Diversity and novelty of actinobacteria in Arctic marine sediments

The actinobacterial diversity of Arctic marine sediments was investigated using culture-dependent and culture-independent approaches. A total of 152 strains were isolated from seven different media; 18 isolates were selected for phylogenetic analysis on the basis of their 16S rRNA gene sequences. Results showed that the 18 isolates belonged to a potential novel genus and 10 known genera including Actinotalea, Arthrobacter, Brachybacterium, Brevibacterium, Kocuria, Kytococcus, Microbacterium, Micrococcus, Mycobacterium, and Pseudonocardia. Subsequently, 172 rDNA clones were selected by restriction fragment length polymorphism analysis from 692 positive clones within four actinobacteria-specific 16S rDNA libraries of Arctic marine sediments, and then these 172 clones were sequenced. In total, 67 phylotypes were clustered in 11 known genera of actinobacteria including Agrococcus, Cellulomonas, Demequina, Iamia, Ilumatobacter, Janibacter, Kocuria, Microbacterium, Phycicoccus, Propionibacterium, and Pseudonocardia, along with other, unidentified actinobacterial clones. Based on the detection of a substantial number of uncultured phylotypes showing low BLAST identities (<95 %), this study confirms that Arctic marine environments harbour highly diverse actinobacterial communities, many of which appear to be novel, uncultured species.     

Diversity of cultivable actinobacteria in geographically widespread marine sediments

Reports describing actinobacteria isolated from marine environments have been dominated by Micromonospora, Rhodococcus and Streptomyces species. Recent culture-independent studies have shown that marine environments contain a high diversity of actinobacterial species that are rarely, if at all, recovered by cultivation-based methods. In this study, it is shown that cultivation-independent methods can be used to guide the application of selective isolation methods. The detection of marine-derived actinobacterial species that have previously only been reported from terrestrial habitats is highlighted. This study provides good evidence that the previously described low diversity of actinobacterial species isolated from marine environments does not reflect an actual low species diversity, and that the use of informed selective isolation procedures can aid in the isolation of members of novel taxa.     

台湾海峡沉积物放线菌多样性及抗菌活性研究

探究台湾海峡海洋沉积物中放线菌的多样性并进行抗菌活性筛选,为发现新的药物先导化合物提供新菌源。采用7种选择性培养基分离10份来自台湾海峡沉积物样品中的海洋放线菌,并对分离菌株的16S rRNA基因序列进行系统进化分析。采用滤纸片法对部分代表放线菌菌株发酵液进行生物活性筛选,共分离到532株放线菌,挑选其中170株代表菌株进行鉴定,分属于8个目10个科14个属。有2株菌的16S rRNA基因序列显示属于潜在的新种,170株菌中有68.8%的菌株显示出至少对一种指示菌有抑菌活性。结果表明台湾海峡海洋沉积物中蕴藏着丰富的放线菌资源,是发现新药的有效途径。     

高温放线菌的多样性

高温微生物能在高温环境下生存,并能维持其自身生理生化过程的酶系和化合物的稳定性[1].自1969年发现水生栖热菌(Thermus aquaticus)以后[2],高温菌就引起微生物学家的极大关注.高温菌两个显著的特点决定了其在现代分子生物学和工业应用上的重要价值:一是热稳定性功能分子;二是生长极快且会自溶,能在高温条件下发酵而不易受污染.     

印度洋红树林沉积物可培养海洋放线菌多样性及其活性

【目的】本研究旨在了解印度洋红树林沉积物可培养海洋放线菌多样性、抗菌活性及产酶活性。【方法】选用24种碳源为唯一能源培养基,利用稀释平板涂布方法对8个印度洋红树林沉积物样品进行分离,并基于16S rRNA基因系统发育分析的方法研究样品中海洋放线菌多样性;对分离得到的菌株进行抗菌活性和产酶活性检测。【结果】24种唯一碳源分离培养基中,非糖类碳源特别是甘油、丙氨酸分离效果最好,其次是多糖物质,最后是单糖。共分离得到521株海洋放线菌,经并菌后选取其中的139株代表性菌株测序,结果发现它们主要分布在放线菌纲7个亚目10个科的16个属,其中35个为潜在新种。有43.1%、33.3%、26.9%、25.5%、15.7%的实验菌株分别对枯草芽孢杆菌、白色念珠菌、大肠埃希氏菌、金黄色葡萄球菌、黑曲霉具有抑制作用;有36.5%、26.5%、22.4%、15.9%的实验菌株分别具有蛋白酶活性、纤维素酶活、淀粉酶活性、酯酶活性。【结论】印度洋红树林沉积物蕴藏着丰富的海洋放线菌资源,并具有较高生物活性,为后续工作提供良好的实验材料。     

