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Bioresources and Bioprocessing Apr 2022Plastic polymers are non-degradable solid wastes that have become a great threat to the whole world and degradation of these plastics would take a few decades. Compared... (Review)
Review
Plastic polymers are non-degradable solid wastes that have become a great threat to the whole world and degradation of these plastics would take a few decades. Compared with other degradation processes, the biodegradation process is the most effective and best way for plastic degradation due to its non-polluting mechanism, eco-friendly nature, and cost-effectiveness. Biodegradation of synthetic plastics is a very slow process that also involves environmental factors and the action of wild microbial species. In this plastic biodegradation, fungi play a pivotal role, it acts on plastics by secreting some degrading enzymes, i.e., cutinase`, lipase, and proteases, lignocellulolytic enzymes, and also the presence of some pro-oxidant ions can cause effective degradation. The oxidation or hydrolysis by the enzyme creates functional groups that improve the hydrophilicity of polymers, and consequently degrade the high molecular weight polymer into low molecular weight. This leads to the degradation of plastics within a few days. Some well-known species which show effective degradation on plastics are Aspergillus nidulans, Aspergillus flavus, Aspergillus glaucus, Aspergillus oryzae, Aspergillus nomius, Penicillium griseofulvum, Bjerkandera adusta, Phanerochaete chrysosporium, Cladosporium cladosporioides, etc., and some other saprotrophic fungi, such as Pleurotus abalones, Pleurotus ostreatus, Agaricus bisporus and Pleurotus eryngii which also helps in degradation of plastics by growing on them. Some studies say that the degradation of plastics was more effective when photodegradation and thermo-oxidative mechanisms involved with the biodegradation simultaneously can make the degradation faster and easier. This present review gives current knowledge regarding different species of fungi that are involved in the degradation of plastics by their different enzymatic mechanisms to degrade different forms of plastic polymers.
PubMed: 38647755
DOI: 10.1186/s40643-022-00532-4 -
PeerJ 2020, as a genus of filamentous fungi, has members that display a variety of different behavioural strategies, which are affected by various environmental factors. The...
, as a genus of filamentous fungi, has members that display a variety of different behavioural strategies, which are affected by various environmental factors. The decoded genomic sequences of many species vary greatly in their evolutionary similarities, encouraging studies on the functions and evolution of the genome in complex natural environments. Here, we present the 26 Mb de novo assembled high-quality reference genome of 'China Changchun halophilic ' (CCHA), which was isolated from the surface of plants growing near a salt mine in Jilin, China, based on data from whole-genome shotgun sequencing using Illumina Solexa technology. The sequence, coupled with data from comprehensive transcriptomic survey analyses, indicated that the redox state and transmembrane transport might be critical molecular mechanisms for the adaptation of 'CCHA' to the high-salt environment of the saltern. The isolation of salt tolerance-related genes, such as , and their overexpression in demonstrated that 'CCHA' is an excellent organism for the isolation and identification of salt tolerant-related genes. These data expand our understanding of the evolution and functions of fungal and microbial genomes, and offer multiple target genes for crop salt-tolerance improvement through genetic engineering.
PubMed: 32140304
DOI: 10.7717/peerj.8609 -
3 Biotech Jul 2017Fipronil is a phenylpryazole insecticide which is extensively used for the protection of agricultural yields. However, this insecticide poses various threats to...
Fipronil is a phenylpryazole insecticide which is extensively used for the protection of agricultural yields. However, this insecticide poses various threats to the environment. Therefore it is essential to develop an effective method to degrade or eliminate this pollutant from the environment. In this present study, a fungal strain AJAG1 capable of degrading fipronil and its metabolite, fipronil sulfone, was isolated through enrichment technique. Isolated fungal strain was identified as Aspergillus glaucus based upon its morphological, and 18S rRNA sequence analysis. Strain AJAG1 could degrade 900 mg L of fipronil efficiently in both aqueous medium and soil. In addition, fipronil degradation was tested with various kinetic models and the results revealed that biodegradation in aqueous medium and soil was ascertained by pseudo-first order and zero order rate kinetics, respectively. The infrared spectrum of fipronil degraded sample confirmed the formation of esters, nitro, and alkanes groups. A tentative degradation pathway of fipronil by strain AJAG1 has been proposed on the basis of gas chromatography-mass spectrometry (GC-MS) analysis. The lignolytic enzymes activities were studied during fipronil degradation by strain AJAG1. Further, scanning electron microscopy (SEM) was used to examine the surface morphology of strain AJAG1 after fipronil degradation. In the present investigation, bioformulation of strain AJAG1 was developed using low cost materials such as groundnut shell powder, molasses, and fly ash to remediate the fipronil from agricultural field. These results highlight A. glaucus strain AJAG1 may have potential for use in bioremediation of fipronil-contaminated environment.
