黑曲霉菌体制备壳聚糖

壳聚糖是利用微生物真菌本身细胞壁的成分中含有壳聚糖,进行自身催化从而脱去乙酰基,如从丝状真菌中提取壳聚糖,但产品产量低。     

Regiospecific hydroxylation of acyclic monoterpene alcohols by aspergillus niger

Aspergillus niger was shown to carry out the regiospecific hydroxylation of acyclic monoterpene alcohols.     

Ultrasensitive detection of pepsinogen I and pepsinogen II by a time-resolved fluoroimmunoassay and its preliminary clinical applications

A fast and highly sensitive assay for pepsinogen I (PG I) and pepsinogen II (PG II) by using time-resolved fluoroimmunoassay (TRFIA) detection technique has been developed for the determination of serum PG I and PG II against gastrointestinal diseases. On the noncompetitive assay, one monoclonal antibody (McAb) coated on wells was directed against a specific antigenic site on the PG I or PG II. The McAb, called as labelling McAb, was prepared with the europium-chelate of N-(p-isothiocyanatobenzyl)-diethylenetriamine-N,N,N,N-tetraacetic acid and directed against a different antigenic site on the PG I or PG II molecule. After bound/free separation by washing, the fluorescence counts of bound Eu³⁺-McAb were measured. The levels of PG in sera from patients or healthy volunteers were determined by PG I and PG II TRFIA using the autoDELFIA₁₂₃₅ system. The measurement ranges of PG I-TRFIA were 3.5-328.0 μg L⁻¹ and those of PG II-TRFIA were 2.0-55.0 μg L⁻¹. The within-run and between-run CVs of the PG I-TRFIA were 1.9% and 4.7%, respectively, and those of PG II-TRFIA were 2.1% and 3.8%, respectively. The recovery rates of PG I-TRFIA and PG II-TRFIA were 102.7% and 104.6%, respectively. The detection limitations of PG I and PG II were 0.05 μg L⁻¹ and 0.02 μg L⁻¹, respectively. The dilution experiments showed the percentage of expected value of PG I-TRFIA was 93.2-102.3% and of PG II-TRFIA was 97.3-110.6%. The cross-reacting rate between PG I and PG II was negligible. The linear correlation of radioimmunoassay (RIA) and TRFIA measurements resulted in a correlation coefficient as 0.926 of PG I and as 0.959 of PG II. The europium-labelling McAbs were stable for at least one year at −20 °C, and the results of the TRFIA with same reagents were reproducible over one year as well. The means of 1600 healthy volunteers were 162.4 ± 52.1 μg L⁻¹ for serum PG I, 11.7 ± 6.8 μg L⁻¹ for serum PG II, and 13.8 ± 7.4 for the PG I/PG II ratio. The normal ranges of Serum PG I levels for healthy volunteers were 58.2-266.6 μg L⁻¹, and those of serum PG II levels were less than 25.3 μg L⁻¹. The availability of a highly sensitive, reliable, and convenient PG-TRFIA method for quantifying PG will allow investigations into the possible diagnostic value of this analysis in various clinical conditions, including gastric carcinoma, duodenal ulcer, gastric ulcer and gastritis. The sensitivity and reproducibility of the assay were satisfactory for clinical applications.     

Simultaneous determination of two serine proteinases by hydrophobic interaction chromatography

Summary An LC clean-up procedure based upon a complexation between polycyclic aromatic hydrocarbons (PAHs) and silica with chemically bonded 2,4-dinitroaniline has been combined with GC/MS. The LC pre-separation makes it possible to obtain a relatively clean fraction of PAHs free from alkanes, alkylbenzenes and naphthalenes, PCBs, chlorinated pesticides and many other interfering compounds. This fraction has been analyzed using capillary GC and mass selective detector (MSD). Substantial improvement of the MS spectra of PAHs with three or more fused benzene rings is achieved.     