Novel actinobacteria from marine sponges

Actinobacteria exclusively within the sub-class Acidimicrobidae were shown by 16S rDNA community analysis to be major components of the bacterial community associated with two sponge species in the genus Xestospongia. Four groups of Actinobacteria were identified in Xestospongia spp., with three of these four groups being found in both Xestospongia muta from Key Largo, Florida and Xestospongia testudinaria from Manado, Indonesia. This suggests that these groups are true symbionts in these sponges and may play a common role in both the Pacific and Atlantic sponge species. The fourth group was found only in X. testudinaria and was a novel assemblage distantly related to any previously sequenced actinobacterial clones. The only actinobacteria that were obtained in initial culturing attempts were Gordonia, Micrococcus and Brachybacterium spp., none of which were represented in the clone libraries. The closest cultured actinobacteria to all the Acidimicrobidae clones from Xestospongia spp. are Microthrix parvicella and Acidimicrobium spp. Xestospongia spp. can now be targeted as source material from which to culture novel Acidimicrobidae to investigate their potential as producers of bioactive compounds. Isolation of sponge-associated Acidimicrobidae will also make it possible to elucidate their role as sponge symbionts.     

Biologically active metabolites of marine actinobacteria

Data on the chemical structures and biologic activities of metabolites of obligate and facultative marine actinobacteria published between 2000 and 2007 are reviewed. The structural features of five groups of metabolites related to macrolides and compounds containing lactone, quinone, and diketopiperazine residues; cyclic peptides; alkaloids; and compounds of combined nature are discussed. The review shows the large chemical diversity of metabolites of actinobacteria isolated from marine ecotopes. In addition to metabolites identical to those previously isolated from terrestrial actinobacteria, marine actinobacteria produce compounds not found in other natural sources, including microorganisms. Probably, the biosynthesis of new chemotypes of bioactive compounds by marine actinobacteria is related to the chemical adaptation of microorganisms to the marine environment. The review emphasizes the importance of chemical studies of metabolites produced by marine actinobacteria. These studies will provide new data on marine microbial producers of biologically active compounds and the chemical structures and biologic activities of new natural lowmolecular-weight bioregulators.     

Estimating and comparing the diversity of marine actinobacteria

This paper reviews the application of species richness estimators to microbial diversity data and describes phylogenetic approaches to comparing microbial communities. The techniques are demonstrated using a community of marine actinobacteria. Results demonstrate that marine environments harbour massive actinobacterial diversity. Furthermore, these predictions are likely to be severe underestimates due to the use of arbitrary OTU definitions.     

Research on marine actinobacteria in India

Marine actinobacteriology is one of the major emerging areas of research in tropics. Marine actinobacteria occur on the sediments and in water and also other biomass (mangrove) and substrates (animal). These organisms are gaining importance not only for their taxonomic and ecological perspectives, but also for their unique metabolites and enzymes. Many earlier studies on these organisms were confined only to the temperate regions. In tropical environment, investigations on them have gained importance only in the last two decades. So far, from the Indian peninsula, 41 species of actinobacteria belonging to 8 genera have been recorded. The genus, Streptomyces of marine origin has been more frequently recorded. Of 9 maritime states of India, only 4 have been extensively covered for the study of marine actinobacteria. Most of the studies conducted pertain to isolation, identification and maintenance of these organisms in different culture media. Further, attention has been focused on studying their antagonistic properties against different pathogens. Their biotechnological potentials are yet to be fully explored.     

