Terrestrial Microorganisms Research Articles

Cytotoxic Anticancer Candidates from Terrestrial Plants

Naturally occurring cytotoxic compounds have been considered to be a valuable pool of lead compounds in the development of potential anticancer drugs. Currently, some cytotoxic compounds of terrestrial plants are being used as cancer therapeutic drugs and more candidates are under clinical trials along with cytotoxic small molecules of terrestrial microorganisms and marine organisms. In the present review, the structures and representative cytotoxicities of new organic small molecules (over 200 molecules) obtained from terrestrial plants between 2001 and 2004 are presented.

Raman spectroscopy as a potentialmethod for the detection of extremely halophilic archaea embedded in halite in terrestrial and possibly extraterrestrial samples.

Evidence for the widespread occurrence of extraterrestrial halite, particularly on Mars, has led to speculations on the possibility of halophilic microbial forms of life; these ideas have been strengthened by reports of viable haloarchaea from sediments of geological age (millions of years). Raman spectroscopy, being a sensitive detection method for future astrobiological investigations onsite, has been used in the current study for the detection of nine different extremely halophilic archaeal strains which had been embedded in laboratory-made halite crystals in order to simulate evaporitic conditions. The cells accumulated preferentially in tiny fluid inclusions, in simulation of the precipitation of salt in natural brines. FT-Raman spectroscopy using laser excitation at 1064 nm and dispersive micro Raman spectroscopy at 514.5 nm were applied. The spectra showed prominent peaks at 1507, 1152 and 1002 cm(-1) which are attributed to haloarchaeal C(50) carotenoid compounds (mainly bacterioruberins). Their intensity varied from strain to strain at 1064-nm laser excitation. Other distinguishable features were peaks due to peptide bonds (amide I, amide III) and to nucleic acids. No evidence for fatty acids was detected, consistent with their general absence in all archaea.These results contribute to a growing database on Raman spectra of terrestrial microorganisms from hypersaline environments and highlight the influence of the different macromolecular composition of diverse strains on these spectra.

Survivability of Psychrobacter cryohalolentis K5 Under Simulated Martian Surface Conditions

Spacecraft launched to Mars can retain viable terrestrial microorganisms on board that may survive the interplanetary transit. Such biota might compromise the search for life beyond Earth if capable of propagating on Mars. The current study explored the survivability of Psychrobacter cryohalolentis K5, a psychrotolerant microorganism obtained from a Siberian permafrost cryopeg, under simulated martian surface conditions of high ultraviolet irradiation, high desiccation, low temperature, and low atmospheric pressure. First, a desiccation experiment compared the survival of P. cryohalolentis cells embedded, or not embedded, within a medium/salt matrix (MSM) maintained at 25 degrees C for 24 h within a laminar flow hood. Results indicate that the presence of the MSM enhanced survival of the bacterial cells by 1 to 3 orders of magnitude. Second, tests were conducted in a Mars Simulation Chamber to determine the UV tolerance of the microorganism. No viable vegetative cells of P. cryohalolentis were detected after 8 h of exposure to Mars-normal conditions of 4.55 W/m(2) UVC irradiation (200-280 nm), -12.5 degrees C, 7.1 mbar, and a Mars gas mix composed of CO(2) (95.3%), N(2) (2.7%), Ar (1.6%), O(2) (0.2%), and H(2)O (0.03%). Third, an experiment was conducted within the Mars chamber in which total atmospheric opacities were simulated at tau = 0.1 (dust-free CO(2) atmosphere at 7.1 mbar), 0.5 (normal clear sky with 0.4 = dust opacity and 0.1 = CO(2)-only opacity), and 3.5 (global dust storm) to determine the survivability of P. cryohalolentis to partially shielded UVC radiation. The survivability of the bacterium increased with the level of UVC attenuation, though population levels still declined several orders of magnitude compared to UVC-absent controls over an 8 h exposure period.

