Chemical Composition, Antibacterial Activity and Mechanism of Action of Fermentation Products from Aspergillus Niger xj.

Six compounds were isolated and purified from the crude acetone extract of Aspergillus niger xj. Characterization of all compounds was done by NMR and MS. On the basis of chemical and spectral analysis structure, six compounds were elucidated as metazachlor (1), nonacosane (2), palmitic acid (3), 5,5'-oxybis(5-methylene-2-furaldehyde) (4), dimethyl 5-nitroisophthalate (5) and cholesta-3,5-dien-7-one (6), respectively, and compounds 1, 4, 5 and 6 were isolated for the first time from A. niger. To evaluate the antibacterial activity of compounds 1-6 against three plant pathogenic bacteria (Agrobacterium tumefaciens T-37, Erwinia carotovora EC-1 and Ralstonia solanacearum RS-2), and the minimum inhibitory concentrations (MICs) were determined by broth microdilution method in 96-well microtiter plates. Results of the evaluation of the antibacterial activity showed that T-37 strain was more susceptible to metazachlor with the lowest MIC of 31.25 µg/mL. The antibacterial activity of metazachlor has rarely been reported, thus the antibacterial mechanism of metazachlor against T-37 strain were investigated. The permeability of cell membrane demonstrated that cells membranes were broken by metazachlor, which caused leakage of ions in cells. SDS-PAGE of T-37 proteins indicated that metazachlor could damage bacterial cells through the destruction of cellular proteins. Scanning electron microscopy results showed obvious morphological and ultrastructural changes in the T-37 cells, further confirming the cell membrane damages caused by metazachlor. Overall, our findings demonstrated that the ability of metazachlor to suppress the growth of T-37 pathogenic bacteria makes it potential biocontrol agents.

Microbial Transformation of the Sesquiterpene Lactone, Vulgarin, by Aspergillus niger.

The biotransformation of vulgarin (1), an eudesmanolides-type sesquiterpene lactone obtained from Artemisia judaica, by the microorganism, Aspergillus niger, was carried out to give three more polar metabolites; 1-epi-tetrahydrovulgarin (1α,4α-dihydroxy-5αH,6,11ßH-eudesman-6,12-olide (2), 20% yield, 1α,4α-dihydroxyeudesm-2-en-5αH,6,11ßH-6,12-olide (3a), 10% yield, and C-1 epimeric mixture (3a, b), 4% yield, in a ratio of 4:1, 3a/3b. The structures of vulgarin and its metabolites were elucidated by 1 and 2D NMR spectroscopy in conjunction with HRESIMS. Metabolites (3a) and (3b) are epimers, and they are reported here for the first time as new metabolites obtained by biotransformation by selective reduction at C-1. Vulgarin and its metabolites were evaluated as anti-inflammatory agents using the human cyclooxygenase (COX) inhibitory assay. The obtained data showed that (1) exhibited a good preferential inhibitory activity towards COX-2 (IC50 = 07.21 ± 0.10) and had a moderate effect on COX-1 (IC50 = 11.32 ± 0.24). Meanwhile, its metabolite (3a) retained a selective inhibitory activity against COX-1 (IC50 = 15.70 ± 0.51). In conclusion, the results of this study revealed the necessity of the presence α, ß unsaturated carbonyl group in (1) for better COX-2 inhibitory activity. On the other hand, the selectivity of (1) as COX-1 inhibitor may be enhanced via the reduction of C-1 carbonyl group.

Xylanase covalent binding onto amidated pectin beads: Optimization, thermal, operational and storage stability studies and application.

