Prevalence Of Fungi Research Articles

Spatiotemporal analysis of meteorological drivers of major foliar fungal diseases in rubber budwood gardens in Cote D'Ivoire

Latex production in Côte d'Ivoire is significantly influenced by meteorological conditions and various diseases, particularly foliar fungal diseases affecting Hevea brasiliensis, which can cause yield losses of up to 100%. This study aims to identify the climatic factors driving the severity of these diseases across different ecological zones. Surveys were conducted in budwood gardens (JBG) across six agroecological zones, with meteorological data collected on-site. The analysis identified Helminthosporium heveae, Colletotrichum gloeosporioides, and Corynespora cassiicola as the most prevalent fungi, exhibiting high incidence and severity in key production areas such as Tabou and Nouamou. Multiple regression analyses revealed that rainfall and relative humidity (correlation coefficients ranging from 0.4 to 0.55, p 0.0001) and leaf wetness duration (correlation coefficient 0.7, p 0.0001) are critical predictors of disease severity. Specifically, each additional unit of leaf wetness increased infection severity by 0.642 for H. heveae, 0.435 for C. gloeosporioides, and 0.832 for C. cassiicola. These findings underscore the importance of meteorological factors in disease development and could support the establishment of early warning systems to manage foliar fungal diseases of H. brasiliensis in Côte d'Ivoire.

Effect of Salicylic Acid in Inhibiting Fungal Contamination in in vitro Cultures of Date Palm (Phoenix dactylifera L.) and Enhancing Embryogenesis and Plantlet Development

Abstract In this study, we evaluated the role of salicylic acid in diminishing fungal contamination in in vitro cultures of date palm and the effect of salicylic acid on the regeneration of somatic embryos from callus formed on shoot tips. The most prevalent fungi were Alternaria alternata (37%), Fusarium solani (25%), Aspergillus fumigatus (18%), and Penicillium expansum (6%). Salicylic acid limited and at higher concentrations retarded mycelial growth using potato dextrose agar. Salicylic acid at concentrations of 1.5 and 2.0 mM added to MS medium with 2iP and NAA significantly increased the embryogenesis rate of calli explants to 64.9% and 56.7%, respectively, compared with the control (12.3%). Salicylic acid also increased plantlet development from embryos by about 27% compared with the control. Salicylic acid caused better shoot and root growth and increased chlorophyll content. The results showed that the addition of salicylic acid at 1.5 mM to the MS medium resulted in a significant increase in the concentrations of IAA and ABA, as well as a decrease in the concentration of IBA in leaves.

Eukaryotic composition across seasons and social groups in the gut microbiota of wild baboons.

Animals coexist with complex microbiota, including bacteria, viruses, and eukaryotes (e.g., fungi, protists, and helminths). While the composition of bacterial and viral components of animal microbiota are increasingly well understood, eukaryotic composition remains neglected. Here we characterized eukaryotic diversity in the microbiomes in wild baboons and tested the degree to which eukaryotic community composition was predicted by host social group membership, sex, age, and season of sample collection. We analyzed a total of 75 fecal samples collected between 2012 and 2014 from 73 wild baboons in the Amboseli ecosystem in Kenya. DNA from these samples was subjected to shotgun metagenomic sequencing, revealing members of the kingdoms Protista, Chromista, and Fungi in 90.7%, 46.7%, and 20.3% of samples, respectively. Social group membership explained 11.2% of the global diversity in gut eukaryotic species composition, but we did not detect statistically significant effect of season, host age, and host sex. Across samples, the most prevalent protists were Entamoeba coli (74.66% of samples), Enteromonas hominis (53.33% of samples), and Blastocystis subtype 3 (38.66% of samples), while the most prevalent fungi included Pichia manshurica (14.66% of samples), and Ogataea naganishii (6.66% of samples). Protista, Chromista, and Fungi are common members of the gut microbiome of wild baboons. More work on eukaryotic members of primate gut microbiota is essential for primate health monitoring and management strategies.

Entomopathogenic Fungi as Mortality Agents in Insect Populations: A Review.

