Biodegradation of chestnut shell and lignin-modifying enzymes production by the white-rot fungi Dichomitus squalens, Phlebia radiata.

As a discarded lignocellulosic biomass, chestnut shell is of great potential economic value, thus a sustainable strategy is needed and valuable for utilization of this resource. Herein, the feasibility of biological processes of chestnut shell with Dichomitus squalens, Phlebia radiata and their co-cultivation for lignin-modifying enzymes (LMEs) production and biodegradation of this lignocellulosic biomass was investigated under submerged cultivation. The treatment with D. squalens alone at 12 days gained the highest laccase activity (9.42 ± 0.73 U mg(-1)). Combined with the data of laccase and manganese peroxidase, oxalate and H2O2 were found to participate in chestnut shell degradation, accompanied by a rapid consumption of reducing sugar. Furthermore, specific surface area of chestnut shell was increased by 77.6-114.1 % with the selected fungi, and total pore volume was improved by 90.2 % with D. squalens. Meanwhile, the surface morphology was observably modified by this fungus. Overall, D. squalens was considered as a suitable fungus for degradation of chestnut shell and laccase production. The presence of LMEs, H2O2 and oxalate provided more understanding for decomposition of chestnut shell by the white-rot fungi.

Ethyl Carbamate in Fermented Beverages: Presence, Analytical Chemistry, Formation Mechanism, and Mitigation Proposals.

Ethyl carbamate (EC) commonly found in fermented beverages has been verified to be a multisite carcinogen in experimental animals. EC was upgraded to Group 2A by the Intl. Agency for Research on Cancer (IARC) in 2007, which indicates that EC is a probable carcinogen to humans. Because of its threat to human safety, the presence of EC may be a big challenge in the alcoholic beverage industry. During the past few years, thorough and systematic research has been carried out in terms of the generation of EC in order to meet the allowed limitation levels in fermented beverages. Previous studies have indicated that EC primarily results from the reaction of ethanol and compounds containing carbamyl groups. These main EC precursors are commonly generated from arginine metabolism by Saccharomyces cerevisiae or lactic acid bacteria accompanied by the fermentation process. This review comprehensively summarizes the genotoxicity, analytical methods, formation pathways, and removal strategies of EC in various beverages. The article also presents the metabolic mechanism of EC precursors and pertinent metabolites, such as urea, citrulline, and arginine.

The synergistic effect on production of lignin-modifying enzymes through submerged co-cultivation of Phlebia radiata, Dichomitus squalens and Ceriporiopsis subvermispora using agricultural residues.

The lignin-modifying enzymes (LMEs) play an important role in decomposition of agricultural residues, which contain a certain amount of lignin. In this study, the production of LMEs by three co-cultivated combinations of Phlebia radiata, Dichomitus squalens and Ceriporiopsis subvermispora and the respective monocultures was comparatively investigated. Laccase and manganese peroxidases (MnP) were significantly promoted in the co-culture of P. radiata and D. squalens, and corncob was verified to be beneficial for laccase and MnP production. Moreover, laccase production by co-culture of P. radiata and D. squalens with high ratio of glucose to nitrogen was higher than low ratio under carbon- and nitrogen-meager conditions. New laccase isoenzymes measured by Native-PAGE were stimulated by co-cultured P. radiata with D. squalens or C. subvermispora, respectively, growing in the defined medium containing corncob, but the expression of laccase was greatly restrained by the co-culturing of D. squalens with C. subvermispora. This study showed that the synergistic and depressing effects of co-cultivation of P. radiata, D. squalens and C. subvermispora on LMEs were species specific.

Majorbio Cloud: A one-stop, comprehensive bioinformatic platform for multiomics analyses.

The platform consists of three modules, which are pre-configured bioinformatic pipelines, cloud toolsets, and online omics' courses. The pre-configured bioinformatic pipelines not only combine analytic tools for metagenomics, genomes, transcriptome, proteomics and metabolomics, but also provide users with powerful and convenient interactive analysis reports, which allow them to analyze and mine data independently. As a useful supplement to the bioinformatics pipelines, a wide range of cloud toolsets can further meet the needs of users for daily biological data processing, statistics, and visualization. The rich online courses of multi-omics also provide a state-of-art platform to researchers in interactive communication and knowledge sharing.

Deletion of Atg22 gene contributes to reduce programmed cell death induced by acetic acid stress in Saccharomyces cerevisiae.