Assessing Panspermia Hypothesis by Microorganisms Collected from The High Altitude Atmosphere

Microbiology at the high altitude atmosphere is imp or t ant for asse ssing the chanc e s and limits of microbial transfer from the earth to extraterrestrial bodies. Among the microorganisms isolated from the high- atmospheric samples, spore formers and vegetative Deinococci were highly resistant against harsh environment at high altitude. From limited knowledge available to date, it is suggested that terrestrial microorganisms may have had chances to be ejected and transferred to outer space. Survival of these organisms during their space travel and proliferation on other planets might be also feasible. Directed Panspermia from Earth to extraterrestrial bodies is discussed on the basis of findings reported in literatures. ©2009 Jpn. Soc. Biol. Sci. Space; Article ID: 092303017

RESOURCE‐RATIO THEORY APPLIED TO LARGE HERBIVORES

The theoretical description of exploitation competition, known as resource competition theory (RCT) or resource-ratio theory, has been tested in terrestrial plant communities and microorganisms in laboratory cultures. Applications in animal ecology have been rare, although the theory itself is generic. A major difficulty is that the description of resources in RCT is fundamentally different from that used in classical studies of animal competition. In presenting the first fully specified RCT models for terrestrial animals, we distinguish between positive attributes (mineral elements) and negative attributes (plant defenses) as indicators of quality in animal resources. Using the latter we apply RCT to ungulate communities that exploit just two resources: the cell wall and cell contents of plant material. We show how coexistence in the same habitats depends on the strategy of resource exploitation. Ungulate species that differ in body size adopt a "demand-minimizing" strategy that permits them to coexist on ratios of the two resources by acquiring less of the resource that most limits their competitor. Ungulates that differ in mouth width adopt an "extraction-maximizing" strategy that leads to competitive exclusion because they acquire more of the resource that most limits their competitor. We conclude that differential resource utilization permits grazing herbivores of different body size to coexist on the same grassland habitats, but that the full diversity of grazing communities depends on spatial heterogeneity in plant defenses at the landscape level.

Formation of Zn–Ca phyllomanganate nanoparticles in grass roots

It is now well established that a number of terrestrial and aquatic microorganisms have the capacity to oxidize and precipitate Mn as phyllomanganate. However, this biomineralization has never been shown to occur in plant tissues, nor has the structure of a natural Mn(IV) biooxide been characterized in detail. We show that the graminaceous plant Festuca rubra (red fescue) produces a Zn-rich phyllomanganate with constant Zn:Mn and Ca:Mn atomic ratios (0.46 and 0.38, respectively) when grown on a contaminated sediment. This new phase is so far the Zn-richest manganate known to form in nature (chalcophanite has a Zn:Mn ratio of 0.33) and has no synthetic equivalent. Visual examination of root fragments under a microscope shows black precipitates about ten to several tens of microns in size, and their imaging with backscattered and secondary electrons demonstrates that they are located in the root epidermis. In situ measurements by Mn and Zn K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray diffraction (XRD) with a micro-focused beam can be quantitatively described by a single-phase model consisting of Mn(IV) octahedral layers with 22% vacant sites capped with tetrahedral and octahedral Zn in proportions of 3:1. The layer charge deficit is also partly balanced by interlayer Mn and Ca. Diffracting crystallites have a domain radius of 33Å in the ab plane and contain only 1.2 layers (∼8.6Å) on average. Since this biogenic Mn oxide consists mostly of isolated layers, basal 00l reflections are essentially absent despite its lamellar structure. Individual Mn layers are probably held together in the Mn–Zn precipitates by stabilizing organic molecules. Zinc biomineralization by plants likely is a defense mechanism against toxicity induced by excess concentrations of this metal in the rhizosphere.

Characterization of Antarctic psychrotrophic bacteria with antibacterial activities against terrestrial microorganisms

Five-hundreds and eighty bacterial strains, isolated from various Antarctic marine sources and locations, were screened for antimicrobial activity against terrestrial microorganisms. Twenty-two Antarctic isolates (3.8%), mainly retrieved from the water column at Terra Nova Bay (Ross Sea), expressed antagonistic activity against one to three indicator organisms. Escherichia coli and Proteus mirabilis resulted as the more susceptible, followed by Micrococcus luteus and Bacillus subtilis. None of the isolates inhibited the growth of Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella enterica and the eukaryotic fungus Candida albicans. Active Antarctic isolates, identified by 16S rDNA sequencing and phenotypically characterized by classical methods, were phylogenetically affiliated to the Actinobacteria (16 strains) and the gamma-Proteobacteria (6 strains). Inhibition patterns, as well as phenotypic characteristics, highly vary for different isolates, even though they were affiliated to the same genus or closely related to the identical microorganism retrieved from the database, suggesting that these features were more likely strain-rather than species-specific.Results obtained from the present study confirm previous observations and highlight the potentiality of Antarctic marine bacteria as novel source of antibacterial substances.

