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Fumaric acid production by fungal fermentation from renewable resources has received much attention, but suffers from low productivity and yield largely because of poor cell morphology limiting mass transfer. In this study, a simple seed culture medium was developed with soybean meal hydrolysate (SMH) as the nitrogen source for controlling the morphology of Rhizopus oryzae ATCC 20344. With the optimal seed culture conditions (pH 3.0, SMH concentration: 30% (v/v), and inoculation spore concentration: 8 × 10 7 /L), uniformly dispersed mycelial clumps with a diameter of ∼0.1 mm were formed, which gave high fumaric acid production from glucose in shake flasks, reaching a fumaric acid titer of 50.2 g/L and yield of 0.72 g/g glucose. Compared to the fermentation with cell pellets, the fermentation with mycelial clumps generated with SMH as nitrogen source increased fumaric acid production because of improved mass transfer. This process can lower the cost for bio-based fumaric acid and provide a novel way of using soybean meal besides its current use as animal feed supplement. [ABSTRACT FROM AUTHOR]

The effect of solid-state fermentation using several types of fungi on the phenolic acid content and antioxidant activity of rice bran (RB) was determined and compared to the non-fermented counterpart. The substrate was fermented with single and mixed cultures of two types of fungi: Rhizopus oligosporus and Monascus purpureus . The total phenolic content (TPC), determined using the Folin–Ciocalteu method, increased upon fermentation. The antioxidant activity was analyzed using the ferric reducing ability of plasma (FRAP) method, which showed the same trend as TPC; that is, the antioxidant activity improved in all fermented samples. In contrast to the TPC and FRAP assays, the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging activity of the fermented samples exhibited either an insignificant improvement or reduced activity. The phenolic acid content in methanol extracts of fermented RB, determined using high performance liquid chromatography (HPLC), generally showed a significant increase in ferulic, sinapic, vanillic, caffeic, syringic, and 4-hydroxybenzoic acids. The results of this study prove that the overall antioxidant activity and phenolic acid content of RB can be enhanced by solid-state fermentation using fungi. [ABSTRACT FROM AUTHOR]

The potential for large-scale production of an edible fungus, Rhizopus oligosporus, on a liquid residue from sugar-to-ethanol production, vinasse, was investigated. An airlift bioreactor (2.5-L working volume) was used for cultivating the fungus on 75% (v/v) vinasse with nutrient supplementation (nitrogen and phosphorus) at 37°C and pH 5.0. Aeration rates were varied from 0.5, 1.0, 1.5 to 2.0volumeair/volumeliquid/min (vvm). The fungal biomass yield depended on the aeration rate, and the highest fungal biomass obtained was 8.04±0.80 (gbiomass increase/ginitial biomass) at 1.5vvm. The observed reductions in organic content by 80% (as soluble chemical oxygen demand) suggest the potential of recycling treated effluent as process water for in-plant use or for land applications. The fungal biomass contained ∼50% crude protein and the essential amino acids contents were comparable to commercial protein sources for aquatic feeds (fishmeal and soybean meal), with the exception of methionine and phenylalanine. [ABSTRACT FROM AUTHOR]

We propose a new process of unified aerobic delignification and anaerobic saccharification and fermentation of wood by a single microorganism, the white-rot fungus Phlebia sp. MG-60. This fungus is able to selectively degrade lignin under aerobic solid state fermentation conditions, and to produce ethanol directly from delignified oak wood under semi-aerobic liquid culture conditions. After 56 d aerobic incubation, 40.7% of initial lignin and negligible glucan were degraded. Then under semi-aerobic conditions without the addition of cellulase, 43.9% of theoretical maximum ethanol was produced after 20 d. Changing from aerobic conditions (biological delignification pretreatment) to semi-aerobic conditions (saccharification and fermentation) enabled the fermentation of wood by solely biological processes. This is the first report of ethanol production from woody biomass using a single microorganism without addition of chemicals or enzymes. [ABSTRACT FROM AUTHOR]

Abstract: This study was to explore the use of thin stillage, a major byproduct in dry milling corn–ethanol plants, for production of eicosapentaenoic acid (EPA) by the fungus Pythium irregulare. Thin stillage contains various compounds that were ideal for fungal growth. Thin stillage concentration and temperature played important roles in fungal growth and EPA production. When 50% thin stillage was used in a stepwise temperature shift culture process, the cell density reached 23g/L at day 9 with EPA yield and productivity of 243 and 27mg/Lday, respectively. The fungal biomass contained 39% lipid, 28% protein, 30% carbohydrate, and 3% ash. The fungal culture also generated a nutrient-depleted liquid by removing organic compounds in the raw thin stillage. The results collectively showed a new use of thin stillage by feeding to the fungus P. irregulare for producing omega-3 fatty acids. [Copyright &y& Elsevier]

The article presents a study which determines the L-Tryptophan (L-Trp) and L-leucine ethyl ester (L-Leu-OEt) derivatives of the monascus pigment for anti-obesity in mice. The study showed that the L-Trp derivative have higher anti-obesity effects compared to the L-Leu-OEt derivative. Moreover, the derivatives also help lower the cholesterol and triglyceride contents in the mice serum and liver.