Natural enemies play a key role in population dynamics of insects and exert significant selective pressures on various traits of these animals. Although there is a wealth of empirical and theoretical research on predators and parasitoids, the ecological role of pathogens (other than viruses) remains less understood. Entomopathogenic fungi (EPF), encompassing over 1000 known species from 11 phyla, have primarily been studied in the context of biocontrol in agroecosystems, while their role in natural ecosystems is poorly known. In this paper, we synthesize case studies reporting the prevalence of EPF infections in field populations of insects. We examine differences in this variable among major host taxa and those of the pathogens. From 79 case studies that met our selection criteria, we retrieved data on 122 species of fungi infecting 104 insect species. The meta-analytic median prevalence of fungal infections was 8.2%; even if likely inflated by publication bias, this suggests that EPF-induced mortality levels are lower than those attributable to predators and parasitoids. We found no substantial differences in fungal prevalence among major insect taxa and only a moderate difference among fungal orders, with Neozygitales showing the highest prevalence and Eurotiales the lowest. Our analysis revealed no significant differences in overall EPF prevalence between tropical and temperate studies, although different fungal taxa showed different geographical patterns. In temperate areas, there is some evidence of increasing infection prevalence toward the end of the growing season. Although quantitative data on the effect of EPF on insect populations are still scarce, evidence is consistent with the emerging generalization that insect populations commonly harbor species-rich assemblages of pathogenic fungi, but infections rarely reach epidemic levels. Further studies on multi-species assemblages of EPF associated with natural insect populations are needed to better understand the ecological role of fungal infections.

Fusarium spp. in Metalworking Fluid Systems: Companions Forever.

Water-miscible metalworking fluids (MWFs) are utilized in a variety of metal removal and forming operations. For end-use, formulation concentrates are diluted in water, creating conditions conducive to microbial growth and metabolism, possibly compromising the fluid's integrity and mechanically obstructing filters or piping systems. Metalworking machines offer additional habitats on surfaces that are in permanent or temporary contact with MWFs. For that reason, biocides have been incorporated into concentrates for years, but legal constraints will restrain their use in the future. While bacterial contamination of MWFs is well documented, fungal contamination is often overseen and infrequently reported in the literature. In this study, we report fungal prevalence in in-use MWFs sampled worldwide over 10 years, and we are convinced that the presence of fungi is the norm rather than the exception. In addition, we evaluated the inhibitory effect of fungicides on fungal growth, sporulation and spore viability using traditional culture-dependent methods and flow cytometry. In essence, we show that the effectiveness of these fungicides is limited and dependent on the chemical construction of the fluid. We think that the ecology created by water-diluted MWFs is of higher importance than the anti-fungal activity of single components.

Unveiling the Substrate-Dependent Dynamics of Mycotoxin Production in Fusarium verticillioides Using an OSMAC-Metabolomics Approach.

Fusarium verticillioides is a prevalent plant pathogenic fungus known to produce harmful mycotoxins, including fumonisins and emerging toxins. This study aimed to investigate the influence of substrate on the temporal patterns of mycotoxin biosynthesis by F. verticillioides, employing a combined OSMAC (One Strain-Many Compounds) strategy and metabolomics approach. The fungus was cultured under various media conditions, and samples were collected over time. LC-MS/MS analyses and a dereplicative workflow were used to profile the secondary metabolite production, focusing on mycotoxins. The results demonstrated that modifying the culture conditions led to significant variations in fungal growth and the nature and relative concentrations of mycotoxins produced. Corn meal agar (CMA) medium was favorable for fumonisins A1 and B1, while malt extract agar (MEA) favored fumonisins A2 and B2. The study also identified the production of other mycotoxins related compounds as fusarins, bikaverin derivatives and fumonisins analogs, under different growth conditions. This study highlights the potential of combining OSMAC and metabolomics to unravel the substrate-dependent and time-dependent variations in mycotoxin biosynthesis by F. verticillioides. The insights gained provide a better understanding of the ecophysiology of this fungus and the occurrence of its mycotoxins, which can inform targeted mitigation strategies to ensure food and feed safety.

Candida tropicalis-derived vitamin B3 exerts protective effects against intestinal inflammation by promoting IL-17A/IL-22-dependent epithelial barrier function