两株海洋放线菌的产色素特性

【背景】生物产生的天然色素在工业、农业和纺织工业上有潜在应用价值。【目的】通过对产色素海洋放线菌的分离与筛选,为开发细菌所产生的天然色素在纺织与食品工业中的应用奠定基础。【方法】筛选胞外产可溶性色素的放线菌,并通过16S rRNA基因序列测定和分析构建其系统发育树,并对影响色素产量的因素和色素稳定性进行实验。【结果】获得了一株产蓝色色素的放线菌Q2N-42和一株产黄绿色色素的放线菌X4C-5,16S rRNA基因序列分析表明它们分别与天蓝色链霉菌(Streptomycescoelicolor)或紫红链霉菌(Streptomycesviolaceoruber)和普拉滕斯链霉菌(Streptomyces pratensis)的16SrRNA基因序列存在较高的相似性。通过研究不同碳源和氮源对放线菌Q2N-42和X4C-5产色素的影响,发现甘油和硝酸钠能明显地增加天蓝色链霉菌(S. coelicolor) Q2N-42的色素产量,而淀粉和硝酸钠能明显地增加普拉滕斯链霉菌(S.pratensis)X4C-5的色素产量。这两种色素对不同浓度的氧化剂、还原剂、盐和pH都表现出良好的稳定性;色素的红外...     

Biologically active metabolites of the marine actinobacteria

This review systematically data on the chemical structure and biological activity of metabolites of obligate and facultative marine actinobacteria, published from 2000 to 2007. We discuss some structural features of the five groups of metabolites related to macrolides and compounds containing lactone, quinone and diketopiperazine residues, cyclic peptides, alkaloids, and compounds of mixed biosynthesis. Survey shows a large chemical diversity of metabolites actinobacteria isolated from marine environment. It is shown that, along with metabolites, identical to previously isolated from terrestrial actinobacteria, marine actinobacteria synthesize unknown compounds not found in other natural sources, including micro organisms. Perhaps the biosynthesis of new chemotypes bioactive compounds in marine actinobacteria is one manifestation of chemical adaptation of microorganisms to environmental conditions at sea. Review stresses the importance of the chemical study of metabolites of marine actinobacteria. These studies are aimed at obtaining new data on marine microorganisms producers of biologically active compounds and chemical structure and biological activity of new low-molecular bioregulators of natural origin.     

Pharmaceutically active secondary metabolites of marine actinobacteria

Marine actinobacteria are one of the most efficient groups of secondary metabolite producers and are very important from an industrial point of view. Many representatives of the order Actinomycetales are prolific producers of thousands of biologically active secondary metabolites. Actinobacteria from terrestrial sources have been studied and screened since the 1950s, for many important antibiotics, anticancer, antitumor and immunosuppressive agents. However, frequent rediscovery of the same compounds from the terrestrial actinobacteria has made them less attractive for screening programs in the recent years. At the same time, actinobacteria isolated from the marine environment have currently received considerable attention due to the structural diversity and unique biological activities of their secondary metabolites. They are efficient producers of new secondary metabolites that show a range of biological activities including antibacterial, antifungal, anticancer, antitumor, cytotoxic, cytostatic, anti-inflammatory, anti-parasitic, anti-malaria, antiviral, antioxidant, anti-angiogenesis, etc. In this review, an evaluation is made on the current status of research on marine actinobacteria yielding pharmaceutically active secondary metabolites. Bioactive compounds from marine actinobacteria possess distinct chemical structures that may form the basis for synthesis of new drugs that could be used to combat resistant pathogens. With the increasing advancement in science and technology, there would be a greater demand for new bioactive compounds synthesized by actinobacteria from various marine sources in future.     

