Aspergillus Tubingensis Research Articles

Biocontrol Ability of Strain Bacillus amyloliquefaciens SQ-2 against Table Grape Rot Caused by Aspergillus tubingensis.

Bacillus amyloliquefaciens strain SQ-2, isolated from a cured product, has been demonstrated to exhibit a highly efficacious performance against phytopathogens, including Stemphylium solani, Fusarium moniliforme, Fusarium graminearum, and Aspergillus tubingensis. In particular, with regard to A. tubingensis, which causes summer bunch rot, SQ-2 has been observed to suppress the mycelial growth of all tested grape cultivars by over 40%. Especially on Kyoho grapes, it has the highest inhibition rate of 53%. Scanning electron microscopy (SEM) confirms that SQ-2 is an effective agent for suppressing the mycelia proliferation, differentiation, and spore formation of A. tubingensis. Furthermore, an LC/MS analysis revealed that SQ-2 produces two principal lipopeptides, namely, bacillibactin and surfactin, in addition to a polyketide, bacillaene. Further analysis through gas chromatography-mass spectrometry (GC/MS) identified 41 distinct volatile organic compounds secreted by SQ-2. Transcriptomic analysis indicated that exposure to the metabolite of SQ-2 induced substantial gene expression alterations in A. tubingensis. These data suggest that B. amyloliquefaciens strain SQ-2 exhibits promising crop protection potential of inhibiting plant pathogens through the secretion of bacillibactin, surfactin, bacillaene, and VOCs.

First Report of Aspergillus tubingensis Causing Leaf Spot on Pogostemon cablin in China

Patchouli (Pogostemon cablin (Blanco) Benth) is an important medicinal and aromatic plant widely cultivated in China, India, and other Southeast Asian countries. It is renowned for its diverse applications in traditional medicine and its detoxification, antibacterial, anti-inflammatory, and other pharmacological properties (Wu et al. 2016; Fang et al. 2022). In May 2023, a severe leaf spot disease was observed on Pogostemon cablin plants grown in most plantations in Yulin, Guangxi, China (22°26′N; 109°83′E), with over 50% incidence rate. Symptoms began as small, circular, brown spots on leaves, enlarging with yellow halos. Lesions expanded into irregular shapes with necrotic centers. Advanced stages showed extensive yellowing, browning, and leaf senescence. A total of 20 symptomatic plants were sampled from 5 different locations within the detected area, with 4 plants sampled per location. To isolate the pathogen, 20 affected leaves were collected from these plants and preliminarily washed with sterile distilled water (SDW). Five small tissue pieces (5×5 mm) were excised from the lesion edge of each leaf, surface-disinfected with 75% ethanol and 1% NaClO, rinsed thrice with SDW, and placed on potato dextrose agar (PDA) at 28 °C in darkness for 7 days. Out of these, 18 plants (90%) yield fungal isolate with recurrent and similar morphological characteristics. Four representative isolates (X5-1-1, X5-1-3, X5-1-5, and X5-1-7) were selected for further analysis. On PDA, colonies were initially white, gradually turning black on the surface, with light yellow on the reverse side of the plate. Conidia were brown to black, globose, rough-walled, and 2.6 to 5.2 µm in diameter. Conidial heads were brown-black, and conidiophores were smooth and hyaline. Morphological characteristics matched those of Aspergillus sp. (Guo et al. 2017). For molecular identification, the internal transcribed spacer (ITS) region and the β-tubulin (TUB) gene of all four isolates were sequenced (Lim et al. 2019). All four isolates (X5-1-1, X5-1-3, X5-1-5, and X5-1-7) showed consistent morphological characteristics and 100% identical ITS and TUB sequences. Representative sequences from isolate X5-1-5 were submitted to GenBank (ITS: PP789632; TUB: PP798205). The obtained ITS and TUB sequences showed 99% similarity to Aspergillus tubingensis (ITS: OP737633; TUB: MG991377). Based on morphological and molecular analyses, the fungus was identified as A. tubingensis (Palmer et al. 2019). For pathogenicity tests, a spore suspension (1 × 10^6 conidia/mL) was prepared from 7-day-old cultures of A. tubingensis grown on PDA. The suspension was sprayed onto leaves of 10 healthy Pogostemon cablin plants until runoff. Control plants were sprayed with SDW. All plants were kept in a controlled greenhouse (12/12h light/dark, 25 ± 2 °C, 90% humidity). After 7 d, symptoms identical to those observed in the field developed on all pathogen inoculated plants, while control plants remained asymptomatic. The fungus was successfully re-isolated from infected leaves in three successive trials, fulfilling Koch's postulates. Notably, A. tubingensis has previously been reported causing field diseases on strawberry in California, Jatropha curcas and Helleborus species in China (Palmer et al. 2019; Guo et al. 2017, Liaquat et al. 2019), and vine canker on table grape in Italy (Vitale et al. 2012). To our knowledge, this is the first report of A. tubingensis causing leaf spot on Pogostemon cablin in China. This finding provides a foundation for further investigate into the biology, epidemiology, and management of this disease.

