Extreme Ecosystems Research Articles

The Antarctic Moss Pohlia nutans Genome Provides Insights Into the Evolution of Bryophytes and the Adaptation to Extreme Terrestrial Habitats.

The Antarctic continent has extreme natural environment and fragile ecosystem. Mosses are one of the dominant floras in the Antarctic continent. However, their genomic features and adaptation processes to extreme environments remain poorly understood. Here, we assembled the high-quality genome sequence of the Antarctic moss (Pohlia nutans) with 698.20 Mb and 22 chromosomes. We found that the high proportion of repeat sequences and a recent whole-genome duplication (WGD) contribute to the large size genome of P. nutans when compared to other bryophytes. The genome of P. nutans harbors the signatures of massive segmental gene duplications and large expansions of gene families, likely facilitating neofunctionalization. Genomic characteristics that may support the Antarctic lifestyle of this moss comprise expanded gene families involved in phenylpropanoid biosynthesis, unsaturated fatty acid biosynthesis, and plant hormone signal transduction. Additional contributions include the significant expansion and upregulation of several genes encoding DNA photolyase, antioxidant enzymes, flavonoid biosynthesis enzymes, possibly reflecting diverse adaptive strategies. Notably, integrated multi-omic analyses elucidate flavonoid biosynthesis may function as the reactive oxygen species detoxification under UV-B radiation. Our studies provide insight into the unique features of the Antarctic moss genome and their molecular responses to extreme terrestrial environments.

Antimicrobial and Enzymatic Profiling of Halophilic and Halotolerant Bacteria from a Hypersaline Lake ‘The Great Sebkha of Oran, Northwestern Algeria’

Extreme ecosystems such as hypersaline habitats are promising source of bacteria able to produce potent natural molecules. Halophilic and halotolerant bacteria associated with an unexplored dry salt lake in Algeria have been investigated. A total of 17 isolates were phenotypically characterized. Optima temperature, pH, and salt concentration for growth have been determined. Bacteria strains have been identified based on the 16S rRNA gene sequencing. Enzymes production and antimicrobial activity against bacteria and fungi strains have been investigated. The results showed that isolates were assigned to three phylotypes, within eight isolates belonging to the genus Virgibacillus, eight isolates to Bacillus, and the genus Halomonas with one representative isolate. All phylotypes were able to thrive on large scales of salt, temperature and pH. In addition, the screening of extracellular enzymes showed that all the isolates were able to produce at least two enzymes. The gelatinase, and caseinase activities were the most produced. The screening of antimicrobial compounds production revealed that these strains exhibited significant activity against Gram-positive, Candida albicans, Fusarium, and Penicillium species. Finally, this biotechnological profiling and the PCA analysis have been shown that LMB3038, LMB3095, and LMB3082 were the most performant strains and present a promising source of important molecules.

Changes in plant biodiversity facets of rocky outcrops and their surrounding rangelands across precipitation and soil gradients

Climate and soil factors induce substantial controls over plant biodiversity in stressful ecosystems. Despite of some studies on plant biodiversity in extreme ecosystems including rocky outcrops, simultaneous effects of climate and soil factors have rarely been studied on different facets of biodiversity including taxonomic and functional diversity in these ecosystems. In addition, we know little about plant biodiversity variations in such extreme ecosystems compared to natural environments. It seems that environmental factors acting in different spatial scales specifically influence some facets of plant biodiversity. Therefore, we studied changes in taxonomic and functional diversity along precipitation and soil gradients in both landscapes (i) rocky outcrops and (ii) their nearby rangeland sites in northeast of Iran. In this regard, we considered six sites across precipitation and soil gradients in each landscape, and established 90 1m2 quadrates in them (i.e. 15 quadrats in each site; 15 × 6 = 90 in each landscape). Then, taxonomic and functional diversity were measured using RaoQ index, FDis and CWM indices. Finally, we assessed impacts of precipitation and soil factors on biodiversity indices in both landscapes by performing regression models and variation partitioning procedure. The patterns of taxonomic diversity similarly showed nonlinear changes along the precipitation and soil factors in both landscapes (i.e. outcrop and rangeland). However, we found a more negative and significant trends of variation in functional diversity indices (except for CWMSLA) across precipitation and soil factors in outcrops than their surrounding rangelands. Variations of plant biodiversity were more explained by precipitation factors in surrounding rangelands, whereas soil factors including organic carbon had more consistent and significant effects on plant biodiversity in outcrops. Therefore, our results represent important impacts of soil factors in structuring plant biodiversity facets in stressful ecosystems. While, environmental factors acting in regional and broad scales such as precipitation generally shape vegetation and plant biodiversity patterns in natural ecosystems. We can conclude that rocky outcrops provide suitable microenvironments to present plant species with similar yields that are less able to be present in rangeland ecosystems.