Organic carbon effects on aerobic polychlorinated biphenyl removal and bacterial community composition in soils and sediments

Certain organic compounds, including biphenyl and salicylic acid, stimulate polychlorinated biphenyl (PCB) degradation by microorganisms in some environments. However, the usefulness of these amendments for improving PCB removal by microorganisms from diverse habitats has not been extensively explored. This study evaluated the effects of biphenyl, salicylic acid, and glucose on changes in aerobic PCB removal and bacterial communities from an agricultural soil, a wetland peat soil, a river sediment, and a mixture of these samples. PCB removal patterns were significantly different between soils and sediments amended with carbon compounds: (i) terrestrial soil microorganisms removed more PCBs than river sediment microorganisms, particularly with regard to PCBs with >4 chlorine substituents, (ii) glucose-supplemented, agricultural soil microorganisms removed more hexachlorobiphenyl than unsupplemented samples, (iii) biphenyl-supplemented, river sediment microorganisms removed more di- and tri-chlorobiphenyls than unamended samples. Carbon amendments also caused unique shifts in soil and sediment bacterial communities, as determined by specific changes in bacterial 16S rRNA denaturing gradient gel electrophoresis banding patterns. These results indicate that organic carbon amendments had site-specific effects on bacterial populations and PCB removal. Further work is needed to more accurately characterize PCB degrading communities and functional gene expression in diverse types of environments to better understand how they respond to bioremediation treatments.

The shielding effect of small-scale martian surface geometry on ultraviolet flux

The atmosphere of Mars does little to attenuate incoming ultraviolet (UV) radiation. Large amounts of UV radiation sterilize the hardiest of terrestrial organisms within minutes, and chemically alter the soil such that organic molecules at or near the surface are rapidly destroyed. Thus the survival of any putative martian life near the surface depends to a large extent on how much UV radiation it receives. Variations in small-scale geometry of the surface such as pits, trenches, flat faces and overhangs can have a significant effect on the incident UV flux and may create “safe havens” for organisms and organic molecules. In order to examine this effect, a 1-D radiative transfer sky model with 836 meshed points (plus the Sun) was developed which includes both diffuse and direct components of the surface irradiance. This model derives the variation of UV flux with latitude and an object's Geometric Shielding Ratio (a ratio which describes the geometry of each situation). The best protection is offered by overhangs with flux reduced to a factor of 1.8 ± 0.2 × 10 −5 of the unprotected value, a reduction which does not vary significantly by latitude. Pits and cracks are less effective with a reduction in UV flux of only up to 4.5 ± 0.5 × 10 −3 for the modeled scenarios; however, they are more effective for the same geometric shielding ratio than overhangs at high latitudes due to the low height of the Sun in the sky. Lastly, polar faces of rocks have the least effective shielding geometry with at most a 1.1 ± 0.1 × 10 −1 reduction in UV flux. Polar faces of rocks are most effective at mid latitudes where the Sun is never directly overhead, as at tropical latitudes, and never exposes the back of the rock, as at polar latitudes. In the most favorable cases, UV flux is sufficiently reduced such that organic in-fall could accumulate beneath overhanging surfaces and in pits and cracks. As well, hardy terrestrial microorganisms such as Bacillus pumilus could persist for up to 100 sols on the outer surfaces of typical spacecraft or several tens of martian years in the most shielded surface niches.

FTICR-MS applications for the structure determination of natural products

Natural products are a source of unique chemical entities with specific biological activities of great value to the pharmaceutical industry. However, the determination of unknown structures is usually time consuming and often becomes a bottleneck in the effort to develop natural products into effective drugs. The high-performance features of high magnetic field FTMS have greatly alleviated the structural elucidation bottleneck to meet increasingly shorter discovery timelines for drug candidates based on natural products. The high-performance features of high field FTMS include unsurpassed mass measurement accuracy for elemental formula determination, ultra-high mass resolution for component separation, the ability to perform multiple levels of tandem mass spectrometry for structural elucidation, and moderate sensitivity for limited supply of isolates. A number of applications utilizing these properties of FTMS have been reported recently for the structural elucidation of novel natural product structures originating from terrestrial and marine microorganisms. In this review, FTMS methods and their applications for the structural elucidation and characterization of natural products will be reviewed.