Survey on the occurrence of Aspergillus section Nigri species in grapes cultivated in Umbria (central Italy) and influence of several factors on their distribution

AbstractSecondary bunch rots caused by Aspergillus species belonging to the section Nigri, commonly called black aspergilli, pose a serious threat to grapes yield and quality. Due to their ability to produce ochratoxin A (OTA), they are considered the primary source of contamination of this mycotoxin in grapes. In this study, a three-year survey was realized to assess the occurrence of black aspergilli in grapes harvested in the Umbria region, a very important grapevine cultivation area in central Italy, by fungal isolation and phylogenetic analysis. In addition, the influence of growing season, vineyard location, farming system and grapes growth stages on black aspergilli distribution was examined. Phylogenetic analysis of the 208 obtained isolates showed the presence of three black aspergilli species: Aspergillus tubingensis, Aspergillus welwitschiae and Aspergillus uvarum. Interestingly, A. carbonarius, one of the most important OTA producers, was not detected in the surveyed years. A. tubingensis, whose ability to produce OTA is controversial, was always the most isolated species followed by A. welwistichiae (OTA producer). The species A. uvarum (unable to produce OTA) was detected only in one surveyed year with a low incidence. A. tubingensis was always the species with the highest incidence, regardless of location, and farming system. Growth stage appeared to influence the incidence of the three species, that, in the case of A tubingensis, was lower during setting in comparison to berries pea-size and berries harvest-ripe. Finally, in the setting and berries pea-size stages, a stereomicroscope analysis, showed that flower debris was the substrate from which black aspergilli mainly developed prior to colonizing berries and bunches.

Bioremediation petroleum wastewater and oil-polluted soils by the non-toxigenic indigenous fungi.

Soil and wastewater samples contaminated by petroleum-related industries were collected from various locations in Saudi Arabia, a country known for its vast oil reserves. The samples were analyzed for their physicochemical properties, including the presence of metals, petroleum hydrocarbons, and aromatic compounds. A total of 264 fungal isolates were analyzed and categorized into eight groups of Aspergillus (194 isolates) and four groups of Penicillium (70 isolates). The potential of these fungal groups to grow in oil or its derivatives was investigated. Two isolates, Aspergillus tubingensis FA-KSU5 and A. niger FU-KSU69, were utilized in two remediation experiments-one targeting wastewater and the other focusing on polluted soil. The FA-KSU5 strain demonstrated complete removal of Fe3+, As3+, Cr6+, Zn2+, Mn2+, Cu2+ and Cd2+, with bioremediation efficiency for petroleum hydrocarbons in the wastewater from these sites ranging between 90.80 and 98.58%. Additionally, the FU-KSU69 strain achieved up to 100% reduction of Co2+, Ba2+, B3+, V+, Ni2+, Pb2+ and Hg2+, with removal efficiency ranging from 93.17 to 96.02% for aromatic hydrocarbons after 180min of wastewater treatment. After 21days of soil incubation with Aspergillus tubingensis FA-KSU5, there was a 93.15% to 98.48% reduction in total petroleum hydrocarbons (TPHs) and an 88.11% to 97.31% decrease in polycyclic aromatic hydrocarbons (PAHs). This strain exhibited the highest removal rates for Cd2+ and As3+ followed by Fe3+, Zn2+, Cr6+, Se4+ and Cu2+. Aspergillus niger FU-KSU69 achieved a 90.37% to 94.90% reduction in TPHs and a 95.13% to 98.15% decrease in PAHs, with significant removal of Ni2+, Pb2+ and Hg2+, followed by Co2+, V+, Ba2+ and B3+. The enzymatic activity in the treated soils increased by 1.54- to 3.57-fold compared to the polluted soil. Although the mixture of wastewater and polluted soil exhibited high cytotoxicity against normal human cell lines, following mycoremediation, all treated soils and effluents with the dead fungal biomass showed no toxicity against normal human cell lines at concentrations up to 500 µL/mL, with IC50 values ≥ 1000 µL/mL. SEM and IR analysis revealed morphological and biochemical alterations in the biomass of A. tubingensis FA-KSU5 and A. niger FA-KSU69 when exposed to petroleum effluents. This study successfully introduces non-toxigenic and environmentally friendly fungal strains play a crucial role in the bioremediation of contaminated environments. Both strains serve as low-cost and effective adsorbents for bio-remediating petroleum wastewater and oil-contaminated soil. Heavy metals and hydrocarbons, the primary pollutants, were either completely removed or reduced to permissible levels according to international guidelines using the dead biomass of FA-KSU5 and FA-KSU69 fungi. Consequently, the environments associated with this globally significant industry are rendered biologically safe, particularly for humans, as evidenced by the absence of cytotoxicity in samples treated with A. tubingensis FA-KSU5 and A. niger FA-KSU69 on various human cell types.

