Stomatococcus mucilaginosus produces a mannose-containing lipoglycan rather than lipoteichoic acid

Five strains of Stomatococcus mucilaginosus were investigated to determine whether the organism produces a lipoteichoic acid or a lipoglycan. Crude phenol extracts were purified by hydrophobic interaction chromatography and shown to contain lipoglycan. The major carbohydrate component present was mannose, indicating that the macroamphiphile is a lipomannan. The fatty acid composition of the lipoglycan was similar to that of stomatococcal whole cells. These data provide additional chemotaxonomic evidence supporting the suprageneric classification of the genus Stomatococcus within a group of actinomycete genera that also includes the genus Micrococcus.Abbreviations LTA Lipoteichoic acid - HIC Hydrophobic interaction chromatography - FAMEs Fatty acid methyl esters     

Structural characterization and functional properties of a novel lipomannan variant isolated from a Corynebacterium glutamicum pimB′ mutant

The genus Corynebacterium is part of the phylogenetic group nocardioform actinomycetes, which also includes the genus Mycobacterium. Members of this phylogenetic group have a characteristic cell envelope structure, which is dominated by complex lipids and amongst these, lipoglycans are of particular interest. The disruption of NCgl2106 in C. glutamicum resulted in a mutant devoid of monoacylated phosphatidyl-myo-inositol dimannoside (Ac(1)PIM(2)) resulting in the accumulation of Ac(1)PIM(1) and cessation of phosphatidyl-myo-inositol (PI) based lipomannan (Cg-LM, now also termed 'Cg-LM-A') and lipoarabinomannan (Cg-LAM) biosynthesis. Interestingly, SDS-analysis of the lipoglycan fraction from the mutant revealed the synthesis of a single novel lipoglycan, now termed 'Cg-LM-B'. Further chemical analyses established the lipoglycan possessed an alpha-D: -glucopyranosyluronic acid-(1 --> 3)-glycerol (GlcAGroAc(2)) based anchor which was then further glycosylated by 8-22 mannose residues, with Man(12-20)GlcAGroAC(2) molecular species being the most abundant, to form a novel lipomannan structure (Cg-LM-B). The deletion of NCgl2106 in C. glutamicum has now provided a useful strain, in addition with a deletion mutant of NCgl0452 in C. glutamicum for the purification of Cg-LM-A and Cg-LM-B. Interestingly, both Cg-LM species induced a similar production of TNF-alpha by a human macrophage cell line suggesting that the phospho-myo-inositol residue of the PI-anchor does not play a key role in lipoglycan pro-inflammatory activity.     

Identification of a lipoarabinomannan-like lipoglycan in the actinomycete Gordonia bronchialis

The cell envelopes of actinomycetes contain lipidated macroamphiphiles, of which the most extensively characterised are the lipoarabinomannans of mycobacteria and related bacteria. We have investigated the mycolic acid-containing actinomycete Gordonia bronchialis and identified the presence of a lipoarabinomannan-like lipoglycan. The extraction and purification procedures recovered a second amphiphilic fraction with properties suggesting a phosphatidylinositol mannoside, consistent with studies of other Gordonia species.Dedicated to the memory of our former colleague Dr. David Bendell.     

Characterization of a truncated lipoarabinomannan from the Actinomycete Turicella otitidis

Lipoarabinomannan (LAM) lipoglycans have been characterized from a range of mycolic acid-containing actinomycetes and from the amycolate actinomycete Amycolatopsis sulphurea. To further understand the structural diversity of this family, we have characterized the lipoglycan of the otic commensal Turicella otitidis. T. otitidis LAM (TotLAM) has been determined to consist of a mannosyl phosphatidylinositol anchor unit carrying an (α 1→6)-linked mannan core and substituted with terminal-arabinosyl branches. Thus, TotLAM has a novel truncated LAM structure. Using the human monocytic THP-1 cell line, it was found that TotLAM exhibited only minimal ability to induce tumor necrosis factor alpha. These findings contribute further to our understanding of actinomycete LAM diversity and allow further speculation as to the correlation between LAM structure and the immunomodulatory activities of these lipoglycans.     

