一株链霉菌发酵液的抗菌谱及稳定性

从土壤中分离得到一株放线菌菌株，杯碟法测定该菌株发酵液对14种植物病原真菌和两种植物病原细菌均有不同程度的抑菌活性，其中对烟草黑胫病菌和黄瓜菌核病菌的抑菌效果最好，抑菌圈直径达56．36mm和56．26mm。枯斑抑制法测定发酵液对TMV的抑制作用表明，发酵液对TMV有很好的钝化作用，发酵液与病毒汁液混合10min后接种，枯斑抑制率为93．88％，接种前24h处理和接种后24h处理的枯斑抑制率分别为87．93％和42．21％。通过对发酵液稳定性的初步研究，表明发酵液中的抗菌物质对温度、光照以及pH值变化都比较稳定。     

Bacteria in a water‐damaged building: associations of actinomycetes and non‐tuberculous mycobacteria with respiratory health in occupants

We examined microbial correlates of health outcomes in building occupants with a sarcoidosis cluster and excess asthma. We offered employees a questionnaire and pulmonary function testing and collected floor dust and liquid/sludge from drain tubing traps of heat pumps that were analyzed for various microbial agents. Forty‐nine percent of participants reported any symptom reflecting possible granulomatous disease (shortness of breath on exertion, flu‐like achiness, or fever and chills) weekly in the last 4 weeks. In multivariate regressions, thermophilic actinomycetes (median = 529 CFU/m²) in dust were associated with FEV₁/FVC [coefficient = ?2.8 per interquartile range change, P = 0.02], percent predicted FEF_25–75% (coefficient = ?12.9, P = 0.01), and any granulomatous disease‐like symptom [odds ratio (OR) = 3.1, 95% confidence interval (CI) = 1.45?6.73]. Mycobacteria (median = 658 CFU/m²) were positively associated with asthma symptoms (OR = 1.5, 95% CI = 0.97?2.43). Composite score (median = 11.5) of total bacteria from heat pumps was negatively associated with asthma (0.8, 0.71?1.00) and positively associated with FEV₁/FVC (coefficient = 0.44, P = 0.095). Endotoxin (median score = 12.0) was negatively associated with two or more granulomatous disease‐like symptoms (OR = 0.8, 95% CI = 0.67?0.98) and asthma (0.8, 0.67?0.96). Fungi or (1→3)‐β‐D‐glucan in dust or heat pump traps was not associated with any health outcomes. Thermophilic actinomycetes and non‐tuberculous mycobacteria may have played a role in the occupants' respiratory outcomes in this water‐damaged building.     

Contribution of Streptomyces in sediment to earthy odor in the overlying water in Xionghe Reservoir, China

Musty and earthy odors frequently characterize the source water and fish of the Xionghe Reservoir in China. Although odorous compounds and odor-producing cyanobacteria have been analyzed in surface water, potential odorants in sediments and their contribution to the water body have remained uninvestigated. In this study, we examined the odorous compounds and possible odor-producers in the sediments and overlying water of Xionghe Reservoir from November 2007 to October 2008. High concentrations of geosmin (up to 5280.1 ng kg⁻¹ dw⁻¹) were detected in sediments, and eight strains of Streptomyces isolated from sediments were verified as producers of geosmin and/or 2-MIB in M liquid medium by HSPME-GC-MS. Geosmin concentrations in the overlying water were correlated with those in the sediments (r = 0.838, p < 0.05). In vitro studies showed that geosmin in the overlying water was released from the sediment, and that within 12 days the amount released from the sediment was 21.4–51.4%. Concentrations of geosmin in sediments were positively correlated with organic matter (r = 0.642, p < 0.01), total nitrogen (r = 0.606, p < 0.01) and Chl a (r = 0.674, p < 0.01), and were negatively associated with temperature (r = −0.425, p < 0.05). This study indicates that odorous compounds that are released from sediments should be taken into account when assessing the sources of these odorants in waters.     

海洋放线菌天然活性产物的发掘

海洋微生物生活在高盐、高压、低温、低营养或无光照等特殊生境,造就了其种类的多样性和特殊性,能产生海洋微生物所特有的结构新颖、作用特殊的生物活性物质。在海洋微生物中放线菌具有较为复杂的发育分化过程,还能产生大量次级代谢产物。该文综述了近年来从海洋放线菌中筛选天然活性化合物的有效方法,包括优化培养基,改进培养方法和检测技术,运用基因组挖掘技术等。这些有效方法的运用使得从海洋放线菌中筛选生物活性物质具有广阔的开发应用前景。     

潮间带产絮凝剂放线菌的筛选及其培养条件的优化

从唐岛湾潮间带泥沙中筛选出放线菌18株,进行含油废水实验复筛后得到较高絮凝活性的菌株Y-3,初步鉴定为链霉菌属.采用单因素实验和正交实验对Y-3菌株进行发酵条件的优化.结果表明,Y-3菌株最适培养基为:乙醇为碳源,酵母膏为氮源,低盐度;最适培养条件为:培养温度30℃,初始pH值7.0,乙醇用量35 mL· (L海水)-...     