Transcriptomic Approach Reveals Contrasting Patterns of Differential Gene Expression during Tannin Biodegredation by Aspergillus tubingensis in Liquid and Solid Cultures

Tannins, one of the most common anti-nutritional factors in feed, can be effectively degraded by various enzymes secreted by Aspergillus tubingensis (A. tubingensis). The cultivation method of fungi significantly impacts gene expression, which influences the production of enzymes and metabolites. In this study, we analyzed the tannin biodegredation efficiency and the transcriptomic responses of A. tubingensis in liquid and solid cultures with tannin added. The observed morphology of A. tubingensis resembled typical fungal hyphae of mycelium submerged and grown in liquid cultures, while mainly spore clusters were observed in solid cultures. Furthermore, the tannin biodegredation efficiency and protein secretion of A. tubingensis in liquid cultures were significantly higher than in solid cultures. Additionally, 54.6% of the 11,248 differentially expressed genes were upregulated in liquid cultures, including AtWU_03490 (encoding ABC multidrug transporter), AtWU_03807 (ribonuclease III), AtWU_10270 (peptidyl-tRNA hydrolase), and AtWU_00075 (arabinogalactan endo-1,4-beta-galactosidase). Functional and gene ontology enrichment analyses indicated upregulation in processes including oxidation reduction, drug metabolism, and monocarboxylic acid metabolism. Overall, this study provides insight into the transcriptomic response to tannin biodegradation by A. tubingensis in different cultures and reveals that liquid cultures induce greater transcriptomic variability compared to solid cultures.

Optimizing bioencapsulation of yeast cells by Aspergillus tubingensis TSIP9 and applications in bioethanol production through repeated-batch fermentation

This study aimed to immobilize yeast cells using filamentous fungi owing to a number of advantages including less chemical usage, spontaneous encapsulation, strong adhesion and biocompatibility. Filamentous fungus, Aspergillus tubingensis TSIP9 could form sphere-shape and packed pellets using either fungal fresh spores or those stored in liquid medium for 6 weeks at 4 °C. The fungus was used to immobilize yeast Saccharomyces cerevisiae FAI via adsorption and co-cultivation methods. Scanning electron microscopy images revealed that the bioencapsulated yeast cells via co-cultivation seemed to be more tightly adhered on fungal mycelia and surrounded by extracellular polymeric substances. The yeast biocapsules also exhibited higher stability and maintained their structural integrity during repeated-batch fermentation while the immobilized yeast cells by adsorption gradually degraded during their repeated uses. The bioethanol production from glucose by yeast biocapsules were in the range of 95–98 g/L with the bioethanol yield of 0.49–0.54 g-ethanol/g-consumed glucose. The yeast biocapsules could produce bioethanol well when using enzymatic hydrolysate of lignocellulosic palm waste, as alternative cheap carbon source, with the comparable bioethanol yield of 0.49 ± 0.17 g-ethanol/g-consumed glucose. The spontaneous and inter-species bioencapsulation show the perspectives as active biocatalysts with high cell retention for repeated uses.