GpdA-promoter-controlled production of glucose oxidase by recombinant aspergillus niger using nonglucose carbon sources

The gpdA-promoter-controlled exocellular production of glucose oxidase (GOD) by recombinant Aspergillus niger NRRL-3 (GOD3-18) during growth on glucose and nonglucose carbon sources was investigated. Screening of various carbon substrates in shake-flask cultures revealed that exocellular GOD activities were not only obtained on glucose but also during growth on mannose, fructose, and xylose. The performance of A. niger NRRL-3 (GOD3-18) using glucose, fructose, or xylose as carbon substrate was compared in more detail in bioreactor cultures. These studies revealed that gpdA-promoter-controlled GOD synthesis was strictly coupled to cell growth. The gpdA-promoter was most active during growth on glucose. However, the unfavorable rapid GOD-catalyzed transformation of glucose into gluconic acid, a carbon source not supporting further cell growth and GOD production, resulted in low biomass yields and, therefore, reduced the advantageous properties of glucose. The total (endo- and exocellular) specific GOD activities were lowest when growth occurred on fructose (only a third of the activity that was obtained on glucose), whereas utilization of xylose resulted in total specific GOD activities nearly as high as reached during growth on glucose. Also, the portion of GOD excreted into the culture fluid reached similar high levels (≅ 90%) by using either glucose or xylose as substrate, whereas growth on fructose resulted in a more pelleted morphology with more than half the total GOD activity retained in the fungal biomass. Finally, growth on xylose resulted in the highest biomass yield and, consequently, the highest total volumetric GOD activity. These results show that xylose is the most favorable carbon substrate for gpdA-promoter-controlled production of exocellular GOD.     

Direct inhibition of pepsinogen secretion from rat gastric chief cells by somatostatin

Effects of somatostatin on pepsinogen secretion was investigated in the rat in vivo and in vitro. In the perfused rat stomach, somatostatin inhibited secretagogue-induced acid secretion in dose-dependent manner. However, effects of somatostatin on secretagogue-induced pepsinogen secretion were obscure. To clarify the effects of somatostatin on the chief cells, gastric mucosal cells were isolated by a proteolytic enzyme. Somatostatin inhibited carbachol- and cholecystokinin octapeptide-induced pepsinogen secretion from dispersed gastric mucosal cells in a dose-dependent manner. Histamine-induced pepsinogen secretion, which was recovered by culturing, was also inhibited by somatostatin. These results suggest that somatostatin inhibits secretagogue-induced pepsinogen secretion directly.     

Isolation and purification of bacterial proteinases by means of autofocusing.

Autofocusing was used for the isolation and purification of neutral and alkaline proteinases from fermentation broth, after separation of cells. The yield of proteinases achieved was 19-78%, and was inversely proportional to the degree of purification, which varied from 3.0 to 7.9. Because of considerable losses of enzyme activity and the long duration of the process, autofocusing seems to be a non-economic technique for industrial isolation of relatively cheap enzymes.     

New cytotoxic bio-transformed sesquiterpene by Rhizopus oryzae fungus

Due to the rapidly increasing number of pathogenic bacteria, viruses, and tumor cells that possess resistance toward established therapies, lead structures for the development of new drugs are in high demand. The plant material of Tanacetum sinaicum is considered a prolific source of the potent biologically active sesquiterpene Tanacetolide A ( 1 ). In our research, we focused on the structural transformation of the substrate Tanacetolide A (compound 1 ) by suspended culture of the novel locally isolated terrestrial fungus Rhizopus oryzae KX685359. The fungal transformation resulted in the formation of 1β,3α-dihydroxy-6α-hydroperoxy-eudsm-4(15)-ene 12-oic acid ( 2 ) with higher antiproliferative activity against colon cancer cell line (Caco-2) than that of the parent compound ( 1 ).     

Mycelial pellet formation by Rhizopus oryzae ATCC 20344

Factors in a cultivation medium affecting fungal growth morphology and funmaric acid production by Rhizopus oryzae ATCC 20344 were investigated. These factors included the initial pH value and trace metals such as zinc, magnesium, iron, and manganese in the cultivation medium. It was found that a significant change in the growth morphology of R. oryzae ATCC 20344 occurs when the initial pH value is varied. A lower initial pH value in the cultivation medium was inhibitory to fungal growth, and fast growth in the cultivation medium at a higher initial pH value promoted, the formation of large pellets or filamentous forms. Trace metals in the cultivation media also had significant effects on pellet formation and fumaric acid fermentation.     

Lignin degrading ability of selected aspergillus Spp.