ABSTRACT Candida tropicalis-a prevalent gut commensal fungus in healthy individuals – contributes to intestinal health and disease. However, how commensal C. tropicalis influences intestinal homeostasis and barrier function is poorly understood. Here, we demonstrated that the reference strain of C. tropicalis (MYA-3404) ameliorated intestinal inflammation in murine models of chemically induced colitis and bacterial infection. Intestinal colonization of C. tropicalis robustly upregulated the expression of IL-17A and IL-22 to increase barrier function and promote proliferation of intestinal epithelial cells in the mouse colon. Metabolomics analysis of fecal samples from mice colonized with C. tropicalis revealed alterations in vitamin B3 metabolism, promoting conversion of nicotinamide to nicotinic acid. Although nicotinamide worsened colitis, treatment with nicotinic acid alleviated disease symptoms and enhanced epithelial proliferation and Th17 cell differentiation. Oral gavage of C. tropicalis mitigated nicotinamide-induced intestinal dysfunction in experimental colitis. Blockade of nicotinic acid production with nicotinamidase inhibitors lowered the protective effects against colitis in mice treated with C. tropicalis. Notably, a clinical C. tropicalis strain isolated from patients with candidemia lacked the protective effects against murine colitis observed with the reference strain. Together, our results highlight a novel role for C. tropicalis in resolving intestinal inflammation through the modulation of vitamin B3 metabolism.

Analysis of microbiomes and mycotoxins revealing the importance in the standardized storage of Aesculus wilsonii Rehd fruit

Aesculus wilsonii Rehd, a medicinal food homology plant, whose fruit are used to treat diseases such as edema and exudation of soft tissue. Nonetheless, the presence of microbial and mycotoxin contaminants in A. wilsonii fruit is still unclear. In this study, high-throughput sequencing and liquid chromatograph tandem-mass spectrometry were conducted to determine the diversity of fungal microbiome and mycotoxin contents in moldy A. wilsonii fruit. The prevalent fungi in A. wilsonii fruit included Fusarium, Colletotrichum, Dictyostelium, and Aspergillus. Furthermore, mycotoxin tests showed that all samples tested positive for ochratoxin A, with deoxynivalenol detected in 72.4 % of samples, zearalenone in 24.1 %, and T-2 toxin in 62.1 %, revealing these mycotoxins constituted the primary contaminants. Moreover, to monitor the mycotoxin-producing fungi, multiplex ligation-dependent probe amplification (MLPA) targeting key genes in toxin biosynthetic pathway of Fusarium and Aspergillus was established. and it can detect fungi with DNA content less than 20 ng. In conclusion, this study reported the microbiome diversity and the prevalence of fungi contamination in A. wilsonii fruit, while also established a rapid method for detecting toxigenic fungi. This work focused on analyzing and detecting microbiomes and mycotoxins in A. wilsonii fruit, providing a reference for the study of potentially harmful microorganisms in the storage of medicinal products.

Isolation, Characterization and Molecular Identification of Multidrug Resistance from Candida Species from Various Clinical Samples.

Background and Purpose: The most prevalent fungus pathogens in humans are said to be Candida species. Candida pathogens have become more common in the last several years. But in the absence of any risk factors, these infections are uncommon. To that end, the current study set out to identify the species of Candida responsible for various clinical samples and establish the risk factors for candiduria. Materials and Methods: The 100 samples from patients who were suspected of having an aging, diabetes, prolonged hospital stays, organ transplantation, recurring bacterial infections, antibiotic use and catheter use were used in the current investigation. Of them, 100 instances involved candidiasis out of which 20 are MDR. Using the germ tube test, colony staining on CHROMagar medium, intracellular beta-glucosidase enzyme activity, and glucose absorption pattern, several species of Candida were identified. Afterwards, internal transcribed spacer region DNA sequencing verified the colonies with the same morphology. Results: Based on the findings, Candida albicans, C. glabrata, C. tropicalis, and C. krusei were identified as 40, 32, 18, and 10% of the isolates, respectively. Diabetes, bacterial infections, and urinary tract infections were the most common predisposing factors (23%); however, it was proven in all patients that one or more other predisposing variables existed. Patients with these serious infections can only be treated with a restricted number of antifungal agents from a small number of drug classes. Resistance can be intrinsic or acquired; as a result, acquired resistance either develops in response to antifungal selection pressure in the particular patient or, less frequently, results from the horizontal transmission of resistant strains between patients. Multidrug resistance is 20%, but more and more reports of it have been observed in several Candida species, most notably C. glabrata and more recently C. auris. The factors that contribute to multidrug resistance include overall antifungal use (fluconazole and amphotericin B), subtherapeutic drug levels at infection/colonization sites, drug sequestration in the biofilm matrix, and, in the event of outbreaks, suboptimal infection control. Conclusion: The most common fungal species, according to the results, was C. albicans. Furthermore, bacterial infections were more common. We go over the molecular causes of resistance, treatment and preventative methods.