The hydrothermal resources of medium and low enthalpy in the diversification of primary sources of energy and biotechnology applications: A case study at the San Bartolome de Los Baños geothermal zone, Guanajuato, Mexico

In the present study, the hydrothermal sources of the community of San Juan de Los Llanitos, Apaseo el Alto, Guanajuato, were physically chemically, and microbiologically characterized. The characterization aims to diversify the use of primary sources of energy, particularly their use in microbial biotechnology. Two types of energy resources were recognized in this geothermal zone: one related to the geothermal energy of medium enthalpy (150 °C > T > 90 °C), while the other is of low enthalpy (90 °C > T > 25 °C). The medium energy resource can be used to produce electricity using binary cycle power plants. The waters of the San Bartolomé de Los Baños geothermal zone are of sulfurous sodium chloride type, hyperthermal and superthermal, with a colloidal content, ionic activity, and a presence of chemical components that can be used for balneotherapeutic purposes. Hot springs are extreme ecosystems that, despite having high temperatures, constitute an environment for many thermophilic microorganisms (bacteria, cyanobacteria, and diatoms). The identification of bacteria (Brevibacillus agri, Paenibacillus sp.), cyanobacterias, and diatoms in the study area could be used in the biotechnological application and as indicators of the water quality and the environment. From thermophilic bacteria found in the studied waters, enzymes can be obtained. Such enzymes include amylases, cellulases, proteases, hydrolases, lipases, DNA polymerases, and nitrates, that could be used in the food industry, paper, detergents, medicines, and toxic waste disposal. Medium and low enthalpy geothermal energy represents an opportunity to promote the diversification of primary energy sources, fight against climate change by reducing CO2 emissions on a global scale, and promote sustainable development of local communities and the region with the implementation of activities such as balneology, therapeutic, biotechnological, and industrial.

Human-ignited fires result in more extreme fire behavior and ecosystem impacts

California has experienced a rapid increase in burned area over the past several decades. Although fire behavior is known to be closely tied to ecosystem impacts, most analysis of changing fire regimes has focused solely on area burned. Here we present a standardized database of wildfire behavior, including daily fire rate-of-spread and fire radiative power for large, multiday wildfires in California during 2012–2018 using remotely-sensed active fire observations. We observe that human-ignited fires start at locations with lower tree cover and during periods with more extreme fire weather. These characteristics contribute to more explosive growth in the first few days following ignition for human-caused fires as compared to lightning-caused fires. The faster fire spread, in turn, yields a larger ecosystem impact, with tree mortality more than three times higher for fast-moving fires (>1 km day−1) than for slow moving fires (<0.5 km day−1). Our analysis shows how human-caused fires can amplify ecosystem impacts and highlights the importance of limiting human-caused fires during period of extreme fire weather for meeting forest conservation targets under scenarios of future change.

Predictive metabolomics of multiple Atacama plant species unveils a core set of generic metabolites for extreme climate resilience.

Summary Current crop yield of the best ideotypes is stagnating and threatened by climate change. In this scenario, understanding wild plant adaptations in extreme ecosystems offers an opportunity to learn about new mechanisms for resilience. Previous studies have shown species specificity for metabolites involved in plant adaptation to harsh environments.Here, we combined multispecies ecological metabolomics and machine learning‐based generalized linear model predictions to link the metabolome to the plant environment in a set of 24 species belonging to 14 families growing along an altitudinal gradient in the Atacama Desert.Thirty‐nine common compounds predicted the plant environment with 79% accuracy, thus establishing the plant metabolome as an excellent integrative predictor of environmental fluctuations. These metabolites were independent of the species and validated both statistically and biologically using an independent dataset from a different sampling year. Thereafter, using multiblock predictive regressions, metabolites were linked to climatic and edaphic stressors such as freezing temperature, water deficit and high solar irradiance.These findings indicate that plants from different evolutionary trajectories use a generic metabolic toolkit to face extreme environments. These core metabolites, also present in agronomic species, provide a unique metabolic goldmine for improving crop performances under abiotic pressure.

