mucor racemosus (97 %), and Trichoderma viride (84 %); its main compounds exhibit interesting activity, such as methyleugenol (87 %) and elemicine (85 %) against T. viride and butyl hydroxytoluene against M. racemosus (90 %) and R. stolonifera (95 %). The EO of R. graveolens and other major chemical constituents showed weak inhibitory effects against other fungi (Aspergillus flavus and Fusarium oxysporum). Then, EO (C. distans and R. graveolens) and its main compounds exhibited obvious repellent activity (more than 85 %) at a concentration of 16 nL/cm2 , which was consistent with the repellency of the positive control (DEET). In terms of insecticidal activity, the mortality of C. distans volatile oil against R. padi (56.4 %) was lower than that of R. graveolens volatile oil (92.4 %), and all compounds showed weak lethal effects. These results provide a natural substance for controlling fungi and insects when storing books and that can be used as a biological pesticide for industrial production. Through our study, the book fragrance in the Chinese idiom 'shu xiang men di' was speculated to be the EO odor of C. distans.

A New α-Cyclopiazonic Acid Alkaloid Identified from the Weizhou Island Coral-Derived Fungus Aspergillus flavus GXIMD 02503

A New α-Cyclopiazonic Acid Alkaloid Identified from the Weizhou Island Coral-Derived Fungus Aspergillus flavus GXIMD 02503

GTPase Rac Regulates Conidiation, AFB1 Production and Stress Response in Pathogenic Fungus Aspergillus flavus.

As a member of the Rho family, Rac plays important roles in many species, including proliferation, differentiation, apoptosis, DNA damage responses, metabolism, angiogenesis, and immunosuppression. In this study, by constructing Rac-deleted mutants in Aspergillus flavus, it was found that the deletion of Rac gene led to the decline of growth and development, conidia production, AFB1 toxin synthesis, and seed infection ability of A. flavus. The deletion of Rac gene also caused the disappearance of A. flavus sclerotium, indicating that Rac is required for sclerotium formation in A. flavus. The sensitivity of Rac-deficient strains responding to cell wall stress and osmotic pressure stress increased when compared to A. flavus WT. The Western blot result showed that mitogen-activated serine/threonine-protein kinase Slt2 and mitogen-activated protein kinase Hog1 proteins were no longer phosphorylated in Rac-deficient strains of A. flavus, showing that Rac may be used as a molecular switch to control the Slt2-MAPK cascade pathway and regulate the osmotic Hog-MAPK cascade pathway in A. flavus in response to external stress. Altogether, these results indicated that Rac was involved in regulating the growth and development, conidia formation and AFB1 synthesis, and response to cell wall stress and osmotic pressure stress in A. flavus.

Recombination-aware phylogeographic inference using the structured coalescent with ancestral recombination.

Movement of individuals between populations or demes is often restricted, especially between geographically isolated populations. The structured coalescent provides an elegant theoretical framework for describing how movement between populations shapes the genealogical history of sampled individuals and thereby structures genetic variation within and between populations. However, in the presence of recombination an individual may inherit different regions of their genome from different parents, resulting in a mosaic of genealogical histories across the genome, which can be represented by an Ancestral Recombination Graph (ARG). In this case, different genomic regions may have different ancestral histories and so different histories of movement between populations. Recombination therefore poses an additional challenge to phylogeographic methods that aim to reconstruct the movement of individuals from genealogies, although also a potential benefit in that different loci may contain additional information about movement. Here, we introduce the Structured Coalescent with Ancestral Recombination (SCAR) model, which builds on recent approximations to the structured coalescent by incorporating recombination into the ancestry of sampled individuals. The SCAR model allows us to infer how the migration history of sampled individuals varies across the genome from ARGs, and improves estimation of key population genetic parameters such as population sizes, recombination rates and migration rates. Using the SCAR model, we explore the potential and limitations of phylogeographic inference using full ARGs. We then apply the SCAR to lineages of the recombining fungus Aspergillus flavus sampled across the United States to explore patterns of recombination and migration across the genome.

Effect of Different Climatic Regions and Seasonal Variation on the Antibacterial and Antifungal Activity, and Chemical Profile of Helichrysum aureonitens Sch. Bip.

