Aspergillus Niger Strain Research Articles

Synthesis, molecular structure, electronic, spectroscopic, NLO and antimicrobial study of N-benzyl-2-(5-aryl-1,3,4-oxadiazol-2-yl)aniline derivatives

The cyclization reaction between two benzohydrazides with 2-(benzylamino)benzoic acid afforded the novel 2,5-disubstituted oxadiazole derivatives; N-benzyl-2-(5-phenyl-1,3,4-oxadiazol-2-yl)aniline (NBPOA) and N-benzyl-2-(5-(4-chlorophenyl)-1,3,4-oxadiazol-2-yl)aniline (NBCPOA). Theoretical investigation of these newly synthesized oxadiazole derivatives was carried out by density functional theory (DFT) method at the B3LYP/6-311++G(d,p) level of theory. TD-DFT computations were performed to have insights into the three singlet electronic states of the electronic absorption spectra and to assign and correlate with the experimental UV-Vis spectra. The electronic absorption measurements were done in DCM and DMSO solvents. The increase in solvent polarity exerted a blue shift on the first singlet electronic excited state and a red shift on the second and the third electronic excited states suggesting different polarities of the excited states. Vibrational band assignments were scaled and compared with the experimental frequencies. Structural parameters and chemical reactivity such as HOMO and LUMO energies, MESP surfaces, Mulliken charges, and global reactivity descriptors were analyzed. It was observed that NBCPOA has a smaller HOMO-LUMO energy gap and larger global softness than NBPOA. The charge transfer that takes place in NBPOA and NBCPOA is supported by the oscillator strength. These compounds were also screened for their in vitro antibacterial activity against two Gram-negative bacterial strains namely Escherichia coli and Salmonella typhi and two Gram-positive bacterial strains namely Bacillus subtilis and Bacillus megaterium and antifungal activity against Aspergillus niger, Rhizopus oryzae, Penicillium chrysogenum, and Candida albicans fungal strains. The synthesized compounds exhibited moderate antibacterial and antifungal properties.

Safety evaluation of the food enzyme α-glucosidase from the Aspergillus niger strain AE-TGU.

The food enzyme α‐glucosidase (α‐d‐glucoside glucohydrolase; EC 3.2.1.20) is produced with the non‐genetically modified Aspergillus niger strain AE‐TGU by Amano Enzyme Inc. The food enzyme is free from viable cells of the production organism. The food enzyme is intended to be used in baking processes, cereal‐based processes, brewing processes and starch processing for the production of glucose syrups and other starch hydrolysates. Since residual amounts of total organic solids (TOS) are removed by the purification steps applied during the production of glucose syrups, dietary exposure was only calculated for the remaining three food processes. Based on the maximum use levels recommended, dietary exposure was estimated to be up to 0.64 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not raise a safety concern. The systemic toxicity was assessed by means of a repeated dose 90‐day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 1,062 mg TOS/kg bw per day, the highest dose tested, which when compared with the estimated dietary exposure, results in a margin of exposure of at least 1,650. A search for similarity of the amino acid sequence of the food enzyme to known allergens was made and no match was found. The Panel considered that, under the intended conditions of use, the risk of allergic sensitisation and elicitation reactions by dietary exposure cannot be excluded, but the likelihood for this to occur is considered to be low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Safety evaluation of the food enzyme mannan endo-1,4-β-mannosidase from the genetically modified Aspergillus niger strain NZYM-NM.

The food enzyme mannan endo‐1,4‐β‐mannosidase (1,4‐β‐d‐mannan mannanohydrolase, EC 3.2.1.78) is produced with the genetically modified Aspergillus niger strain NZYM‐NM by Novozymes A/S. The genetic modifications do not give rise to safety concerns. The food enzyme is considered free from viable cells of the production organism and its DNA. The food enzyme is intended to be used in coffee processing. Based on the maximum use levels, dietary exposure to the food enzyme total organic solids (TOS) was estimated to be up to 0.956 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90‐day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 1,151.7 mg TOS/kg bw per day, the highest dose tested, which when compared with the estimated dietary exposure, results in a margin of exposure of more than 1,200. A search for similarity of the amino acid sequence of the food enzyme to known allergens was made and no match was found. The Panel considered that, under the intended conditions of use the risk of allergic sensitisation and elicitation reactions by dietary exposure cannot be excluded, but the likelihood for this to occur is considered to be low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Effective Bioconversion of Locally obtained Apple Waste into Citric Acid using Aspergillus Niger (NRRL 567)