Comparative transcriptomic analysis and volatile compound characterization of Aspergillus tubingensis and Penicillium oxalicum during their infestation of Japonica rice

Volatile organic compounds (VOCs), a byproduct of mold metabolism, have garnered increasing interest because the VOCs can be used to detect food early contamination. So far, the use of VOCs as indicators of rice mildew, specifically caused by Aspergillus tubingensis and Penicillium oxalicum, and the mechanisms of their generation are not well investigated. This study examines the VOCs produced by these molds during paddy storage, utilizing headspace solid-phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC–MS). We further elucidate the mechanisms underlying the formation of these VOCs through a comparative transcriptomic analysis. The VOCs characteristic to A. tubingensis and P. oxalicum, identified with a VIP value > 1 in the partial least squares discriminant analysis (PLS-DA) model, are primarily alkenes. Our transcriptome analysis uncovers key metabolic pathways in both molds, including energy metabolism and pathways related to volatile substance formation, and identifies differentially expressed genes associated with alkane and alcohol formation.

Adsorption of extracellular lipase in a packed-bed reactor: an alternative immobilization approach.

In light of the growing demand for novel biocatalysts and enzyme production methods, this study aimed to evaluate the potential of Aspergillus tubingensis for producing lipase under submerged culture investigating the influence of culture time and inducer treatment. Moreover, this study also investigated conditions for the immobilization of A. tubingensis lipase by physical adsorption on styrene-divinylbenzene beads (Diaion HP-20), for these conditions to be applied to an alternative immobilization system with a packed-bed reactor. Furthermore, A. tubingensis lipase and its immobilized derivative were characterized in terms of their optimal ranges of pH and temperature. A. tubingensis was shown to be a good producer of lipase, obviating the need for inducer addition. The enzyme extract had a hydrolytic activity of 23 U mL-1 and achieved better performance in the pH range of 7.5 to 9.0 and in the temperature range of 20 to 50°C. The proposed immobilization system was effective, yielding an immobilized derivative with enhanced hydrolytic activity (35 U g-1), optimum activity over a broader pH range (5.6 to 8.4), and increased tolerance to high temperatures (40 to 60 ℃). This research represents a first step toward lipase production from A. tubingensis under a submerged culture and the development of an alternative immobilization system with a packed-bed reactor. The proposed system holds promise for saving time and resources in future industrial applications.

Generation of citric acid-hyperproducers independent of methanol effect by high-level expression of cexA encoding citrate exporter in Aspergillus tubingensis.

Methanol reportedly stimulates citric acid (CA) production by Aspergillus niger and A. tubingensis; however, the underlying mechanisms remain unclear. Here, we elucidated the molecular functions of the citrate exporter gene cexA in relation to CA production by Aspergillus tubingensis WU-2223L. Methanol addition to the medium containing glucose as a carbon source markedly increased CA production by strain WU-2223L by 3.38-fold, resulting in a maximum yield of 65.5 g/L, with enhanced cexA expression. Conversely, the cexA-complementing strain with the constitutive expression promoter Ptef1 (strain LhC-1) produced 68.3 or 66.7 g/L of CA when cultivated without or with methanol, respectively. Additionally, strain LhC-2 harboring two copies of the cexA expression cassette produced 80.7 g/L of CA without methanol addition. Overall, we showed that cexA is a target gene for methanol in CA hyperproduction by A. tubingensis WU-2223L. Based on these findings, methanol-independent CA-hyperproducing strains, LhC-1 and LhC-2, were successfully generated.