BACKGROUND: Programmed cell death (PCD) induced by acetic acid, the main by-product released during cellulosic hydrolysis, cast a cloud over lignocellulosic biofuel fermented by Saccharomyces cerevisiae and became a burning problem. Atg22p, an ignored integral membrane protein located in vacuole belongs to autophagy-related genes family; prior study recently reported that it is required for autophagic degradation and efflux of amino acids from vacuole to cytoplasm. It may alleviate the intracellular starvation of nutrition caused by Ac and increase cell tolerance. Therefore, we investigate the role of atg22 in cell death process induced by Ac in which attempt is made to discover new perspectives for better understanding of the mechanisms behind tolerance and more robust industrial strain construction. RESULTS: In this study, we compared cell growth, physiological changes in the absence and presence of Atg22p under Ac exposure conditions. It is observed that disruption and overexpression of Atg22p delays and enhances acetic acid-induced PCD, respectively. The deletion of Atg22p in S. cerevisiae maintains cell wall integrity, and protects cytomembrane integrity, fluidity and permeability upon Ac stress by changing cytomembrane phospholipids, sterols and fatty acids. More interestingly, atg22 deletion increases intracellular amino acids to aid yeast cells for tackling amino acid starvation and intracellular acidification. Further, atg22 deletion upregulates series of stress response genes expression such as heat shock protein family, cell wall integrity and autophagy. CONCLUSIONS: The findings show that Atg22p possessed the new function related to cell resistance to Ac. This may help us have a deeper understanding of PCD induced by Ac and provide a new strategy to improve Ac resistance in designing industrial yeast strains for bioethanol production during lignocellulosic biofuel fermentation.

RNA-Seq-based transcriptomic and metabolomic analysis reveal stress responses and programmed cell death induced by acetic acid in Saccharomyces cerevisiae.

As a typical harmful inhibitor in cellulosic hydrolyzates, acetic acid not only hinders bioethanol production, but also induces cell death in Saccharomyces cerevisiae. Herein, we conducted both transcriptomic and metabolomic analyses to investigate the global responses under acetic acid stress at different stages. There were 295 up-regulated and 427 down-regulated genes identified at more than two time points during acetic acid treatment (150 mM, pH 3.0). These differentially expressed genes (DEGs) were mainly involved in intracellular homeostasis, central metabolic pathway, transcription regulation, protein folding and stabilization, ubiquitin-dependent protein catabolic process, vesicle-mediated transport, protein synthesis, MAPK signaling pathways, cell cycle, programmed cell death, etc. The interaction network of all identified DEGs was constructed to speculate the potential regulatory genes and dominant pathways in response to acetic acid. The transcriptional changes were confirmed by metabolic profiles and phenotypic analysis. Acetic acid resulted in severe acidification in both cytosol and mitochondria, which was different from the effect of extracellular pH. Additionally, the imbalance of intracellular acetylation was shown to aggravate cell death under this stress. Overall, this work provides a novel and comprehensive understanding of stress responses and programmed cell death induced by acetic acid in yeast.

Bacterial Diversity Analysis during the Fermentation Processing of Traditional Chinese Yellow Rice Wine Revealed by 16S rDNA 454 Pyrosequencing.

Rice wine is a traditional Chinese fermented alcohol drink. Spontaneous fermentation with the use of the Chinese starter and wheat Qu lead to the growth of various microorganisms during the complete brewing process. It's of great importance to fully understand the composition of bacteria diversity in rice wine in order to improve the quality and solve safety problems. In this study, a more comprehensive bacterial description was shown with the use of bacteria diversity analysis, which enabled us to have a better understanding. Rarefaction, rank abundance, alpha Diversity, beta diversity and principal coordinates analysis simplified their complex bacteria components and provide us theoretical foundation for further investigation. It has been found bacteria diversity is more abundant at mid-term and later stage of brewing process. Bacteria community analysis reveals there is a potential safety hazard existing in the fermentation, since most of the sequence reads are assigned to Enterobacter (7900 at most) and Pantoea (7336 at most), followed by Staphylococcus (2796 at most) and Pseudomonas (1681 at most). Lactic acid bacteria are rare throughout the fermentation process which is not in accordance with other reports. This work may offer us an opportunity to investigate micro ecological fermentation system in food industry.

Optimization of culture medium compositions for gellan gum production by a halobacterium Sphingomonas paucimobilis.

