Showing papers on "Aspergillus niger published in 2020"
TL;DR: In this paper, superparamagnetic iron oxide nanoparticles (IONPs) (Fe3O4) were successfully fabricated by using manglicolous (mangrove) fungus Aspergillus niger BSC-1 and utilized for the removal of hexavalent chromium from aqueous solution.
103 citations
TL;DR: A cerium-based MOFzyme with multi-enzyme-like activity for the disruption and inhibition of fungal recolonization and its applications in agriculture and materials science are proposed.
Abstract: A cerium-based metal–organic framework (Ce-MOF, denoted as AU-1) was synthesized using a solvothermal method by employing 4,4′,4′′-nitrilotribenzoic acid (H3NTB) as the linker and cerium clusters as the metal center. The material was considered as a MOFzyme based on the peroxidase-like activity of Ce-MOF that could eliminate and kill fungi, such as Aspergillus flavus, Aspergillus niger, Aspergillus terreus, Candida albicans, and Rhodotorula glutinis. Ce-MOF showed high antifungal activity against airborne opportunistic human pathogens isolated from the outside of a hospital. The antifungal activity of CeMOF was evaluated using the colony-forming units, dry mass method, soluble proteins, and microscopic imaging. It exhibited an inhibition efficiency of 93.3–99.3% based on the colony-forming unit method. The Ce-MOF caused extensive deformation of the conidiophores, vesicles, and phialides with growth inhibition between 7.55–77.41% (based on the dry mass method). Ce-MOF showed different efficiencies in inhibiting the different fungal species. The biological activity of Ce-MOF was due to its enzymatic activity, such as those of antioxidants, catalase, superoxide dismutase, and peroxidase. Ce-MOF exhibited excellent enzymatic activity towards the fungal cells. Our results may facilitate the design of a MOFzyme system and pave the way for more profound applications of nanozymes.
65 citations
TL;DR: Results indicate that CIN can be used as an alternative food preservative due to its antifungal effects that are exerted, at least in part in A. niger, through the induction of oxidative stress, which caused cell damage and increased membrane permeability.
60 citations
01 May 2020
TL;DR: In conclusion, the cost-effective production of biosurfactant, along with novel structural and multifunctional characteristics, this study may be useful for different industrial and biotechnological applications.
Abstract: Biosurfactants are surface-active natural polymers produced within several microorganisms and are secreted outside the cellular environment. They are the focus of modern researches due to their eco-friendly nature and high production capability using low-cost agro-industrial wastes. In this research, we have evaluated Aspergillus niger (A. niger) for its biosurfactant production potential during solid state fermentation of banana stalks powder. The native strain of A. niger produced 2.3 g/L of biosurfactant with 49.74 cm2 oil displacement, 57% emulsification index and an emulsification activity of 1.024 (OD540). Sequential mutagenesis was induced in the native strain of A. niger by exposing the strain with different concentrations of ethidium bromide (EtBr), for different time periods. Significantly higher amount of biosurfactant (3.3 g/L) was obtained from the mutant strain A. niger M2 exposed to 50 µg/10 mL of EtBr for 60 min. The screening tests revealed the improvement in oil displacement (59.81 cm2), emulsification index (62.3%) and emulsification activity (OD540, 1.262) of biosurfactant. FTIR analysis confirmed the presence of amine, amide, fatty acids and triglycerides functional groups. The maximum biosurfactant synthesizing mutant (A. niger M2) was further optimized using RSM under CCD. After optimization, the highest biosurfactant (5.50 g/L) was obtained at 35 °C temperature, 7 pH, 5.75 g substrate concentration and 168 h of overall incubation period. In conclusion, the cost-effective production of biosurfactant, along with novel structural and multifunctional characteristics, this study may be useful for different industrial and biotechnological applications.
49 citations
TL;DR: The availability of genome sequence of this organism has facilitated numerous studies in gene function, gene regulation, primary and secondary metabolism, and an attempt has been also made to address the molecular mechanisms and application of recent advanced techniques such as CRISPR/Cas9 systems in enhancement of citric acid production.