A comparative study of two α-L-rhamnosidases with high sequence identity

The GH78 α-L-rhamnosidase from Aspergillus tubingensis (AT-Rha) was proved to be a new clade of Aspergillus α-L-rhamnosidases in the previous study. A putative α-L-rhamnosidase from A. kawachii IFO 4308 (AK-Rha) has 92 % identity in amino acid sequence with AT-Rha. In this study, AK-Rha was expressed in P. pastoris and characterized. Similar to AT-rRha, the recombinant AK-Rha (AK-rRha) showed a narrow substrate specificity to naringin. Interestingly, the enzyme activity of AK-rRha was 0.816 U/mg toward naringin, significantly lower than 125.142 U/mg of AT-rRha. Their large differences in catalytic efficiency was mainly due to their differences in kcat values between AK-rRha (0.67 s−1) and AT-rRha (4.89 × 104 s−1). The molecular dynamics simulation exhibited that the overall conformation of AK-Rha was rigid and that of AT-Rha was flexible; the Loop Y-L located above the catalytic domain formed different steric hindrances to naringin, and interacted with the flavonoid matrices at different strengths. The polar solvation energy analysis implied that the glycosidic bond was more easily hydrolysed in AT-Rha. The comparative study verified that the main feature of AK-Rha and AT-Rha represented Aspergillus α-L-rhamnosidase was the narrow substrate specificity toward naringin, and provided an insight of the relationships between their catalytic abilities and structures.

Exploring the nematicidal mechanisms and control efficiencies of oxalic acid producing Aspergillus tubingensis WF01 against root-knot nematodes.

Root-knot nematodes (RKN; Meloidogyne spp.) are among the highly prevalent and significantly detrimental pathogens that cause severe economic and yield losses in crops. Currently, control of RKN primarily relies on the application of chemical nematicides but it has environmental and public health concerns, which open new doors for alternative methods in the form of biological control. In this study, we investigated the nematicidal and attractive activities of an endophytic strain WF01 against Meloidogyne incognita in concentration-dependent experiments. The active nematicidal metabolite was extracted in the WF01 crude extract through the Sephadex column, and its structure was identified by nuclear magnetic resonance and mass spectrometry data. The strain WF01 was identified as Aspergillus tubingensis based on morphological and molecular characteristics. The nematicidal and attractive metabolite of A. tubingensis WF01 was identified as oxalic acid (OA), which showed solid nematicidal activity against M. incognita, having LC50 of 27.48 μg ml-1. The Nsy-1 of AWC and Odr-7 of AWA were the primary neuron genes for Caenorhabditis elegans to detect OA. Under greenhouse, WF01 broth and 200 μg ml-1 OA could effectively suppress the disease caused by M. incognita on tomatoes respectively with control efficiency (CE) of 62.5% and 70.83%, and promote plant growth. In the field, WF01-WP and 8% OA-WP formulations showed moderate CEs of 51.25%-61.47% against RKN in tomato and tobacco. The combined application of WF01 and OA resulted in excellent CEs of 66.83% and 69.34% toward RKN in tomato and tobacco, respectively. Furthermore, the application of WF01 broth or OA significantly suppressed the infection of J2s in tomatoes by upregulating the expression levels of the genes (PAL, C4H, HCT, and F5H) related to lignin synthesis, and strengthened root lignification. Altogether, our results demonstrated that A. tubingensis WF01 exhibited multiple weapons to control RKN mediated by producing OA to lure and kill RKN in a concentration-dependent manner and strengthen root lignification. This fungus could serve as an environmental bio-nematicide for managing the diseases caused by RKN.

Incidence, Characterization and Pathogenicity of Seed-Borne Fungi of Lentil (<em>Lens culinaris</em> L.) in Pakistan

Lentil (Lens culinaris Medik.) is an important protein-rich Rabi pulse crop after chickpea in Pakistan. Its area and production in the country is decreasing drastically due to its susceptibility to various biotic and abiotic stresses. Among biotic-stresses, seed-borne fungi are the most imperative issue and the accurate identification and characterization of target pathogen isolates/races is crucial for the management of plant diseases in lentils. Therefore, the current study was performed to identify the fungi associated with lentil seeds, to confirm their pathogenicity and to assess their incidence. For this purpose, isolation of fungal pathogens was made on potato dextrose agar medium (PDA) from 56 Lens culinaris L. genotypes. These pathogens were characterized using morphological and molecular techniques and their pathogenicity was performed following blotter paper and agar plate method. Seven fungi belonging to five genera were isolated from lentil seeds (Fusarium avenaceum, Alternaria alternata, Aspergillus flavus, Aspergillus niger, Aspergillus tubingensis, Penicillium citrinum and Bipolaris sorokiniana) of different genotypes. Of these seven fungal species, F. avenaceum, A. tubingensis and B. sorokiniana are new records for lentil seeds from Pakistan. Aspergillus flavus was found to occur in high frequency followed by A. niger, F. avenaceum, P. citrinum, A. alternata, A. tubingensis and B. sorokiniana. Under pathogenicity test on blotter paper and on PDA F. avenaceum, A. flavus, A. niger, A. tubingensis were highly pathogenic, while A. alternata, P. citrinum and B. sorokiniana were found to be less pathogenic. The presence of well-known toxigenic fungal pathogens in lentil seeds suggests the possible risk of contamination of the seeds and enhances the possibility of pre- and post-infections of crop. Therefore, the present study will help to devise effective management strategies to reduce contamination in seeds and also to control the further spread of these pathogens to reduce crop losses.