PubMed: 28667652
DOI: 10.1007/s13205-017-0820-8 -
Bioresources and Bioprocessing Oct 2023Tannases are valuable industrial enzymes used in food, pharmaceutical, cosmetic, leather manufacture and in environmental biotechnology. In this study, 15 fungal...
Tannases are valuable industrial enzymes used in food, pharmaceutical, cosmetic, leather manufacture and in environmental biotechnology. In this study, 15 fungal isolates were obtained from Egyptian cultivated soil and marine samples. The isolated fungi were qualitatively and quantitatively screened for their abilities to produce tannase. The selected fungal isolate NRC8 giving highest tannase activity was identified by molecular technique (18S rRNA) as Aspergillus glaucus. Among different tannin-containing wastes tested, the black tea waste was the best substrate for tannase production by Aspergillus glaucus in solid-state fermentation (SSF). Optimization of the different process parameters required for maximum enzyme production was carried out to design a suitable SSF process. Maximal tannase production was achieved with moisture content of 75%, an inoculums size of 6 × 10 spore/ml and sodium nitrate 0.2% (pH of 5.0) at 30 °C after 5 days of incubation. Box-Behnken experiment was designed to get a quadratic model for further optimization studies. Four-factor response-surface method with 27 runs was prepared using independent parameters including (moisture content %, initial pH, substrate concentration (g) and sodium nitrate concentration (g) for tannase model. The F- and P-values of the model were 4.30 and 0.002, respectively, which implied that the model is significant. In addition, the lack-of-fit was 1040.37 which indicates the same significance relative to the pure error. A. glaucus tannase was evaluated by the efficiency of conversion of tannic acid to gallic acid. Moreover, production of gallic acid from SSF process of A. glaucus using black tea waste was found to be 38.27 mg/ml. The best bioconversion efficiency was achieved at 40 °C with tannic acid concentration up to 200 g/L.
PubMed: 38647901
DOI: 10.1186/s40643-023-00686-9 -
Frontiers in Microbiology 2022Microbial consortia with high cellulase activities can speed up the composting of agricultural wastes with high cellulose contents and promote the beneficial utilization...
Microbial consortia with high cellulase activities can speed up the composting of agricultural wastes with high cellulose contents and promote the beneficial utilization of agricultural wastes. In this paper, rabbit feces and sesame oil cake were used as feedstocks for compost production. Cellulose-degrading microbial strains were isolated from compost samples taken at the different composting stages and screened Congo red staining and filter paper degradation test. Seven strains, , , , , , , and , with high activities of carboxymethyl cellulase (CMCase), filter paper cellulase (FPase), and β-glucosidase (β-Gase) were identified and selected for consortium design. Six microbial consortia were designed with these strains. Compared with the other five consortia, consortium VI composed of all seven strains displayed the highest cellulase activities, 141.89, 104.56, and 131.18 U/ml of CMCase, FPase, and β-Gase, respectively. The single factor approach and response surface method were employed to optimize CMCase production of consortium VI. The optimized conditions were: culture time 4.25 days, culture temperature 35.5°C, pH 6.6, and inoculum volume 5% (v/v). Under these optimized conditions, the CMCase activity of consortium VI was up to 170.83 U/ml. Fermentation experiment of rabbit feces was carried out by using the consortium VI cultured under the optimal conditions. It was found that the application effect was better than other treatments, and the fermentation efficiency and nutrient content of the pile were significantly improved. This study provides a basis for the design of microbial consortia for the composting of agricultural wastes with high cellulose contents and provides a support for beneficial utilization of agricultural wastes.
PubMed: 35910619
DOI: 10.3389/fmicb.2022.957444 -
Applied Microbiology and Biotechnology Apr 2023Industrial fungi need a strong environmental stress tolerance to ensure acceptable efficiency and yields. Previous studies shed light on the important role that...