A viable and sustainable method was used to produce citric acid. Apple waste (pomace) was used as a substrate and displayed a good efficiency for citric acid yield. The fermentation process was carried out using Aspergillus Niger (NRRL 567) strain. This fungal strain showed a competent performance in fermenting apple waste to produce citric acid. Various key parameters were analyzed and optimized such as incubation temperature, amount of substrate, ph, moisture content, nitrogen source, metal ions, methanol inducer and inoculum density. Among such parameters, the highest citric acid yield of 158 g/kg of apple pomace was achieved with the use of methanol inducer. Methanol inducer, moisture content, amount of substrate and nitrogen source were found to have significant impact on CA production. The fungal strain used in the present study is known to possess an impressive biomass fermentation capacity, as also demonstrated by the present work. In Pakistan, this strain has not been analyzed for its efficiency to produce citric acid using pomace of locally cultivated apple, hence the novelty of the present work. All the experimental work, analysis and optimization was accomplished on laboratory scale at Advanced Research Laboratory, Zoology Department, GC University, Faisalabad, Pakistan.

Synthesis, characterization, antimicrobial and anticancer evaluation of (E)-N'-benzylidene-6-methyl-4-(2-nitrophenyl)-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carbohydrazide derivatives

The synthesis of a novel family of pyrimidine derivatives has been completed. Infrared–infrared (IR) and proton nuclear magnetic resonance (1H NMR) spectrum data were used to describe these pyrimidine derivatives. All the compounds were evaluated for their in vitro antimicrobial activity against Gram negative strain (Escherichia coli) and Gram positive strains (Bacillus subtilis and Staphylococcus aureus) and fungal strain (Candida albicans and Aspergillus niger) and anticancer potential against Human breast cancer cell line (MCF-7). Results of antimicrobial and anticancer study revealed that compounds (E)-N'-(3-nitrobenzylidene)-6-methyl-4-(2-nitrophenyl)-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carbohydrazide (4) and (E)-N'-(3-chlorobenzylidene)-6-methyl-4-(2-nitrophenyl)-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carbohydrazide (10) were found to be the most potent antimicrobial and anticancer agents respectively. Keywords: Pyrimidine, Anti-microbial activity, Anti-cancer activity, Benzaldehyde, Pyrimidine derivatives.

Synthesis, characterization, antimicrobial and anticancer evaluation of pyrimidines Clubbed with thiazolidinone

A series of novel derivatives of pyrimidine clubbed with thiazolidinone was synthesized in good yield and characterized by physiochemical and spectral means. All the synthesized derivatives were evaluated for their antimicrobial and anticancer activity. Antimicrobial properties of the title compounds were investigated against Gram positive (Bacillus subtilis and Staphylococcus aureus) and Gram negative bacterial (Escherichia coli) as well fungal strains (Candida albicans and Aspergillus niger). The anticancer evaluation of synthesized compounds against HeLa Cervical cancer cell Line indicated that (Z)-N-(5-(4-nitrobenzylidene)-4-oxo-2-phenylthiazolidin-3-yl)-6-methyl-4-(2-nitrophenyl)-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxamide and (Z)-N-(5-(4-(diethylamino)benzylidene)-4-oxo-2-phenylthiazolidin-3-yl)-6-methyl-4-(2-nitrophenyl)-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxamide (PT9, IC50 = 12.68μM and PT14, IC50 = 15.27μM) was the most active anticancer agent and was more potent than standard drug, Doxorubicin (IC50 =16.12μM). All newly synthesized compounds also exhibited promising results against microbial strains. Keywords: Pyrimidine, Thiazolidinone, Antimicrobial activity, HeLa Cancer cell line, Anti-cancer activity.

