Nobachelins,new siderophores from Nocardiopsis baichengensis protecting Caenorhabditis elegans from Pseudomonas aeruginosa infection

The biosynthetic potential of actinobacteria to produce novel natural products is still regarded as immense.In this paper,we correlated a cryptic biosynthetic gene cluster to chemical molecules by genome mining and chemical analyses,leading to the discovery of a new group of catecholate-hydroxamate siderophores,nobachelins,from Nocardiopsis baichengensis DSM 44845.Nobachelin biosynthesis genes are conserved in several bacteria from the family Nocardiopsidaceae.Structurally,nobachelins feature fatty-acylated hydroxy-ornithine and a rare chlorinated catecholate group.Intriguingly,nobachelins rescued Caenorhabditis elegans from Pseudomonas aeruginosa-mediated killing.

Nocardiopsistins A-C:New angucyclines with anti-MRSA activity isolated from a marine sponge-derived Nocardiopsis sp.HB-J378

Marine natural products have become an increasingly important source of new drug leads during recent years.In an attempt to identify novel anti-microbial natural products by bioprospecting deep-sea Actinobacteria,three new angucyclines,nocardiopsistins A-C,were isolated from Nocardiopsis sp.strain HB-J378.Notably,the supplementation of the rare earth salt Lanthanum chloride(LaCl3)during fermentation of HB-J378 significantly increased the yield of these angucyclines.The structures of nocardiopsistins A-C were identified by 1D and 2D NMR and HR-MS data.Nocardiopsistins A-C have activity against MRSA(methicillin-resistant Staphylococcus aureus)with MICs of 3.12–12.5μg/mL;the potency of nocardiopsistin B is similar to that of the positive control,chloramphenicol.Bioinformatic analysis of the draft genome of HB-J378 identified a set of three core genes in a biosynthetic gene cluster that encode a typical aromatic or type II polyketide synthase(PKS)system,including ketoacyl:ACP synthaseα-subunit(KSα),β-subunit(KSβ)and acyl carrier protein(ACP).The production of nocardiopsistins A-C was abolished when the three genes were knocked out,indicating their indispensable role in the production of nocardiopsistins.

Preliminary screening of Ni(II)metal tolerance and dye-decolorizing by Nocardiopsis sp.SD8

Objective:To reveal the screening of metal tolerance and dye-decolorizing of Nocardiopsis sp.Methods:NiSO_(4) and Congo red dye were used for evaluating the metal tolerance and dyedecolorizing of the randomly selected actinobacterial isolates.Results:Nocardiopsis sp.SD8 showed a better efficiency in Ni(II)tolerance,though a longer lag phase was observed for this microorganism grown for 7 days in integrated mismatch negativity.Interestingly,we also found that Nocardiopsis sp.SD8 had dye-decolorizing,hemolytic,lipase and protease activity.Conclusions:The present results revealed the bioremediation of metal resistant and diverse properties of Nocardiopsis sp.SD8 and further investigations are needed to extract and identify the potent molecule.

具抗肿瘤活性放线菌菌株YIM 90022的分离和系统发育分析

从青海盐碱土壤样品中分离到一株兼性嗜碱放线菌YIM 90022，该菌株的发酵产物具有很强的体外抗胃癌、肺癌、乳腺癌、皮肤癌、肾癌和子宫癌肿瘤细胞株活性。基于16S rRNA基因序列的系统发育分析表明，菌株YIM 90022属于拟诺卡氏属（Nocardiopsis）的成员，与该属的4个有效发表种N．exhalans DSM 44407^T，N．prasina DSM 43845^T，N．metallicus DSM 44598^T和N．listeri DSM 40297^T系统发育关系最密切，与其分别以98．8％，98．5％，98．4％和97．8％的16S rRNA基因核苷酸序列相似性聚为一簇。但菌株YIM 90022不与这4个有效种中任何一个单独相聚，形成了一个独立亚分枝。结合形态特征、生理生化特性、细胞化学分类特征，以及rep-PCR基因指纹分析等方面的研究结果，菌株YIM 90022可能为拟诺卡氏菌属的一个潜在新种。菌株YIM 90022在大多数培养基上生长良好，气生菌丝和基内菌丝丰富，在酵母膏麦芽膏琼脂、燕麦片琼脂等培养基中产生可溶性色素。生长pH范围6．0．12．0，最适pH8．5；能在含0—15％NaCl（W／V）的培养基上生长。

1株产纤维素酶嗜盐放线菌的鉴定、发酵优化及酶学性质的研究

从内蒙古腾格里沙漠红盐湖泥样中分离到一株高产纤维素酶菌株,根据菌株形态特征及分子生物学鉴定,确定为拟诺卡氏菌属（Nocardiopsis sp.）,命名为Nocardiopsis sp.DN-A4。采用单因素筛选和正交试验方法优化产纤维素酶的发酵条件,结果表明最适产酶条件：低粘度CMC 4%（w/v）,明胶0.05g/100 mL,pH=7.0,NaCl3g/100mL,接种量60mL/100mL,装液量80mL/250mL,优化后纤维素酶活力达到1.25U/mL。部分酶学性质研究表明,酶反应最适温度55℃,pH=7.0,NaCl 0g/100mL,该酶具有较强的热、pH及盐度的稳定性,酶反应55℃保温8h,pH=6.0-10.0保温6h,NaCl（0-25）g/100mL保温12h,酶活力仍保持在80%以上。

Cultivable Sponge-Associated Actinobacteria from Coastal Area of Eastern Mediterranean Sea

In this study, 16 marine sponge samples collected from Eastern Mediterranean Sea were used for the isolation of sponge-associated Actinobacteria. Different media and pre-treatment methods were applied for the isolation experiments. In total, 7578 actinomycetes colonies were observed on the primary isolation plates, and 20 representative isolates were selected for further studies based on their morphologies and chemical profiles. These isolates were investigated for their antimicrobial activities, seawater requirements and 16S rRNA gene sequences. The phylogenetic analysis revealed that 80% of the isolated Actinobacteria was a member of the Streptomyces genus. All the isolates showed no absolute requirement for seawater. Fifteen of the selected isolates exhibited antimicrobial activity against methicillin resistant Staphylococcus aureus and vancomycin resistant Enterococcus faecium, whereas 3 isolates were active against Candida albicans.

2株南极来源放线菌所产的二酮哌嗪类化合物研究

目的对从南极潮间带沉积物样品中分离得到的2株具有抗菌活性的放线菌进行分类鉴定并进行次生代谢产物研究。方法通过形态学分析及构建系统发育进化树鉴定菌株并对其发酵产物进行生物活性评价;利用硅胶、凝胶柱层析、semi-HPLC等色谱分离手段对2株菌的发酵产物进行分离纯化;采集所得化合物的质谱、NMR等数据并分析后鉴定其结构。结果 2株菌分别鉴定为Streptomyces sp.SCSIO 40061和Nocardiopsis sp.SCSIO KS107;从相应的发酵产物中分离得到2个二酮哌嗪类化合物,结构分别鉴定为:(3Z,6E)-1-N-甲基-3-苯亚甲基-6-(2-甲基-3-羟基丙烷)-2,5-二酮哌嗪(1)以及(3Z,6Z)-3-(4-对甲氧苯亚甲基)-6-(2-甲基丙烷)-2,5-二酮哌嗪(2)。结论发现了2株能产二酮哌嗪类化合物的南极来源放线菌。