Abstract: Microbial citric acid has high economic importance and widely used in beverage, food, detergents, cosmetics and pharmaceutical industries. The filamentous fungus Aspergillus niger is a work horse and important cell factory in industry for the production of citric acid. Although in-depth literatures and reviews have been published to explain the biochemistry, biotechnology and genetic engineering study of citric acid production by Aspergillus niger separately but the present review compiled, all the aspects with upto date brief summary of the subject describing microorganisms, substrates and their pre-treatment, screening, fermentation techniques, metabolic engineering, biochemistry, product recovery and numerous biotechnological application of citric acid for simple understanding of microbial citric acid production. The availability of genome sequence of this organism has facilitated numerous studies in gene function, gene regulation, primary and secondary metabolism. An attempt has been also made to address the molecular mechanisms and application of recent advanced techniques such as CRISPR/Cas9 systems in enhancement of citric acid production.
49 citations
TL;DR: The progress and challenges of developing A. niger for the production of food enzymes are reviewed, including its genetic manipulations, strategies for more efficient production ofFood enzymes, and elimination of mycotoxins for product safety.
47 citations
TL;DR: The present study has shown that A. hypogaea shells can be used as a carbon source by A. niger for the production of cellulase and the enzyme has higher specificity for CMC compared to other substrates.
47 citations
TL;DR: Cadmium-tolerant Aspergillus niger biomass biomass was challenged with aqueous cadmium chloride followed by sodium sulfide at 37°C for 96 h under shaking conditions, resulting in the formation of highly stable polydispersed Cadmium sulfide nanoparticles (CdSNPs) capped with fungal proteins.
Abstract: Cadmium-tolerant (6 mM) Aspergillus niger (RCMB 002002) biomass was challenged with aqueous cadmium chloride (1 mM) followed by sodium sulfide (9 mM) at 37°C for 96 h under shaking conditions (200 rpm), resulting in the formation of highly stable polydispersed cadmium sulfide nanoparticles (CdSNPs). Scanning electron microscopy revealed the presence of spherical particles measuring approximately 5 nm. A light scattering detector (LSD) showed that 100% of the CSNPs measure from 2.7 to 7.5 nm. Structural analyses by both powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) confirmed the presence of cubic CdS nanoparticles (CdSNPs) capped with fungal proteins. These CdSNPs showed emission spectra with a broad fluorescence peak at 420 nm and UV absorption onset at 430 nm that shifted to 445 nm after three months of incubation. The CdSNPs showed antimicrobial activity against E. coli, Pseudomonas vulgaris, Staphylococcus aureus, and Bacillus subtilis, and no antimicrobial activity was detected against Candida albicans. The biosynthesized CdSNPs have cytotoxic activity, with 50% inhibitory concentrations (IC50) of 190 μg mL-1 against MCF7, 246 μg mL-1 against PC3, and 149 μg mL-1 against A549 cell lines.
46 citations
TL;DR: The non-dried pomegranate peel waste in SSF under non-aseptic conditions is a cheap and useful substrate for the commercial production of citric acid with low energy cost.
Abstract: Citric acid production from dried and non-dried pomegranate peel wastes by the fungus Aspergillus niger B60 in solid-state fermentation (SSF) under non-aseptic conditions was investigated. The maximum amount of citric acid (278.5 g/kg dry peel) was achieved using dried (at 45 °C for 48 h) pulverized pomegranate peels with moisture content 75% and initial pH 8.0, after 8 days of fermentation at 25 °C. Under the same fermentation conditions, a higher amount of citric acid (306.8 g/kg dry peel) was observed during SSF of non-dried peels as a substrate. The addition of methanol as an inducer at a concentration of 3% (w/w) into the dried and non-dried pomegranate peel wastes increased the amount of citric acid to 300.7 and 351.5 g/kg dry peel, respectively. The non-dried pomegranate peel waste in SSF under non-aseptic conditions is a cheap and useful substrate for the commercial production of citric acid with low energy cost. The utilization of inexpensive agro-industrial wastes through SSF can contribute to achieve industrially feasible and environmentally sustainable bio-production of citric acid.
46 citations
TL;DR: A strain with great industrial application potential was developed by engineering 9 genes in A. niger and a pilot fermentation technology was exploited, which eliminated the accumulation of citric acid and enhanced glycolytic flux in malic acid biosynthesis.