Investigation of eye flora in cats infected with Herpesvirus and Calicivirus.

The ocular surface is perpetually exposed to the external environment, rendering it susceptible to microbial contamination. The ocular surface microbiota consists of non-pathogenic microorganisms that inhabit the conjunctiva and cornea. This study's objective was to extensively review the prevalence of bacterial and fungal organisms in the conjunctiva of healthy and diseased cats. (Herpes- and Calici-infected groups). The current study was performed on 240 cats that had visited veterinary health centers (Tehran, Iran) for examination. Sterile swabs from each cat's eyes were investigated for microbiological assessment. After sample collection, viral pathogens (Herpes and Calici viruses) were isolated and identified using the PCR method. The ages of the investigated group were 3.76, 3.93, and 4.15 months. The highest frequency of bacteria in the normal, Herpes-infected/Calici-infected, and Herpes/Calici-infected groups were associated with Staphylococcus intermedius and Streptococcus agalactiae, Staphylococcus epidermidis, and Staphylococcus intermedius, respectively. In addition, it was found that the high prevalence of fungal microorganisms in the isolated samples was related to yeasts, Aspergillus (Aspergillus fumigatus, Aspergillus niger), and Penicillium species. Bacterial prevalence was significantly higher in all groups than the prevalence of fungi in the eyes of cats. The statistical comparison between the study groups regarding microbial and fungal frequency showed that significant differences were found between them, such that the frequency was higher in all disease groups, against the control group. In addition, a significant relation was observed between the Herpes-infected and Calici-infected groups regarding microbial and fungal prevalence.

Transcriptomic Insights into the Physiological Aspects of the Saprotrophic Fungus Penicillium citrinum During the Spoilage of Tobacco Leaves

Penicillium citrinum is one of the most prevalent tobacco spoilage fungi. However, the mechanisms underlying fungal growth on tobacco leaves remain largely unknown. In this study, transcriptomic analyses were performed to reveal the genome-wide expression profiles of P. citrinum growing on tobacco leaves. First, a comparative analysis was conducted between two sets of transcriptomic data from P. citrinum growing on chemically defined media and tobacco leaves. Enrichment analyses showed that differentially regulated genes were mainly associated with carbohydrate degradation (e.g., cellulose, pectin, and xylan) and the catabolism of fatty acids and aromatic compounds. Comparative transcriptomic analyses between different time points indicated that the fungal transcriptome varied dynamically during the spoilage process, and the enriched terms were associated with small-molecule degradation and fungal development. Enrichment analyses indicated that more up-regulated genes appeared in all enriched Gene Ontology terms. Notably, more organelles significantly contributed to further fungal growth on tobacco leaves. In conclusion, P. citrinum activates a comprehensive transcriptome that changes dynamically when causing tobacco mildew.

Air quality assessment of poultry and swine houses in Chonburi Province

ABSTRACT The increased consumption of animal products has led to a proliferation of animal husbandry operations, particularly in agricultural countries. Animal husbandry facilities or livestock farming directly impact the physical, chemical, and biological aspects of the environment, giving rise to various issues such as odors, contamination of water and air sources with pathogens, and potential contamination of meat products originating from these facilities. This research aims to assess the impacts on the physical (temperature, relative humidity and air velocity), chemical (carbon dioxide, total volatile organic compounds and particulate matter), and biological air quality assessment (amount and type of bioaerosols) aspects resulting from pig and poultry farming. The findings will serve as valuable data for managing and addressing these aforementioned issues. It was found that both in poultry and swine houses generated total suspended particles (TSP) and PM10 (Particulate Matter with a diameter of 10 µm or less). Analysis of poultry house exhaust revealed elevated concentrations of TSP and PM10 exceeding established health benchmarks. Chickens tend to produce a higher concentration of VOCs (2.07 ± 0.57 ppm) compared to swine (0.82 ± 0.53 ppm). Staphylococcus epidermidis was predominant bacteria in both swine and poultry houses while Cladosporium sp was the most prevalent fungi in poultry houses. These results in this study are very useful for developing targeted mitigation strategies, products, devices to address specific pollutants produced by each type of livestock, reducing overall environmental impact and improving air quality within and around animal husbandry facilities. Implications: This research highlights how the growing demand for meat is affecting the environment, especially in farming areas. By studying the effects of pig and poultry farming on things like air and water quality, the study shows the challenges these farms pose, like bad smells and pollution. They found that both types of farms release a lot of tiny particles and smelly chemicals into the air, but there are differences between them. Understanding these findings can help us develop ways to reduce the pollution from these farms and make the air cleaner for everyone.