Lipoarabinomannan localization and abundance during growth of Mycobacterium smegmatis

Lipoarabinomannan (LAM) is a structurally heterogeneous amphipathic lipoglycan present in Mycobacterium spp. and other actinomycetes, which constitutes a major component of the cell wall and exhibits a wide spectrum of immunomodulatory effects. Analysis of Mycobacterium smegmatis subcellular fractions and spheroplasts showed that LAM and lipomannan (LM) were primarily found in a cell wall-enriched subcellular fraction and correlated with the presence (or absence) of the mycolic acids in spheroplast preparations, suggesting that LAM and LM are primarily associated with the putative outer membrane of mycobacteria. During the course of these studies significant changes in the LAM/LM content of the cell wall were noted relative to the age of the culture. The LAM content of the M. smegmatis cell wall was dramatically reduced as the bacilli approached stationary phase, whereas LM, mycolic acid, and arabinogalactan content appeared to be unchanged. In addition, cell morphology and acid-fast staining characteristics showed variations with growth phase of the bacteria. In the logarithmic phase, the bacteria were found to be classic rod-shaped acid-fast bacilli, while in the stationary phase M. smegmatis lost the characteristic rod shape and developed a punctate acid-fast staining pattern with carbolfuchsin. The number of viable bacteria was independent of LAM content and phenotype. Taken together, the results presented here suggest that LAM is primarily localized with the mycolic acids in the cell wall and that the cellular concentration of LAM in M. smegmatis is selectively modulated with the growth phase.     

Bacterial Endosymbionts of Pyrodinium bahamense var. compressum

The study presents evidence in support of the bacterial theory associated with the toxicity of Pyrodinium bahamense var. compressum. Bacterial endosymbionts from Philippine P. bahamense var. compressum strain Pbc MZRVA 042595 were isolated and identified via 16S rDNA sequence analysis. Taxonomic diversity of the identified culturable intracellular microbiota associated with Philippine P. bahamense var. compressum was established to be limited to the Phyla Proteobacteria, Actinobacteria, and Firmicutes. Major endosymbionts identified included Moraxella spp., Erythrobacter spp., and Bacillus spp., whereas Pseudomonas putida, Micrococcus spp., and Dietzia maris were identified as minor isolates. All identified strains except D. maris, P. putida, and Micrococcus spp. were shown to contain either saxitoxin or neo saxitoxin or both at levels ≤73 ng/10⁷ bacterial cells based on high-performance liquid chromatography analysis. Paralytic shellfish poisoning-like physiologic reactions in test animals used in the mouse assay were recorded for the endosymbionts except for P. putida. The study is the first to elucidate the possible contribution of bacterial endosymbionts in the toxicity of P. bahamense var. compressum isolated in the Philippines.     

Polysaccharide structural variability in mycobacteria: identification and characterization of phosphorylated mannan and arabinomannan

Arabinomannan (AMannan) and mannan (Mannan) are major polysaccharides antigens of the mycobacterial capsule. They are highly related to the lipoarabinomannan (LAM) and lipomannan (LM) lipoglycans of the cell wall, known to participate to the immunopathogenesis of mycobacterial infections. Here we present the identification of two related polysaccharides from Mycobacterium kansasii that co-purified with AMannan and Mannan. Structural analysis using GC, MALDI-MS and NMR clearly established these molecules as non-acylated phosphorylated AMannan and Mannan designated P-AMannan and P-Mannan, respectively. These glycoconjugates represent a new source of polysaccharide structural variability in mycobacteria and constitute unique tools for structure-activity relationship studies in order to investigate the role of fatty acids in the biological functions of LAM and LM. The potential participation of these polysaccharides in influencing the outcome of the infection is also discussed.     

地黄内生放线菌的分离及地黄轮纹病拮抗菌Streptomyces folium leaf-16的新种鉴定

药用植物内生放线菌具有合成天然活性化合物的潜力,放线菌新种是寻找新型抗生素先导化合物的一个重要来源。【目的】挖掘药用植物地黄内生放线菌资源,并对地黄轮纹病拮抗菌株leaf-16进行新种鉴定。【方法】本研究采用五步消毒法分离河南道地药材地黄的内生放线菌,以地黄轮纹病原真菌草茎点霉(Phoma herbarum)为指示菌,采用平板对峙法筛选对该病菌有抑制作用的菌株,16S rRNA基因测序发现一株抗地黄轮纹病的放线菌新种leaf-16。通过形态、生理生化、细胞壁化学组分和分子生物学等特征对菌株leaf-16进行多相分类学鉴定。【结果】经平板对峙实验得到8株抗地黄轮纹病的放线菌,其中菌株leaf-16经16S rRNA基因测序、形态比较、生理生化、化学组分和分子生物学以及DNA-DNA杂交分析,确定菌株leaf-16为1株链霉菌新种,并命名为Streptomyces folium。【结论】菌株leaf-16为1株链霉菌新种,具有抑制地黄轮纹病原真菌的活性,为进一步分离新型抗地黄轮纹病的生物制剂奠定物质基础。     