Abstract: Microbial fermentation was widely explored to produce malic acid. Previously, Aspergillus niger has been successfully engineered, and a high titer of malic acid was achieved with strain S575, but it also produced a high level of byproduct citric acid. Here, the capability of A. niger in malic acid biosynthesis was further improved by eliminating the accumulation of citric acid and enhancing glycolytic flux. Characterization of variant mutants suggested that disruption of cexA, a gene encoding citric acid transporter located on cell membrane, abolished citric acid accumulation. However, cexA-deficient strain S895 showed significantly decreased malic acid production. Further analysis of S895 indicated that the transcription level of genes involved in glucose transportation and glycolytic pathway was significantly reduced, and the corresponding enzyme activity was also lower than those of S575. Individual overexpression of genes encoding glucose transporter MstC and key enzymes (hexokinase HxkA, 6-phosphofructo-2-kinase PfkA, and pyruvate kinase PkiA) involved in irreversible reactions of glycolic pathway increased malic acid production. Accordingly, genes of mstC, hxkA, pfkA, and pkiA were overexpressed altogether in S895, and the resultant strain S1149 was constructed. The titer of malic acid in fed-batch fermentation with S1149 reached 201.13 g/L. Compared with S575, the byproduct of citric acid was completely abolished in S1149, and the ratio of malic acid/glucose was increased from 1.27 to 1.64 mol/mol, the highest yield reported so far, and the fermentation period was shortened from 9 to 8 days. Thus, a strain with great industrial application potential was developed by engineering nine genes in A. niger, and a pilot fermentation technology was exploited.
42 citations
TL;DR: Results of this study describe this delicate approach to be species and metal dependent and suggest a potential utilization of this fungal strain for the bioremediation of contaminated soils.
Abstract: Rapidly increasing industry has resulted in greater discharge of hazardous chemicals in the soil. In the current study, soil samples were collected from Nanjing mine (32°09'19.29″ N 118°56'57.04″ E) and subjected to heavy metal analysis and microbe isolation. A total of 460 fungi were isolated, and five of these were yeast strains. Most of the strains exhibited tolerance to one metal. Five multimetal tolerant strains were selected and identified as Aspergillus sclerotiorum, Aspergillus aculeatus, Komagataella phaffii, Trichoderma harzianum, and Aspergillus niger. Isolated strains were grown in high concentrations of cadmium (Cd), chromium (Cr) and lead (Pb), for induced-tolerance training. The tolerance index (TI) revealed the highest Cd tolerance of novel K. phaffii strain at 5500 ppm (TI: 0.2). K. phaffii also displayed resistance at 4000 ppm against Cr (TI: 0.32) and Pb (TI: 0.32). In contrast, tolerance training for A. niger was not that successful. K. phaffii also displayed the highest bioaccumulation capacity for Cd (25.23 mg/g), Cu (21.63 mg/g), and Pb (20.63 mg/g) at 200 ppm. Scanning electron microscopy (SEM) explored the morphological changes in the mycelia of stressed fungi. Results of this study describe this delicate approach to be species and metal dependent and suggest a potential utilization of this fungal strain for the bioremediation of contaminated soils.
TL;DR: Optimistic medium composition was successfully determined by PBD and also the kinetic models fitted the experimental data very well with high regression coefficient, indicating that A. niger mainly utilizes the sugars for enzyme production and fungal growth.
Abstract: The goals of this study were to optimize the medium formulation for enhanced production of Aspergillus niger inulinase using Plackett–Burman Design (PBD) and to model the fermentation in optimal medium formulation. Results indicated that (NH4)2SO4 (negative effect), yeast extract and peptone (positive effect) were determined as significant factors affecting the inulinase production. Different media including Medium A (non-enriched), Medium B (contains both negative and positive factors) and Medium C (contains only positive factors) were formed and inulinase fermentations were performed. Findings showed that the best nutritional formulation was Medium C, which yielded to be 1011.02 U/mL, 834.28 U/mL, 1.22, 4383.44 U/mg, 4186 U/mg, 158.49 U/mL/day, 128.60 U/mL/day and 94.54% of PInulinase, SInulinase, I/S ratio, SInulinase, SSucrase, QInulinase, QSucrase and SUY, respectively. Additionally, fungal growth, enzyme or protein production and substrate consumption were modeled using the logistic model, Luedeking–Piret model, and modified Luedeking–Piret model, respectively, and found that enzyme or protein production was non-growth associated. Besides, maintenance value (Z) was lower than γ value, indicating that A. niger mainly utilizes the sugars for enzyme production and fungal growth. Consequently, optimum medium composition was successfully determined by PBD and also the kinetic models fitted the experimental data very well with high regression coefficient.