Scope, Distribution, and Cause of the Peanut Kernel Shrivel (PKS) Syndrome: An Emerging Threat to Australia’s Peanut Industry

The cause of peanut kernel shrivel (PKS) syndrome, affecting peanut crops in Australia’s growing regions, is currently unknown. It is estimated that PKS is costing the peanut industry more than AUD 5 M p.a. and is a potential threat to the industry. Previous investigations have ruled out all abiotic factors and most biotic factors as the cause of PKS. This research aimed at investigating the scope, distribution, and cause of the PKS syndrome. The survey showed PKS symptoms to be present in peanut crops in all the growing regions surveyed. Based on our study of culturable microorganisms, there appears to be no clear-cut involvement of plant pathogenic bacteria and fungi; however, Fusarium spp. were revealed as the most prevalent fungi in affected plants. Moreover, the soil metagenomics study revealed Fusarium spp. as the most abundant fungal communities in the soil microbial profile, and they could contribute to the PKS syndrome. The consistent presence observed of the identified Fusarium oxysporum in PKS-affected samples could indicate a role for this pathogen in the syndrome, especially in conjunction with abiotic stressors. The pathogenicity testing of F. oxysporum resulted in very mild PKS symptoms. A separate report suggesting the involvement of phytoplasma in the PKS syndrome raises the possibility of an interplay of biotic factors in the development of this disease. Further investigation is warranted to determine the true cause or causes of this disease.

Activity and mechanism of action of antimicrobial peptide ACPs against Candida albicans

AimsCandida albicans is the most prevalent pathogenic fungus, exhibiting escalating multidrug resistance (MDR). Antimicrobial peptides (AMPs) represent promising candidates for addressing this issue. In this research, five antimicrobial peptides, ACP1 to ACP5 which named ACPs were studied as alternative fungicidal molecules. Main methodsCD assay was used to analyze the 2D structures, Absorbance method was used to test the antimicrobial activity, haemolytic activity, time-kill kinetics, biofilm inhibition and reduction activity, resistance induction activity and assessment against fluconazole-resistant C. albicans. SEM, TEM, CLSM, flow cytometer and FM were carried out to provide insight into the mechanisms of anti-Candida action. Key findingsACPs possessed an α-helical structure and strong anti-Candida activities, with minimum inhibitory concentrations (MICs) from 3.9 to 15.6 μg/mL. In addition, ACPs did not produce hemolysis at concentrations lower than 10 or 62 × MIC, indicating their low cytotoxicity. Fungicidal kinetics showed that they completely killed C. albicans within 8 h at 2 to 4 × MIC. Notably, ACPs were highly fungicidal against fluconazole-resistant C. albicans and showed low resistance. In addition, they were effective in inhibiting mycelium and biofilm formation. Fluorescence microscopy revealed that while fluconazole had minimal to no inhibitory effect on biofilm-forming cells, ACPs induced apoptosis in all of them. The research on mechanism of action revealed that ACPs disrupted the cell membranes, with ROS increasing and cellular mitochondrial membrane potential decreasing. SignificanceACPs could be promising candidates for combating fluconazole-resistant C. albicans infections.

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An incubation study investigated the decomposition patterns, microbial activities, soil aggregates distribution, and soil organic carbon (SOC) contents, using four crop residues; wheat (Triticum aestivum L.), rice (Oryza sativa L.), cotton (Gossypium hirsutum L.), and maize (Zea mays L.), at low and high rates (10 and 20 g kg–1). An average increase of about 35% in cumulative C-CO2 emissions and 26% in soil microbial biomass carbon (MBC) was observed at high residue rates as compared to low rates. A positive and strong correlation (0.96) was found between C-CO2 emissions and MBC, and the effect of residue quality on decomposition was found to be less at high rates. The relative reduction in C-CO2 emissions by adding rice residues may be due to their high silica content. Differences in extracellular enzyme activities (EEA) with different residues indicated the effect of residue quality on microbial activities. Cotton residues increased β-glucosidase and chitinase activities by 41 and 38%, respectively, at high rates than at low rates. High maize residues also markedly increased chitinase activity by 41%, implying higher N cycling and fungal prevalence. Acid phosphatase activity was found to increase by about 25 to 32% with high rice and wheat residues, respectively. Higher EEA at high residues input likely reflected the microbial nutritional limitations. Crop residues raised SOC content from 0.7 under control to 1.0% at low residues input but not at high input. Increased macro-aggregates fraction at high residues input may be attributed to higher microbial activities. In summary, high residues input can minimize residue biochemical quality’s effect on decomposition, with no further increase in SOC content. While a positive effect on the soil MBC, but not on the SOC content, was observed at high residue input, suggesting moderation in the additions of organic amendments is key for SOC buildup. Crop residues, added at 10 g kg–1, may help maintain a positive SOC balance in the arid agroecosystems by moderating higher microbial activities and soil respiration.