Two isocitrate dehydrogenases from a psychrophilic bacterium, Colwellia psychrerythraea

Two structurally different monomeric and dimeric types of isocitrate dehydrogenase (IDH; EC 1.1.1.42) isozymes were confirmed to exist in a psychrophilic bacterium, Colwellia psychrerythraea, by Western blot analysis and the genes encoding them were cloned and sequenced. Open reading frames of the genes (icd-M and icd-D) encoding the monomeric and dimeric IDHs of this bacterium, IDH-M and IDH-D, were 2,232 and 1,251 bp in length and corresponded to polypeptides composed of 743 and 416 amino acids, respectively. The deduced amino acid sequences of the IDH-M and IDH-D showed high homology with those of monomeric and dimeric IDHs from other bacteria, respectively. Although the two genes were located in tandem, icd-M then icd-D, on the chromosomal DNA, a Northern blot analysis and primer extension experiment revealed that they are transcribed independent of each other. The expression of the monomeric and dimeric IDH isozyme genes in C. maris, a psychrophilic bacterium of the same genus as C. psychrerythraea, is known to be induced by low temperature and acetate, respectively, but no such induction in the expression of the C. psychrerythraea icd-M and icd-D genes was detected. IDH-M and IDH-D overexpressed in Escherichia coli were purified and characterized. In C. psychrerythraea, the IDH-M isozyme is cold-active whereas IDH-D is mesophilic, which is similar to C. maris that contains both cold-adapted and mesophilic isozymes of IDH. Experiments with chimeric enzymes between the cold-adapted monomeric IDHs of C. psychrerythraea and C. maris (IDH-M and ICD-II, respectively) suggested that the C-terminal region of the C. maris IDH-II is involved in its catalytic activity.     

Antagonistic interactions between garden yeasts and microfungal garden pathogens of leaf-cutting ants

We investigate the diversity of yeasts isolated in gardens of the leafcutter ant Atta texana. Repeated sampling of gardens from four nests over a 1-year time period showed that gardens contain a diverse assemblage of yeasts. The yeast community in gardens consisted mostly of yeasts associated with plants or soil, but community composition changed between sampling periods. In order to understand the potential disease-suppressing roles of the garden yeasts, we screened isolates for antagonistic effects against known microfungal garden contaminants. In vitro assays revealed that yeasts inhibited the mycelial growth of two strains of Escovopsis (a specialized attine garden parasite), Syncephalastrum racemosum (a fungus often growing in gardens of leafcutter lab nests), and the insect pathogen Beauveria bassiana. These garden yeasts add to the growing list of disease-suppressing microbes in attine nests that may contribute synergistically, together with actinomycetes and Burkholderia bacteria, to protect the gardens and the ants against diseases. Additionally, we suggest that garden immunity against problem fungi may therefore derive not only from the presence of disease-suppressing Pseudonocardia actinomycetes, but from an enrichment of multiple disease-suppressing microorganisms in the garden matrix.     

南方红豆杉内生及根际放线菌多样性及其生物活性

【目的】研究药用植物南方红豆杉内生及根际土壤放线菌的多样性及其抑菌、抗肿瘤等重要生物活性并获得一些具有强抑制植物病原真菌以及抗肿瘤等重要生物活性的菌株。【方法】选择7种培养基从南方红豆杉及其根际土壤中分离放线菌,对链霉菌进行形态学分类,去重复后对其进行抑制植物病原真菌以及抗肿瘤活性的筛选并对高活性菌株进行初步鉴定。对部分菌株进行16S rRNA基因测序分析研究其多样性。【结果】研究共分离得到277株放线菌,经去重复后剩余111株放线菌,可归类到6个亚目、7个科、8个属。其中链霉菌可分为10个类群。生物活性研究结果显示:30.9%的菌株具有抑制植物病原真菌活性,其中6株放线菌对多种植物病原真菌显示了强的抑菌活性。分别有44.1%和33.3%的菌株对胃癌肿瘤细胞株SGC-7901和肺癌肿瘤细胞株NCI-H460的抑制率在40%以上。【结论】药用植物南方红豆杉及其根际土壤蕴含种类丰富的放线菌资源,具有良好的生物学活性。菌株KLBMP 2170具有显著的抑菌以及抗肿瘤活性,值得我们去进一步研究。     