Industrial fungi need a strong environmental stress tolerance to ensure acceptable efficiency and yields. Previous studies shed light on the important role that Aspergillus nidulans gfdB, putatively encoding a NAD-dependent glycerol-3-phosphate dehydrogenase, plays in the oxidative and cell wall integrity stress tolerance of this filamentous fungus model organism. The insertion of A. nidulans gfdB into the genome of Aspergillus glaucus strengthened the environmental stress tolerance of this xerophilic/osmophilic fungus, which may facilitate the involvement of this fungus in various industrial and environmental biotechnological processes. On the other hand, the transfer of A. nidulans gfdB to Aspergillus wentii, another promising industrial xerophilic/osmophilic fungus, resulted only in minor and sporadic improvement in environmental stress tolerance and meanwhile partially reversed osmophily. Because A. glaucus and A. wentii are phylogenetically closely related species and both fungi lack a gfdB ortholog, these results warn us that any disturbance of the stress response system of the aspergilli may elicit rather complex and even unforeseeable, species-specific physiological changes. This should be taken into consideration in any future targeted industrial strain development projects aiming at the fortification of the general stress tolerance of these fungi. KEY POINTS: • A. wentii c' gfdB strains showed minor and sporadic stress tolerance phenotypes. • The osmophily of A. wentii significantly decreased in the c' gfdB strains. • Insertion of gfdB caused species-specific phenotypes in A. wentii and A. glaucus.
Topics: Aspergillus nidulans; Fungal Proteins; Glycerolphosphate Dehydrogenase; Stress, Physiological; Phenotype
PubMed: 36811707
DOI: 10.1007/s00253-023-12384-9 -
Applied and Environmental Microbiology Oct 2015Aquaglyceroporins (GlpFs) that transport glycerol along with water and other uncharged solutes are involved in osmoregulation in myriad species. Fungal species form a...
Aquaglyceroporins (GlpFs) that transport glycerol along with water and other uncharged solutes are involved in osmoregulation in myriad species. Fungal species form a large group of eukaryotic organisms, and their GlpFs may be diverse, exhibiting various activities. However, few filamentous fungal GlpFs have been biologically investigated. Here, a glpF gene from the halophilic fungus Aspergillus glaucus (AgglpF) was verified to be a channel of water or glycerol in Xenopus laevis oocytes and was further functionally analyzed in three heterologous systems. In Saccharomyces cerevisiae, cells overexpressing AgglpF possessed significant tolerance of drought, salt, and certain metal ions. AgglpF was then characterized in the filamentous fungus of Neurospora crassa. Based on the N. crassa aquaporin gene (NcAQP) disruption mutant (the Δaqp mutant), a series of complementary strains carrying NcAQP and AgglpF and three asparagine-proline-alanine-gene (NPA)-deleted AgglpF fragments were created. As revealed by salt resistance analysis, the AgglpF complementary strain possessed the highest salt resistance among the tested strains. In addition, the intracellular glycerol content in the AgglpF complementary strain was markedly higher than that in the other strains. The AgGlpF-green fluorescent protein (GFP) fusion protein was subcellularly localized in the plasma membrane of onion epidermal cells, suggesting that AgglpF functions in plants. Indeed, when AgglpF was expressed in Arabidopsis thaliana, transgenic lines survived under conditions of high osmotic stress and under conditions of drought stress in particular. Overall, our results revealed that AgGlpF as a water/glycerol transporter is required for survival of both fungi and plants under conditions of high osmotic stress and may have value in applications in genetic engineering for generating high salt and drought resistance.
Topics: Animals; Aquaglyceroporins; Arabidopsis; Aspergillus; Droughts; Fungal Proteins; Gene Expression; Glycerol; Oocytes; Osmosis; Plants, Genetically Modified; Saccharomyces cerevisiae; Water; Xenopus laevis
PubMed: 26209670
DOI: 10.1128/AEM.02127-15 -
Fungal Biology May 2016The Antarctic fungal strain Aspergillus glaucus 363 produces cold-active (CA) Cu/Zn-superoxide dismutase (SOD). The strain contains at least one gene encoding Cu/Zn-SOD...
The Antarctic fungal strain Aspergillus glaucus 363 produces cold-active (CA) Cu/Zn-superoxide dismutase (SOD). The strain contains at least one gene encoding Cu/Zn-SOD that exhibited high homology with the corresponding gene of other Aspergillus species. To our knowledge, this is the first nucleotide sequence of a CA Cu/Zn-SOD gene in fungi. An effective laboratory technology for A. glaucus SOD production in 3 L bioreactors was developed on the basis of transient cold-shock treatment. The temperature downshift to 10 °C caused 1.4-fold increase of specific SOD activity compared to unstressed culture. Maximum enzyme productivity was 64 × 10(3) U kg(-1) h(-1). Two SOD isoenzymes (Cu/Zn-SODI and Cu/Zn-SODII) were purified to electrophoretic homogeneity. The specific activity of the major isoenzyme, Cu/Zn-SODII, after Q-Sepharose chromatography was 4000 U mg(-1). The molecular mass of SODI (38 159 Da) and of SODII (15 835 Da) was determined by electrospray quadropole time-of-flight (ESI-Q-TOF) mass spectrometry and dynamic light scattering (DLS). The presence of Cu and Zn were confirmed by inductively coupled plasma mass spectrometry (ICP-MS). The N-terminal amino acid sequence of Cu/Zn-SODII revealed a high degree of structural homology with Cu/Zn-SOD from other fungi, including Aspergillus species.