TL;DR: This study addressed the effectiveness of light emitting diodes to achieve inactivation of three different Aspergillus species in a real water matrix using less than 20 mJ/cm2 and found the ultraviolet-C dioders were found to be more effective than the 255 nm wavelength.
12 Dec 2020
TL;DR: Aloe vera is a well-known medicinal plant used in many therapeutic purposes as discussed by the authors, it is composed of many useful compounds that have ability to use for treatment of many diseases, it is used for antibacterial and antifulgal activity against different strains of bacteria and pathogenic fungal strains.
Abstract: Aloe vera is a well-known medicinal plant used in many therapeutic purposes. Naturally it is composed of many useful compounds that have ability to use for treatment of many diseases. The active compounds reported in this plant are saponins, sugar, enzymes, vitamins, aloesin, aloeemodin, aloin, acemannan aloemannan, aloeride, methylchromones, flavonoids, naftoquinones, sterols, minerals, anthraquinones, amino acids, lignin and salicylic acid and other different compounds including fat-soluble and water-soluble vitamins, enzymes, minerals, simple/complex sugars, organic acid and phenolic compounds. In this study aloe vera is used for antibacterial and antifulgal activity against different strains of bacteria and pathogenic fungal strains. Ethanol extract of Aloe vera leaves and roots is applied on these bacterial and fungal strains in different concentrations (15, 20, 25, 30µl). Bacillus cereus, Bacillus subtitis, Bacillus megaterium, Streptococcus pyogenes, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, and some other bacterial strains are used for this study. Escherichia coli and Agrobacterium tumefacins shows zone of inhibition around 18mm which consider as good result. Bacillus subtitis and Bacillus megaterium also shows good result around 16mm. Proteus mirabilis and Pseudomonas aeruginosa shows minimum zone of inhibition which is around 11mm. among all used fungal strains (fuserium oxysporum, Candida albicans, Aspergillus fumigatus, Aspergillus niger) fuserium oxysporum and Aspergillus niger shows excellent results around 19mm both against root extract and leaves extract.
TL;DR: In this article, an optimization of Aspergillus niger lipase production has been performed on solid state fermentation of rice bran and Jathropa seed cake for 5 days with variations of inducer and extractant.
TL;DR: A new 6-benzyl-γ-pyrone, named aspergyllone, showed strong selective antifungal activity against Candida parapsilosis and Aurasperone A and pyrophen showed moderate to strong antimicrobial activity inhibiting seven different test pathogens.
TL;DR: Positive results suggested that A. niger can be used as a heat-stress ameliorative tool for crops in the future.
Abstract: Plants can be severely affected by heat stress due to rapid environmental changes. Use of endophytic fungi is a new tool to protect crops from the environmental stresses. Here we claim a potent end...
TL;DR: In this article, the potential antifungal activity of low molecular weight peptides being a natural preservative generated from palm kernel cake via solid state lacto-fermentation was investigated.
Abstract: This study aimed at investigating the potential antifungal activity of low molecular weight peptides being a natural preservative generated from palm kernel cake (PKC) via solid state lacto-fermentation. Palm kernel cake was hydrolysed by L. casei generating a peptide mixture with a DH of 43.39% under predetermined optimum conditions of 5.6 days incubation, 3% glucose, and substrate/water ratio of 48/52 w/v. A total of 10 cationic peptides with molecular weight ranging from 932 to 1869 Da were identified by LC/MS-MS, in which 7 belonged to oil palm proteins and 3 de novo peptides biosynthesized by the microorganism during the fermentation process. The aqueous extract of the peptides mixture demonstrated strong antifungal activity against Aspergillus flavus (69.15%), Aspergillus niger (88.08%), Fusarium sp. (87.14%), and Penicillium sp. (71.84%). 1H-NMR spectroscopy results showed the presence of trace amounts of lactic and acetic acid, indicating that the antimicrobial activity was solely attributed by the low molecular weight peptides. The peptides mixture successfully delayed fungal growth, thus extending the shelf life of bread for up to 10 days when added to the bread at 2000 mg/kg. These findings indicated a promising application of the peptides mixture as a bio-preservative in extending the shelf life of bread.