Most lignin research has been on wood-rot fungi and not on other lignolytic organisms. Members of the genusAspergillus inhabit lignin-rich environments, and we have studied their relative lignin-degrading potential.Aspergillus fumigatus, A. japonicus, A. niger, andA. terreus were tested for their ability to metabolize¹⁴C-labeled aromatic compounds. The species tested decarboxylated, demethoxylated, and cleaved the rings of coumaric, ferulic, vanillic, veratric, and anisic acids. More than 90% of C-ring-labeled ferulic and vanillic acids disappeared from the medium in 96 h of cultivation. More than half of the above was respired, the rest was incorporated in unknown form into the mycelium. Mycelia were homogenized and about 3% of the initial label was found in TCA precipitate of the cell-free supernatant. Protocatechuic acid 3,4-dioxygenase (EC 1.13.11.3) and catechol 1,2-dioxygenase (EC 1.13.11.1) activities were detected in the mycelial extracts of theAspergillus spp. All theAspergillus spp. were capable of degrading both aromatic and carbohydrate components of water-soluble lignocarbohydrate complexes (LCC) from wheat straw. The degradation of the aromatic moiety of soluble LCC with apparent molecular mass more than 100,000 daltons was far more active in theAspergillus spp. than in the whiterot fungi tested; i.e.Polyporus versicolor, Pleurotus ostreatus, andForties annosus. The aromatics present in the soluble LCC, as well as a variety of lignin-related compounds tested, did not affect the production of hemicellulases byA. japonicus. Aspergillus spp. degraded¹⁴C-dehydrogenative polymerizates, converting carbon from the ring as well as from the -O¹⁴CH₃ groups to¹⁴CCO₂.¹⁴CO₂ release after 21 d did not exceed 10% of the total¹⁴C input. This situation is comparable to some white-rot fungi. Lignosulfonate was poorly degraded byA. japonicus, but clearly modified.Fomes annosus was able to grow much better on lignosulfonate whenA. japonicus had previously grown on it.Aspergillus spp. grew efficiently on wheat straw, utilizing lignin and some carbohydrates, and rendering the remaining carbohydrates more available to attack of carbohydrases.     

Protection of aspergillus niger cellulases by urea during growth on glucose or glycerol supplemented media

The cellulase enzymes ofAspergillus niger were found to undergo catabolite repression in the presence of glucose and glycerol accompanied by sudden drop in pH of the fermentation medium below 2.0. This sudden drop in pH caused inactivation of cellulolytic enzymes produced byAspergillus niger. The supplementation of nitrogen sources, especially urea, protectsA. niger cellulases from inactivation caused by a sudden drop in pH, since urea helped to maintain the pH of the fermentation medium between 3.5 and 4.5. The role of urea in the protection of cellulase was more prominent when it was used in combination with glycerol (5%).     

Immobilization of carboxylic proteinases on amino-Silochrome

Summary Highly purified porcine pepsin and aspergillopepsin A immobilized on amino-Silochrome have been obtained. The enzymatic properties of these insoluble derivatives have been studied.All-Union Scientific-Research Institute of the Genetics and Breeding of Industrial Microorganisms, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 373–379, May–June, 1978.     

Purification of carboxylic proteinases on aminosilochrome

Summary 1. The possibility has been shown of the preparative production of a number of carboxylic proteinases by the ion-exchange chromatography of commercial preparations of these enzymes on a column of Aminosilochrome C-80 or C-120. Preparations of calf pepsin and chymosin and of bovine and porcine pepsins with a high degree of purity have been obtained in practically quantitative yield.2. An accelerated preparative method for purifying commercial preparations of porcine pepsin on Aminosilochrome C-120 by the sorption-desorption of the enzyme under static conditions has been proposed.All-Union Scientific-Research Institute of the Genetics and Breeding of Industrial Microorganisms, Moscow. Translated from Khimiya Prirodykh Soedinenii, No. 3, pp. 398–403, May–June, 1977.     

海洋烟曲霉菌产脱乙酰酶发酵条件优化

几丁质酶是一类复合酶,包括脱乙酰酶、几丁质酶、壳聚糖酶、几丁寡糖酶、几丁二糖酶等,将脱乙酰酶应用于壳聚糖的制备中,不仅可以有效地从甲壳素(几丁质)分子中脱除乙酰基,而且不会把甲壳素的长链降解为小分子,可以制备出高脱乙酰度且性能独特的壳聚糖,同时不存在排放废碱液而对环境造成严重污染.     

Activation of hexafluoroethane by calcium atoms

Cocondensation of calcium atoms and hexafluoroethane yields a black powder that evolves hydrogen, methane, ethyne, and other unsaturated hydrocarbons upon hydrolysis.     

Activation of magnesia by hydrogen spillover

Magnesia aerogel activated by hydrogen spillover at 430 °C or at 200 °C becomes a catalyst for the hydrogenation of ethylene. This catalytic activity, observed already at 50 °C, is further enhanced by a treatment in oxygen at 430 °C.

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, 430 200°C, . 50°C 430°C.