Rhizosheath\u2013root system changes exopolysaccharide content but stabilizes bacterial community across contrasting seasons in a desert environment

BackgroundIn hot deserts daily/seasonal fluctuations pose great challenges to the resident organisms. However, these extreme ecosystems host unique microenvironments, such as the rhizosheath–root system of desert speargrasses in which biological activities and interactions are facilitated by milder conditions and reduced fluctuations. Here, we examined the bacterial microbiota associated with this structure and its surrounding sand in the desert speargrass Stipagrostis pungens under the contrasting environmental conditions of summer and winter in the Sahara Desert.ResultsThe belowground rhizosheath–root system has higher nutrient and humidity contents, and cooler temperatures than the surrounding sand. The plant responds to the harsh environmental conditions of the summer by increasing the abundance and diversity of extracellular polymeric substances (EPS) compared to the winter. On the contrary, the bacterial community associated with the rhizosheath–root system and its interactome remain stable and, unlike the bulk sand, are unaffected by the seasonal environmental variations. The rhizosheath–root system bacterial communities are consistently dominated by Actinobacteria and Alphaproteobacteria and form distinct bacteria communities from those of bulk sand in the two seasons. The microbiome-stabilization mediated by the plant host acts to consistently retain beneficial bacteria with multiple plant growth promoting functions, including those capable to produce EPS, which increase the sand water holding capacity ameliorating the rhizosheath micro-environment.ConclusionsOur results reveal the capability of plants in desert ecosystems to stabilize their below ground microbial community under seasonal contrasting environmental conditions, minimizing the heterogeneity of the surrounding bulk sand and contributing to the overall holobiont resilience under poly-extreme conditions.

Spatial and Vertical Benthic Foraminifera Diversity in the Oxygen Minimum Zone of Mejillones Bay, Northern Chile

Mejillones Bay is located in northern Chile (23°S) and is influenced by an Oxygen Minimum Zone (OMZ), with oxygen levels below 0.5 ml l–1. This area presents particular ecological characteristics, such as circulation of currents, hotspot, high productivity and industrial activity. This extreme ecosystem generates the need to understand their dynamics and changes across time and space, as well as to identify the main differences with other OMZs. For this reason, we studied the benthic foraminifera to use them as environmental and oxygenation proxies. For this purpose, two sediment cores (ZA and Z1A) were collected, obtaining 14 samples of the first 8 cm (vertical distribution), and 18 samples with a mini boxcore (spatial distribution). When analyzing the foraminifera community, some similarities were found in environmental characteristics of other OMZs, such as the predominance of Bolivina seminuda, Bolivina costata, Epistominella exigua, Fursenkoina sp., and Nonioella stella (species typical of hypoxic conditions). In addition, a high abundance of angular-asymmetric morphologies was observed, indicating eutrophied silty substrates and low current circulation. However, the Mejillones Bay recorded a particular spatial and vertical dynamics respect to others OMZs, due to presence of other species of Bolivinids not reported for this area before, and a high abundance of Buliminella elegantissima, which is not recorded in most of OMZs. Foraminifera with rounded-symmetric morphologies were present and dominant in deeper layers, reflecting a turbulent and high-energy environment. On the basis of depth and conditions of microxia or dysoxia, no significative pattern of spatial and vertical distribution was observed. The latter can be explained by local factors such as cyclonic and anticyclonic whirlpools, wastewater from industrial activity and natural disaster such a Tsunami occurred in 1877. These factors contributed to the mixture of the benthic foraminifera and prevented the formation of spatial and vertical patterns. Finally, an intensification of hypoxia was identified, indicating microxia (0,01 ml l–1) in the superficial layers (0–3 cm from years 1996 to 2012), while the deeper layers (4–8 cm from years 1985 to 1877) presented foraminiferal species that indicated dysoxia conditions (0,07 ml l–1). The latter differs from other OMZs, which show greater oxygenation in the most superficial layers and microxia in deeper layers. This study represents the first ecological reconstruction using benthic foraminifera proxies for the Mejillones Bay, which results indicate an OMZ with ecological and environmental features that differ from other OMZs.

Fungal Diversity in Sediments From Deep-Sea Extreme Ecosystems: Insights Into Low- and High-Temperature Hydrothermal Vents, and an Oxygen Minimum Zone in the Southern Gulf of California, Mexico

Deep-sea sediments are vast microbial habitats that cover almost two-thirds of the planet’s surface. Particularly, sediments in hydrothermal vents and oxygen minimum zones (OMZ) represent emblematic, and poorly understood extreme niches that pose strong selective pressures to life, representing untapped reservoirs of a unique microbial diversity. Nonetheless, the mycobiota in these systems remains relatively unknown. Here, we explored fungal diversity and community structure in deep-sea sediments collected from low- and high-temperature vent systems (Pescadero Basin, Pescadero Transform Fault, and Alarcón Rise) and an OMZ (Alfonso Basin) in the southern Gulf of California, by using high-throughput Illumina sequencing of the ITS1 region. We identified 102 fungal amplicon sequence variants (ASVs), principally affiliated to the Ascomycota and Basidiomycota. Our results also evidenced a high proportion of widely distributed, uncultured phylotypes (e.g., unknown clades closely related to the Basidiomycota such asFungisp. 18 and 19 formerly reported from deep-sea), evidencing the copious occurrence of novel fungal lineages with limited distribution to deep-sea sediments. Overall, the largest number of ASVs was recovered from high-temperature vent systems, corroborating these as diversity hotspots. In addition, clustering patterns across samples and the FUNGuild analysis revealed characteristic assemblages in each ecosystem, which could be linked to site-specific processes. This study provides baseline data paving the way for a better understanding of deep-sea fungal diversity, evidencing its potential importance in ecosystem functioning.