Amidated pectin-polyethylene imine-glutaraldehyde (AP-PEI-GA) immobilizer was prepared. The ideal protocol that should be adopted during the immobilizer preparation was investigated via Box-Behnken design (BBD), and it comprised processing the AP beads with 3.4 % (w/w) PEI solution of pH 9.65 followed by 5.96 % (v/v) GA solution. The obtained AP-PEI-GA immobilizer was efficient, and it acquired 3.03 U.g-1 of immobilized xylanase (im-xylanase) activity. The computed Km and Vmax values for AP-PEI-GA im-xylanase were 16.67 mg.ml-1 and 20 g.ml-1.min-1, respectively. Through covalent coupling to AP-PEI-GA, Aspergillus niger xylanase thermodynamic properties T1/2 and D-values were increased by 2.05, 3.08, and 1.35 at 40, 50, and 60 °C, respectively. ΔHd and ΔGd for AP-PEI-GA im-xylanase at 40, 50, and 60 °C were higher than those for free form emphasizing more resistance to thermal denaturation. Im-xylanase showed 100 % activity for 20 successive cycles and hydrolyzed different agro-industrial wastes into reducing sugar and xylooligosaccharides (XOS) with more efficiency on pea peel (PP). AP-PEI-GA im-xylanase, PP weight, and hydrolysis time that should be adopted to obtain the highest reducing sugar and XOS yield were optimized through central composite design (CCD). Extracted XOS showed prebiotic and anti-oxidant activities.

Chitosan coated - biogenic silver nanoparticles from wheat residues as green antifungal and nanoprimig in wheat seeds.

In this study, chitosan-coated biogenic silver nanoparticles (AgNP-CH) were obtained through green chemistry by recycling wheat crop leaf residues. The nanoparticles were characterized by UV-VIS spectroscopy, and total reflectance-Fourier transform infrared spectroscopy confirmed the nanoparticle formation, and the incorporation of chitosan surrounding silver nanoparticles. The size and morphology of nanoparticles were evaluated by microscopy techniques, showing a size range of 2-10 nm, with spherical shape and narrow distribution. The antifungal assay indicated a higher antimicrobial activity showing values of minimum inhibitory concentrations of 41.7 µg/mL against Fusarium oxysporum, and 208.37 µg/mL for Aspergillus niger, A. versicolor and A. brasiliensis. Finally, non-phytotoxic effects were observed in germination assays at early plant stage of development, and an increase in chlorophyll levels were observed at the doses tested with AgNP-CH. Thus, the use of AgNP-CH could be a potential alternative for the prevention of fungal infections in cereals in the early stages of wheat crop development.

Production, concentration and partial characterization of an enzymatic extract produced by an Aspergillus niger mutant in solid state fermentation.

An enzymatic extract from Aspergillus niger 3T5B8 was produced by Solid State Fermentation (SSF) in aerated columns, using wheat bran as substrate. A combination of extracts produced using three different process conditions varying temperature, pH and aeration formed the final extract (Mixture). The Mixture was concentrated by an ultrafiltration process that partially purified and provided an efficient recovery of the enzymatic activities of xylanase (88.89%), polygalacturonase (89.3%), ß-glucosidase (93.15%), protease (98.68%) and carboxymethylcellulase (CMCase) (98.93%). SDS-PAGE analysis showed 15 visible protein bands in the crude and concentrated Mixture with molecular weights ranging from 15.1 to 104.6 kDa. Thin layer chromatography confirmed the effective action of ß-glucosidase and xylanase hydrolysis activities over cellobiose and xylan, respectively. A central composite design (CCD) with two variables and four replicates at the center points was used to determine the optimal temperature and pH for CMCase and ß-glucosidase. The optimal temperature was 78.9 °C and pH 3.8 for CMCase and 52.8 °C and pH 4.8 for ß-glucosidase, respectively.

Predictive modeling and sensitivity analysis to estimate the experimental data of inulinase fermentation by Aspergillus niger grown on sugar beet molasses-based medium optimized using Plackett-Burman Design.

The present work aimed to model Aspergillus niger inulinase fermentation performed in the medium using sigmoidal functions, validate the selected models using an independent set of the experimental values, and perform a sensitivity analysis of the selected models. Based on the results, the selected models were Stannard and Fitzhugh models for substrate consumption (R2  = 0.9976 and 0.9974, respectively), Huang model for inulinase production (R2  = 0.9967), Weibull model for invertase-type production (R2  = 0.9963), and modified logistic model for invertase-type activity/inulinase activity ratio (R2  = 0.9292) with high R2 values (>0.90). Kinetics predicted by particularly selected models mentioned above fit well with the experimental kinetic results. Besides, validation of the selected models with an independent set of the experimental data indicated that they gave satisfying results with high R2 values for consumption and production (R2  > 0.90). Sensitivity analysis of the selected models showed that the yielded R2 values (R2  ≥ 0.9775) were in good agreement with those obtained from the selected models. Consequently, A. niger inulinase fermentation was successfully modeled and the selected models were successfully validated with an independent set of the observed data. Besides, the sensitivity analysis also verified the reliability of the selected models. Those models can serve as universal equations to describe the A. niger inulinase fermentation.