TL;DR: These findings contribute further understanding of struvite solubilization, element release and secondary oxalate formation, relevant to the biogeochemical cycling of phosphate minerals, and further directions utilizing these mechanisms in environmental biotechnologies such as element biorecovery and biofertilizer applications.
Abstract: Struvite (magnesium ammonium phosphate-MgNH4 PO4 ·6H2 O), which can extensively crystallize in wastewater treatments, is a potential source of N and P as fertilizer, as well as a means of P conservation. However, little is known of microbial interactions with struvite which would result in element release. In this work, the geoactive fungus Aspergillus niger was investigated for struvite transformation on solid and in liquid media. Aspergillus niger was capable of solubilizing natural (fragments and powder) and synthetic struvite when incorporated into solid medium, with accompanying acidification of the media, and extensive precipitation of magnesium oxalate dihydrate (glushinskite, Mg(C2 O4 ).2H2 O) occurring under growing colonies. In liquid media, A. niger was able to solubilize natural and synthetic struvite releasing mobile phosphate (PO43- ) and magnesium (Mg2+ ), the latter reacting with excreted oxalate resulting in precipitation of magnesium oxalate dihydrate which also accumulated within the mycelial pellets. Struvite was also found to influence the morphology of A. niger mycelial pellets. These findings contribute further understanding of struvite solubilization, element release and secondary oxalate formation, relevant to the biogeochemical cycling of phosphate minerals, and further directions utilizing these mechanisms in environmental biotechnologies such as element biorecovery and biofertilizer applications.
TL;DR: Results suggested that the thermally stable tannase exhibited potential applications in the enzymatic extraction of green tea beverage.
Abstract: Tannase is widely used in tea beverage processing because of its ability to catalyze the hydrolysis of hydrolysable tannins or gallic acid esters and effectively improve the quality of tea extracts through enzymatic extraction. A new thermophilic tannase was cloned from Aspergillus niger FJ0118 and characterized. The tannase exhibited an optimal reaction temperature of 80 °C and retained 89.6% of the initial activity after incubation at 60 °C for 2 h. The enzymatic extraction of green tea at high temperature (70 °C) for a short time (40 min) was devised on the basis of the superior thermal stability of tannase. The enzymatic reaction significantly increased the total polyphenol content of green tea extract from 137 g·kg−1 to 291 g·kg−1. The enzymatic reaction effectively degraded the ester catechins into non-ester catechins compared with the water extraction method. Results suggested that the thermally stable tannase exhibited potential applications in the enzymatic extraction of green tea beverage.
TL;DR: Optimal enzyme production requires controlling the transient availability of inducers, and α-Galactosidase production always followed the pectinase production with a 16-24 h lag; presumably, the former relied on pect in hydrolysis for inducers generation.
TL;DR: In this paper, a natural variant of Aspergillus niger P-19 was used for the in-house production of cellulase-hemicellulase consortium for efficient and low-cost saccharification of rice straw.
TL;DR: Effective purification by ion chromatography and improvement in β-glucosidase properties by covalent immobilization can be considered as a productive method to improve enzyme efficacy in order to decrease the costs of food processing.
Abstract: β-glucosidase was produced using different carbon sources by Aspergillus niger. The enzyme purification was performed by two steps anion exchange (DEAE-Sepharose) and cation exchange (Resource-S) chromatography (molecular weight ~115 kDa). The enzyme immobilization was performed on CNBr-activated sepharose. The optimal temperature for the free enzyme was 60 °C but for immobilized one reached to 70 °C. Optimum pH of β-glucosidase was 5 that after immobilization shifted to 4.5, while pH stability was not changed significantly. Immobilizing the enzyme increased Km (19.7–31.77) and decreased Vmax (1.199–0.85) for salicin as substrate. Moreover, heat stability, resistant to organic solvents and particularly recyclability improved after immobilization. Also, both free and immobilized enzymes showed trans-glycosylation activity. As a result, effective purification by ion chromatography and improvement in β-glucosidase properties by covalent immobilization can be considered as a productive method to improve enzyme efficacy in order to decrease the costs of food processing.