Fungi associated with the Asian citrus psyllid, Diaphorina citri Kuwayama, in northeastern Mexico

ABSTRACT Diaphorina citri Kuwayama (Asian citrus psyllid, ACP) is a devastating pest due to transmission of Liberibacter spp. to citrus plants. We identified presumed entomopathogenic fungi (EF) naturally associated with field-collected adult ACP, both killed (mycosed) and alive, at 14 field sites in the Gulf Coastal Plain of NE Mexico. On dead ACP, five species of EF (Hypocreales) were observed: Hirsutella citriformis Speare (Ophiocordycipitaceae), Cordyceps javanica (Frieder. & Bally) Kepler, Shrestha & Spatafora, Beauveria cf. bassiana (Bals.) Vuill., and Akanthomyces cf. lecanii (Cordycipitaceae); also, Niveomyces J.P.M. Araújo & C. de Bekker (Cordycipitaceae), a hyperparasite of Ophiocordycipitaceae, in this case H. citriformis. The most prevalent fungi on field ACP were H. citriformis and C. javanica, on dead and on live, incubated insects, respectively. In laboratory bioassays, C. javanica and H. citriformis conidia from cultures killed >60% of ACP adults. H. citriformis, C. javanica, and A. lecanii killed >60% nymphs. Niveomyces was observed only growing on H. citriformis fructifications on field-killed ACP; it was absent from live incubated insects, indicating Niveomyces is a mycoparasite on H. citriformis. Niveomyces cultures (ARSEF 10230) on agar grew as a Pleurodesmospora synanamorph; its LSU rRNA region D1–D2 sequences (Genbank OM780101) were 99.81% identical to Niveomyces sequences. Conidia from Niveomyces cultures were entomopathogenic on ACP nymphs and adults. These are the first reports of Niveomyces associated with H. citriformis; of the in vitro dimorphic growth (synanamorphs) Niveomyces/Pleurodesmospora; and of experimental verification of entomopathogenicity of Niveomyces. Understanding the interactions of these fungi will support sustainable ACP management.

Detection and quantification of aflatoxins in farmers’ stored rice seeds in some selected areas of Bangladesh

Detection and quantification of total aflatoxins in farmers’ stored rice seeds at different storage intervals in two cropping seasons (Boro 2017–2018: cv. BRRI Dhan28 and cv. BRRI Dhan29 and Aman 2017: cv. BR 11 and cv. BRRI dhan49) was focused in this study. Aflatoxin was quantified in two cropping seasons (Boro and Aman). Blotter incubation test was conducted for fungal prevalence assessment and a one-step lateral flow immune-chromatographic assay was used to quantify the aflatoxins. Seed moisture content ranged from 11.59 to 13.32% and aflatoxin concentrations ranged from 2.41 to 11.12 ppb. Variation in fungal contamination in stored seeds was correlated with seed moisture content. The moisture content in stored rice seeds increased with storage time and was positively correlated with fungal infestation and toxin production. The findings of this study indicate that moisture content of stored rice seeds and storage duration are determining factors for aflatoxin contamination.

An improved expression and purification protocol enables the structural characterization of Mnt1, an antifungal target from Candida albicans