Biotransformation of the Phenolic Constituents from Licorice and Cytotoxicity Evaluation of Their Metabolites.

Biotransformation of four bioactive phenolic constituents from licorice, namely licoisoflavanone (1), glycyrrhisoflavone (2), echinatin (3), and isobavachalcone (4), was performed by the selected fungal strain Aspergillus niger KCCM 60332, leading to the isolation of seventeen metabolites (5-21). Structures of the isolated compounds were determined on the basis of extensive spectroscopic methods, twelve of which (5-7, 10-17 and 19) have been previously undescribed. A series of reactions including hydroxylation, hydrogenation, epoxidation, hydrolysis, reduction, cyclization, and alkylation was observed in the biotransformation process. All compounds were tested for their cytotoxic activities against three different human cancer cell lines including A375P, MCF-7, and HT-29. Compounds 1 and 12 exhibited most considerable cytotoxic activities against all the cell lines investigated, while compounds 2 and 4 were moderately cytotoxic. These findings will contribute to expanding the chemical diversity of phenolic compounds, and compounds 1 and 12 may serve as leads for the development of potential cancer chemopreventive agents.

The Cultivation Method Affects the Transcriptomic Response of Aspergillus niger to Growth on Sugar Beet Pulp.

In nature, filamentous fungi are exposed to diverse nutritional sources and changes in substrate availability. Conversely, in submerged cultures, mycelia are continuously exposed to the existing substrates, which are depleted over time. Submerged cultures are the preferred choice for experimental setups in laboratory and industry and are often used for understanding the physiology of fungi. However, to what extent the cultivation method affects fungal physiology, with respect to utilization of natural substrates, has not been addressed in detail. Here, we compared the transcriptomic responses of Aspergillus niger grown in submerged culture and solid culture, both containing sugar beet pulp (SBP) as a carbon source. The results showed that expression of CAZy (Carbohydrate Active enZyme)-encoding and sugar catabolic genes in liquid SBP was time dependent. Moreover, additional components of SBP delayed the A. niger response to the degradation of pectin present in SBP. In addition, we demonstrated that liquid cultures induced wider transcriptome variability than solid cultures. Although there was a correlation regarding sugar metabolic gene expression patterns between liquid and solid cultures, it decreased in the case of CAZyme-encoding genes. In conclusion, the transcriptomic response of A. niger to SBP is influenced by the culturing method, limiting the value of liquid cultures for understanding the behavior of fungi in natural habitats. IMPORTANCE Understanding the interaction between filamentous fungi and their natural and biotechnological environments has been of great interest for the scientific community. Submerged cultures are preferred over solid cultures at a laboratory scale to study the natural response of fungi to different stimuli found in nature (e.g., carbon/nitrogen sources, pH). However, whether and to what extent submerged cultures introduce variation in the physiology of fungi during growth on plant biomass have not been studied in detail. In this study, we compared the transcriptomic responses of Aspergillus niger to growth on liquid and solid cultures containing sugar beet pulp (a by-product of the sugar industry) as a carbon source. We demonstrate that the transcriptomic response of A. niger was highly affected by the culture condition, since the transcriptomic response obtained in a liquid environment could not fully explain the behavior of the fungus in a solid environment. This could partially explain the differences often observed between the phenotypes on plates compared to liquid cultures.

Enzymatically synthesized α-galactooligosaccharides attenuate metabolic syndrome in high-fat diet induced mice in association with the modulation of gut microbiota.