03 Feb 2020
TL;DR: The results revealed that PP extract was better than PCL extract for vanillic acid and vanillin production, and it was proved that large volume feeding was more efficient than small volume feeding for high vanilli acid andVanillin yield.
Abstract: This study was conducted to evaluate the potential of pineapple peel (PP) and pineapple crown leaves (PCL) as the substrate for vanillic acid and vanillin production. About 202 ± 18 mg L−1 and 120 ± 11 mg L−1 of ferulic acid was produced from the PP and PCL respectively. By applied response surface methodology, the ferulic acid yield was increased to 1055 ± 160 mg L−1 by treating 19.3% of PP for 76 min, and 328 ± 23 mg L−1 by treating 9.9% of PCL for 36 min in aqueous sodium hydroxide solution at 120 °C. The results revealed that PP extract was better than PCL extract for vanillic acid and vanillin production. Furthermore, the experiment also proved that large volume feeding was more efficient than small volume feeding for high vanillic acid and vanillin yield. Through large volume feeding, about 7 ± 2 mg L−1 of vanillic acid and 5 ± 1 mg L−1 of vanillin was successfully produced from PP extract via Aspergillus niger fermentation.
TL;DR: The RNP-based CRISPR–Cas9 system was successfully applied in genetic engineering of A. niger and significantly improved the succinic acid production in the engineered strain and the future challenges in strain development.
Abstract: Succinic acid has great potential to be a new bio-based building block for deriving a number of value-added chemicals in industry. Bio-based succinic acid production from renewable biomass can provide a feasible approach to partially alleviate the dependence of global manufacturing on petroleum refinery. To improve the economics of biological processes, we attempted to explore possible solutions with a fungal cell platform. In this study, Aspergillus niger, a well-known industrial production organism for bio-based organic acids, was exploited for its potential for succinic acid production. With a ribonucleoprotein (RNP)-based CRISPR–Cas9 system, consecutive genetic manipulations were realized in engineering of the citric acid-producing strain A. niger ATCC 1015. Two genes involved in production of two byproducts, gluconic acid and oxalic acid, were disrupted. In addition, an efficient C4-dicarboxylate transporter and a soluble NADH-dependent fumarate reductase were overexpressed. The resulting strain SAP-3 produced 17 g/L succinic acid while there was no succinic acid detected at a measurable level in the wild-type strain using a synthetic substrate. Furthermore, two cultivation parameters, temperature and pH, were investigated for their effects on succinic acid production. The highest amount of succinic acid was obtained at 35 °C after 3 days, and low culture pH had inhibitory effects on succinic acid production. Two types of renewable biomass were explored as substrates for succinic acid production. After 6 days, the SAP-3 strain was capable of producing 23 g/L and 9 g/L succinic acid from sugar beet molasses and wheat straw hydrolysate, respectively. In this study, we have successfully applied the RNP-based CRISPR–Cas9 system in genetic engineering of A. niger and significantly improved the succinic acid production in the engineered strain. The studies on cultivation parameters revealed the impacts of pH and temperature on succinic acid production and the future challenges in strain development. The feasibility of using renewable biomass for succinic acid production by A. niger has been demonstrated with molasses and wheat straw hydrolysate.
TL;DR: The obtained strains with constitutively active XlnR and GaaR versions resulted in increased production of plant biomass degrading enzymes and improved release of d-xylose and l-arabinose from wheat bran, and d-galacturonic acid from sugar beet pulp.
TL;DR: Aspergillus niger has able to remove diazinon with the lowest cost and a high efficiency from aqueous solutions by using the response surface methodology.
