Summary
Glycerol is a key compound for the understanding of the microbiology of hypersaline environments. At the highest salt concentrations the main or even sole primary producer is the green ...unicellular alga Dunaliella, which uses photosynthetically produced glycerol as osmotic stabilizer and compatible solute. Glycerol can be expected to be a major carbon source available to the heterotrophic communities of Archaea and Bacteria in hypersaline ecosystems. Use of Dunaliella has even been explored for the commercial production of glycerol. This article reviews our current understanding of glycerol metabolism in Dunaliella and of the ways glycerol can be degraded by heterotrophic prokaryote communities under aerobic and under anaerobic conditions. Dunaliella‐derived glycerol may also be the key toward long‐term survival of heterotrophic prokaryotes in fluid inclusions within salt crystals.
As an addendum to the earlier proposal to include the rank of phylum in the International Code of Nomenclature of Prokaryotes (Oren et al., Int J Syst Evol Microbiol 2015;65:4284-4287) we propose the ...suffix -ota to denote phyla, replacing the somewhat awkward -aeota. We therefore present a new draft modified version of Rule 8 of the International Code of Nomenclature of Prokaryotes and a corrected list of names of phyla to be considered for validation after approval of the proposal to include the rank of phylum in the Code.
We present a comparison of the performance of four miniature portable Raman spectrometers for the discrimination of carotenoids in samples of carotene-producing microorganisms. Two spectrometers ...using a green laser allowing to obtain Resonance Raman (or pre-Resonance Raman) signals, one instrument with a 785 nm laser, and a recently developed Portable Sequentially Shifted Excitation Raman spectrometer (PSSERS) were used for identifying major pigments of different halophilic (genera
,
,
,
,
,
) and non-halophilic microorganisms (
,
). Using all the tested instruments including the PSSERS, strong carotenoids signals corresponding to the stretching vibrations in the polyene chain and in-plane rocking modes of the attached CH
groups were found at the correct positions. Raman spectra of carotenoids can be obtained from different types of microbiological samples (wet pellets, lyophilized culture biomass and pigment extracts in organic solvents), and can be collected fast and without time-consuming procedures.
Three alternative proposals to emend the Rules of the International Code of Nomenclature of Prokaryotes are presented to resolve the status of the
Cyanobacteria
in the prokaryotic nomenclature. Two ...were earlier published (Oren and Garrity,
Int J Syst Evol Microbiol
2014;64 : 309–310; Pinevich,
Int J Syst Evol Microbiol
2015;65 : 1070–1074). The third proposal is based on reciprocation of Article 45.1 of the International Code of Nomenclature for algae, fungi, and plants. According to Article 13b of the Statutes of the International Committee on Systematics of Prokaryotes, a decision on these proposals must be reached within 11 months from the date of this publication.
Summary
Hypersaline environments are dominated by archaea and bacteria and are almost entirely devoid of eukaryotic organisms. In addition, hypersaline environments contain considerable numbers of ...viruses. Currently, there is only a limited amount of information about these haloviruses. The ones described in detail mostly resemble head‐tail bacteriophages, whereas observations based on direct microscopy of the hypersaline environmental samples highlight the abundance of non‐tailed virus‐like particles. Here we studied nine spatially distant hypersaline environments for the isolation of new halophilic archaea (61 isolates), halophilic bacteria (24 isolates) and their viruses (49 isolates) using a culture‐dependent approach. The obtained virus isolates approximately double the number of currently described archaeal viruses. The new isolates could be divided into three tailed and two non‐tailed virus morphotypes, suggesting that both types of viruses are widely distributed and characteristic for haloarchaeal viruses. We determined the sensitivity of the hosts against all isolated viruses. It appeared that the host ranges of numerous viruses extend to hosts in distant locations, supporting the idea that there is a global exchange of microbes and their viruses. It suggests that hypersaline environments worldwide function like a single habitat.
Salts are abundant on Mars, and any liquid water that is present or may have been present on the planet is expected to be hypersaline. Halophilic archaea (family Halobacteriaceae) are the ...microorganisms best adapted to life at extremes of salinity on Earth. This paper reviews the properties of the Halobacteriaceae that may make the group good candidates for life also on Mars. Many species resist high UV and gamma radiation levels; one species has survived exposure to vacuum and radiation during a space flight; and there is at least one psychrotolerant species. Halophilic archaea may survive for millions of years within brine inclusions in salt crystals. Many species have different modes of anaerobic metabolism, and some can use light as an energy source using the light-driven proton pump bacteriorhodopsin. They are also highly tolerant to perchlorate, recently shown to be present in Martian soils, and some species can even use perchlorate as an electron acceptor to support anaerobic growth. The presence of characteristic carotenoid pigments (α-bacterioruberin and derivatives) makes the Halobacteriaceae easy to identify by Raman spectroscopy. Thus, if present on Mars, such organisms may be detected by Raman instrumentation planned to explore Mars during the upcoming ExoMars mission.