Native South Africans make use of Helichrysum aureonitens Sch. Bip. extracts for the treatment of a variety of infections and they are important in traditional medicinal preparations. This study investigated the effect of seasonal variation and geographical location on the antibacterial and antifungal activities of H. aureonitens. Material was collected in two different seasons: early spring, with high rainfall and high temperatures (October), and late autumn, with low rainfall and lower temperatures (May). Further analysis was carried out using 1H-NMR based metabolomics to analyse and compare the chemical profiles of the plants in both seasons and locations. Plant materials were collected from two sites for each season, at Wakefield farm (KwaZulu-Natal), representing a colder, wetter environment, and Telperion (Mpumalanga), representing a drier and warmer environment. Leaves of H. aureonitens were tested against bacteria (Proteus vulgaris (P. vulgaris) and Bacillus subtilis (B. subtilis)) as well as fungi (Aspergillus flavus (A. flavus), Aspergillus nomius (A. nomius), Cladosporium cladosporioides (C. cladosporioides), Fusarium oxysporum (F. oxysporum) and Penicillum halotolerans (P. halotolerans)). Extracts from the October harvest showed significant activities against the Gram-negative bacterium P. vulgaris compared to the May harvest, with an MIC value of 62.5 µg/mL. Similar activity was observed between the extracts from the wet season across the two geographically different locations. There was generally very good antifungal activity observed for all the species, with the exception of A. nomius, which had MIC values ranging from 0.39–1.56 µg/mL. Extracts of plant materials harvested in the wetter region had a significantly higher activity against A. flavus and F. oxysporum in both seasons than those from plants harvested in the drier region. Telperion-harvested plants exhibited better activity against F. oxysporum in the autumn. Hydrogen-1 NMR metabolomic analysis confirmed the significant effects of the seasons and the peculiar climates of different localities on the secondary metabolite profile of H. aureonitens.

Set2 family regulates mycotoxin metabolism and virulence via H3K36 methylation in pathogenic fungus Aspergillus flavus

ABSTRACT Aspergillus flavus infects various crops with aflatoxins, and leads to aspergillosis opportunistically. Though H3K36 methylation plays an important role in fungal toxin metabolism and virulence, no data about the biological function of H3K36 methylation in A. flavus virulence has been reported. Our study showed that the Set2 histone methyltransferase family, AshA and SetB, involves in morphogenesis and mycotoxin anabolism by regulating related transcriptional factors, and they are important for fungal virulence to crops and animals. Western-blotting and double deletion analysis revealed that AshA mainly regulates H3K36me2, whereas SetB is mainly responsible for H3K36me3 in the nucleus. By construction of domain deletion A. flavus strain and point mutation strains by homologous recombination, the study revealed that SET domain is indispensable in mycotoxin anabolism and virulence of A. flavus, and N455 and V457 in it are the key amino acid residues. ChIP analysis inferred that the methyltransferase family controls fungal reproduction and regulates the production of AFB1 by directly regulating the production of the transcriptional factor genes, including wetA, steA, aflR and amylase, through H3K36 trimethylation in their chromatin fragments, based on which this study proposed that, by H3K36 trimethylation, this methyltransferase family controls AFB1 anabolism through transcriptional level and substrate utilization level. This study illuminates the epigenetic mechanism of the Set2 family in regulating fungal virulence and mycotoxin production, and provides new targets for controlling the virulence of the fungus A. flavus. AUTHOR SUMMARY The methylation of H3K36 plays an important role in the fungal secondary metabolism and virulence, but no data about the regulatory mechanism of H3K36 methylation in the virulence of A. flavus have been reported. Our study revealed that, in the histone methyltransferase Set2 family, AshA mainly catalyzes H3K36me2, and involves in the methylation of H3K36me1, and SetB mainly catalyzes H3K36me3 and H3K36me1. Through domain deletion and point mutation analysis, this study also revealed that the SET domain was critical for the normal biological function of the Set2 family and that N455 and V457 in the domain were critical for AshA. By ChIP-seq and ChIP-qPCR analysis, H3K36 was found to be trimethylation modified in the promotors and ORF positions of wetA, steA, aflR and the amylase gene (AFLA_084340), and further qRT-PCR results showed that these methylation modifications regulate the expression levels of these genes. According to the results of ChIP-seq analysis, we proposed that, by H3K36 trimethylation, this methyltransferase family controls the metabolism of mycotoxin through transcriptional level and substrate utilization level. All the results from this study showed that Set2 family is essential for fungal secondary metabolism and virulence, which lays a theoretical groundwork in the early prevention and treatment of A. flavus pollution, and also provides an effective strategy to fight against other pathogenic fungi.

Effect of Biodegradable Coatings on the Growth of Aspergillus flavus In Vitro, on Maize Grains, and on the Quality of Tortillas during Storage.

The fungus Aspergillus flavus causes serious damage to maize grains and its by-products, such as tortilla. Currently, animal and plant derivatives, such as chitosan and propolis, and plant extract residues, respectively, are employed as alternatives of synthetic fungicides. The objective of this research was to evaluate the efficacy of several formulations based on propolis-chitosan-pine resin extract on the in vitro growth of A. flavus, the growth of maize grain plantlets and the quality of stored tortillas at 4 and 28 °C. The most outstanding formulation was that based on 59.7% chitosan + 20% propolis nanoparticles + 20% pine resin extract nanoparticles; since the in vitro conidia germination of A. flavus did not occur, disease incidence on grains was 25–30% and in tortillas, 0% infection was recorded, along with low aflatoxin production (1.0 ppb). The grain germination and seedling growth were markedly reduced by the nanocoating application. The percentage weight loss and color of tortillas were more affected by this coating compared to the control, and the rollability fell within the scale of non-ruptured at 4 °C and partially ruptured at 28 °C. The next step is to evaluate the toxicity of this formulation.