Changes in nitrogen cycling during the past century in a northern hardwood forest.

Nitrogen (N) availability, defined here as the supply of N to terrestrial plants and soil microorganisms relative to their N demands, limits the productivity of many temperate zone forests and in part determines ecosystem carbon (C) content. Despite multidecadal monitoring of N in streams, the long-term record of N availability in forests of the northeastern United States is largely unknown. Therefore, although these forests have been receiving anthropogenic N deposition for the past few decades, it is still uncertain whether terrestrial N availability has changed during this time and, subsequently, whether forest ecosystems have responded to increased N deposition. Here, we used stable N isotopes in tree rings and lake sediments to demonstrate that N availability in a northeastern forest has declined over the past 75 years, likely because of ecosystem recovery from Euro-American land use. Forest N availability has only recently returned to levels forecast from presettlement trajectories, rendering the trajectory of future forest N cycling uncertain. Our results suggest that chronic disturbances caused by humans, especially logging and agriculture, are major drivers of terrestrial N cycling in forest ecosystems today, even a century after cessation.

Simulation of the environmental climate conditions on martian surface and its effect on Deinococcus radiodurans

The resistance of terrestrial microorganisms under the thermo-physical conditions of Mars (diurnal temperature variations, UV climate, atmospheric pressure and gas composition) at mid-latitudes was studied for the understanding and assessment of potential life processes on Mars. In order to accomplish a targeted search for life on other planets, e.g. Mars, it is necessary to know the limiting physical and chemical parameters of terrestrial life. Therefore the polyextremophile bacterium Deinococcus radiodurans was chosen as test organism for these investigations. For the simulation studies at the Planetary and Space Simulation Facilities (PSI) at DLR, Cologne, Germany, conditions that are present during the southern summer at latitude of 60° on Mars were applied. We could simulate several environmental parameters of Mars in one single experiment: vacuum/low pressure, anoxic atmosphere and diurnal cycles in temperature and relative humidity, energy-rich ultraviolet (UV) radiation as well as shielding by different martian soil analogue materials. These parameters have been applied both single and in different combinations in laboratory experiments. Astonishingly the diurnal Mars-like cycles in temperature and relative humidity affected the viability of D. radiodurans cells quite severely. But the martian UV climate turned out to be the most deleterious factor, though D. radiodurans is red-pigmented due to carotenoids incorporated in its cell wall, which have been assigned not only a possible role as free radical scavenger but also as a UV-protectant. An additional UV-protection was accomplished by mixing the bacteria with nano-sized hematite.

Brominated cyclodipeptides from the marine sponge Geodia barretti as selective 5-HT ligands

The production of bioactive compounds by plants, animals and microorganisms has long been exploited in the search for drug candidates to serve as leads in drug development. Traditionally, such bioprospecting for drug candidates has focused on terrestrial microorganisms and plants; the equivalent research in marine systems is in its infancy, but the much larger diversity of major lineages in the sea promises a wealth of new molecular structures with as yet unknown functions. In the ocean, sessile sponges have proved a rich source of bioactive compounds many of which are believed to constitute a chemical defense against predators or foulers aimed at protecting the body surface. We have previously reported on the production of the brominated cyclodipeptides barettin (cyclo[(6-bromo-8-entryptophan)arginine]) and 8,9-dihydrobarettin (cyclo[(6-bromotryptophan)arginine in the marine sponge Geodia barretti Bowerbank and their ability to inhibit settlement of barnacle larvae in a dose-dependent manner [1].