The composition and structure of gut microbiota plays an important role in obesity induced by a high-fat diet (HFD) and related metabolic syndrome (MetS). Previous studies have shown that galacto-oligosaccharides (GOSs) have an effective anti-obesity effect. In this study, we aimed to investigate the effect of enzymatically synthesized α-galacto-oligosaccharides (ES-α-GOSs) on MetS and gut microbiota dysbiosis in HFD-fed mice, and to further investigate whether the attenuation of MetS is associated with the modulation of gut microbiota. Our results indicated that ES-α-GOS could notably ameliorate obesity-related MetS, including hyperlipidemia, insulin resistance and mild inflammation. The subsequent analysis of gut microbiota further showed that ES-α-GOS supplements can significantly modulate the overall composition of the gut microbiota and reverse the gut microbiota disorder caused by HFD feeding. Moreover, Spearman correlation analysis showed that 40 key bacteria reversed by ES-α-GOS were highly associated with metabolic parameters. These results suggested that ES-α-GOSs could serve as a potential candidate for preventing obesity-induced MetS in association with the modulation of gut microbiota.

Influence of Eurotium cristatum and Aspergillus niger individual and collaborative inoculation on volatile profile in liquid-state fermentation of instant dark teas.

The three instant dark teas were produced from instant green tea (IGT) by liquid-state fermentations using the microorganisms Eurotium cristatum (EFT), Aspergillus niger (AFT), and sequential inoculation of E. cristatum/A. niger (EAFT), respectively. The volatile compounds of four tea samples were extracted by headspace-solid phase microextraction (HS-SPME) and analyzed using gas chromatography-mass spectrometry (GC-MS) coupled with chemometrics. A total of 97 volatile compounds were tentatively identified to distinguish three fermented instant dark from IGT. Alcohols, acids, esters, ketones, aldehydes, and heterocyclics could be clearly distinguished by principal component analysis (PCA), venn diagram, heatmap analysis and hierarchical cluster analysis (HCA). Descriptive sensory analysis revealed that AFT had a moldy, woody and herbal aroma; EFT showed woody and herbal aroma; and EAFT smelled an herbal, sweet, minty and floral aroma. This study indicates that fermentation using different microorganisms is critical in forming unique aroma characteristics of instant dark teas.

Specialized antiplasmodial secondary metabolites from Aspergillus niger 58, an endophytic fungus from Terminalia catappa.

ETHNOPHARMACOLOGICAL RELEVANCE: Terminalia catappa L. (West Indian-Almond) is a medicinal plant used in traditional medicine for the treatment of infectious diseases. Moreover, various organic extracts prepared from this plant have been reported to exhibit antiplasmodial activity. AIM OF THE STUDY: The need for new antimalarials is still an urgency driven by the alarmingly high burden of malaria in endemic regions, with multitude of people dying annually. We have previously identified an endophytic fungus Aspergillus niger 58 harboured by T. catappa as having promising specialized secondary metabolites against the malaria parasites. In the present study, we report the antiplasmodial activity-guided chromatographic isolation of some metabolites secreted by this endophytic fungus. MATERIALS AND METHODS: The SYBR Green I-based fluorescence microtiter plate assay was used to monitor the growth of Plasmodium falciparum parasites in culture in the presence and absence of inhibitors and results were validated by microscopic analysis of Giemsa-stained culture smears. Giemsa-stain microscopy was also used to study the cell cycle stage-specific action of selected fractions. RESULTS: The results revealed that the multidimensional purification of the crude extract (IC50: 4.03 µg/mL) provided RPHPLC F17 (IC50: 0.09 µg/mL) and RPHPLC F18 (IC50: 0.1 µg/mL) with activity against P. falciparum 3D7 (Pf3D7) strain. Moreover, both fractions at IC99 (0.5 µg/mL) exhibited multi-stages action by targeting all the three stages of the life cycle of blood-stage Pf3D7. Two compounds, flavasperone (1) and aurasperone A (2) were isolated, of which aurasperone A exhibited good potency against Pf3D7 (IC50: 4.17 µM) and P. falciparum INDO (PfINDO) (IC50: 3.08 µM). CONCLUSION: Our study adds credence to the notion that endophytic extracts are potential storehouses for potent specialized secondary metabolites that can be harnessed to fight the malaria parasite and reduce the burden of this disease worldwide. An endophyte that can be cultured in laboratory with ability to secrete promising metabolites of medicinal value holds the promise of conserving Nature from the threat of annihilation of flora for medicinal purposes.

Degradation and Detoxification of Aflatoxin B1 by Tea-Derived Aspergillus niger RAF106.

