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Marine Microorganisms (marine + microorganism)

Distribution by Scientific Domains

Chemistry	40%

Selected Abstracts

Biochemische Interaktionen in Marinen Biofilmen.

CHEMIE IN UNSERER ZEIT (CHIUZ), Issue 3 2009
Kampf, Kommunikation, Kooperation
Abstract Marine Mikroorganismen sind als vielseitige Produzenten von Sekundärmetaboliten bekannt. Auch wenn das Meer tausende von bioaktiven Metaboliten in den letzten zwei Jahrzehnten hervorgebracht hat, so stehen wir erst am Anfang, die natürlichen Funktionen dieser Moleküle zu erforschen. Viele Mikroorganismen kommen in der Umwelt als mehrzellige Lebensgemeinschaften, so genannten Biofilmen, vor. Dabei stellt die chemische Kommunikation einen wichtigen Mechanismus dar, wie Biofilmpopulationen ihre Verhaltensweisen koordinieren und auf Umweltveränderungen reagieren. Aktuelle Untersuchungen bringen ein komplexes Netz biochemischer Wechselbeziehungen ans Licht, über das mikrobielle Symbiosen, Konkurrenz und Verteidigung gegenüber Fraßfeinden und Parasiten vermittelt wird. Das Verstehen der molekularen Grundlagen von Biofilminteraktionen in ihrem ökologischen Kontext birgt das Potential, die Suche nach wirkspezifischen Naturstoffen und die Entwicklung von Biofilm-basierter Biotechnologien zu verfeinern. Marine microorganisms are versatile producers of secondary metabolites. Although the sea has yielded thousands of bioactive metabolites over the past two decades, we are only beginning to explore the natural functions of these molecules. Many microorganisms exist in the environment as multicellular communities, so-called biofilms. Chemical communication is an essential part of the way in which biofilm populations coordinate their behavior and respond to environmental challenges. Recent research has been unravelling a complex web of chemical crosstalk mediating microbial symbiosis, competition and defense against predators and pathogens. Understanding the molecular basis of biofilm interactions in their ecological context bears the potential of refining natural product discovery and the development of biofilm-derived biotechnologies. [source]

Marine Drugs , Macrolactins

CHEMISTRY & BIODIVERSITY, Issue 9 2008
Xiao-Ling Lu
Abstract The increasing demands for new lead compounds in pharmaceutical and agrochemical industries have driven scientists to search for new bioactive natural products. Marine microorganisms are rich sources of novel, bioactive secondary metabolites, and have attracted much attention of chemists, pharmacologists, and molecular biologists. This mini-review mainly focuses on macrolactins, a group of 24-membered lactone marine natural products, aiming at giving an overview on their sources, structures, biological activities, as well as their potential medical applications. [source]

Thermophilic anaerobes in Arctic marine sediments induced to mineralize complex organic matter at high temperature

ENVIRONMENTAL MICROBIOLOGY, Issue 4 2010
Casey Hubert
Summary Marine sediments harbour diverse populations of dormant thermophilic bacterial spores that become active in sediment incubation experiments at much higher than in situ temperature. This response was investigated in the presence of natural complex organic matter in sediments of two Arctic fjords, as well as with the addition of freeze-dried Spirulina or individual high-molecular-weight polysaccharides. During 50°C incubation experiments, Arctic thermophiles catalysed extensive mineralization of the organic matter via extracellular enzymatic hydrolysis, fermentation and sulfate reduction. This high temperature-induced food chain mirrors sediment microbial processes occurring at cold in situ temperatures (near 0°C), yet it is catalysed by a completely different set of microorganisms. Using sulfate reduction rates (SRR) as a proxy for organic matter mineralization showed that differences in organic matter reactivity determined the extent of the thermophilic response. Fjord sediments with higher in situ SRR also supported higher SRR at 50°C. Amendment with Spirulina significantly increased volatile fatty acids production and SRR relative to unamended sediment in 50°C incubations. Spirulina amendment also revealed temporally distinct sulfate reduction phases, consistent with 16S rRNA clone library detection of multiple thermophilic Desulfotomaculum spp. enriched at 50°C. Incubations with four different fluorescently labelled polysaccharides at 4°C and 50°C showed that the thermophilic population in Arctic sediments produce a different suite of polymer-hydrolysing enzymes than those used in situ by the cold-adapted microbial community. Over time, dormant marine microorganisms like these are buried in marine sediments and might eventually encounter warmer conditions that favour their activation. Distinct enzymatic capacities for organic polymer degradation could allow specific heterotrophic populations like these to play a role in sustaining microbial metabolism in the deep, warm, marine biosphere. [source]

Widespread known and novel phosphonate utilization pathways in marine bacteria revealed by functional screening and metagenomic analyses

ENVIRONMENTAL MICROBIOLOGY, Issue 1 2010
Asuncion Martinez
Summary Phosphonates (Pn), compounds with a direct C,P bond instead of the more common C,O,P ester bond, constitute a significant fraction of marine dissolved organic phosphorus and recent evidence suggests that they may be an alternative source of P for marine microorganisms. To further characterize the microorganisms and pathways involved in Pn utilization, we screened bacterioplankton genomic libraries for their ability to complement an Escherichia coli strain unable to use Pns as a P source. Using this approach we identified a phosphonatase pathway as well as a novel pair of genes that allowed utilization of 2-aminoethylphosphonate (2-AEPn) as the sole P source. These pathways are present in diverse bacteria common in marine plankton including representatives of Proteobacteria, Planctomycetes and Cyanobacteria. Analysis of metagenomic databases for Pn utilization genes revealed that they are widespread and abundant among marine bacteria, suggesting that Pn metabolism is likely to play an important role in P-depleted surface waters, as well as in the more P-rich deep-water column. [source]

Crash of a population of the marine heterotrophic flagellate Cafeteria roenbergensis by viral infection

ENVIRONMENTAL MICROBIOLOGY, Issue 11 2007
Ramon Massana
Summary Viruses are known as important mortality agents of marine microorganisms. Most studies focus on bacterial and algal viruses, and few reports exist on viruses infecting marine heterotrophic protists. Here we show results from several incubations initiated with a microbial assemblage from the central Indian Ocean and amended with different amounts of organic matter. Heterotrophic flagellates developed up to 30 000 cells ml,1 in the most enriched incubation. A 18S rDNA clone library and fluorescent in situ hybridization counts with newly designed probes indicated that the peak was formed by Cafeteria roenbergensis and Caecitellus paraparvulus (90% and 10% of the cells respectively). Both taxa were below detection in the original sample, indicating a strong positive selective bias during the enrichment. During the peak, C. roenbergensis cells were observed with virus-like particles in the cytoplasm, and 4 days later this taxa could not be detected. Transmission electron microscopy confirmed the viral nature of these particles, which were large (280 nm), had double-stranded DNA, and were produced with a burst size of ,70. This virus was specific of C. roenbergensis as neither C. paraparvulus that was never seen infected, nor other flagellate taxa that developed in later stages of the incubation, appeared attacked. This is one of the few reports on a heterotrophic flagellate virus and the implications of this finding in the Indian Ocean are discussed. [source]