Bioelectroremediation of hexadecane in electrical cells containing Aspergillus niger immobilized in alginate

Bioelectroremediation (BER) uses electrical current to stimulate catabolism of environmental pollutants, such as petroleum spills. However, applying current to soil may have adverse effects on the microorganisms involved in petroleum degradation. We identify and evaluate the BER capabilities of a strain of Aspergillus niger obtained from petroleum-contaminated soil. Spores of this strain immobilized in alginate spheres (2 g) were mixed with 100 g of hexadecane-contaminated sandy loam soil and exposed to 5, 10, or 15 mA direct current in a 200 cm3 cell with copper electrodes. Soil hexadecane concentration was measured by gas chromatography. More than 94% of hexadecane was removed from the soil within 12 days for the currents tested, and the A. niger grew to 6 x106 CFU g-1 in 15 days at 10 mA current. The maximum hexadecane degradation was achieved using a 10-mA current for 20 days, but more than 99% of the hexadecane was removed by the fifth day. These results suggest that the use of spore-containing alginate beads promotes growth and petroleum biodegradation of A. niger exposed to electrical currents.
 Keywords: Aspergillus, bioelectroremediation, hexadecane, petroleum, soil.

Antioxidant and antimicrobial evaluation of the methanol leaf extract and fractions of dacryodes klaineana pierre (burseraceae)

ABSTRACT. Dacryodes klaineana is used in traditional medicine for the treatment of painful menstruation; tachycardia and cough. The study aims to evaluate the antioxidant and antimicrobial properties of the plant. The extract and fractions of D. klaineana were screened for their antioxidant effects using the 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and the total phenolic contents (TPC) assay methods. The antimicrobial activity of the plant was evaluated using the agar diffusion method against four different bacterialstrains (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa) and two fungi strains (Aspergillus niger and Candida albicans). The crude methanol extract (MLE), hexane fraction (MLHF), ethyl acetate fraction (MLEF) and butanol fraction (MLBF) produced dose-dependent antioxidant activity using DPPH and FRAP assays. The antioxidant activity of MLEF was comparable to the standard drug, ascorbic acid. MLEF also gave the highest content of total phenol content with a percent gallic acid equivalent of 100.68 ± 1.17 mg GAE/g. The extract and fractions were active against the bacteria species, but inactive against the fungi species. The study demonstrated that the antioxidant and antimicrobial potentials of D. klaineana may offer a promising source of new antioxidants and antimicrobials in the ethnomedicinal management of diseases.
 
 KEY WORDS: Medicinal plant, FRAP, TPC, DPPH, Antioxidant, Dacryodes klaineana
 
 Bull. Chem. Soc. Ethiop. 2022, 36(1), 85-94. 
 DOI: https://dx.doi.org/10.4314/bcse.v36i1.8

Aroma profile and in-silico molecular docking studies of essential oil against “Aspergillosis” from Eucalyptus polybrachtea

Essential oil from Eucalyptus plant is used as traditional and complementary medicine worldwide. It is used as therapeutic agent in food and pharmaceutical companies due to various biological activities. The objective of present study was aromatic profile of essential oil and molecular docking of Eucalyptus essential oil component eucalyptol (1-8 cineole) against Glucosamine-6-phosphate synthase chitin synthase and UDP-glycosyltransferase, fungal enzymes as an appropriate sites to design drug against “Aspergillosis” and in vitro validation. GC-FID analysis was used to find out aromatic profile. For docking, Patch-dock analysis was used. Ligand Protein 2D and 3D Interactions were also studied. Drug likeliness, toxicity profile and cancer cell line toxicity were also studied. GC-FID profiling revealed the presence of eucalyptol as major bioactive compound, hence selected for further docking studies. Docking analysis indicated effective binding of eucalyptol to Glucosamine-6-phosphate synthase, chitin synthase and UDP-glycosyltransferase. Wet lab validation was performed by two fungal strains Aspergillus niger and Aspergillus oryzae. Molecular docking results indicated that eucalyptol forms tight complexes with Glucosamine-6-phosphate synthase, chitin synthase and UDP-glycosyltransferase enzymes by hydrophobic and hydrogen interactions. Eucalyptol also depicted drug likeliness by LIPINSKY rule, sufficient level of bioactivity, drug likeliness and cancer cell line toxicity. In vitro results revealed that Eucalyptus oil was able to inhibit growth of fungal strains toxicity thus signifying its role as potent anti-fungal drug

Elucidating Therapeutic and Biological Potential of Berberis baluchistanica Ahrendt Bark, Leaf, and Root Extracts.