Using Rosemary Essential Oil as a Potential Natural Preservative during Stirred-like Yogurt Making.

The popularity of rosemary has grown as a natural alternative over the synthetic supplements due to its potential health benefits. The rosemary plant has been utilized to preserve food due to its ability to prevent oxidation and microbial contamination. The reason for this study was to determine the phytochemical components and antimicrobial activity of rosemary essential oil (REO) and the effect of REO addition (0.5 and 0.7%) on the chemical, microbiological, and sensory properties of stirred-like yogurt (SLY) during 16 days of storage at 4 °C. The obtained data observed that REO exhibited antimicrobial action against Escherichia coli, Staphylococcus aureus, and Salmonella marcescens, as well as fungi (Aspergillus flavus) and yeasts (Candida albicans). Increased REO to 0.7% accelerated (p < 0.05) the development of lactic acid bacteria (LAB) in SLY (8.3 log cfu/g) and delayed yeast growth up to 12 days. Molds and coliforms were also not found in the SLY samples with REO. In comparison to control samples, sensory results showed that the addition of REO improves the overall acceptance of SLY (p < 0.05). In conclusion, the current study found that REO could be used as a natural preservative during the production of SLY to extend shelf-life and promote LAB development.

Antagonistic potentiality of six wheat rhizosphere fungi against leaf blight pathogen Bipolaris sorokiniana (Sacc.) Shoemaker

Six wheat rhizosphere fungi (Aspergillus flavus, A. fumigatus, A. niger, Penicillium sp., Trichoderma harzianum and T. viride) were evaluated for their antagonistic potentiality towards sixteen isolates of Bipolaris sorokiniana (Sacc.) Shoemaker under different cultural groups. Colony interaction using duel culture technique, inhibition owing to volatile and non-volatile substances in different concentrations were performed. Among them Trichoderma harzianum showed the best performance (colony interaction 61.69-79.02%, volatile substances 44.14-61.34% and non-volatile culture filtrate 47.28-68.14% at 20% concentration) to control Bipolaris sorokiniana followed by Trichoderma viride, Aspergillus niger, Aspergillus flavus, A. fumigatus and Penicillium sp.. Bioresearch Commu. 8(2): 1124-1131, 2022 (July)

Characterization of Chitinolytic and Antifungal Activities in Marine-Derived Trichoderma bissettii Strains

Trichoderma fungi have been intensively studied for mycoparasitism, and the latter is closely related to their cell-wall degrading enzymes including chitinase. Here, we studied marine-derived Trichoderma spp., isolated from distinct sources and locations, for chitinolytic and antifungal activity. Based on morphological and phylogenetic analyses, two strains designated GJ-Sp1 and TOP-Co8 (isolated from a marine sponge and a marine alga, respectively) were identified as Trichoderma bissettii. This species has recently been identified as a closely related species to Trichoderma longibrachiatum. The extracellular crude enzymes of GJ-Sp1 and TOP-Co8 showed activities of chitobiosidase and β-N-acetylglucosaminidase (exochitinase) and chitotriosidase (endochitinase). The optimum chitinolytic activity of the crude enzymes was observed at 50 °C, pH 5.0, 0–0.5% NaCl concentrations, and the activities were stable at temperatures ranging from 10 to 40 °C for 2 h. Moreover, the crude enzymes showed inhibitory activity against hyphal growth of two filamentous fungi Aspergillus flavus and Aspergillus niger. To the best of our knowledge, this is the first report of the chitinolytic and antifungal activity of T. bissettii.

Effect of Aspergillus flavus on Seed Germination and Seedlings Growth of Barley and Some of Associated Weeds

The research was conducted during the 2021 growing season which included a series of experiments to investigate the effect the fungus Aspergillus flavus presence on germination and growth of barley and some barley weeds including annual ryegrass Lolium rigidum, darnel Lolium temulentum and yellow sweet clover Melilotus officinalis. Results of isolation and identification of fungi associated with seedlings roots of barley and the weeds showed that A. flavus was the most prevalent fungus associated with roots and surrounding soil recording the highest frequency among all the found fungi. In plastic pots, Aspergillus flavus was added to the potting soil and tested for its the effect on seed germination and seedlings growth of barley and weeds under study. The results showed after 20 days of planting that the fungus led to an increase in the percentage of germination and fresh weight and lengths of barley seedlings while the presence of the fungus decreased germination and seedlings growth of studied weeds with the highest negative impact on the darnel. Incubation at different temperatures were tested for their effects on A. flavus growth, and results showed that the fungus grows higher when incubated at relatively high temperatures (25-35°C), while the lowest growth was at 15 °C and the fungus did not grow at 10 °C.