Abstract: Fungi are employed to produce industrially important glucoamylases. Most glucoamylases are glycosylated. Glycosylation enhances the enzyme stability. Glucoamylases contain both starch binding and catalytic binding domains, the former being responsible for activity on raw (insoluble) starch. Proteases may act on this domain causing the enzyme to lose its activity on insoluble starch. Optimal activity is observed at pH 4.5 to 6.5 and 50 to 70 °C. Glucoamylases contain up to 7 sub-sites with highly varying affinity. They can be produced by different methods including submerged, solid state and semi-solid state fermentation processes. [Copyright &y& Elsevier]

It has been known for many years that oxygen (O2) may have toxic effects on aerobically growing microorganisms, mainly due to the threat arising from reactive oxygen species (ROS). In submerged culture industrial fermentation processes, maintenance of adequate levels of O2 (usually measured as dissolved oxygen tension (DOT)) can often be critical to the success of the manufacturing process. In viscous cultures of filamentous cultures, actively respiring, supplying adequate levels of O2 to the cultures by conventional air sparging is difficult and various strategies have been adopted to improve or enhance O2 transfer. However, adoption of those strategies to maintain adequate levels of DOT, that is, to avoid O2 limitation, may expose the fungi to potential oxidative damage caused by enhanced flux through the respiratory system. In the past, there have been numerous studies investigating the effects of DOT on fungal bioprocesses. Generally, in these studies moderately enhanced levels of O2 supply resulted in improvement in growth, product formation and acceptable morphological changes, while the negative impact of higher levels of DOT on morphology and product synthesis were generally assumed to be a consequence of "oxidative stress." However, very little research has actually been focused on investigation of this implicit link, and the mechanisms by which such effects might be mediated within industrial fungal processes. To elucidate this neglected topic, this review first surveys the basic knowledge of the chemistry of ROS, defensive systems in fungi and the effects of DOT on fungal growth, metabolism and morphology. The physiological responses of fungal cells to oxidative stress imposed by artificial and endogenous stressors are then critically reviewed. It is clear that fungi have a range of methods available to minimize the negative impacts of elevated ROS, but also that development of the... [ABSTRACT FROM AUTHOR]

Semicontinuous fungal fermentation of lactic acid (LA) by Rhizopus arrhizus was performed using a periodical bleed and feed (PBF) operation in a stirred tank bioreactor with a volume of 4.5 dm3. LA productivity up to 2.91 kg m−3 h−1 and yield up to 75.3% were achieved. Using PBF cycles, fermentation was prolonged to 240 h with an average LA productivity of 2.31 kg m−3 h−1 and a total yield of 67.3% at a mean pH of 5.30. The most effective production of LA required filamentous morphology of the biomass. When such morphology changed to pellets biomass growth stopped, the LA productivity decreased to 1.63 kg m−3 h−1 and the yield decreased to 62.6%. The filamentous morphology was successfully maintained for 152 h when the inoculation was with spores. CaCO3 initially used for pH neutralisation did not dissolve well since it was entrapped by biomass. It was successfully replaced by 25% ammonia. Long-time operation below pH 5 decreased LA productivity. Accumulating biomass in the fermenter did not increase the LA productivity. With an increase in the biomass growth rate, the LA productivity increased. The on-line extraction or pertraction of LA by trialkylamines demands a pH value of feed below 4. This can be achieved for a short time by interruption neutralisation at the end of each PBF cycle without a decrease in LA productivity after the restoration of the optimal pH value. [Copyright &y& Elsevier]