Berberis baluchistanica Ahrendt is a medicinal plant known to have potential for the treatment of various diseases. In the present study, the ethanolic extracts of the bark, leaves, and roots of B. baluchistanica plant were evaluated for in vitro antimicrobial, anti-leishmanial, anticancer, and anti-inflammatory activities. The antibacterial and antifungal activities were determined by agar mix and agar well diffusion method. All extracts showed potential activity against the target bacteria (Bacillus subtilis, Bacillus licheniformis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Rhodococcus erythropolis, Salmonella typhi, and Staphylococcus aureus) and fungal strains (Aspergillus flavus, Aspergillus niger, and Mucor mucedo). S. aureus proved to be the most sensitive strain for each extract, with a maximum zone of inhibition for bark at 23 ± 0.12 mm, for leaves at 22 ± 0.36 mm, and for root extracts at 20.21 ± 0.06 mm). The minimum inhibitory concentration values of B. baluchistanica bark, leaves, and roots for different target bacterial strains ranged from 1.56 to 25 mg ml–1, and the minimum bactericidal concentrations were in the range of 3.12 to 25 mg ml–1, respectively. The root extract possessed potent antifungal activity against A. flavus with 83% of growth inhibition, A. niger with 80%, and M. mucedo with 73%. The bark extract was found active against M. mucedo with 86% of inhibition, followed by 70% against A. flavus and 60% against A. niger. The leaf extract showed a significant response by 83% inhibition against M. mucedo, followed by A. flavus and A. niger with 73 and 72% inhibition, respectively. In an anti-leishmanial bioassay, the inhibitory concentration (IC50) was observed for each extract against Leishmania major. The bark showed good activity (IC50 = 4.95 ± 0.36 mg/ml), followed by the roots (IC50 = 7.07 ± 0.18 mg/ml) and the leaves (IC50 = 8.25 ± 0.29 mg/ml). An evaluation of anticancer activity was done by using MTT cell assay against HeLa cell line. Upon comparing the values of each extract to the standard, it was revealed that the ethanolic bark extract showed the highest anticancer activity with IC50 = (12 ± 0.15 μg/ml), followed by the roots (14 ± 0.15 μg/ml) and the leaves (17 ± 0.21 μg/ml), respectively. The anti-inflammatory assay was undertaken by the inhibition of albumin denaturation activity, proteinase inhibitory activity, and heat-induced hemolysis activity. The IC50 value for protein denaturation of the bark was IC50 = 0.64 ± 0.25 mg/ml, followed by the roots (0.67 ± 0.21 mg/ml) and the leaves (0.73 ± 0.13 mg/ml). The proteinase inhibitory activity of the bark extract was IC50 = 0.55 ± 0.12 mg/ml, followed by the leaves (0.62 ± 0.23 mg/ml) and the roots (0.69 ± 0.15 mg/ml), respectively. For heat-induced hemolysis assay, the bark showed the lowest IC50 value (0.48 ± 0.15 mg/ml) compared to the leaves (0.52 ± 0.35 mg/ml) and the roots (0.58 ± 0.05 mg/ml) of the plant. All analyzed parts of the B. baluchistanica plant showed significant biological activities which make the plant medicinally important and a good candidate for the isolation of antimicrobial, inflammatory, and anticancer compounds. Further studies may lead us to determine the active compounds responsible for the biological activities of the plant extracts.

Safety evaluation of the food enzyme glucose oxidase from the genetically modified Aspergillus niger strain DP-Aze23.

The food enzyme glucose oxidase (β‐D‐glucose:oxygen 1‐oxidoreductase; EC 1.1.3.4) is produced with the genetically modified Aspergillus niger strain DP‐Aze23 by Danisco US, Inc. The genetic modifications do not give rise to safety concerns. The food enzyme is considered free from viable cells of the production organism and its DNA. It is intended to be used in baking processes, cereal‐based processes and egg processing. Based on the maximum use levels, dietary exposure to the food enzyme‐total organic solids (TOS) was estimated to be up to 0.05 mg TOS/kg body weight (bw) per day in European populations. Genotoxicity tests did not indicate a safety concern. The systemic toxicity was assessed by means of a repeated dose 90‐day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 19.55 mg TOS/kg bw per day, the highest dose tested, which, when compared with the estimated dietary exposure, results in a margin of exposure above 380. A search for similarity of the amino acid sequence of the food enzyme to known allergens was made and one match was found. The Panel considered that, under the intended conditions of use, the risk of allergic sensitisation and elicitation reactions by dietary exposure cannot be excluded, but the likelihood for this to occur is considered to be low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns, under the intended conditions of use.