Microbial degradation is an effective and attractive method for eliminating aflatoxin B1 (AFB1), which is severely toxic to humans and animals. In this study, Aspergillus niger RAF106 could effectively degrade AFB1 when cultivated in Sabouraud dextrose broth (SDB) with contents of AFB1 ranging from 0.1 to 4 µg/mL. Treatment with yeast extract as a nitrogen source stimulated the degradation, but treatment with NaNO3 and NaNO2 as nitrogen sources and lactose and sucrose as carbon sources suppressed the degradation. Moreover, A. niger RAF106 still degraded AFB1 at initial pH values that ranged from 4 to 10 and at cultivation temperatures that ranged from 25 to 45 °C. In addition, intracellular enzymes or proteins with excellent thermotolerance were verified as being able to degrade AFB1 into metabolites with low or no mutagenicity. Furthermore, genomic sequence analysis indicated that the fungus was considered to be safe owing to the absence of virulence genes and the gene clusters for the synthesis of mycotoxins. These results indicate that A. niger RAF106 and its intracellular enzymes or proteins have a promising potential to be applied commercially in the processing and industry of food and feed to detoxify AFB1.

Enhanced bio-recovery of aluminum from low-grade bauxite using adapted fungal strains.

Filamentous fungi have been proved to have a pronounced capability to recover metals from mineral ores. However, the metal recovery yield is reduced due to toxic effects triggered by various heavy metals present in the ore. The current study highlights the fungal adaptations to the toxic effects of metals at higher pulp densities for the enhanced bio-recovery of aluminum from low-grade bauxite. In the previous studies, a drastic decrease in the aluminum dissolution was observed when the bauxite pulp density was increased from 1 to 10% (w/v) due to the high metal toxicity and low tolerance of Aspergillus niger and Penicillium simplicissium to heavy metals. These fungi were adapted in order to increase heavy metal tolerance of these fungal strains and also to get maximum Al dissolution. A novel approach was employed for the adaptation of fungal strains using a liquid growth medium containing 5% bauxite pulp density supplemented with molasses as an energy source. The mycelia of adapted strains were harvested and subsequently cultured in a low-cost oat-agar medium. Batch experiments were performed to compare the aluminum leaching efficiencies in the direct one-step and the direct two-step bioleaching processes. FE-SEM analysis revealed the direct destructive and corrosive action by the bauxite-tolerant strains due to the extension and penetration of the vegetative mycelium filaments into the bauxite matrix. XRD analysis of the bioleached bauxite samples showed a considerable decline in oxide minerals such as corundum and gibbsite. Results showed a high amount of total Al (≥ 98%) was successfully bioleached and solubilized from low-grade bauxite by the adapted fungal strains grown in the presence of 5% pulp density and molasses as a low-cost substrate. Graphical abstract.

Enhanced production of Aspergillus niger inulinase from sugar beet molasses and its kinetic modeling.

OBJECTIVE: The fermentation medium contains many complex components (vitamins, minerals, etc.) for better growth of the microorganisms. The increasing purity and number of these components used in the medium seriously affect the cost of the microbial process. This study aimed to further optimize the concentration of the components used in the medium (yeast extract and peptone) for inulinase fabrication by Aspergillus niger from sugar-beet molasses in shake flask fermentation by using Central Composite Design (CCD) and to kinetically identify the fermentation. RESULTS: The results indicated that the optimal medium composition consisted of only 4.2% (w/v) yeast extract. By using the fermentation environment, the inulinase generation, inulinase/sucrase ratio, maximum inulinase generation rate, maximum sugar depletion rate, and substrate utilization yield were determined as 1294.5 U/mL, 1.2, 159.6 U/mL/day, 7.4 g/L/day, and 98.1%, respectively. The kinetic analysis of the fungal development (logistic model) indicated that a specific development rate and initial biomass concentration were 0.89/day and 1.79 g/L, respectively. Inulinase and sucrase productions are mixed-development associated since the α value ≠ 0 (8.46 and 4.31 U/mgX) and the ß value ≠ 0 (5.15 and 4.83 U/mgX day), respectively (Luedeking-Piret model). Besides, the maintenance value (Z) (0.009 gS/gX day) was lower than γ value (1.044 gS/gX), showing that A. niger commonly uses the substrates for enzyme fabrication and fungal development (modified Luedeking-Piret model). CONCLUSIONS: The enzyme activity was increased by optimizing the concentration of the components used. It was demonstrated that the proposed kinetic models can victoriously define fungal development, enzyme fabrication, and sugar depletion.

