Jutta Wiese

The genus Laminaria sensu lato : recent insights and developments

This review about the genus Laminaria sensu lato summarizes the extensive literature that has been published since the overview of the genus given by Kain in 1979. The recent proposal to divide the genus into the two genera Laminaria and Saccharina is acknowledged, but the published data are discussed under a ‘sensu lato’ concept, introduced here. This includes all species which have been considered to be ‘Laminaria’ before the division of the genus. In detail, after an introduction the review covers recent insights into phylogeny and taxonomy, and discusses morphotypes, ecotypes, population genetics and demography. It describes growth and photosynthetic performance of sporophytes with special paragraphs on the regulation of sporogenesis, regulation by endogenous rhythms, nutrient metabolism, storage products, and salinity tolerance. The biology of microstages is discussed separately. The ecology of these kelps is described with a focus on stress defence against abiotic and biotic factors and the role of Laminaria as habitat, its trophic interactions and its competition is discussed. Finally, recent developments in aquaculture are summarized. In conclusion to each section, as a perspective and guide to future research, we draw attention to the remaining gaps in the knowledge about the genus and kelps in general.

Phylogenetic analysis of bacteria associated with Laminaria saccharina.

Bacterial communities associated with the brown alga Laminaria saccharina from the Baltic Sea and from the North Sea were investigated using denaturing gradient gel electrophoresis and 16S rRNA gene clone libraries. The rhizoid, cauloid, meristem and phyloid revealed different 16S rRNA gene denaturing gradient gel electrophoresis banding patterns indicating a specific association of bacterial communities with different parts of the alga. Associations with cauloid and meristem were more specific, while less specific associations were obtained from the old phyloid. In addition, seasonal and geographical differences in the associated communities were observed. Results from 16S rRNA gene libraries supported these findings. Bacterial phylotypes associated with the alga were affiliated with the Alphaproteobacteria (nine phylotypes), Gammaproteobacteria (nine phylotypes) and the Bacteroidetes group (four phylotypes). A number of bacteria associated with other algae and other marine macroorganisms were among the closest relatives of phylotypes associated with L. saccharina.

Diversity of antibiotic-active bacteria associated with the brown alga Laminaria saccharina from the Baltic Sea.

Bacteria associated with the marine macroalga Laminaria saccharina, collected from the Kiel Fjord (Baltic Sea, Germany), were isolated and tested for antimicrobial activity. From a total of 210 isolates, 103 strains inhibited the growth of at least one microorganism from the test panel including Gram-negative and Gram-positive bacteria as well as a yeast. Most common profiles were the inhibition of Bacillus subtilis only (30%), B. subtilis and Staphylococcus lentus (25%), and B. subtilis, S. lentus, and Candida albicans (11%). In summary, the antibiotic-active isolates covered 15 different activity patterns suggesting various modes of action. On the basis of 16S rRNA gene sequence similarities >99%, 45 phylotypes were defined, which were classified into 21 genera belonging to Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. Phylogenetic analysis of 16S rRNA gene sequences revealed that four isolates possibly represent novel species or even genera. In conclusion, L. saccharina represents a promising source for the isolation of new bacterial taxa and antimicrobially active bacteria.

Linear and Cyclic Peptides from the Entomopathogenic Bacterium Xenorhabdus nematophilus

Three new peptides, xenortides A and B and xenematide, were isolated from a culture of the nematode-associated entomopathogenic bacterium Xenorhabdus nematophilus. Their structures were elucidated using NMR, MS, and chemical derivatization methods. Xenortides A and B are the N-phenethylamide and tryptamide derivatives, respectively, of the dipeptide (NMe-L-Leu-NMe-L-Phe). The cyclodepsipeptide xenematide has the sequence (Thr-Trp-Trp-Gly), with a 2-phenylacetamide substituent at the threonine residue and one d-tryptophan. The new peptides and the two known compounds xenocoumacin II and nematophin were tested for antibacterial, antifungal, insecticidal, and anti-Artemia salina activities. Xenematide and xenocoumacin II showed moderate antibacterial activities. Xenocoumacin II, nematophin, and the two xenortides were active in the Artemia salina assay, and xenematide acted weakly insecticidal.

Mayamycin, a Cytotoxic Polyketide from a Streptomyces Strain Isolated from the Marine Sponge Halichondria panicea

A new benz[a]anthracene derivative called mayamycin (1) was identified in cultures of Streptomyces sp. strain HB202, which was isolated from the marine sponge Halichondria panicea and selected because of its profound antibiotic activity. The ability to produce aromatic polyketides was indicated by genetic analyses, demonstrating the presence of a type II polyketide synthase. The production of mayamycin (1) was induced by variation of the culture conditions. The structure of 1 was elucidated by HPLC-UV/MS and NMR spectroscopy. Mayamycin (1) exhibited potent cytotoxic activity against eight human cancer cell lines and showed activity against several bacteria including antibiotic-resistant strains.

Subinhibitory concentrations of antibiotics induce phenazine production in a marine Streptomyces sp.