L-Asparaginase producing ability of Aspergillus species isolated from tapioca root soil and optimized ideal growth parameters for L-Asparaginase production

This research was designed to isolate the predominant L-asparaginase-producing fungus from rhizosphere soil of tapioca field and assess the suitable growth conditions required to produce maximum L-asparaginase activity. The Aspergillus tubingensis was identified as a predominant L-asparaginase producing fungal isolate from 15 isolates, and it was characterized by 18S rRNA sequencing. The L-asparaginase-producing activity was confirmed by pink color zone formation around the colonies in modified Czapek Dox agar plate supplemented with 1% L-Asparagine. The optimal growth conditions required for the L-asparaginase production by A. tubingensis were optimized as pH 6.0, temperature 30 °C, glucose as carbon source, 1.5% of L-Asparagine, ammonium sulphate as nitrogen source, rice husk as natural L-Asparagine enriched source, and 8 days of the incubation period. The L-Asparaginase activity from A. tubingensis was excellent under these optimal growth conditions. It significantly used rice husk as an alternative to synthetic L-Asparagine. As a result, this may be considered a sustainable method of converting organic waste into valuable raw material for microbial enzyme production.

Monitoring fungi and mycotoxin potential in pistachio nuts of Turkish origin: A snap-shot for climate change scenario

Pistachio (Pistacia vera L.) is an economically important tree nut. Due to its nutritional properties and health benefits, it is considered a healthy food and thus widely consumed worldwide. However, fungal contamination of the commodities has received considerable attention because of possible contamination by toxigenic fungi, important source of mycotoxins, resulting from secondary metabolism and hazards to health consumer. Members of the genus Aspergillus, mainly Aspergillus flavus and Aspergillus niger, are reported as occurring most frequently on pistachio nuts, because able to grow in the presence of low amounts of water and to produce mycotoxins (aflatoxins and ochratoxins), that are well known for their harmful health effects on humans.Monitoring the contaminating fungal species is particularly worthy of note also in climate change scenario, allowing to notice changes in fungal population composition through the time.This study aimed to contribute to collect data about fungal population and mycotoxins occurred in pistachio samples collected in Turkey: prevalence of 2 species, A. flavus and Aspergillus tubingensis, was assessed. The A. flavus strains consisted of a mixed population of aflatoxin producers and non-producing strains in vitro, with evidence of a new genotype in gene cluster within strains of aflatoxin non-producing chemotype.

Reconstruction of a genome-scale metabolic model and in-silico flux analysis of Aspergillus tubingensis: a non-mycotoxinogenic citric acid-producing fungus

BackgroundAspergillus tubingensis is a citric acid-producing fungus that can utilize sugars in hydrolysate of lignocellulosic biomass such as sugarcane bagasse and, unlike A. niger, does not produce mycotoxins. To date, no attempt has been made to model its metabolism at genome scale.ResultsHere, we utilized the whole-genome sequence (34.96 Mb length) and the measured biomass composition to reconstruct a genome-scale metabolic model (GSMM) of A. tubingensis DJU120 strain. The model, named iMK1652, consists of 1652 genes, 1657 metabolites and 2039 reactions distributed over four cellular compartments. The model has been extensively curated manually. This included removal of dead-end metabolites and generic reactions, addition of secondary metabolite pathways and several transporters. Several mycotoxin synthesis pathways were either absent or incomplete in the genome, providing a genomic basis for the non-toxinogenic nature of this species. The model was further refined based on the experimental phenotypic microarray (Biolog) data. The model closely captured DJU120 fermentative data on glucose, xylose, and phosphate consumption, as well as citric acid and biomass production, showing its applicability to capture citric acid fermentation of lignocellulosic biomass hydrolysate.ConclusionsThe model offers a framework to conduct metabolic systems biology investigations and can act as a scaffold for integrative modelling of A. tubingensis.