High Performance Liquid Chromatography and Metabolomics Analysis of Tannase Metabolism of Gallic Acid and Gallates in Tea Leaves.

Tannase (E.C. 3.1.1.20) is hypothesized to be involved in the metabolism of gallates and gallic acid (GA) in pu-erh tea fermentation. In this work, we measured tannase in Aspergillus niger fermented tea leaves and confirmed the production of fungal tannase during pu-erh tea fermentation. A decrease in catechin and theaflavin gallates and a significant increase in GA content and the relative peak areas of ethyl gallate, procyanidin A2, procyanidin B2, procyanidin B3, catechin-catechin-catechin, epiafzelechin, and epicatechin-epiafzelechin [variable importance in the projection (VIP) > 1.0, p < 0.05, and fold change (FC) > 1.5] were observed using high performance liquid chromatography (HPLC) and metabolomics analysis of tea leaves fermented or hydrolyzed by tannase. In vitro assays showed that hydrolysis by tannase or polymerization of catechins increased the antioxidant activity of tea leaves. In summary, we identified a metabolic pathway for gallates and their derivatives in tea leaves hydrolyzed by tannase as well as associated changes in gallate and GA concentrations caused by fungal tannase during pu-erh tea fermentation.

Synthesis of Catechin-Rare Earth Complex with Efficient and Broad-Spectrum Anti-Biofilm Activity.

Biofilm is the crucial reason of clinical infections. Herein, green tea based polyphenol (catechin) and rare earth (RE) metal ions were employed for the preparation of catechin-RE complexes with significant anti-biofilm properties. The complexes were characterized by FT-IR, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and dynamic light scattering (DLS), which suggested that catechin coordinated with RE3+ through its ortho phenolic hydroxy groups. The prepared catechin-RE showed significant effects in anti-biofilm growth against P. aeruginosa (Gram-negative bacteria), S. sciuri (Gram-positive bacteria), and A. niger (fungi), which significantly exceeded the utilization of catechin or RE3+ . Morphological observations indicated that catechin supplied cell affinity to transfer RE3+ and helped to damage cell membrane, which act as a carrier to exert cytotoxicity of RE3+ to realize anti-biofilm. Differential gene expression analysis described gene expression changes induced by catechin-RE, including 56, 272 and 2160 downregulated genes for P. aeruginosa, S. sciuri and A. niger, respectively, which suggested critical changes in cellular metabolism, growth and other processes. These results illustrate the outstanding superiority of catechin-RE complexes in anti-infection aspect, i. e., the green tea based rare earth complexes are promising candidates for anti-biofilm applications to address serious challenges in the prevention of multiple infections.

Aspergillus niger enhances oxalate production as a response to phosphate deficiency induced by aluminium(III).

This paper investigates Aspergillus niger's behaviour in the presence of mobile Al3+ species by evaluating the changes in oxalate exudation at various aluminium contents. When the fungus was exposed to Al3+, no significant changes in oxalate production were observed until 100 mg.L-1 aluminium was reached resulting in oxalate production decrease by 18.2%. By stripping the culture medium completely of phosphate, even more prominent decrease by 34.8% and 67.1% at 10 and 100 mg.L-1 aluminium was observed, respectively, indicating the phosphate's significance instead of Al3+ in oxalate production. Our results suggest that the low phosphate bioavailability, which most likely resulted from its interaction with Al3+, stimulated the overproduction of oxalate by A. niger. Furthermore, when the fungus was incubated in aluminium-free media supplemented with 0.1 mM of phosphate, oxalate production increased up to 281.5 µmol.g-1, while at 1.85 mM of available phosphate only 80.7 µmol.g-1 of oxalate was produced. This indicates that oxalic acid is produced by fungus not as a mean to detoxify aluminium, but as an attempt to gain access to additional phosphate.

Colonies of the fungus Aspergillus niger are highly differentiated to adapt to local carbon source variation.