Safety evaluation of the food enzyme glucan 1,4 α-glucosidase from the genetically modified Aspergillus niger strain NZYM-BR.

The food enzyme glucan 1,4‐α‐glucosidase (4‐α‐d‐glucan glucohydrolase, EC 3.2.1.3) is produced with the genetically modified Aspergillus niger strain NZYM‐BR by Novozymes A/S. The genetic modifications do not give rise to safety concerns. The food enzyme is free from viable cells of the production organism and its DNA. The food enzyme is intended to be used in starch processing for the production of glucose syrups and distilled alcohol. Since residual amounts of total organic solids (TOS) are removed by the purification steps applied during the production of glucose syrups and by distillation, dietary exposure estimation was considered not necessary. Genotoxicity tests did not raise a safety concern. The systemic toxicity was assessed by means of a repeated dose 90‐day oral toxicity study in rats. The Panel identified a no observed adverse effect level of 1,135 mg TOS/kg body weight (bw) per day, the highest dose tested. Similarity of the amino acid sequence of the food enzyme to those of known allergens was searched for and two matches were found. The Panel considered that under the intended conditions of use (other than distilled alcohol production) the risk of allergic sensitisation and elicitation reactions by dietary exposure cannot be excluded, but the likelihood for this to occur is considered to be low. Based on the data provided, the Panel concluded that this food enzyme does not give rise to safety concerns under the intended conditions of use.

Biodiesel Production from Bioremediation of Palm Oil Mill Effluent via Oleaginous Fungi

AbstractPalm oil mill effluent (POME) is a by‐product of palm oil production. POME can be considered as harmful waste without any treatment. POME, however, has the potential to be a source of low‐cost carbon for lipid production. This study aims to isolate potential oleaginous fungi from POME and to evaluate the ability of lipid production capacity of the purified isolates and commercial oleaginous fungi strains (Aspergillus niger, Aspergillus oryzae and Rhizopus spp.) from POME. POME is converted into lipid via the metabolic pathway of oleaginous fungi, where the lipids can be further trans‐esterified into microbial biodiesel. In this study, two fungal strains are successfully isolated from POME. The combination of Bligh and Dyer with Soxhlet extraction results in better lipid extraction efficiency. A. niger has the highest lipid yield from the cultivation on POME. The projected fuel properties of microbial biodiesel from A. niger are within the limits of Biodiesel Standard. Chemical oxygen demand (COD) removal from POME using A. niger is proven to be effective with 70% COD removal. The production of biodiesel from wastes of the palm oil industry may improve the industry's sustainability through the use of nonfood feedstock coupled with simultaneous bioremediation of POME.

Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism.

Fatty acid ethyl esters are important flavor chemicals in strong-flavor baijiu. Microorganisms are the main contributors to ester synthesis during baijiu manufacture. However, the ester synthesis was unstable between batches. This was owing to a limited knowledge of the mechanisms for ester synthesis by microorganisms. In this work, a fatty acid ethyl ester synthesizing Aspergillus niger strain CGMCC (China General Microbiological Culture Collection) 3.4309 was identified. The conversion ratios of ethyl valerate, ethyl caproate, ethyl caprylate, and ethyl caprate were 7.87, 29.20, 94.80, and 85.20%, respectively, under the optimized conditions. A comparison of transcriptomes under the initial and optimized ester synthetic conditions indicated that 23 genes were upregulated in transcription level and encoded enzymes with potential abilities for ester synthesis. Eleven of the enzymes were expressed, and three of them, numbered An605, An1097, and An3131, showed the ability to catalyze fatty acid ethyl ester synthesis under aqueous phase, with capric acid as the preferred substrate. The possible enzymatic catalytic mechanism was proposed based on homology modeling and molecular docking. This study reported for the first time that A. niger showed the ability to efficiently catalyze the synthesis of short- and medium-chain fatty acid ethyl esters in aqueous phase, identified the key enzymes, and analyzed the basic enzymatic properties. This is helpful to promote the application of related microorganisms and enzyme resources in the baijiu industry.