BackgroundCandida albicans is one of the most prevalent fungi causing infections in the world. Mnt1 is a mannosyltransferase that participates in both the cell wall biogenesis and biofilm growth of C. albicans. While the cell wall performs crucial functions in pathogenesis, biofilm growth is correlated with sequestration of drugs by the extracellular matrix. Therefore, antifungals targeting CaMnt1 can compromise fungal development and potentially also render Candida susceptible to drug therapy. Despite its importance, CaMnt1 has not yet been purified to high standards and its biophysical properties are lacking.ResultsWe describe a new protocol to obtain high yield of recombinant CaMnt1 in Komagataella phaffii using methanol induction. The purified protein’s identity was confirmed by MALDI-TOF/TOF mass spectroscopy. The Far-UV circular dichroism (CD) spectra demonstrate that the secondary structure of CaMnt1 is compatible with a protein formed by α-helices and β-sheets at pH 7.0. The fluorescence spectroscopy results show that the tertiary structure of CaMnt1 is pH-dependent, with a greater intensity of fluorescence emission at pH 7.0. Using our molecular modeling protocol, we depict for the first time the ternary complex of CaMnt1 bound to its two substrates, which has enabled the identification of residues involved in substrate specificity and catalytic reaction. Our results corroborate the hypothesis that Tyr209 stabilizes the formation of an oxocarbenium ion-like intermediate during nucleophilic attack of the acceptor sugar, opposing the double displacement mechanism proposed by other reports.ConclusionsThe methodology presented here can substantially improve the yield of recombinant CaMnt1 expressed in flask-grown yeasts. In addition, the structural characterization of the fungal mannosyltransferase presents novelties that can be exploited for new antifungal drug’s development.

Resistance to Azole Drugs by Fungal Species Isolated from Date Palm Samples within Lafia Metropolis, Nigeria

Fungal species infecting fruits are developing resistance to some antifungals. The study determined prevalent fungi in date palm fruits and their resistance to azole antifungals. Dried date palm fruit samples were collected from Modern Market, Old Market, Alhamis Market, Koro Market and Tomato Market in Lafia Metropolis, Nigeria and fungi isolated from them. Antifungal susceptibility test as a zone of inhibition of fungal mycelial growth were recorded for terbinafine, clotrimazole, nystatin, metronidazole and fluconazole. Dates from the old market had the highest contamination with 6.0×103 ± 4.2 cfu/g, while samples from Koro market with 2.5×103 ± 1.7 cfu/g were the least contaminated. A total of 84 fungi were isolated, Aspergillus niger was the most predominant species while Aspergillus versicolor was the least predominant. Terbinafine was the most effective azole against the fungal species isolated with a zone of inhibition of 43 mm in diameter, while fluconazole was the least effective with the zone of inhibition of 0 mm. The organism most susceptible to the antifungal drugs was Aspergillus niger, while Penicillium chrysogenum was the most resistant. Results of this study indicated that, date palm fruits around the Lafia markets were more susceptible to Aspergillus niger contamination than other fungal species, and Terbinafine was the best azole antifungal drug. The study recommends that further research should be carried out with respect to the resistance developed against azoles by the fungal species.

Biosurfactant production potentials of microorganisms isolated from atmosphere of five petroleum stations at Tanke, Ilorin, Kwara State, Nigeria

Biosurfactants aid in bioremediation by improving the bioavailability of hydrocarbon contaminants. The objective of this work was to isolate, enumerate and identify bacteria and fungi for their biosurfactant production potential in the atmosphere of five petroleum stations at Tanke, Ilorin, Kwara State, Nigeria using appropriate, standard microbiological methods (haemolysis test, emulsification index test, drop collapse test and oil displacement test). Fourteen bacteria and ten fungi were isolated in this study. The bacterial isolates belong to the genus Bacillus, Corynebacterium, Micrococcus, Staphylococcus, Listeria, Clostridium. The fungal isolates are of the genus Neurospora, Curvularia, Aspergillus, Fusarium, Rhizopus, Cladosporium, Colletotrichum, Sclerotinia. The mean number of bacteria counted during the sampling ranged from 3.48±1.15*102 CFU to 4.82 ±1.69*102 CFU, with petrol station 4 having the highest bacteria count (2.41*102 CFU) and petrol station 3 having the lowest bacteria count (1.74*102 CFU). The mean fungal count ranged from 7±3.7 CFU to 8.6±4.7 *102 CFU, with petrol station 4 having the highest fungal count (4.3 *10 CFU) and petrol station 3 having the lowest fungal count (3.4*10 CFU). Bacillus species showed promise of biosurfactant production after screening. Aspergillus fumigatus was the most prevalent fungus isolated (24%) while Staphylococcus epidermidis was the most prevalent bacterium isolated (11%). Some of these organisms are known opportunistic pathogens therefore, improved ventilation and sanitation of the petrol stations should be carried out to reduce the microbial load in the air. Also, bacteria that produce biosurfactant can be isolated from air of gas stations.