Photocatalytic degradation of biological contaminant (E. coli) in drinking water under direct natural sunlight irradiation using incorporation of green synthesized TiO2, Fe2O3 nanoparticles

AbstractGlobally, there is a severe problem of widespread water contamination. Adsorption and photocatalytic degradation are considered the most suitable methods for removing these water pollutants because of their simplicity, environmental friendliness, and capacity to generate high-quality water. By a completely green route, in this recent study, the fungus Aspergillus tubingensis was able to synthesize TiO2 and Fe2O3 NPs with an average diameter of 28.0 and 65 nm, respectively. The smallest NPs diameters were produced when the precursor salt concentrations were 10−3 M and 10−2 M for TiO2 and Fe2O3, respectively, at pH 3 and an incubation time of 72 h. The biosynthesized NPs were characterized using DLS, TEM, EDX, and VSM. They were then applied in the preparation of titanium-iron nanocomposites with different ratios (1:1, 1:2, and 2:1 (w/w)) and characterized by FTIR and XRD. In this study, Escherichia coli (E. coli) was photo-catalytically inactivated using a TiO2–Fe2O3 nanocomposite as a photocatalyst in the presence of direct sunlight. This material’s photocatalytic performance was evaluated in comparison to that of TiO2 and Fe2O3 NPs. After 60 min of exposure to direct sunlight, the cell death was estimated as 97.97%, 99.32%, 89.06%, 30.96%, and 25.14% in the presence of TF-1, TF-2, TF-3, TiO2, and Fe2O3, respectively. Under direct natural sunlight irradiation for 60 min, TiO2 and Fe2O3 nanoparticles alone have the least impact on E. coli, whereas TF-2 nanocomposite has a higher level of photocatalytic bacterial inactivation competency than TF-1 and TF-3 nanocomposites. No significant toxicity has been observed for TF-2-treated water samples in the toxicity assessment.

Purification, characterisation and visualisation of soybean protein hydrolysis by aspergillopepsin I from mangrove Aspergillus tubingensis

In order to obtain marine-derived enzymes suitable for protein hydrolysis in acid brewing system, seven species of fungi were obtained from mangrove soil. One of the strains, Aspergillus tubingensis, was determined to have a high acid protease production capacity. Its fermentation broth was purified and the obtained protease was identified as aspergillopepsin I (ATAP) with a molecular weight of 41205 Da. Homology modelling shows that ATAP contains three active sites, each containing to a Zn atom and amino acid residues. The enzyme had the highest relative activity at pH 3.5 and 35–40 °C, and exhibited pH and thermal stability at pH 3.0–3.5 and 20–50 °C. ATAP showed certain salt tolerance. K+ and Zn2+ promoted the enzyme activity, while Mg2+, Cu2+, Co2+, and Fe2+ slightly inhibited the enzyme activity. The results of inhibitors suggest that ATAP belongs to the class of aspartic proteases containing metal atoms. Furthermore, the results of enzymatic hydrolysis of defatted soybean powder showed that the contents of soluble protein, amino nitrogen, free amino acids and the proportion of small molecular peptides (<3 kDa) in the hydrolysate increased significantly. In addition, molecular docking of ATAP and aspergillopepsin I from Aspergillus oryzae 3.042 with soybean globulins (7S and 11S), respectively, showed better hydrolysis of soybean globulins by the former, especially for 7S globulin. Visual analysis indicated the interaction forces between enzymes and soybean globulins were dominated by hydrogen bond and hydrophobic interaction. In conclusion, ATAP may be a candidate as an enzyme preparation for the hydrolysis of soybean proteins.