Effect of waste grape pomace on citric acid bioproduction by submerged fermentation

Citric acid is of great economic importance due to its wide range of applications. Citric acid, which is a versatile and widely used organic acid, constitutes 60% of organic acids used in the food industry and 10% of those in the pharmaceutical industry. Citric acid is produced using various agricultural wastes as a substrate through solid state or submerged fermentation. In this study waste grape pomace was proposed as a valuable substrate alternative for citric acid production using submerged fermentation. Initially screening of citric acid production capacity was conducted using 6 different Aspergillus niger strains (3 wildtype strains isolated from dried figs and 3 commercial ATCC strains) on synthetic medium. The wild type AN2 was determined as the highest producing strain with 14.32 mg/mL citric acid following 192 h fermentation. Then the waste grape pomace concentration effect on citric acid production was studied by five different concentrations in the range of 100-300 g of pomace in 1 L medium for 192 h fermentation. Using the wild type AN2 strain the highest production of citric acid and yield was achieved with 250 g/L grape pomace concentration as 28.26 mg/mL and 87%, respectively. Moreover, biomass production of the strains in grape pomace medium showed similar pattern with the citric acid production except biomass formation was increased with the grape pomace concentration increases. This study presented that comparing with synthetic medium waste grape pomace can be valuable substrate alternative for citric acid production using submerged fermentation. The study also contributed to the literature as waste grape pomace could be valuable substrate for future research studies

Synthesis and biological evaluation of novel 2‐arylquinoline‐3‐fused thiazolo[2,3‐c]1,2,4‐triazole heterocycles as potential antiproliferative and antimicrobial agents

AbstractA series of novel 2‐arylquinoline‐3‐fused thiazolo[2,3‐c]1,2,4‐triazole heterocycles 9a‐t were efficiently synthesized using simple conventional methods in good yields. The structure of newly synthesized molecules was characterized on the basis of their IR, 1H NMR, 13C NMR and mass spectral data. Among 9a‐t, compounds 9h, 9n, 9b and 9d exhibited highly significant antiproliferative activity against two cancer cell lines C6 (nerve cells) and MCF‐7 (human breast adenocarcinoma cells) when compared with standard reference Doxorubicin. In vitro antimicrobial activities of target compounds 9h, 9b, 9d, 9m and 9n were effectuated on Gram‐positive Staphylococcus aurus (ATCC 25923), Bacillus subtilis (ATCC 6633) and Gram‐negative strains Klebsiella Pneumonia (ATCC 31488) and Escherichia coli (ATCC 25966) strains and found to exhibit promising activity against standard Ciprofloxacin drug. Further, when in vitro antifungal activity was conducted on Aspergillus flavus and Aspergillus niger strains 9h, 9b, 9d and 9n were exhibited potent activity when compared with standard Fluconazole drug moiety.

Development of gelatin-carboxymethylcellulose coatings incorporated with avocado epicarp and coconut endocarp extracts to control fungal growth in strawberries for shelf-life extension

ABSTRACT The objective of this study was to incorporate avocado peel (AEE) and coconut (CEE) extracts as antifungal additive in the development of gelatin and carboxymethylcellulose coatings to extend shelf life in strawberries. Fractions of 200 mg/L of extracts were incorporated in the coating and characterized during storage at 2°C. AEE and CEE in the coating delayed significantly (P < .05) weight loss (40%), softening, color, and compositional changes (°Brix, sugars, titratable acidity). Rhizopus stolonifer and Aspergillus niger strains were isolated and inoculated to evaluate the effectiveness of the coatings on strawberries. The use of the coating + plant extracts decreased the proliferation of fungi by 45% compared to the uncoated fruit and extended the shelf life for 15 days. With these findings, it is suggested that biopolymeric coatings + plant extracts can be used as a potential method of ecological preservation in strawberries against microbial deterioration.