Subinhibitory concentrations of antibiotics were found to enhance and modulate the production of new phenazines, streptophenazines A-H, in a marine Streptomyces isolate. The streptophenazines differ in length and substitution of an alkyl chain. The pattern of metabolites formed depends on the antibiotic used. In the presence of tetracycline, streptophenazines F and G were induced and the production of streptophenazines A-D was increased. When using bacitracin, mainly streptophenazine H was produced. Streptophenazines C and H showed moderate activity against Bacillus subtilis, while streptophenazine C was also active against Staphylococcus lentus.

Atacamycins A–C, 22-membered antitumor macrolactones produced by Streptomyces sp. C38*

Three new 22-membered macrolactone antibiotics, atacamycins A–C, were produced by Streptomyces sp. C38, a strain isolated from a hyper-arid soil collected from the Atacama Desert in the north of Chile. The metabolites were discovered in our HPLC-diode array screening and isolated from the mycelium by extraction and chromatographic purification steps. The structures were determined by mass spectrometry and NMR experiments. Atacamycins A, B and C exhibited moderate inhibitory activities against the enzyme phosphodiesterase (PDE-4B2), whereas atacamycin A showed a moderate antiproliferative activity against adeno carcinoma and breast carcinoma cells.

A new member of the family Micromonosporaceae, Planosporangium flavigriseum gen. nov., sp. nov.

A novel actinomycete, designated strain YIM 46034(T), was isolated from an evergreen broadleaved forest at Menghai, in southern Yunnan Province, China. Phenotypic characterization and 16S rRNA gene sequence analysis indicated that the strain belonged to the family Micromonosporaceae. Strain YIM 46,034(T) showed more than 3 % 16S rRNA gene sequence divergence from recognized species of genera in the family Micromonosporaceae. Characteristic features of strain YIM 46,034(T) were the production of two types of spores, namely motile spores, which were formed in sporangia produced on substrate mycelia, and single globose spores, which were observed on short sporophores of the substrate mycelia. The cell wall contained meso-diaminopimelic acid, glycine, arabinose and xylose, which are characteristic components of cell-wall chemotype II of actinomycetes. Phosphatidylethanolamine was the major phospholipid (phospholipid type II). Based on morphological, chemotaxonomic, phenotypic and genetic characteristics, strain YIM 46,034(T) is considered to represent a novel species of a new genus in the family Micromonosporaceae, for which the name Planosporangium flavigriseum gen. nov., sp. nov. is proposed. The type strain of Planosporangium flavigriseum is YIM 46,034(T) (=CCTCC AA 205,013(T) =DSM 44,991(T)).

Tenacibaculum adriaticum sp. nov., from a bryozoan in the Adriatic Sea

A rod-shaped, translucent yellow-pigmented, Gram-negative bacterium, strain B390(T), was isolated from the bryozoan Schizobrachiella sanguinea collected in the Adriatic Sea, near Rovinj, Croatia. 16S rRNA gene sequence analysis indicated affiliation to the genus Tenacibaculum, with sequence similarity levels of 94.8-97.3 % to type strains of species with validly published names. It grew at 5-34 degrees C, with optimal growth at 18-26 degrees C, and only in the presence of NaCl or sea salts. In contrast to other type strains of the genus, strain B390(T) was able to hydrolyse aesculin. The predominant menaquinone was MK-6 and major fatty acids were iso-C(15 : 0), iso-C(15 : 0) 3-OH and iso-C(15 : 1). The DNA G+C content was 31.6 mol%. DNA-DNA hybridization and comparative physiological tests were performed with type strains Tenacibaculum aestuarii JCM 13491(T) and Tenacibaculum lutimaris DSM 16505(T), since they exhibit 16S rRNA gene sequence similarities above 97 %. These data, as well as phylogenetic analyses, suggest that strain B390(T) (=DSM 18961(T) =JCM 14633(T)) should be classified as the type strain of a novel species within the genus Tenacibaculum, for which the name Tenacibaculum adriaticum sp. nov. is proposed.

Actinomycetospora chiangmaiensis gen. nov., sp. nov., a new member of the family Pseudonocardiaceae

A novel actinomycete strain, YIM 0006(T), was isolated from soil of a tropical rainforest in northern Thailand. The isolate displayed the following characteristics: aerial mycelium is absent, short spore chains are formed directly on the substrate mycelium, contains meso-diaminopimelic acid, arabinose and galactose (cell-wall chemotype IV), the diagnostic phospholipid is phosphatidylcholine, MK-9(H(4)) is the predominant menaquinone and the G+C content of the genomic DNA is 69.0 mol%. Phylogenetic analysis and phenotypic characteristics showed that strain YIM 0006(T) belongs to the family Pseudonocardiaceae but can be distinguished from representatives of all genera classified in the family. The novel genus and species Actinomycetospora chiangmaiensis gen. nov., sp. nov. are proposed, with strain YIM 0006(T) (=CCTCC AA 205017(T) =DSM 45062(T)) as the type strain of Actinomycetospora chiangmaiensis.