Development and application of a molecular assay to detect and monitor geosmin-producing cyanobacteria and actinomycetes in the Great Lakes

Geosmin is a potent earthy-smelling sesquiterpene responsible for the majority of biologically induced taste-and-odor (T/O) episodes in drinking and recreational water, and major economic losses to commercial, farmed and sports fisheries. Geosmin is produced by a range of microorganisms, notably by cyanobacteria and actinomycetes. However, the effective management of geosmin T/O episodes has been hindered by our inability to identify the major biological sources, and absence of sensitive methods for early detection of T/O events. The main goal of this study was to develop taxon-specific PCR and RT-PCR assays that facilitate early detection of potential geosmin releases and identification of the likely biological sources. We developed a molecular assay for the detection and expression of geosmin synthase (geoA), a gene involved in geosmin biosynthesis in cyanobacteria and actinomycetes. Using the molecular probes, we detected geoA in a wide range of geosmin-producing taxa in both laboratory cultures and environmental samples which provided an important new database of geoA sequences from a diversity of GSM producers, allowing an evaluation of their phylogenetic relationships based on this gene. This study indicated that potential geosmin producers in the Laurentian Great Lakes water and sediment samples are predominantly represented by members of the Nostocaceae, and in particular Anabaena spp. No correlations were apparent between gene expression and ambient temperature, nutrient concentrations and total phytoplankton biomass. Rather, evaluation of the geoA expression pattern in the environmental samples tested from various watersheds and seasons suggested constitutive gene expression.     

放线菌对发酵过程产酱香功能菌的生物学特性研究

从酱香型白酒酒醅中分离到的30株放线菌中复筛出2株具有生物活性的菌株A2、A22,对2株放线菌代谢产物的生物学活性进行了比较研究,考察了放线菌发酵时间对其代谢生物学活性产物的影响,并且对其生物学活性物质进行了初步提取与生物活性检测。结果表明,放线菌A22、A2均能代谢产生生物学活性物质,A22代谢产物相对A2抑菌活性更强,在30℃、120 r/min摇床培养30~36 h时,代谢产物抑菌效果最强,初步结果表明此代谢产物极可能为一种非蛋白类和非肽类抗生素。     

Streptomyces sp. A22对酱香白酒酿造风味调控的研究

应用从酱香型白酒发酵过程中分离获得的一株产土臭味放线菌（Actinomycetes sp.）A22与产酱香解淀粉芽孢杆菌（Bacillus amyloliquefaciens）B6进行模拟固态发酵,研究其对发酵过程主要特征风味化合物形成的影响及其调控。结果表明,放线菌Streptomyces sp. A22可导致解淀粉芽孢杆菌（B. amyloliquefaciens）B6代谢富集吡嗪类化合物总量降低,对其代谢吡嗪具有调控作用;而B. amyloliquefaciens B6抑制Streptomyces sp. A22代谢富集土臭素,降低发酵糟醅中的异味;Streptomyces sp. A22与B. amyloliquefaciens B6之间存在相互的生物学调节关系,混菌发酵过程可相互抑制其生物量,这是导致其发酵过程风味调控的根本机制,影响酒体中酸类、醇类、酯类等风味物质的形成,改善酒体风味。     

土壤来源抗MRSA放线菌的筛选及次级代谢潜力评估

该研究采用4种分离培养基对32份土壤样本中的放线菌进行初步分离纯化,通过抗耐甲氧西林金黄色葡萄球菌（MRSA）抑菌活性实验进行菌株初筛,并采用聚合酶链式反应（PCR）扩增菌株16S rRNA和次级代谢相关基因,对活性菌株的代谢潜力进行评估。结果表明,从32份样本中共分离纯化到169株放线菌,其中68株放线菌具有抗MRSA活性。活性菌株主要为链霉菌属（Streptomyces sp.）,且16S rRNA基因序列相似性＜98%的菌株有10株,卤化酶（Hal）基因阳性菌株占17.65%,聚酮合酶I型（PKS I）基因阳性菌株占36.47%,聚酮合酶II（PKS II）基因阳性菌株占61.77%,非核糖体多肽合成酶（NRPS）基因阳性菌株占32.35%。表明黔北地区土样中放线菌资源丰富,具有从中发现放线菌新种和抗生素的潜力。     

Kitasetaline, a novel β-carboline alkaloid from Kitasatospora setae NBRC 14216T

With the genetically modified Kitasatospora setae NBRC 14216(T) strain, a new β-carboline alkaloid, kitasetaline (1), was produced on solid medium. The structure was elucidated on the basis of physicochemical evidence. This is the first report of this type of alkaloid found in the genus Kitasatospora.