Within the cyanobacterial world there are many species adapted to life in hypersaline environments. Some can even grow at salt concentrations approaching NaCl saturation. Halophilic cyanobacteria ...often form dense mats in salt lakes, and on the bottom of solar saltern ponds, hypersaline lagoons, and saline sulfur springs, and they may be found in evaporite crusts of gypsum and halite. A wide range of species were reported to live at high salinities. These include unicellular types (
Aphanothece halophytica
and similar morphotypes described as
Euhalothece
and
Halothece
), as well as non-heterocystous filamentous species (
Coleofasciculus
chthonoplastes
, species of
Phormidium
,
Halospirulina tapeticola
,
Halomicronema excentricum
, and others). Cyanobacterial diversity in high-salt environments has been explored using both classic, morphology-based taxonomy and molecular, small subunit rRNA sequence-based techniques. This paper reviews the diversity of the cyanobacterial communities in hypersaline environments worldwide, as well as the physiological adaptations that enable these cyanobacteria to grow at high salt concentrations. To withstand the high osmotic pressure of their surrounding medium, halophilic cyanobacteria accumulate organic solutes: glycine betaine is the preferred solute in the most salt-tolerant types;
Coleofasciculus
produces the heteroside glucosylglycerol, and the less salt-tolerant cyanobacteria generally accumulate the disaccharides sucrose and trehalose under salt stress. Some cyanobacteria growing in benthic mats in hypersaline environments are adapted to life under anoxic conditions and they can use sulfide as an alternative electron donor in an anoxygenic type of photosynthesis through a process which involves photosystem I only.
The Editorial Board of the International Code of Nomenclature of Prokaryotes here explains the proposed procedure towards the production of the next revision of the Prokaryotic Code, to include ...public discussion of a draft version, to be prepared by the editors, followed by balloting of the members of the International Committee on Systematics of Prokaryotes.
The nomenclature of prokaryotes is regulated by the rules of the International Code of Nomenclature of Prokaryotes (ICNP) and is based on the Linnaean binomial system. The current rules of the Code ...only cover the nomenclature of the cultivated minority. Proposals to incorporate the uncultivated majority of bacteria and archaea under the rules of the Code were recently rejected by the International Committee on Systematics of Prokaryotes. The provisional rank of
can be used to name uncultivated prokaryotes whose names cannot be validly published under the rules of the ICNP, but their names can now be validated under the Code of Nomenclature of Prokaryotes Described from Sequence Data (the SeqCode), which was recently established to cover the nomenclature of the uncultivated majority. Metagenomics, single-cell genomics, and high-throughput cultivation techniques have led to a flood of new organisms currently waiting to be named. Automated programs such as GAN and Protologger can assist researchers in naming and describing newly discovered prokaryotes, cultivated as well as uncultivated. However, Latin and Greek skills remain indispensable for proper quality control of names that must meet the standards set by the codes of nomenclature.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The study of microbial communities is hampered by the large fraction of still unknown bacteria. However, many of these species have been isolated, yet lack a validly published name or description. ...The validation of names for novel bacteria requires that the uniqueness of those taxa is demonstrated and their properties are described. The accepted format for this is the protologue, which can be time-consuming to create. Hence, many research fields in microbiology and biotechnology will greatly benefit from new approaches that reduce the workload and harmonise the generation of protologues.We have developed Protologger, a bioinformatic tool that automatically generates all the necessary readouts for writing a detailed protologue. By producing multiple taxonomic outputs, functional features and ecological analysis using the 16S rRNA gene and genome sequences from a single species, the time needed to gather the information for describing novel taxa is substantially reduced. The usefulness of Protologger was demonstrated by using three published isolate collections to describe 34 novel taxa, encompassing 17 novel species and 17 novel genera, including the automatic generation of ecologically and functionally relevant names. We also highlight the need to utilise multiple taxonomic delineation methods, as while inconsistencies between each method occur, a combined approach provides robust placement. Protologger is open source; all scripts and datasets are available, along with a webserver at www.protologger.de.
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