Saprobic fungi, such as Aspergillus niger, grow as colonies consisting of a network of branching and fusing hyphae that are often considered to be relatively uniform entities in which nutrients can freely move through the hyphae. In nature, different parts of a colony are often exposed to different nutrients. We have investigated, using a multi-omics approach, adaptation of A. niger colonies to spatially separated and compositionally different plant biomass substrates. This demonstrated a high level of intra-colony differentiation, which closely matched the locally available substrate. The part of the colony exposed to pectin-rich sugar beet pulp and to xylan-rich wheat bran showed high pectinolytic and high xylanolytic transcript and protein levels respectively. This study therefore exemplifies the high ability of fungal colonies to differentiate and adapt to local conditions, ensuring efficient use of the available nutrients, rather than maintaining a uniform physiology throughout the colony.

Environmental fungi and bacteria facilitate lecithin decomposition and the transformation of phosphorus to apatite.

Organophosphorus compounds (OP) are stable P source in nature, and can increase eutrophication risk in waterbodies. Lecithin was the most difficult OP to be broken down. In this study, two typical phosphate-solubilizing microorganisms, Aspergillus niger and Acinetobacter sp., were applied to evaluate their ability to decompose both inorganic phosphates and lecithin. A. niger and Acinetobacter sp. could solubilize calcium phosphates by secreting various organic acids, e.g., oxalic and formic acids. The fungus, A. niger, shows significantly higher ability of solubilizing these inorganic phosphates than Acinetobacter sp., primarily due to its secretion of abundant oxalic acid. However, the bacterium, Acinetobacter sp., could secrete more acid phosphatase than A. niger for lecithin decomposition, i.e., 9300 vs. 8500 µmol L-1 h-1. Moreover, after addition of CaCl2, the released P from lecithin was transformed to stable chlorapatite in the medium. To the contrast, Ca cations inclined to form calcium oxalate (rather than stable phosphate mineral) after the incubation of A. niger, as it induced relatively acidic environment after breaking down lecithin. Therefore, this work sheds light on the bright future of applying bacteria and Ca cations in OP pollutant management.

Fermentation of flaxseed cake increases its nutritional value and utilization in ducklings.

Flaxseed cake (FSC) is a potential alternative feed source in poultry. However, cyanogenetic glycosides limit its widespread use in feed. In this study, we optimized the parameters of fermentation by Aspergillus niger and Candida utilis and compared the growth performance, serum lipid parameters, and organ indexes of Cherry Valley duckling feed with unfermented FSC (UFSC) or fermented FSC (FFSC). A total of 420 one-day-old male Cherry Valley ducklings were randomly assigned into a 1 plus 2 × 3 factorial design including 2 different FSC resources (UFSC and FFSC) at 3 levels (50, 100, or 150 g/kg) for 3 wk. Each treatment group included 6 pens with 10 ducklings per pen. The hydrocyanic acid (HCN) level was reduced under the following conditions: 1:0.8 FSC:water (w:v), inoculum ratio of 1 mL:1 mL, 30°C, and 60 h. FFSC had higher crude protein (CP) and calcium (Ca) levels and lower HCN levels compared with UFSC (P < 0.05). There was no interactive effect between FSC sources and levels on growth performance. Final body weight (FBW), average daily feed intake (ADFI), and average daily gain (ADG) in UFSC groups and ADFI in FFSC groups decreased linearly with increasing FSC levels (P < 0.01). There were no differences in FBW, ADG, or feed:gain ratio (F/G) among FFSC groups, and all 7 FSC groups had no differences in the F/G ratio (P > 0.05). Dietary FSC supplementation decreased triglyceride (TG) (P < 0.01), total cholesterol (TC) (P < 0.01), high-density lipoprotein (HDL) (P = 0.01), and low-density lipoprotein (LDL) (P < 0.01). No interactive effect between FSC levels and sources was observed for serum TG, TC, HDL, or LDL. Ducklings fed FFSC had lower TG (P < 0.01), TC (P = 0.05), and LDL (P < 0.01) levels compared with ducklings fed UFSC. The 150 g/kg FFSC group had the lowest TG, TC, HDL, and LDL levels among all 7 groups. Flaxseed cake supplementation decreased the relative weight of the left breast, but FFSC increased the relative weight of the gizzard compared with UFSC. In conclusion, fermentation could increase the nutritional value and usage of FSC in ducklings.