Tungsten Dissolution from Hutti Goldmine Overburden by Aspergillus niger

Tungsten is an important alloying component for the production of different materials. Its efficient extraction from different sustainable resources is necessary to meet the growing demand in the future. In this context, an attempt has been made to recover it from a goldmine overburden sample using the fungal bioleaching technique. The sample contains 0.023% of WO3 in the form of scheelite. The prospect of bioleaching for tungsten recovery from the sample was evaluated by varying pulp density from 1 to 7% (w/v). The leaching rate of tungsten decreased with the increase of pulp density. The maximum tungsten recovery of 86.8% (w/w) could be achieved at the condition of pulp density, 1% (w/v); pH, 6.8; temperature, 32 °C; speed, 120 rpm; contact time, 10 days. Growth of the fungal strain Aspergillus niger in terms of organic acids production was evaluated during the bioleaching experiment and found to be maximum at the pulp density of 1% (w/v). The leaching kinetics of tungsten followed the chemical control model.

Unraveling the Genome Sequence of Plant Growth Promoting Aspergillus niger (CSR3) Provides Insight into the Synthesis of Secondary Metabolites and Its Comparative Genomics.

Aspergillus niger strain CSR3 is an endophytic fungus that regulates plant endogenous hormones, secondary metabolites, and promotes plant growth during abiotic stress conditions. In this study, we sequenced the genome of A. niger (CSR3) and compared it with previously available A. niger strains. The final genome assembly was 35.8 Mb in size, consisting of 23 scaffolds with N50 scaffold length of 2.4 Mb. A total of 12,442 protein coding genes, 270 tRNA, and 57 rRNA were predicted in the CSR3 genome. We used comparative genomic analysis to provide insights into the genome’s evolution and to elucidate the adaptive genomic signatures for bioactive secondary metabolite biosynthesis, hormones biosynthesis, and plant growth promoting activities. We also analyzed the transposable elements (TEs), simple sequence repeats (SSRs), CAZymes families, genes involved in gibberellin biosynthesis, and secondary metabolite clusters in the CSR3 genome. A total of 21 secondary metabolite biosynthesis gene clusters were detected, with 18 essential enzymes involved in the mevalonate pathway (MVA). The repeat analysis revealed about 3431 SSR, 274 TEs, and 205 inverted repeats (IR). Further gene family analysis revealed that 124 gene families were gained, whereas 125 gene families were lost in CSR3 genome, compared to A. niger ASM151534V and A. niger ASM285V2 genomes. The results improve our understanding of the CSR3 genome and will assist in future investigations on the genetic basis of A. niger CSR3, including the identification of CSR3 phytostimulant properties.

Salt and nitrogen amendment and optimization for cellulase and xylanase production using dilute acid hydrolysate of distillers' dried grains with solubles (DDGS) as the feedstock.

Distillers' dried grains with solubles (DDGS) is a by-product of dry-mill corn ethanol production comprising a high nutritional value due to residual fiber, protein, and lipid contents. The fiber content of DDGS is high enough to be considered a valuable source for the production of hydrolytic enzymes, such as cellulase and xylanases, which can be used for hydrolysis of lignocellulosic feedstock during ethanol production. The DDGS-based medium prepared after acid hydrolysis provides adequate sugars for enzyme production, while additional macronutrients, such as salts and nitrogen sources, can enhance the enzyme production. Therefore, this study was undertaken to evaluate the effect of salts (KH2PO4, CaCl2·2H2O, MgSO4·7H2O, FeSO4·7H2O, CoCl2·6H2O, and MnSO4·H2O), peptone, and yeast extract on enzyme secretion by four different Aspergillus niger strains and to optimize the nitrogen source for maximum enzyme production. Yeast extract improved the cellulase production (0.38IU/ml) for A. niger (NRRL 1956) as compared to peptone (0.29IU/ml). However, maximum cellulase productions of 0.42IU/ml and 0.45IU/ml were obtained by A. niger (NRRL 330) and A. niger (NRRL 567), respectively, in presence of ammonium sulfate. The optimized nitrogen amounts resulted in a significant increase in the cellulase production from 0.174 to 0.63IU/ml on day 9 of the fermentation with A. niger (NRRL 330). The composite model improved both cellulase and xylanase production. In conclusion, the optimization of all three nitrogen sources improved both cellulase and xylanase production in the DDGS-based media.