Mycobacterium tuberculosis Lipoprotein LprG Binds Lipoarabinomannan and Determines Its Cell Envelope Localization to Control Phagolysosomal Fusion

Mycobacterium tuberculosis (Mtb) virulence is decreased by genetic deletion of the lipoprotein LprG, but the function of LprG remains unclear. We report that LprG expressed in Mtb binds to lipoglycans, such as lipoarabinomannan (LAM), that mediate Mtb immune evasion. Lipoglycan binding to LprG was dependent on both insertion of lipoglycan acyl chains into a hydrophobic pocket on LprG and a novel contribution of lipoglycan polysaccharide components outside of this pocket. An lprG null mutant (Mtb ΔlprG) had lower levels of surface-exposed LAM, revealing a novel role for LprG in determining the distribution of components in the Mtb cell envelope. Furthermore, this mutant failed to inhibit phagosome-lysosome fusion, an immune evasion strategy mediated by LAM. We propose that LprG binding to LAM facilitates its transfer from the plasma membrane into the cell envelope, increasing surface-exposed LAM, enhancing cell envelope integrity, allowing inhibition of phagosome-lysosome fusion and enhancing Mtb survival in macrophages.     

The Lipoprotein LpqW Is Essential for the Mannosylation of Periplasmic Glycolipids in Corynebacteria

Phosphatidylinositol mannosides (PIM), lipomannan (LM), and lipoarabinomannan (LAM) are essential components of the cell wall and plasma membrane of mycobacteria, including the human pathogen Mycobacterium tuberculosis, as well as the related Corynebacterineae. We have previously shown that the lipoprotein, LpqW, regulates PIM and LM/LAM biosynthesis in mycobacteria. Here, we provide direct evidence that LpqW regulates the activity of key mannosyltransferases in the periplasmic leaflet of the cell membrane. Inactivation of the Corynebacterium glutamicum lpqW ortholog, NCgl1054, resulted in a slow growth phenotype and a global defect in lipoglycan biosynthesis. The NCgl1054 mutant lacked LAMs and was defective in the elongation of the major PIM species, AcPIM2, as well as a second glycolipid, termed Gl-X (mannose-α1–4-glucuronic acid-α1-diacylglycerol), which function as membrane anchors for LM-A and LM-B, respectively. Elongation of AcPIM2 and Gl-X was found to be dependent on expression of polyprenol phosphomannose (ppMan) synthase. However, the ΔNCgl1054 mutant synthesized normal levels of ppMan, indicating that LpqW is not required for synthesis of this donor. A spontaneous suppressor strain was isolated in which lipoglycan synthesis in the ΔNCgl1054 mutant was partially restored. Genome-wide sequencing indicated that a single amino acid substitution within the ppMan-dependent mannosyltransferase MptB could bypass the need for LpqW. Further evidence of an interaction is provided by the observation that MptB activity in cell-free extracts was significantly reduced in the absence of LpqW. Collectively, our results suggest that LpqW may directly activate MptB, highlighting the role of lipoproteins in regulating key cell wall biosynthetic pathways in these bacteria.     

Variations in the alginate content and composition of Durvillaea antarctica and D. willana from southern New Zealand

The brown seaweeds Durvillaea antarctica andD. willana are dominant components of the lowerlittoral and upper sublittoral of exposed rocky shoresin southern New Zealand. Tissue samples of bothspecies, harvested from a site on the south-east coastof South Island over a period of 2 years, wereanalysed for alginate content and composition.Individuals of both species were further separatedinto different blade (lamina and palm) and stipe(cortex and medulla) fractions to assess variationwithin the thallus. On average the alginate contentand frequency of mannuronic acid (F_m) was higherin D. antarctica than in D. willana. Blades contained more alginate than stipes, laminaeand stipes were rich in mannuronic acid whereasholdfasts were rich in guluronic acid. Variations incomposition are considered to reflect the functionaldifferences of the tissue, giving flexibility to bladeand stipe and rigidity to the holdfast. Despitefluctuations in content and composition betweencollection times no seasonal trends in eithercomponent were apparent.     