Abstract: The Lake Burullus is one of most important lakes in north Delta of Egypt. It is exposed to huge amounts of contaminated drainage water contain serious pollutants especially Organophosphours. Diazinon is an organophosphorus pesticide widely used in agriculture. Evidence of diazinon residues in water has generated an urgent need to develop treatment systems for protected human health and the environment from damage. The aim of this work was the optimization of diazinon biodegradation from aqueous solutions by Aspergillus niger MK640786 using the response surface methodology. Aspergillus niger MK640786 was succeeded to reduce the diazinon at optimal conditions were as follows: temperature 30 °C, initial concentration 25 mg/l, pH 5 and within 7 days of incubation. Under these conditions, the degradation rate of diazinon was 82%. The half-life values of diazinon with strain Aspergillus niger were,3.8, 3.9,7.2,10.9 and 15.8 d − 1 respectively. In contrast, the t1/2 values of diazinon in the non-inoculated were 14.36549, 17.71808, 34.83199, 40.65586 and 47.8675 d − 1 respectively. We can conclude that Aspergillus niger has able to remove diazinon with the lowest cost and a high efficiency.
TL;DR: The potential of algae should be investigated for the production of natural fungicide for pharmaceutical and food industries and almost all of the extracts obtained from algae species were revealed to have antifungal activity against selected fungal pathogens.
Abstract: It is known that cell extracts of various algae have antifungal activity against microorganisms in vitro. Antifungal activities of Ulva lactuca, Chlorella vulgaris, Chlorella minutissima, and Chlorella protothecoides were investigated against: Aspergillus niger, Alternaria alternata, and Penicillium expansum fungi to present their fungicide potentials. Aspergillus niger, Alternaria sp., and Penicillium expansum are typical soft-rotting fungi and cause important loss of apple fruit in the storage. In vitro antifungal activity was evaluated by agar disc diffusion assay against pathogenic apple rot fungi. As a result, almost all of the extracts obtained from algae species were revealed to have antifungal activity against selected fungal pathogens. Free radical-scavenging activity of the extracts was determined with 1,1-diphenyl-2 picryl hydrazyl (DPPH) free radical-scavenging method. Extract of C. protothecoides was determined to have a stronger antioxidant activity than other algae extracts. This study reveals that the potential of algae should be investigated for the production of natural fungicide for pharmaceutical and food industries.
TL;DR: The hypothesis that uridine/pyrimidine biosynthetic pathway offer future avenues for strain engineering efforts is supported, and it is demonstrated for the first time that A. niger pyrG is a promising genetic lead for generating citric acid hyper-producing strains.
Abstract: Aspergillus niger is a filamentous fungus used for the majority of global citric acid production. Recent developments in genome editing now enable biotechnologists to engineer and optimize A. niger. Currently, however, genetic-leads for maximizing citric acid titers in industrial A. niger isolates is limited. In this study, we try to engineer two citric acid A. niger production isolates, WT-D and D353, to serve as platform strains for future high-throughput genome engineering. Consequently, we used genome editing to simultaneously disrupt genes encoding the orotidine-5′-decarboxylase (pyrG) and non-homologous end-joining component (kusA) to enable use of the pyrG selection/counter selection system, and to elevate homologous recombination rates, respectively. During routine screening of these pyrG mutant strains, we unexpectedly observed a 2.17-fold increase in citric acid production when compared to the progenitor controls, indicating that inhibition of uridine/pyrimidine synthesis may increase citric acid titers. In order to further test this hypothesis, the pyrG gene was placed under the control of a tetracycline titratable cassette, which confirmed that reduced expression of this gene elevated citric acid titers in both shake flask and bioreactor fermentation. Subsequently, we conducted intracellular metabolomics analysis, which demonstrated that pyrG disruption enhanced the glycolysis flux and significantly improved abundance of citrate and its precursors. In this study, we deliver two citric acid producing isolates which are amenable to high throughput genetic manipulation due to pyrG/kusA deletion. Strikingly, we demonstrate for the first time that A. niger pyrG is a promising genetic lead for generating citric acid hyper-producing strains. Our data support the hypothesis that uridine/pyrimidine biosynthetic pathway offer future avenues for strain engineering efforts.
TL;DR: Results showed that the enzymes production process serves as the main contributor to the profitability of the biorefinery plant.