[Display omitted] • The metabolite levels in IDT changed distinctly from day 3 to 5 of fermentation. • Chemical constituents of IDT have changed dramatically during fermentation. • Critical metabolites from different times were revealed by multivariate statistical analyses. • The correlation between 66 metabolites and functional characteristics were evaluated. Instant green tea powder was used as raw material to prepare an instant dark tea via liquid-state fermentation by Eurotium cristatum. To understand how the chemical constituents present in fermented green tea develop during fermentation, samples were collected on different days during fermentation for qualitative analyses by ultra-performance liquid chromatography-Q Exactive Orbitrap/Mass spectrometry. Untargeted metabolomics analyses revealed that the levels of original secondary metabolites in the instant green tea changed significantly from day 3 to day 5 during fermentation. Targeted metabolomics indicated that the levels of galloylated catechins (GCs) and free amino acids (FAAs) significantly decreased, but the nongalloylated catechins (NGCs), alkaloids, thearubigins and theabrownins increased dramatically after fermentation. The changes in the contents of catechins, gallic acid and free amino acids in the instant dark tea samples were positively related to the DPPH radical scavenging activities in vitro, and the phenolic acids and FAAs were positively related to the inhibitory effects towards α-glucosidase. These results showed that fermentation by Eurotium cristatum is critical to the formation of certain qualities of instant dark tea. [ABSTRACT FROM AUTHOR]

Scope: Aspergillus terreus is an industrial microorganism used in the brewing and sauce industries. It produces monacolin K, a natural statin. The study conducted an 8-week randomized controlled trial with hypercholesterolemic subjects to examine the hypocholesterolemic effects and mechanisms of supplementation with yellow yeast rice (YYR) prepared by growing Aspergillus fungi on steamed rice., Methods and Results: YYR supplementation markedly reduced total cholesterol, LDL, and apolipoprotein B100 levels in plasma compared with the placebo. In addition, YYR induced a significantly increased ATP binding cassette subfamily B member 11 (ABCB11) gene expression compared with the placebo, indicating the role of YYR in lowering intrahepatic cholesterol availability by stimulating the bile salt export pump. Upregulation of LDL receptor (LDLR) and 3-methylglutaryl-CoA reductase (HMGCR) gene expressions provided additional evidence to support the role of YYR in reducing hepatic cholesterol availability. Plasma metabolomic profiling revealed the possibility of diminishing bile acid absorption. Finally, Spearman rank analysis showed correlations of plasma cholesterol profiles with HMGCR and LDLR gene expressions (negative) and plasma bile acids (positive). Plasma bile acids also correlated with ABCB11 (negative) and LDLR (positive) gene expressions., Conclusion: These findings suggest that daily YYR supplementation exerted hypocholesterolemic effects in mild-to-moderate hypercholesterolemic subjects by reducing intrahepatic cholesterol availability through stimulating bile salt export pumps and inhibiting cholesterol biosynthesis., (© 2021 Wiley-VCH GmbH.)

• A 3D-printed micro-fluidized bed was used to study fungal pellet fluidization. • Liquid-solid and gas-liquid-solid fluidization systems were characterized. • Gas flow promoted pellet axial velocity but had little impact on radial velocity. • This study broadens the potential of micro-fluidized bed in bioprocessing field. Micro-fluidized bed (MFB) can be used as a fast screening tool for preliminary testing of engineering designs, but the applications of MFB for bioprocessing research such as microorganism cultivation is still deficient. This paper reports the unique fluidization performance of fungal pellets in a 3D-printed micro-fluidized bed, thus giving insights to the hydrodynamic study of pellets and broadening the potential of MFB in the bioprocessing and bioproduction fields. The results indicated that the static bed voidage were substantially larger (around 0.6) than the conventionally used value of 0.4. The observed decrease in packed bed voidage with increasing pellet mass was attributed to the increased compaction of pellets. A novel extended bed regime was observed prior to partially and fully fluidized bed regimes for liquid-solid fluidization. Due to the wall effect and surface forces, higher values of the minimum fluidization velocity and Richardson-Zaki empirical constants (n and K) were determined. In liquid-solid-gas fluidization system, fluidization regimes including packed-bed regime, fluidization regime and elutriation regimes were mapped. The effects on gas flow and pellet weight on fluidization performance were also investigated. It was noticed that pellets were fully fluidized at low biomass weight (i.e. 0.5 g) but the increase of pellet mass led to partially fluidization where the packed bed height increased with increasing pellet mass but decreased with increasing gas flowrate. Pellet fluidization velocity including axial velocity and radial velocity were measured by PIVlab analysis. The results indicated that pellet axial velocity was mainly affected by vertical gas flow while radial velocity was dominated by vortexes and surface forces. [ABSTRACT FROM AUTHOR]