Differential Arabinan Capping of Lipoarabinomannan Modulates Innate Immune Responses and Impacts T Helper Cell Differentiation

Toll-like receptors (TLRs) recognize pathogens by interacting with pathogen-associated molecular patterns, such as the phosphatidylinositol-based lipoglycans, lipomannan (LM) and lipoarabinomannan (LAM). Such structures are present in several pathogens, including Mycobacterium tuberculosis, being important for the initiation of immune responses. It is well established that the interaction of LM and LAM with TLR2 is a process dependent on the structure of the ligands. However, the implications of structural variations on TLR2 ligands for the development of T helper (Th) cell responses or in the context of in vivo responses are less studied. Herein, we used Corynebacterium glutamicum as a source of lipoglycan intermediates for host interaction studies. In this study, we have deleted a putative glycosyltransferase, NCgl2096, from C. glutamicum and found that it encodes for a novel α(1→2)arabinofuranosyltransferase, AftE. Biochemical analysis of the lipoglycans obtained in the presence (wild type) or absence of NCgl2096 showed that AftE is involved in the biosynthesis of singular arabinans of LAM. In its absence, the resulting molecule is a hypermannosylated (hLM) form of LAM. Both LAM and hLM were recognized by dendritic cells, mainly via TLR2, and triggered the production of several cytokines. hLM was a stronger stimulus for in vitro cytokine production and, as a result, a more potent inducer of Th17 responses. In vivo data confirmed hLM as a stronger inducer of cytokine responses and suggested the involvement of pattern recognition receptors other than TLR2 as sensors for lipoglycans.     

Grape marc compost: microbial studies and suppression of soil-borne mycosis in vegetable seedlings

Compost suppression of soil-borne diseases in horticultural crops has been attributed to the activities of antagonistic microorganisms. A great diversity of microorganisms, capable of suppressing pathogens naturally colonize compost. A large number of microbes appeared in microbiological analyses of grape marc compost. Most microorganisms were bacteria. Average percentages were 31% mesophilic and 28% thermophylic bacteria, 16% mesophilic actinomycetes and 20% thermophylic actinomycetes. Only a few mould and yeast morphologies were obtained, 4% and 1% respectively. Antagonist in vitro assays were performed with 432 microbial morphologies isolated from grape marc compost. The microbes isolated were extremely effective antagonists in in vitro assays against all the fungal pathogens tested. Seven microorganisms were selected for further bioassay with Rhizoctonia solani in radish, Fusarium oxysporum f. sp. radicis-cucumerinum in melon, and Phytophthora parasitica in tomato and two microorganisms with Pythium aphanidermatum in cucumber. Those experiments indicate that grape marc compost reduces the severity of Pythium damping-off in cucumber, but does not reduce the severity of Phytophthora root rot in tomato, Fusarium oxysporum f. sp. radicis-cucumerinum in melon and Rhizoctonia solani in radish. Better suppressive effects were not demonstrated by either compost or vermiculite amended with microbes selected from grape marc compost.     

Ppm1-Encoded Polyprenyl Monophosphomannose Synthase Activity Is Essential for Lipoglycan Synthesis and Survival in Mycobacteria

The biosynthesis of mycobacterial mannose-containing lipoglycans, such as lipomannan (LM) and the immunomodulator lipoarabinomanan (LAM), is carried out by the GT-C superfamily of glycosyltransferases that require polyprenylphosphate-based mannose (PPM) as a sugar donor. The essentiality of lipoglycan synthesis for growth makes the glycosyltransferase that synthesizes PPM, a potential drug target in Mycobacterium tuberculosis, the causative agent of tuberculosis. In M. tuberculosis, PPM has been shown to be synthesized by Ppm1 in enzymatic assays. However, genetic evidence for its essentiality and in vivo role in LM/LAM and PPM biosynthesis is lacking. In this study, we demonstrate that MSMEG3859, a Mycobacterium smegmatis gene encoding the homologue of the catalytic domain of M. tuberculosis Ppm1, is essential for survival. Depletion of MSMEG3859 in a conditional mutant of M. smegmatis resulted in the loss of higher order phosphatidyl-myo-inositol mannosides (PIMs) and lipomannan. We were also able to demonstrate that two other M. tuberculosis genes encoding glycosyltransferases that either had been shown to possess PPM synthase activity (Rv3779), or were involved in synthesizing similar polyprenol-linked donors (ppgS), were unable to compensate for the loss of MSMEG3859 in the conditional mutant.     