The effect of culture medium compositions on gellan gum production produced by fermentation with a halobacterium Sphingomonas paucimobilis QHZJUJW CGMCC2428 was studied. In this work, a fractional factorial design was applied to investigate the main factors that affected gellan gum production by S. paucimobilis QHZJUJW CGMCC2428. Sucrose was the best carbon source for gellan gum and peptone displayed better inducing effect. Central composite design and response surface methodology were adopted to derive a statistical model for optimizing submerged culture medium composition. These experimental results showed that the optimum culture medium for producing gellan gum was composed of 40.00 (w/v) sucrose, 3.00% peptone (w/v), MgSO4 (w/v), 9.20% KH2PO4 (w/v), 7.50% Na2HPO4 (w/v), 4.30% K2SO4 (w/v), pH 6.8-7.0. The maximal gellan gum was 19.89±0.68 g/L, which was agreed closely with the predicated value (20.12 g/L). After incubated for 72 h under the optimized culture medium in 5-L bioreactor, the gellan gum fermentation reached about 19.90±0.68 g/L, which was higher than that in the initial cultivation medium.

Production and identification of mannosylerythritol lipid-A homologs from the ustilaginomycetous yeast Pseudozyma aphidis ZJUDM34.

Mannosylerythritol lipids (MELs) are mainly produced by strains of the genus Pseudozyma and by Ustilago maydis. These glycolipid biosurfactants exhibit not only excellent surface-active properties but also versatile bioactivities. Mannosylerythritol lipid-A (MEL-A) is worth investigating due to its self-assembling property. In this work, crude MELs were produced by resting Pseudozyma aphidis ZJUDM34 cells using different culture media. MEL-A fractions were isolated and identified using high-performance liquid chromatography combined with mass spectrometry (HPLC-MS) and gas chromatography combined with mass spectrometry (GC-MS). The results showed that MEL-A homologs had long unsaturated fatty acid chains, and the chain lengths range from C8 to C20. Nuclear magnetic resonance (NMR) was employed to confirm the chemical structures of the MEL-A homologs. Fermentation medium without NaNO3 and medium with manganese ions enhanced MEL-A production by Pseudozyma aphidis ZJUDM34.

Gastrodin production from p-2-hydroxybenzyl alcohol through biotransformation by cultured cells of Aspergillus foetidus and Penicillium cyclopium.

The objective of this work was to take advantage of the resting cells of suitable fungus as an in vitro model to prepare gastrodin from p-2-hydroxybenzyl alcohol (HBA), which mainly exists in the metabolites of the plant Gastrodia elata Blume. The one-step biotransformation of HBA into gastrodin was examined with the filamentous fungi cells of Aspergillus foetidus and Penicillium cyclopium AS 3.4513 in this study. The fundamental conditions of biotransformation were screened and compared for both fungi. P. cyclopium AS 3.4513 had better gastrodin-producing capability than A. foetidus through one-step bioconversion. The highest yield of gastrodin was 36 mg/L for A. foetidus ZU-G1 and 65 mg/L for P. cyclopium AS 3.4513 under the respective development condition during 6 days of biotransformation. The comparative results show that P. cyclopium AS 3.4513 reveals great potential to form gastrodin using HBA as the precursor. The products catalyzed by the resting cells of P. cyclopium AS 3.4513 were identified through NMR and ESI-MS. Current results can be applied not only to the chemical synthesis processes that may involve the hydroxylation reaction but also to the industrial production. The selected fungus is the potential biocatalyst for HBA glucosylation.

[Advance in glycolipid biosurfactants--mannosylerythritol lipids].

Mannosylerythritol lipids (MELs), mainly produced by Ustilago and Pseudozyma, are surface active compounds that belong to the glycolipid class of biosurfactants. MELs have potential application in food, pharmaceutical and cosmetics industries due to their excellent surface activities and other peculiar bioactivities. In recent years, the research field of MELs has regained much attention abroad. However, MELs are rarely studied in China. In this review, the producing microorganisms and production conditions, diverse structures, biochemical properties, structure-function relationship and biosynthetic pathways of MELs are described. Some research problems and prospects are summarized and discussed as well.

Production of 8-prenylnaringenin from isoxanthohumol through biotransformation by fungi cells.

8-Prenylnaringenin (8PN), which presents in hop, enjoys fame as the most potential phytoestrogen. Although a number of health effects are attributed to 8PN, few reports are available about the production of it. In this work, screening of fungi to efficiently transform isoxanthohumol (IXN) into 8PN was designed. The biotransformation of IXN was significantly observed in Eupenicillium javanicum, Cunninghamella blakesleana, and Ceriporiopsis subvermispora under five kinds of transformation conditions. As a comparative result of IXN transformation, E. javanicum was the optimal biocatalyst to produce 8PN. Transformation caused by growing precultured fungal mycelia, a process designated as G2, was a favorable condition for IXN transformation in view of the yield of 8PN. The possible transformation pathway of 8PN bioproduction is postulated in this work. The construction of fungus and transformation mode derived from the current work is viable and an alternative procedure for 8PN formation.