Topics: Antarctic Regions; Aspergillus; Cold Temperature; Conserved Sequence; Copper; Mass Spectrometry; Molecular Weight; Sequence Analysis, DNA; Sequence Homology, Amino Acid; Superoxide Dismutase; Zinc
PubMed: 27109365
DOI: 10.1016/j.funbio.2016.03.002 -
Microbial Cell Factories May 2014For filamentous fungi, the basic growth unit of hyphae usually makes it sensitive to shear stress which is generated from mechanical force and dynamic fluid in...
BACKGROUND
For filamentous fungi, the basic growth unit of hyphae usually makes it sensitive to shear stress which is generated from mechanical force and dynamic fluid in bioreactor, and it severely decreases microbial productions. The conventional strategies against shear-sensitive conundrum in fungal fermentation usually focus on adapting agitation, impeller type and bioreactor configuration, which brings high cost and tough work in industry. This study aims to genetically shape shear resistant morphology of shear-sensitive filamentous fungus Aspergillus glaucus to make it adapt to bioreactor so as to establish an efficient fermentation process.
RESULTS
Hyphal morphology shaping by modifying polarized growth genes of A. glaucus was applied to reduce its shear-sensitivity and enhance aspergiolide A production. Degenerate PCR and genome walking were used to obtain polarized growth genes AgkipA and AgteaR, followed by construction of gene-deficient mutants by homologous integration of double crossover. Deletion of both genes caused meandering hyphae, for which, ΔAgkipA led to small but intense curves comparing with ΔAgteaR by morphology analysis. The germination of a second germ tube from conidiospore of the mutants became random while colony growth and development almost maintained the same. Morphology of ΔAgkipA and ΔAgteaR mutants turned to be compact pellet and loose clump in liquid culture, respectively. The curved hyphae of both mutants showed no remarkably resistant to glass bead grinding comparing with the wild type strain. However, they generated greatly different broth rheology which further caused growth and metabolism variations in bioreactor fermentations. By forming pellets, the ΔAgkipA mutant created a tank environment with low-viscosity, low shear stress and high dissolved oxygen tension, leading to high production of aspergiolide A (121.7 ± 2.3 mg/L), which was 82.2% higher than the wild type.
CONCLUSIONS
A new strategy for shaping fungal morphology by modifying polarized growth genes was applied in submerged fermentation in bioreactor. This work provides useful information of shaping fungal morphology for submerged fermentation by genetically modification, which could be valuable for morphology improvement of industrial filamentous fungi.
Topics: Anthraquinones; Antineoplastic Agents; Aspergillus; Batch Cell Culture Techniques; Fungal Proteins; Mutation; Open Reading Frames; Polyketides
PubMed: 24886193
DOI: 10.1186/1475-2859-13-73 -
Applied Microbiology Jul 1962Numbers and kinds of microflora were determined in 160 samples of barley grown in different regions of the United States; microflora were more abundant in the grains...
Numbers and kinds of microflora were determined in 160 samples of barley grown in different regions of the United States; microflora were more abundant in the grains grown in the central states than in those grown in the western states. During steeping and germination in micromalting equipment, the number of colonies of filamentous fungi increased from two to five times, colonies of yeasts from five to ten times, and bacteria from 50 to more than 100 times the numbers present in the grain before malting. Kiln drying according to a commercial schedule reduced the number of all types of microflora below the number present before kilning, but all were present in larger numbers in the kilned malt than in the original grain. In barley stored at room temperature and at a moisture content of 15 to 18%, members of the Aspergillus glaucus group increased with increasing time and increasing moisture content, and germination percentage of the seeds decreased. Stored free of storage fungi at room temperature, barley with a moisture content just over 15% retained a high germination percentage for 5 months, but at a moisture content of 16% the germination decreased to zero.
Topics: Bacteria; Desiccation; Edible Grain; Fungi; Germination; Hordeum; Seeds
PubMed: 13893856
DOI: 10.1128/am.10.4.331-336.1962