Sewage sludge poses a serious environmental problem for large cities, and large amounts of materials in sludge, including organics, should be recovered rather than wasted. To achieve both sludge reduction and organic resource recovery, this study developed a new biorefinery technology that includes the hydrothermal treatment of sludge followed by fungal fermentation to form hyphae fibers and acidogenic fermentation to produce volatile fatty acids (VFAs). Hydrothermal treatment at 160 °C or 180 °C allows solubilization of approximately 40% of solid organics in sludge into the supernatant, resulting in significant sludge reduction and dewaterability improvement. The fermentation of the fungus Aspergillus niger converted waste organics in the hydrolyzed sludge liquor, with a chemical oxygen demand (COD) concentration of around 15,000 mg/L, into hyphae fibers, resulting in fungal biomass production of more than 1.7 g/L. After the recovery of hyphae fibers, the residual sludge liquor was further fermented to produce VFAs to a concentration of about 2500 mg COD/L. The genera Petrimonas , Arcobacter , and Aminobacterium played important roles in acidogenic fermentation. The stepped biorefinery strategy can transform approximately 35% of waste organics in the hydrothermal sludge liquor into valuable fibrous materials and VFAs for effective resource recovery. Image 1 • A new biorefinery process is developed for sludge treatment and resource recovery. • Fungal fermentation converted hydrolyzed sludge organics to hyphae fibers. • Fungal hyphae grew to 1.84 g/L in the sludge liquor with 16.2% organic conversion. • Acidogenic fermentation of the residual sludge liquor produced volatile fatty acids. • 36% organics in sludge liquor was converted to hyphae fibers and volatile fatty acids. [ABSTRACT FROM AUTHOR]

Coconut endosperm waste (CEW) was treated by Rhizopus oligosporus via in situ and ex situ fermentations together with bioconversion into valuable black soldier fly larval biomass. The ex situ fermentation could overall enrich the nutritional compositions of CEW by hydrolyzing its complex organic polymers and exuding assimilable nutrients to enhance the black soldier fly larvae (BSFL) growth. Nevertheless, the larval gut bacteria were competing with Rhizopus oligosporus in in situ fermentation, derailing the hydrolysis processes and larval growth. Accordingly, the highest growth rates achieved were around 0.095 g/day, as opposed to only 0.065 g/day whilst using 0.5 wt% of Rhizopus oligosporus to perform ex situ and in situ fermentations, respectively. These were also underpinned by the greater amount of total CEW consumed when employing ex situ fermentation, with comparable metabolic costs to feeding on in situ-fermented CEW. The mature BSFL were subsequently harvested and the amounts of protein and lipid produced were assessed in terms of their feasibility for biodiesel production. While the statistical analyses showed that the larval protein yields derived from both fermentation modes were insignificant, the BSFL could attain higher lipid and protein productivities upon feeding with ex situ- rather than in situ-fermented CEW mediums. Better yet, the larval biodiesel quality measured in terms of the fatty acid methyl ester composition were not varied significantly by Rhizopus oligosporus through the fermentation process. Thereby, the presence of 1.0 wt% Rhizopus oligosporus was considered optimum to perform ex situ fermentation, giving rise to the acceptable growth of BSFL loaded with the highest lipid yield and productivity for producing biodiesel and protein simultaneously. [ABSTRACT FROM AUTHOR]

• Fungal fermentation induces improved nutritional qualities of soybean meal. • These changes are accurately and precisely quantified by FTIR spectroscopy. • FTIR spectroscopy is a fast and robust measurement method using no chemicals. • The method be used in industrial fermentation line to comply with desired effects. A FTIR spectro-chemometric measurement was first-ever made available to monitor chemical and molecular structural changes during the fungal fermentation of soybean meal. The samples of soybean meal were fermented for 72 hr using single Aspergillus ficuum or combined Aspergillus ficuum + Aspergillus niger inoculants. Nutrient contents determined by chemical methods on three independent sub-samples taken at 24 hr intervals were predicted by a method of FTIR. Furthermore, secondary protein components were quantified by FTIR spectra deconvolution method. Fungal fermentation caused enriched soybean meal with protein and organic acids with lowered dietary fibre, tannin, phytic acid and urease contents, while there was increased trypsin inhibitors. The chemometric model excellently predicted the nutrient contents with high accuracy (99% recovery rate) and precision (R2 = 0.98), except for the crude ash and total carbohydrate. Fermented soybean meal has a re-organised secondary protein structure: a complete degradation of α-helix component caused to an increased β-sheet (6%), β-turn (15%) and random coil component (100%). It is recommended that infrared spectroscopic monitoring of fermentation process can replace the chemical methods due to its low cost and robustness. [ABSTRACT FROM AUTHOR]