Interactive effects of hypobaria, low temperature, and CO 2 atmospheres inhibit the growth of mesophilic Bacillus spp. under simulated martian conditions

Robotic spacecraft are launched with finite levels of terrestrial microorganisms that are similar to the microbial communities within facilities in which spacecraft are assembled. In particular, spores of mesophilic aerobic Bacillus species are common spacecraft contaminants considered most likely to survive interplanetary transfer to Mars. During the cruise phase to Mars, and then again during surface operations, microbial bioloads are exposed to a diversity of biocidal factors that are likely to render the microbial species either dead or significantly inhibited from active metabolic activity and replication. We report here, for the first time, that interactive effects of low pressure, low temperature, and high CO 2 atmospheres approaching conditions likely to be encountered on the martian surface strongly inhibit the growth and replication of seven common Bacillus spp. isolated from spacecraft. Tests were conducted within a small glass bell-jar system maintained in a low-temperature microbial incubator. Atmospheric pressures were controlled at 1013 (Earth-normal), 100, 50, 35, 25, or 15 mb, and temperatures were maintained at 30, 20, 15, 10, or 5 °C. Experiments were carried out for 48 h or 7 days under either Earth-normal O 2/N 2 or pure CO 2 atmospheres. Results indicated that low pressure, low temperature, and high CO 2 atmospheres, applied separately or in combination, were capable of inhibiting the growth and replication of B. pumilus SAFR-032, B. pumilus FO-36B, B. subtilis HA-101, B. subtilis 42HS-1, B. megaterium KL-197, B. licheniformis KL-196, and B. nealsonii FO-092 under simulated martian conditions. Endospores of all seven Bacillus spp. strains failed to germinate and grow at 25 mb at 30 °C. Although, vegetative cells of these strains exhibited a slightly greater ability to replicate at lower pressures than did endospores, vegetative cells of these species failed to grow at pressures below 25 mb. Interactive effects of these environmental parameters acted to generally increase the inhibitory nature of the low-pressure conditions on growth and replication of the seven Bacillus spp. tested.

Drug discovery from natural sources

Organic compounds from terrestrial and marine organisms have extensive past and present use in the treatment of many diseases and serve as compounds of interest both in their natural form and as templates for synthetic modification. Over 20 new drugs launched on the market between 2000 and 2005, originating from terrestrial plants, terrestrial microorganisms, marine organisms, and terrestrial vertebrates and invertebrates, are described. These approved substances, representative of very wide chemical diversity, together with several other natural products or their analogs undergoing clinical trials, continue to demonstrate the importance of compounds from natural sources in modern drug discovery efforts.

Microbial Survival Rates of Escherichia coli and Deinococcus radiodurans Under Low Temperature, Low Pressure, and UV-Irradiation Conditions, and Their Relevance to Possible Martian Life

Viability rates were determined for microbial populations of Escherichia coli and Deinococcus radiodurans under the environmental stresses of low temperature (-35 degrees C), low-pressure conditions (83.3 kPa), and ultraviolet (UV) irradiation (37 W/m(2)). During the stress tests the organisms were suspended in saltwater soil and freshwater soil media, at variable burial depths, and in seawater. Microbial populations of both organisms were most susceptible to dehydration stress associated with low-pressure conditions, and to UV irradiation. However, suspension in a liquid water medium and burial at larger depths (5 cm) improved survival rates markedly. Our results indicate that planetary surfaces that possess little to no atmosphere and have low water availability do not constitute a favorable environment for terrestrial microorganisms.

Planetary protection: Elements for cost minimization

In line with the UN Outer Space Treaty (article IX of the Outer Space Treaty—London/Washington January 27, 1967) [United Nations Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (the “Outer Space Treaty”) referenced 610 UNTS 205—resolution 2222(XXI) of December 1966 [1]] and with COSPAR recommendations, for ethical, safety and scientific reasons, exploration of the solar system needs to comply with planetary protection constraints in order to avoid extraterrestrial bodies contamination, particularly biological contamination by terrestrial microorganisms. It is also required to protect Earth from an eventual contamination carried by return systems or samples. The search for life in extraterrestrial samples, in situ or in the frame of sample return missions, must be conducted in order to state with the maximum possible confidence, because the discovery or the non-discovery of life in sample has a direct impact on updations of planetary protection specifications for future missions. This last requirement imposes consequently also for implementation in order to preserve extra terrestrial sample properties, protecting also indirectly exobiological science. These constraints impose to set up unusual requirements for project teams involved in such solar system exploration missions, requirements based on hardware sterilization, sterile integration, organic cleanliness, microbiological and cleanliness control, the use of high-reliability system in order to avoid crashes, the definition of specific trajectories and their control, recontamination prevention, etc. Implementation of such requirements induces costs, difficult to estimate, but which can be important depending on the solar system target and the mission definition (fly-by, orbiter or lander). The cost impact of a planetary protection program could be important if some basic rules are not taken into account enough early and consequently, upon past experience, some recommendations can be proposed here in order to manage properly such programs and to minimize their cost.