基于高通量测序分析西藏沙棘根瘤内生菌的多样性

根瘤是微生物侵染植物根部并与之形成的共生结构,这些微生物都可被称为植物内生菌。豆科植物根瘤中的内生菌常常又被称为根瘤菌,而侵染非豆科植物形成根瘤的主要是放线菌弗兰克氏菌,这些非豆科植物又被称为放线菌结瘤植物。西藏沙棘是一种典型的放线菌结瘤植物,由于其分布生境的特殊性,对其根瘤内生菌的研究具有重要的生态意义。对于西藏沙棘根瘤内生菌的研究,培养方法因难以模拟自然条件而不易获得纯培养,高通量测序技术对其多样性的研究提供了便利。因此,本研究以生长在甘肃省天祝县金强河河滩地的西藏沙棘根瘤为材料,采用16S rRNA基因扩增子高通量测序方法,结合OTU分析,对西藏沙棘根瘤内生菌的多样性进行探讨。实验结果表明,西藏沙棘根瘤内生菌具有丰富的多样性,根瘤内的优势属为共生固氮的弗兰克氏菌属（Frankia）,其相对丰度为47.63%,共检测到7个弗兰克氏菌属的OTUs;根瘤内除弗兰克氏菌外,还存在大量的非弗兰克氏菌,共检测到1523个OTUs,隶属于22个门、33个纲、69个目、113个科和202个属,相对丰度排名前9的属中有25个非弗兰克氏菌属的OTUs。该研究也表明,西藏沙棘根瘤内生菌具有丰富的多样性,西藏沙棘根瘤中不仅存在着可共生固氮的弗兰克氏菌,并且还分布着非弗兰克氏菌;在同一根瘤样品中,弗兰克氏菌属还具有不同的物种。本研究不仅拓展了西藏沙棘根瘤内生菌多样性的研究方法,还为同一寄主植物中弗兰克氏菌多样性的研究提供了分析思路。     

Novel lipoarabinomannan-like lipoglycan (CdiLAM) contributes to the adherence of <Emphasis Type="Italic">Corynebacterium diphtheriae</Emphasis> to epithelial cells

The genus Corynebacterium is part of the phylogenetic group nocardioform actinomycetes. Members of this group have a characteristic cell envelope structure composed primarily of branched long-chain lipids, termed mycolic acids, and a rich number of lipoglycans such as lipoarabinomanans (LAM) and lipomannans. In this study, we identified a novel LAM variant isolated from Corynebacterium diphtheriae named CdiLAM. The key structural features of CdiLAM are a linear α-1→6-mannan with side chains containing 2-linked α-D-Manp and 4-linked α-D-Araf residues. The polysaccharide backbone is linked to a phosphatidylinositol anchor. In contrast to the LAMs of other members of actinomycetales, CdiLAM presents an unusual substitution at position 4 of α-1→6-mannan backbone by α-D-Araf. Unlike the non-fimbrial adhesin 62–72p, CdiLAM did not function as a hemagglutinin to human red blood cells. Experimental evidences pointed to CdiLAM as an adhesin of C. diphtheriae to human respiratory epithelial cells, thereby, contributing to the pathogenesis of diphtheria.     

西沙海藻共附生放线菌的分离鉴定及其抗菌活性评价

【目的】为了探究南海海藻共附生放线菌资源的多样性及潜在的应用价值,对中国西沙群岛来源的海藻进行共附生放线菌的分离鉴定与抗菌活性筛选。【方法】利用稀释涂布平板法,采用2种不同分离培养基对不同采样位点的6种海藻进行放线菌分离;通过16S rRNA基因序列分析、构建系统发育树对分离的放线菌进行鉴定;用打孔法对无乳链球菌(Streptococcus agalactiae)等10种敏感细菌进行抗菌活性筛选;对筛选得到的目标活性菌株HZ014进行全基因组测序,通过AntiSMASH在线工具分析其次级代谢产物生物合成基因簇,预测其产生新型活性物质的潜力。【结果】从6种海藻中分离得到36株共附生放线菌,基于16S rRNA基因序列比对和系统发育分析,鉴定结果为链霉菌属(Streptomyces) 2株、红球菌属(Rhodococcus) 2株、诺卡氏菌属(Nocardia)3株、小单孢菌属(Micromonospora) 5株和盐孢菌属(Salinispora) 24株;抗菌活性筛选结果表明,36株共附生放线菌发酵粗提物对至少1种敏感细菌表现出一定的抑制作用,不同菌株发酵粗提物的抗菌活性存在明显差异,...