The commonly discarded mussel cooking liquor (MCL) of Mytilus edulis is an important resource for industrial preparation of fungus (Aspergillus oryzae) fermented condiment. In this study, the fermentation degree of MCL was evaluated by analyzing the changes of volatile flavor using a newly established laser irradiation desorption (LID) method coupling a 450 nm blue semiconductor laser to a headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME GC/MS). Under the optimized laser conditions (laser power 10 W, irradiation time 5 min, sample volume 3 g), the effect of fungal fermentation was investigated, and a total of 52 volatile compounds in the fermented MCL were detected, such as furans, aromatic compounds, and sulphur and nitrogen containing compounds. By strictly analyzing the characteristic volatiles, the MCL was well processed and the fermentation product showed a desirable and umami flavor, whereas the fishy and burnt smell was roughly removed. Compared with traditional analytical methods, the proposed LID–HS–SPME analysis showed significant characteristic profile and reduced time to only 5 min. The results indicated that the LID–HS–SPME analysis is reliable, efficient, and suitable for industrially used for monitoring the preparation of fungal fermented MCL. Image 1 • The waste of mussel cooking liquor (MCL) was processed by fungal fermentation. • A laser was coupled to HS-SPME GC/MS for monitoring the fermentation degree. • The volatile compounds were evaluated during the industrial production of condiment. • The proposed strategy showed superiority when compared with traditional methods. [ABSTRACT FROM AUTHOR]

Background: Anaerobic digestate is the effluent from anaerobic digestion of organic wastes. It contains a significant amount of nutrients and lignocellulosic materials, even though anaerobic digestion consumed a large portion of organic matters in the wastes. Utilizing the nutrients and lignocellulosic materials in the digestate is critical to significantly improve efficiency of anaerobic digestion technology and generate value-added chemical and fuel products from the organic wastes. Therefore, this study focused on developing an integrated process that uses biogas energy to power fungal fermentation and converts remaining carbon sources, nutrients, and water in the digestate into biofuel precursor-lipid., Results: The process contains two unit operations of anaerobic digestion and digestate utilization. The digestate utilization includes alkali treatment of the mixture feed of solid and liquid digestates, enzymatic hydrolysis for mono-sugar release, overliming detoxification, and fungal fermentation for lipid accumulation. The experimental results conclude that 5 h and 30 °C were the preferred conditions for the overliming detoxification regarding lipid accumulation of the following fungal cultivation. The repeated-batch fungal fermentation enhanced lipid accumulation, which led to a final lipid concentration of 3.16 g/L on the digestate with 10% dry matter. The mass and energy balance analysis further indicates that the digestate had enough water for the process uses and the biogas energy was able to balance the needs of individual unit operations., Conclusions: A fresh-water-free and energy-positive process of lipid production from anaerobic digestate was achieved by integrating anaerobic digestion and fungal fermentation. The integration addresses the issues that both biofuel industry and waste management encounter-high water and energy demand of biofuel precursor production and few digestate utilization approaches of organic waste treatment.

Background: Animal wastes are of particular environmental concern due to greenhouse gases emissions, odor problem, and potential water contamination. Anaerobic digestion (AD) is an effective and widely used technology to treat them for bioenergy production. However, the sustainability of AD is compromised by two by-products of the nutrient-rich liquid digestate and the fiber-rich solid digestate. To overcome these limitations, this paper demonstrates a biorefinery concept to fully utilize animal wastes and create a new value-added route for animal waste management., Results: The studied biorefinery includes an AD, electrocoagulation (EC) treatment of the liquid digestate, and fungal conversion of the solid fiber into a fine chemical-chitin. Animal wastes were first treated by an AD to produce methane gas for energy generation to power the entire biorefinery. The resulting liquid digestate was treated by EC to reclaim water. Enzymatic hydrolysis and fungal fermentation were then applied on the cellulose-rich solid digestate to produce chitin. EC water was used as the processing water for the fungal fermentation. The results indicate that the studied biorefinery converts 1 kg dry animal wastes into 17 g fungal biomass containing 12 % of chitin (10 % of glucosamine), and generates 1.7 MJ renewable energy and 8.5 kg irrigation water., Conclusions: This study demonstrates an energy positive and freshwater-free biorefinery to simultaneously treat animal wastes and produce a fine chemical-chitin. The sustainable biorefinery concept provides a win-win solution for agricultural waste management and value-added chemical production.