Diversity and biogeography of testate amoebae

Testate amoebae are amoeboid protists inhabiting a test (shell). They occur globally in soils, wetlands and freshwater, especially peats and mosses. They are of ancient origin, dating from at least the Mesozoic, with possible ancestors as old as the Neoproterozoic. Approximately 2,000 taxa have been described—a number which could easily rise to 4,000 with comprehensive recording. Whilst many protists appear to be cosmopolitan as morphospecies, some of the larger testate species (exceeding 100 μm) have long been considered, controversially, to be geographically restricted. Definitive conclusions have often been confounded by gaps in distributional data and misidentification. Recent increases in recording from previously little known regions, and the rise of molecular taxonomy, have started to resolve outstanding issues—processes still far from complete. Accordingly, biogeographical studies have concentrated on “flagship” species—those which can be identified with certainty and are sufficiently recorded to determine their ecological ranges. Apodera vas (Certes) has been proved to be largely restricted to the Gondwanaland continents and sub-Antarctic islands, but absent from the Holartic despite the availability of much suitable habitat. An early analysis postulated a Mesozoic origin of the species and a distribution influenced by continental drift. Recent molecular evidence could imply a later origin. Either way, its current distribution is clearly influenced by the pattern of global wind currents and lack of lowland tropical habitat. By contrast a “Gondwana-tropical” group of species appears to be restricted to latitudes unaffected by glaciation. Instances of local endemism, such as restriction to a single island, are also known, which await molecular evidence for substantiation. Special Issue: Protist diversity and geographic distribution. Guest editor: W. Foissner.     

五种动物粪便纯培养放线菌的多样性及生物活性

【目的】以资源利用为出发点,研究了五种动物粪便放线菌的多样性及生物活性。【方法】从云南野生动物园采集5种半野生动物的新鲜粪便样品,用5种培养基分离其中的放线菌,将放线菌鉴定到属,测定纯培养放线菌的抗菌活性,抗肿瘤活性等。【结果】结果表明,所试5种动物粪便放线菌的种类非常丰富,组成各不相同,以链霉菌和微球菌占优势,可能存在大量未知放线菌;粪便放线菌的抗菌活性,抗肿瘤活性,酶活性,分解纤维素、角蛋白的活性非常普遍,尤其是具有抗肿瘤活性的菌株比例较大;产生的具有生物活性的次生代谢产物也是多种多样的。【结论】因此,粪便放线菌与土壤,海洋及植物的放线菌一样,是开发药物、农药和其他产品的重要来源之一,应当加强粪便放线菌的研究和保护利用。     

肇庆星湖湿地可培养放线菌多样性

摘要:【目的】探究星湖湿地可培养放线菌物种多样性,筛选潜在药源活性代谢产物产生菌,为后续菌种资源开发奠定基础。【方法】采用5种选择性分离培养基分离星湖湿地底泥中的放线菌,通过16S rRNA基因同源性分析代表性菌株的物种多样性;以3株病原细菌为指示菌检测分离菌株的抑菌活性;PCR扩增代表菌株的聚酮合酶(PKS I、PKS II)基因、非核糖体多肽合成酶(NRPS)基因、安莎类化合物(AHBA)基因及3-羟基-3-甲基戊二酰辅酶A还原酶(HMGA)基因。【结果】分离到135株放线菌菌株,被鉴定为放线菌纲的7 个目、10个科、13个属,优势类群为链霉菌、小单孢菌及诺卡氏菌。83株检测菌中,24.09%抗金黄色葡萄球菌(Staphylococcus aureus),4.8%抗大肠杆菌(Escherichia coli);24株高活性菌株中PKS I阳性率16.7%,PKS II阳性率62.5%,NRPS阳性率16.7%,AHBA阳性率12.5%,HMGA阳性率29.2%。活性复筛及HPLC结果显示,菌株XD007、XD114和XD128显著抑制3株病原指示菌,且能产生大量次级代谢产物。【结论】星湖湿地底泥中放线菌资源丰富,筛选到的活性菌株可用于后续药源活性次级代谢产物的分离。     

