Organic arsenic removal from an aqueous solution by iron oxide-coated fungal biomass: An analysis of factors influencing adsorption

A two-level seven-factor (2^7-2) fractional factorial design analysis was conducted to examine the parameters influencing dimethylarsinic acid (DMA) removal from an aqueous solution using iron oxide-coated A. niger biomass. The factors examined were the concentration of DMA in solution, the mass of the adsorbent, the solution temperature, the Ca²⁺ ions in solution, the Fe²⁺ ions in solution, the SO₄²⁻ ions in solution, and the Cl⁻ ions in solution. The magnitude of the influence of the factors considered on DMA removal was observed in the order: presence of Ca²⁺ ions in solution > the DMA concentration > solution temperature > presence of SO₄²⁻ in solution > presence of Fe²⁺ in solution > the mass of adsorbent > the presence of Cl⁻ in solution.     

Evolutionary Imprint of Catalytic Domains in Fungal PKS–NRPS Hybrids

Fungal hybrid enzymes consisting of a polyketide synthase (PKS) and a nonribosomal peptide synthetase (NRPS) module are involved in the biosynthesis of a vast array of ecologically and medicinally relevant natural products. Whereas a dozen gene clusters could be assigned to the requisite PKS–NRPS pathways, the programming of the multifunctional enzymes is still enigmatic. Through engineering and heterologously expressing a chimera of PKS (lovastatin synthase, LovB) and NRPS (cytochalasin synthase, CheA) in Aspergillus terreus, we noted the potential incompatibility of a fungal highly reducing PKS (hrPKS) with the NRPS component of fungal PKS–NRPS hybrids. To rationalize the unexpected outcome of the gene fusion experiments, we conducted extensive bioinformatic analyses of fungal PKS–NRPS hybrids and LovB‐type PKS. From motif studies and the function of the engineered chimeras, a noncanonical function of C‐terminal condensation (C) domains in truncated PKS–NRPS homologues was inferred. More importantly, sequence alignments and phylogenetic trees revealed an evolutionary imprint of the PKS–NRPS domains, which reflect the evolutionary history of the entire megasynthase. Furthermore, a detailed investigation of C and adenylation (A) domains provides support for a scenario in which not only the A domain but also the C domain participates in amino acid selection. These findings shed new light on the complex code of this emerging class of multifunctional enzymes and will greatly facilitate future combinatorial biosynthesis and pathway engineering approaches towards natural product analogues.     

Demonstration of starter unit interprotein transfer from a Fatty Acid synthase to a multidomain, nonreducing polyketide synthase

The pathway for substrate transacylation between a fungal type I fatty acid synthase (FAS) and a nonreducing polyketide synthase (NR-PKS) was determined by in vitro reconstitution of dissected domains. System kinetics were influenced by domain dissections, and the FAS phosphopantetheinyl transferase (PPT) monodomain exhibited coenzyme A selectivity for the post-translational activation of the FAS acyl carrier protein (ACP).     

真菌壳聚糖的研究进展

壳聚糖是很多真菌（尤其是接合菌纲真菌）细胞壁的主要组成部分,可用真菌培养法直接获得。与传统强碱处理的虾蟹壳来源的壳聚糖相比,真菌来源的壳聚糖原料易得,生产过程污染少,所得产品理化性质均一,优势明显。介绍了真菌壳聚糖的合成机理、菌种选育、发酵工艺优化及提取方法等方面的研究进展。     

A comparative study on the fungal communities of wheat Qu for Qingshuang‐type Chinese rice wine

A traditional culture‐dependent method and ribosomal intergenic spacer analysis (RISA) were employed to investigate the fungal communities in two representative samples of wheat Qu (S1, S2). A total of seven species were isolated on media of potato dextrose agar, Czapek and wheat Qu extraction. Owing to the difference in the culture media, a high variability of predominant species was observed. RISA profiles of total DNA exhibited distinguishable bands corresponding to nine fungal species. Similar RISA profiles of two starter cultures were obtained. Sequencing of the internal transcribed spacer fragments from fungal isolates and RISA fingerprint profiles revealed the presence of nine species of fungi in wheat Qu S1: Lichtheimia ramosa, Absidia corymbifera, Aspergillus sydowii, Aspergillus oryzae, Rhizomucor pusillus, Eurotium amstelodami, Issatchenkia orientalis, Emericella nidulans and Cladosporium cladosporioides. In comparison with S1, S2 had a richer fungal diversity. The fungal species derived from S1 were all present in S2 coupled with another two species, namely, Aspergillus niger and Clavispora lusitaniae. Among all species isolated, Aspergillus sydowii was the dominant species in Qingshuang‐type Chinese rice wine wheat Qu. Copyright © 2012 The Institute of Brewing & Distilling     

