A New Brominated Isocoumarin from the Marine Starfish-Associated Fungus Aspergillus sp. WXF1904.

Based on the one strain many compounds strategy, a new brominated isocoumarin, 5-bromo-6,8-dihydroxy-3,7-dimethylisocoumarin (1), along with four new natural products, methyl 3-bromo-2,4-dihydroxy-6-methylbenzoate (2), methyl 2-bromo-4,6-dihydroxybenzoate (3), (E)-3-(3-bromo-4-hydroxyphenyl) acrylic acid (4) and 4-hydroxy-3-methyl-6-phenyl-2H-pyran-2-one (5), and four known compounds, methyl orsellinate (6), 4-hydroxy-3-methyl-6-(1-methyl-1-propenyl)-2H-pyran-2-one (7), pilobolusate (8) and cis-ferulic acid (9), were isolated from the ethyl acetate extract of the fungus Aspergillus sp. WXF1904 under the condition of adding bromine salt to the production medium. The structures of the new compounds were established by analysis of NMR and MS data. Compounds (1-9) were evaluated for inhibitory activity of acetylcholinesterase and pancreatic lipase, the new compound 1, known compounds 6 and 7 displayed weak inhibitory activity against acetylcholinesterase, compounds 2, 5, 7 and 8 showed weak inhibitory activity against pancreatic lipase.

Quantitative Proteome Profiling Reveals Cellobiose-Dependent Protein Processing and Export Pathways for the Lignocellulolytic Response in Neurospora crassa.

Filamentous fungi are intensively used for producing industrial enzymes, including lignocellulases. Employing insoluble cellulose to induce the production of lignocellulases causes some drawbacks, e.g., a complex fermentation operation, which can be overcome by using soluble inducers such as cellobiose. Here, a triple ß-glucosidase mutant of Neurospora crassa, which prevents rapid turnover of cellobiose and thus allows the disaccharide to induce lignocellulases, was applied to profile the proteome responses to cellobiose and cellulose (Avicel). Our results revealed a shared proteomic response to cellobiose and Avicel, whose elements included lignocellulases and cellulolytic product transporters. While the cellulolytic proteins showed a correlated increase in protein and mRNA levels, only a moderate correlation was observed on a proteomic scale between protein and mRNA levels (R2 = 0.31). Ribosome biogenesis and rRNA processing were significantly overrepresented in the protein set with increased protein but unchanged mRNA abundances in response to Avicel. Ribosome biogenesis, as well as protein processing and protein export, was also enriched in the protein set that showed increased abundance in response to cellobiose. NCU05895, a homolog of yeast CWH43, is potentially involved in transferring a glycosylphosphatidylinositol (GPI) anchor to nascent proteins. This protein showed increased abundance but no significant change in mRNA levels. Disruption of CWH43 resulted in a significant decrease in cellulase activities and secreted protein levels in cultures grown on Avicel, suggesting a positive regulatory role for CWH43 in cellulase production. The findings should have an impact on a systems engineering approach for strain improvement for the production of lignocellulases.IMPORTANCE Lignocellulases are important industrial enzymes for sustainable production of biofuels and bio-products. Insoluble cellulose has been commonly used to induce the production of lignocellulases in filamentous fungi, which causes a difficult fermentation operation and enzyme loss due to adsorption to cellulose. The disadvantages can be overcome by using soluble inducers, such as the disaccharide cellobiose. Quantitative proteome profiling of the model filamentous fungus Neurospora crassa revealed cellobiose-dependent pathways for cellulase production, including protein processing and export. A protein (CWH43) potentially involved in protein processing was found to be a positive regulator of lignocellulase production. The cellobiose-dependent mechanisms provide new opportunities to improve the production of lignocellulases in filamentous fungi.

[Isolation, screening nd characterization of hydrogen-oxidizing bacteria in soybean rhizosphere].

Soil hydrogen-oxidizing bacteria can utilize soil gaseous hydrogen as an energy source to assimilate carbon dioxide. In this paper, a gas-cycle incubation system (H2 treatment system) which can provide stable H2 flow (41.6-125 micromol x L(-1)) via H2O electrolysis was developed, and a mineral salt agar medium (MSA) was used to separate the hydrogen-oxidizing bacteria in soybean rhizosphere. A total of 40 bacterial strains were isolated from the incubation system, and their hydrogen uptake was measured. 20 of the strains could utilize hydrogen and grow autotrophically, which were preliminarily identified as hydrogen-oxidizing bacteria. Their colony form and physiological-biochemical characteristics were studied.