烟曲霉生物吸附剂对活性艳红吸附性能的研究

将具有高效吸附作用的真菌烟曲霉制成生物吸附剂后用于偶氮染料活性艳红X-3B的吸附,研究了初始pH值、金属离子、盐度和脲对吸附容量的影响,并比较了生物吸附剂和粉状活性炭的吸附性能。结果表明:pH值对生物吸附剂吸附活性艳红X-3B的影响较大,吸附容量随pH值升高而降低;二价金属离子在一定质量浓度范围内(不大于1mg/L)对生物吸附剂的吸附性能具有一定的协同促进作用;NaCl对生物吸附剂的吸附性能具有一定的促进作用;相同条件下,生物吸附剂对X-3B的吸附容量较粉状活性炭高。     

表面修饰烟曲霉对刚果红的吸附性能研究

采用阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)对无活性烟曲霉菌体(AFB)进行化学修饰,对比研究了AFB和改性后的烟曲霉菌体(MAFB)对阴离子染料刚果红(CR)的吸附性能。结果表明,AFB和MAFB均可有效吸附溶液中的CR;相比于AFB,MAFB对CR的吸附效果明显增强。吸附过程符合伪二级动力学模型以及Freundlich等温线模型。氨基是吸附CR的主要基团,羟基和羧基则起着一定的作用。     

磁性生物吸附剂对Cu2+吸附性能的研究

以环氧氯丙烷为交联剂,用壳聚糖、纳米磁粉悬浮液(Fe3O4)和纯菌丝体制备了磁性生物吸附剂,用XRD对该吸附剂进行了结构表征.研究了溶液pH、吸附时间和Cu2 初始浓度对其吸附性能的影响,结果表明,在pH为5～5.5,Cu2 初始质量浓度为0.1 g/L,吸附时间为8 h的条件下,它的Cu2 去除率为88.73%,吸附容量为16.530 mg/g.该磁性生物吸附剂经5次重复使用后,对Cu2 去除率仍然达到79%以上,具有良好的重复使用性.     

含砷废水处理研究进展

介绍了含砷废水的危害和处理技术发展现状,分析了传统除砷工艺技术的特点及局限性。对吸附法处理含砷废水进行了重点阐述。结果表明,吸附法是同时实现废水除砷和砷资源回收利用的有效技术,而吸附法处理含砷废水的关键在于吸附剂的性能。因此为应对新的生活饮用水水质标准的要求,开发廉价、高效、稳定的新型除砷吸附材料将是重点关注的研究方向。     

骨炭吸附去除溶液中砷的研究

采用骨炭作吸附剂,通过静态和动态吸附试验,研究了其对饮用水中砷的脱除效果及其影响因素,以及骨炭反复吸附一解吸一再生一再吸附后性能的稳定性.结果表明,骨炭能够高效除砷.骨炭吸附砷符合Langmuir和Freundlich等温吸附模型.吸附柱的饱和吸附容量为4.688 mg/g,饮用水出水砷浓度符合世界卫生组织(WHO)规定的饮用水标准(As<0.01 mg/L),说明骨炭除砷具有很好的应用前景.     

吸附法处理废水中砷的研究现状及进展

水体中的砷严重危害到人体健康,寻求高效廉价的除砷技术已成为研究热点。吸附法因其简单易行、去除效果好、能回收废水中的砷、对环境不产生或很少产生二次污染,且吸附材料来源广泛、价格低廉、可重复使用备受人们关注。综述了当前国内外用不同吸附方法去除水中砷的研究进展,分析了各种方法的吸附性能和特点,提出生物质吸附剂和废弃物吸附剂应成为水体中砷去除的研发热点。     

改性膨润土在含砷废水处理中的应用

砷严重的威胁着生态的平衡和人类的健康,砷污染的治理任重而道远。文章简单比较了几种常见含砷废水处理方法的优、缺点,重点介绍了膨润土的基本性质、膨润土的改性方法以及改性膨润土这种高效吸附剂在含砷废水处理中的应用,并对其吸附机理进行了初步的探讨。     

低浓度含砷废水处理试验探究

采用复合铁盐、石灰、磷酸盐、PAM对含砷废水进行除砷实验探究,结果表明：在复合铁盐加入量为2%～3%,磷酸盐加入量为3%～4%,石灰加入量为5%～20%,调节pH为7～9,PAM加入量为1%的条件下,废水中砷含量从1018 mg/L降至0.32 mg/L,除砷率达99.968%。处理后的废水能达到《污水综合排放标准》GB8978-1996(0.5 mg/L)的要求,处理后产生的污泥能达到《危险废物填埋污染控制标准》GB18598-2019规定的含量1.2 mg/L以下。     