高压二氧化碳杀灭大肠杆菌过程中的蛋白质变化研究

本研究采用37℃、10~50 MPa的高压二氧化碳(HPCD)处理大肠杆菌及其全蛋白溶液30 min,检测菌落总数、表观形态、蛋白质溶解性、蛋白质组和蛋白质二级结构的变化,研究HPCD胁迫下大肠杆菌的蛋白质变化规律。结果表明:HPCD处理压强升至30 MPa,菌落总数对数值有显著降低;经不同压强处理,菌体形态没有发生显著变化;与对照组(0.1 MPa)相比,可溶性蛋白经20 MPa的HPCD处理后含量显著降低,从1.77 mg/mL降为0.57 mg/mL,并随压强继续上升逐渐降低;30 MPa的HPCD处理菌液,经双向电泳分离到46个差异最大的蛋白点,质谱鉴定具代表性的16个点,分别涉及细胞骨架、新陈代谢、信号转换、运输与翻译等功能;蛋白溶液圆二色谱结果显示,对照组中α-螺旋占68.04%,β-折叠占0.33%,随HPCD处理压强增加,α-螺旋含量显著降低(P0.05)。经20 MPa的HPCD处理,β-折叠含量显著增加(P0.05),但随压强继续增加含量变化不显著。     

基于高通量测序技术分析不同地区自然陈化广陈皮表面微生物群落多样性

采用高通量测序技术对不同地区自然陈化1年广陈皮表面微生物群落多样性进行分析,比较群落结构的差异。结果表明,不同地区自然陈化1年广陈皮微生物丰富度和多样性差异不显著（P＞0.05）,群落结构相似,但相对丰度存在差异。北京地区优势细菌属为Methylocella、苔藓杆菌属（Bryobacter）等,优势真菌属为短梗霉属（Aureobasidium）、炭疽菌属（Colletotrichum）等;四川地区优势细菌属为甲基杆菌属（Methylobacterium）、鞘氨醇单胞菌属（Sphingomonas）、芽孢杆菌属（Bacillus）、乳球菌属（Lactococcus）等,优势真菌属为Symmetrospora、曲霉属（Aspergillus）等;广东地区优势细菌属为Rubellimicrobium、乳杆菌属（Lactobacillus）等,优势真菌属为假尾孢属（Pseudocercospora）、毛壳菌属（Chaetomium）等;云南地区优势细菌属为罗尔斯顿菌属（Ralstonia）、Glutamicibacter等,优势真菌属为平脐疣孢属（Zasmidium）、拟暗球腔菌属（Phaeosphaeriopsis）等。     

Determination of ergosterol in paddy rice using solid phase extraction

Ergosterol, the predominant sterol found in most fungi, is considered as an indicator of fungal invasion in grain. An extraction method based on solid phase extraction (SPE) has been developed for determination of ergosterol in unmilled rice, generally called paddy. The samples obtained by extraction through SPE have been analysed by HPLC. The method has been validated in experiments with paddy subjected to different drying treatments and recoveries above 85% have been obtained. SPE appeared to be simple, quick, reliable and consistent for ergosterol analysis. The ergosterol levels obtained in the paddy samples were found to be within the expected range and were comparable with those found using conventional methods. Copyright © 2004 Society of Chemical Industry     

玉米储藏过程中真菌群落结构的影响因素分析

玉米是我国最重要的储粮之一,仓储玉米的真菌污染问题可造成严重的经济损失,危害国家粮食安全。研究仓储玉米真菌群落演变规律,是预防和控制仓储玉米真菌污染的有效手段。本研究以河南和黑龙江采样的仓储玉米为样本,利用高通量测序技术分析样本中真菌群落的组成结构,并分析采样地域、仓储时间、仓储方位、仓储深度等因素对微生物群落的影响。研究结果表明黑龙江和河南仓储玉米的真菌微生物群落组成均以子囊菌门和担子菌门生物为主,采样地域、储存时间和储存深度对仓储玉米中微生物群落具有较大的影响,而仓储玉米在仓库中的位置对仓储玉米微生物群落影响较小。本研究可以为仓储玉米中真菌群落的发生演变模型的建立提供基础数据支持,为仓储玉米真菌控制提供可行方案。     

蒸汽爆破棉秆的微生物降解研究

蒸汽爆破棉秆的韧皮、枝和主干经嗜碱芽孢杆菌NT-19降解14天后，其失重率分别为23．8％、20．2％和14．0％。该嗜碱菌株在初始14天培养中能保持与白腐真菌Phanerochaete chrysosporium相近的降解率，并能优先降解棉秆主干的半纤维素组分。X-衍射显示，棉秆的韧皮纤维经嗜碱芽孢杆菌NT-19降解后，其相对结晶度降低了7．91％。扫描电镜证实微生物降解去除了韧皮纤维束中的部分中胶层。