Antimicrobial screening and active compound isolation from marine bacterium NJ6-3-1 associated with the sponge Hymeniacidon perleve

Twenty-nine marine bacterial strains were isolated from the sponge Hymeniacidon perleve at Nanji island, and antimicrobial screening showed that eight strains inhibited the growth of terrestrial microorganisms. The strain NJ6-3-1 with wide antimicrobial spectrum was identified as Pseudoalteromonas piscicida based on its 16S rRNA sequence analysis. The major antimicrobial metabolite, isolated through bioassay-guide fractionation of TLC bioautography overlay assay, was identified as norharman (a beta-carboline alkaloid) by EI-MS and NMR.

Ecotoxicogenomics: the challenge of integrating genomics into aquatic and terrestrial ecotoxicology

Rapid progress in the field of genomics (the study of how an individual’s entire genetic make-up, the genome, translates into biological functions) is beginning to provide tools that may assist our understanding of how chemicals can impact on human and ecosystem health. In many ways, if scientific and regulatory efforts in the 20th century have sought to establish which chemicals cause damage to ecosystems, then the challenge in ecotoxicology for the 21st century is to understand the mechanisms of toxicity to different wildlife species. In the human context, ‘ toxicogenomics’ is the study of expression of genes important in adaptive responses to toxic exposures and a reflection of the toxic processes per se. Given the parallel implications for ecological (environmental) risk assessment, we propose the term ‘ ecotoxicogenomics’ to describe the integration of genomics (transcriptomics, proteomics and metabolomics) into ecotoxicology. Ecotoxicogenomics is defined as the study of gene and protein expression in non-target organisms that is important in responses to environmental toxicant exposures. The potential of ecotoxicogenomic tools in ecological risk assessment seems great. Many of the standardized methods used to assess potential impact of chemicals on aquatic organisms rely on measuring whole-organism responses (e.g. mortality, growth, reproduction) of generally sensitive indicator species at maintained concentrations, and deriving ‘endpoints’ based on these phenomena (e.g. median lethal concentrations, no observed effect concentrations, etc.). Whilst such phenomenological approaches are useful for identifying chemicals of potential concern they provide little understanding of the mechanism of chemical toxicity. Without this understanding, it will be difficult to address some of the key challenges that currently face aquatic ecotoxicology, e.g. predicting toxicant responses across the very broad diversity of the phylogenetic groups present in aquatic ecosystems; estimating how changes at one ecological level or organisation will affect other levels (e.g. predicting population-level effects); predicting the influence of time-varying exposure on toxicant responses. Ecotoxicogenomic tools may provide us with a better mechanistic understanding of aquatic ecotoxicology. For ecotoxicogenomics to fulfil its potential, collaborative efforts are necessary through the parallel use of model microorganisms (e.g. Saccharomyces cerevisiae) together with aquatic (e.g. Danio rerio, Daphnia magna, Lemna minor and Xenopus tropicalis) and terrestrial (e.g. Arabidopsis thailiana, Caenorhabdites elegans and Eisenia foetida) plants, animals and microorganisms.

Terrestrial Microorganisms at an Altitude of 20,000 m in Earth's Atmosphere

A joint effort between the U.S. Geological Survey's (USGS) Global Desert Dust and NASA's Stratospheric and Cosmic Dust Programs identified culturable microbes from an air sample collected at an altitude of 20,000 m. A total of 4 fungal (Penicillium sp.) and 71 bacteria colony-forming units (70 colonies of Bacillus luciferensis believed to have originated from a single cell collected at altitude and one colony ofBacillus sphaericus) were enumerated, isolated and identified using a morphological key and 16S rDNA sequencing respectively. All of the isolates identified were spore-forming pigmented fungi or bacteria of terrestrial origin and demonstrate that the presence of viable microorganisms in Earth's upper atmosphere may not be uncommon.