Fe-Mn-Zr复合磁性吸附材料对As(V)的吸附性能研究

本研究成功制备了一种Fe-Mn-Zr复合磁性吸附材料,并研究了其对As(V)的吸附性能。结果表明,大部分砷吸附在最初的6 h完成,30 h内可以达到吸附平衡。吸附最佳pH值为3.0,吸附等温线符合Langmuir吸附等温模型。在初始pH值5.0时,最大吸附量为81.3 mg/g。     

Chemoenzymatic synthesis of prenylated indole derivatives by using a 4-dimethylallyltryptophan synthase from Aspergillus fumigatus

A 4-dimethylallyltryptophan synthase, FgaPT2, has been identified in the genome of Aspergillus fumigatus. In a previous study, FgaPT2 was overexpressed in Saccharomyces cerevisiae and characterized biochemically. A higher protein yield (up to 100-fold higher than that for S. cerevisiae) has now been achieved by overexpression in E. coli; this has permitted investigation into substrate specificity with alternative substances. FgaPT2 accepted 17 of 37 commercially available indole derivatives as substrates. Tryptophan derivatives that carry methyl groups at the indole ring showed a different acceptance from those with methyl groups on the side chain. 5-Hydroxytryptophan was well accepted by FgaPT2, while the halogenated derivatives were not accepted. Decarboxylation, deamination, or oxidative deamination of tryptophan, as well as replacement of the NH(2) group by OH, or of the COOH group by CH(2)COOH or CONHOH resulted in decreased but still significant enzymatic activity. None of the tested tryptophan-containing dipeptides was accepted by FgaPT2. Structural elucidation of isolated enzymatic products by NMR and MS analyses proved unequivocally that the prenylation was regioselective at position C4 of the indole ring in the presence of dimethylallyl diphosphate. Determination of the kinetic parameters revealed that L-tryptophan was accepted as the best substrate by the enzyme, followed by 5-,6-,7-methyltryptophan and L-abrine. The enzymatic rate constant (k(cat) K(m) (-1)) of nine selected substrates were found to be about 1.0 to 6.5 % of that for L-tryptophan. Overnight incubation with eight substances showed that the conversion ratio to their prenylated derivatives was in the range 32.5 to 99.7 %. This provides evidence that 4-dimethylallylated indole derivatives can be produced by chemoenzymatic synthesis with FgaPT2.     

Investigation of cytochrome P450 mediated benzo(a)pyrene hydroxylation in Aspergillus fumigatus

Microsomal fractions of Aspergillus fumigatus exhibited a reduced carbon monoxide difference spectrum with a maximum at 448 nm and a substrate-induced Type I spectrum on addition of benzo(a)pyrene. Metabolism of benzo(a)pyrene, as measured using the aryl hydrocarbon hydroxylase assay, was found to be P450-dependent and activity was observed to have a K_m of 82 μM and V_max of 33·3 pmol min⁻¹ mg⁻¹ protein. P450 productivity was investigated during growth from spore inocula and observed to be constant until the stationary phase, where the specific content declined to undetectable levels. The specific content of P450 was found to increase in higher concentrations of glucose.     

烟曲霉分泌蛋白质提取方法的比较

目的比较3种丝状真菌烟曲霉分泌蛋白质的提取方法,并通过双向凝胶电泳对提取的蛋白质进行分离。方法利用TCA沉淀、丙酮沉淀及TCA-丙酮沉淀法分别提取烟曲霉的分泌蛋白质,SDS-PAGE比较其结果,初步确定最佳提取方法,并利用双向凝胶电泳分离提取的蛋白质。结果TCA-丙酮沉淀法提取的蛋白质浓度最高,种类和数量最多,双向凝胶电泳显示蛋白质点聚合较好,无非特异的条带和杂质,背景透明。结论TCA-丙酮沉淀法提取的烟曲霉分泌蛋白质图谱较好,为丝状真菌分泌蛋白质的研究奠定了基础。     

The fumitremorgin gene cluster of Aspergillus fumigatus: identification of a gene encoding brevianamide F synthetase