大熊猫肠道放线菌的种群组成及多样性分析

【目的】探究不同年龄、不同性别大熊猫肠道放线菌的多样性及群落结构,为寻找潜在产生活性化合物的放线菌资源提供理论依据。【方法】采用PCR-DGGE技术对大熊猫肠道放线菌进行分析,对电泳结果进行UPGMA聚类分析、主成分分析、生物多样性等多重比较。【结果】变性梯度凝胶电泳(DGGE)图谱显示,不同大熊猫肠道中放线菌的多样性及群落结构存在明显差异。随着年龄的增长,雌性大熊猫肠道中放线菌的多样性指数(H')和丰富度(S)逐渐减少,而雄性大熊猫肠道内放线菌的多样性指数(H')和丰富度(S)逐渐增多。不同个体的大熊猫肠道放线菌的群落结构存在明显差异,但相同性别之间的相似性很高。DGGE条带回收测序结果表明,获得的28条序列归属于10个放线菌属,其中链霉菌属(Streptomyces)为优势菌属,占总数的46%;北里孢菌属(Kitasatospora)、红球菌属(Rhodococcus)、棒杆菌属(Corynebacterium)、迪茨氏菌属(Dietziaceae)、大理石雕菌属(Marmoricola)、布登堡菌属(Beutenbergia)、微杆菌属(Microbacterium)、链嗜酸菌属(Streptacidiphilus)和芽生球菌属(Blastococcus)等为非链霉菌属,占总数的54%。【结论】大熊猫肠道内蕴藏着丰富的放线菌资源,其肠道菌群的结构与组成受年龄和性别的影响。     

Screening of marine actinobacteria for amylase enzymes inhibitors

Amylase inhibitor producing actinobacteria were isolated and characterized from terrestrial environment and there is no much report found from marine environment, hence in the present study, 17 strains isolated from the rhizosphere sediments of mangroves were tested for their amylase inhibition ability. Seawater requirement test for the growth of actinobacteria found that the strains SSR-3, SSR-12 and SSR-16 requires at least 50% and SSR-6 requires at least 25% seawater for their growth. The inhibition activity of both prokaryotic and eukaryotic amylase was tested by using Bacillus subtilis and Aspergillus niger. The maximum amylase activity (40mm) produced by the A. niger was taken as positive control, when the test actinobacteria strains grown in the medium they inhibited amylase activity and was evidenced by the reduction in inhibition zone (14–37 mm) similarly the amylase produced by the Bacillus subtilis was also recorded maximum (35 mm) amylase activity and was taken as positive control, and the test atinobacterial strains reduced enzyme action(12–33 mm) it varied levals. This indicates that the actinobacteria strains were controlled amylase enzyme activity in both the cases. The strain SSR-10 was highly effective and SSR-8 was less effective in inhibiting eukaryotic amylase produced by A. niger. The strain SSR-2 was effective and SSR-6 showed very less effect in inhibiting the prokaryotic amylase produced by the B subtilis.     

Diversity and biogeography of the Antarctic flora

Aim To establish how well the terrestrial flora of the Antarctic has been sampled, how well the flora is known, and to determine the major patterns in diversity and biogeography. Location Antarctica south of 60° S, together with the South Sandwich Islands, but excluding South Georgia, Bouvetøya and the periantarctic islands. Methods Plant occurrence data were collated from herbarium specimens and literature records, and assembled into the Antarctic Plant Database. Distributional patterns were analysed using a geographic information system. Biogeographical patterns were determined with a variety of multivariate statistics. Results Plants have been recorded from throughout the Antarctic, including all latitudes between 60° S and 86° S. Species richness declines with latitude along the Antarctic Peninsula, but there was no evidence for a similar cline in Victoria Land and the Transantarctic mountains. Multi‐dimensional scaling ordinations showed that the species compositions of the South Orkney, South Shetland Islands and the north‐western Antarctic Peninsula are very similar to each other, as are the floras of different regions in continental Antarctica. They also suggest, however, that the eastern Antarctic Peninsula flora is more similar to the flora of the southern Antarctic Peninsula than to the continental flora (with which it has traditionally been linked). The South Sandwich Islands have a flora that is very dissimilar to that in all Antarctic regions, probably because of their isolation and volcanic nature. Main conclusions The Antarctic flora has been reasonably well sampled, but certain areas require further floristic surveys. Available data do, however, allow for a number of robust conclusions. A diversity gradient exists along the Antarctic Peninsula, with fewer species (but not fewer higher taxa) at higher latitudes. Multi‐dimensional scaling ordination suggests three major floral provinces within Antarctica: northern maritime, southern maritime, and continental. Patterns of endemism suggest that a proportion of the lichen flora may have an ancient vicariant distribution, while most bryophytes are more recent colonists.