Protective role of endophytic fungi and salicylic acid as therapeutic nutrients to improve immune responses of tomato plants against fusarial wilt disease

The exacerbation of climatic changes helped to increase the risk of plant diseases in the world. Based on this concept, we suggest Endophytic fungi (EF) and Salicylic acid (SA) alternatives to reduce the spread of Fusarium wilt disease, which is one of the most important agricultural crops globally. Therefore, this study aims to isolate endophytic fungi and test their ability to stimulate plant resistance against Fusarium wilt disease and study the possibility of combining these isolates with salicylic acid as a therapeutic nutrient for tomato plants. Two fungal endophytes were isolated from Vigna unguiculata seeds (VUS) and identified as Aspergillus oryzae and Aspergillus tubingensis according to morphological and molecular identification. Under pot circumstances, the influence of these two fungal endophytes as tomato fusarial wilt depressants and as plant stimulants was evaluated. The combination of A. oryzae and A. tubingensis exhibited a simultaneous efficacy of 80% in conferring protection against Fusarium wilt, while simultaneously resulting in a notable decreasing diseases index to 16.66%. Treatment of infected plants with A. oryzae and A. tubingensis (single or mixed) and salicylic acid not only deterioration influence of Fusarium wilt on plant fitness, but also showed a significant improvement in the levels of photosynthetic pigments, sugars, proteins and phenols, and enhancement in the activity of antioxidant enzymes. The analysis of variability among endophytic fungi revealed the presence of 17 distinct bands exhibiting polymorphism, accounting for approximately 35.294% of the observed genetic variation. In conclusion, endophytic A. oryzae and A. tubingensis work well as stimuli for tomato plant growth and as a means of boosting the plants’ resistance to Fusarium wilt. Further, A. oryzae and A. tubingensis act synergistically with SA toward improving plant growth and fusarial wilt disease resistance.

Marine cyanobacterial biomass is an efficient feedstock for fungal bioprocesses

BackgroundMarine cyanobacteria offer many sustainability advantages, such as the ability to fix atmospheric CO2, very fast growth and no dependence on freshwater for culture. Cyanobacterial biomass is a rich source of sugars and proteins, two essential nutrients for culturing any heterotroph. However, no previous study has evaluated their application as a feedstock for fungal bioprocesses.ResultsIn this work, we cultured the marine cyanobacterium Synechococcus sp. PCC 7002 in a 3-L externally illuminated bioreactor with working volume of 2 L with a biomass productivity of ~ 0.8 g L−1 day−1. Hydrolysis of the biomass with acids released proteins and hydrolyzed glycogen while hydrolysis of the biomass with base released only proteins but did not hydrolyze glycogen. Among the different acids tested, treatment with HNO3 led to the highest release of proteins and glucose. Cyanobacterial biomass hydrolysate (CBH) prepared in HNO3 was used as a medium to produce cellulase enzyme by the Penicillium funiculosum OAO3 strain while CBH prepared in HCl and treated with charcoal was used as a medium for citric acid by Aspergillus tubingensis. Approximately 50% higher titers of both products were obtained compared to traditional media.ConclusionsThese results show that the hydrolysate of marine cyanobacteria is an effective source of nutrients/proteins for fungal bioprocesses.

Isolation and Characterization of Paenibacillus polymyxa B7 and Inhibition of Aspergillus tubingensis A1 by Its Antifungal Substances.

Screening of Bacillus with antagonistic effects on paddy mold pathogens to provide strain resources for biological control of mold in Oryza sativa L. screening of Bacillus isolates antagonistic towards Aspergillus tubingensis from rhizosphere soil of healthy paddy; classification and identification of antagonistic strains by biological characteristics and 16S rDNA sequence analysis; transcriptome sequencing after RNA extraction from Bacillus-treated Aspergillus tubingensis; and extraction of inhibitory crude proteins of Bacillus by ammonium sulfate precipitation; inhibitory crude protein and Bacillus spp. were treated separately for A. tubingensis and observed by scanning electron microscopy (SEM). An antagonistic strain of Bacillus, named B7, was identified as Paenibacillus polymyxa by 16S rDNA identification and phylogenetic evolutionary tree comparison analysis. Analysis of the transcriptome results showed that genes related to secondary metabolite biosynthesis such as antifungal protein were significantly downregulated. SEM results showed that the mycelium of A. tubingensis underwent severe rupture after treatment with P. polymyxa and antifungal proteins, respectively. In addition, the sporocarp changed less after treatment with P. polymyxa, and the sporangium stalks had obvious folds. P. polymyxa B7 has a good antagonistic effect against A. tubingensis and has potential for biocontrol applications of paddy mold pathogens.