A gene encoding a putative dimodular nonribosomal peptide synthetase (NRPS) was identified within a gene cluster of Aspergillus fumigatus, a species reported to produce fumitremorgins and other prenylated alkaloids. The gene was deleted and overexpressed in the genome reference strain Af293, and was also expressed in the naïve host Aspergillus nidulans, which lacks the equivalent gene cluster. While neither fumitremorgins nor the dipeptide brevianamide F (cyclo‐L ‐Trp‐L ‐Pro), an early intermediate, were detected in wild‐type and deletion strains of A. fumigatus, brevianamide F accumulated in fungal cultures following increased expression of the NRPS gene in both A. fumigatus and A. nidulans. We conclude that the gene Afu8g00170, named ftmA, encodes the NRPS brevianamide synthetase. Brevianamide F is the precursor of a variety of fungal prenylated alkaloids with biological activity, including fumitremorgins A, B and C and tryprostatin B.     

Identification of a hybrid PKS/NRPS required for pseurotin A biosynthesis in the human pathogen Aspergillus fumigatus

The genome sequence of Aspergillus fumigatus revealed the presence of a single hybrid polyketide synthase-non-ribosomal peptide synthetase (PKS/NRPS) gene that is present within a cluster of five genes suggestive of its involvement in secondary metabolism. Here, we present evidence that it is required for the biosynthesis of pseurotin A, a compound with an unusual heterospirocyclic gamma-lactam structure. We have confirmed that the genome reference strain A. fumigatus Af293 produces pseurotin A, a compound previously reported to be a competitive inhibitor of chitin synthase and an inducer of nerve-cell proliferation. Deletion or overexpression of the PKS/NRPS gene psoA in A. fumigatus leads to the absence or accumulation of pseurotin A, respectively; this indicates that this gene is essential for the biosynthesis of pseurotin A. It is likely that the first product of psoA is converted to pseurotin A by the products of other genes in this cluster.     

Asian Sand Dust Particles Enhance the Development of Aspergillus fumigatus Biofilm on Nasal Epithelial Cells

Background: Asian sand dust (ASD) and Aspergillus fumigatus are known risk factors for airway mucosal inflammatory diseases. Bacterial and fungal biofilms commonly coexist in chronic rhinosinusitis and fungus balls. We evaluated the effects of ASD on the development of A. fumigatus biofilm formation on nasal epithelial cells. Methods: Primary nasal epithelial cells were cultured with A. fumigatus conidia with or without ASD for 72 h. The production of interleukin (IL)-6, IL-8, and transforming growth factor (TGF)-β1 from nasal epithelial cells was determined by the enzyme-linked immunosorbent assay. The effects of ASD on A. fumigatus biofilm formation were determined using crystal violet, concanavalin A, safranin staining, and confocal scanning laser microscopy. Results: ASD and A. fumigatus significantly enhanced the production of IL-6 and IL-8 from nasal epithelial cells. By coculturing A. fumigatus with ASD, the dry weight and safranin staining of the fungal biofilms significantly increased in a time-dependent manner. However, the increased level of crystal violet and concanavalin A stain decreased after 72 h of incubation. Conclusions: ASD and A. fumigatus induced the production of inflammatory chemical mediators from nasal epithelial cells. The exposure of A. fumigatus to ASD enhanced the formation of biofilms. The coexistence of ASD and A. fumigatus may increase the development of fungal biofilms and fungal inflammatory diseases in the sinonasal mucosa.     

An Iterative O‐Methyltransferase Catalyzes 1,11‐Dimethylation of Aspergillus fumigatus Fumaric Acid Amides

S‐adenosyl‐l ‐methionine (SAM)‐dependent methyltransfer is a common biosynthetic strategy to modify natural products. We investigated the previously uncharacterized Aspergillus fumigatus methyltransferase FtpM, which is encoded next to the bimodular fumaric acid amide synthetase FtpA. Structure elucidation of two new A. fumigatus natural products, the 1,11‐dimethyl esters of fumaryl‐l ‐tyrosine and fumaryl‐l ‐phenylalanine, together with ftpM gene disruption suggested that FtpM catalyzes iterative methylation. Final evidence that a single enzyme repeatedly acts on fumaric acid amides came from an in vitro biochemical investigation with recombinantly produced FtpM. Size‐exclusion chromatography indicated that this methyltransferase is active as a dimer. As ftpA and ftpM homologues are found clustered in other fungi, we expect our work will help to identify and annotate natural product biosynthesis genes in various species.