New Insights into Microbial Interactions with Dissolved Organic Matter in Acid Mine Drainage with the Integration of Microbial Community and Chemical Composition Analysis

Acid mine drainage (AMD) environments are one of the most extreme ecosystems on earth, and their biogeochemical cycling has been widely studied. However, the carbon cycling underlying microbial interactions with dissolved organic matter (DOM) is poorly understood in these environments. Here, we evaluated the relationships between microbial populations and DOM pools in an AMD lake by combining high-throughput microbial and chemical compositional analyses. The results demonstrated that microalgae were the predominant primary producers in the system and significantly contributed to the total DOM concentration in the water column, whereas DOM chemodiversity was correlated with bacterial community diversity. Network analyses further revealed that DOM associated with microalgae had low diversity but high relative abundance, suggesting microalgal selective organic matter contribution to the DOM pool. Conversely, diverse DOM molecules with generally low abundance were associated with heterotrophic acidophiles, including members of Alphaproteobacteria, Actinobacteria, Firmicutes, and Acidobacteria. Moreover, microalgae and bacteria exhibited predominantly positive co-occurrences with potential metabolic interactions via DOM exchange. Taken together, this study provides new insights into the microbe–DOM interactions in extreme AMD ecosystems and has significant implications for understanding the carbon cycle and microbial metabolism in extreme environments.

The distribution pattern of mire specialist butterflies in raised bogs of the northern lowlands of Central Europe

Raised bogs are extreme and azonal ecosystems with a characteristic hydrological balance, microclimatic conditions and a specific flora and fauna. Recently, these ecosystems have increasingly become the focus of scientific and general attention because of their important ecosystem roles in the face of global warming and providing biodiversity refuges. From a biogeographical and evolutionary context, the peat bogs of the European Lowlands serve as palaeorefugia, acting as cold, edaphic island habitats for arcto-alpine or boreo-montane insect species in temperate biomes. Analysing 105 peat bog sites in the northern lowlands of Central Europe, we compare the diversity and geographic distribution pattern of a subset of six butterfly species, which appear to be tyrphobiontic or tyrphophile mire specialists. We demonstrate a decrease in mean species number in the European Lowlands on a gradient from the east (Northern Belarus, about 4 species) to the west (Northern Germany, about 1 species), and suggest that the decreasing species number may be mainly caused by human impact in the past. The individual distribution pattern shows a nearly complete gap in occurrence of the sensitive bog specialist species Colias palaeno and Boloria eunomia in Northern Germany and an increasing presence of those species in peat bogs of eastern Europe. Boloria aquilonaris shows a different pattern, which, in contrast to C. palaeno, is continuously distributed in all sampled regions and seems to be the more tolerant of tyrphobiontic butterflies in the face of human impact on peat bogs. In the light of other recent findings our results also suggest that Boloria aquilonaris and Plebejus optilete may serve as target species reflecting success in ecological restoration of peat bog ecosystems.

Phytoplankton Biodiversity in Two Tropical, High Mountain Lakes in Central Mexico

Lakes El Sol and La Luna, inside the crater of the Nevado de Toluca volcano, Central Mexico, are the only two perennial high mountain lakes [HML] in the country. HML are considered among the most comparable ecosystems worldwide. These lakes are “extreme” environments with diluted, oligotrophic, and cold waters exposed to high UV radiation doses. In this paper, we document the phytoplankton species inhabiting these two extreme tropical ecosystems. The phytoplankton diversity of Lakes El Sol and La Luna is low compared to the global phytoplankton diversity from other Mexican inland waters. Nonetheless, the phytoplankton diversity turned out to be high compared to other HML worldwide, both temperate and tropical. The phytoplankton community in Lake El Sol was formed by 92 morphospecies and in Lake La Luna by 63; in both, the most diverse groups were Bacillariophyceae and Chlorophyceae. All species found in Lake La Luna were present in Lake El Sol, but 29 species present in Lake El Sol were absent in Lake La Luna. Nevertheless, 57% of the most frequent and abundant taxa in Lake El Sol were rare in La Luna, and 47% of the most frequent and abundant taxa in Lake La Luna were rare in Lake El Sol. Associated with their shallowness and polymictic thermal pattern, 87.5% of the Bacillariophyceae morphospecies are tychoplantonic, while the remaining 12.5% are truly planktonic. Dominant taxa were Chlorophyceae in Lake El Sol and Cyanobacteria in Lake La Luna. The most extreme conditions of Lake La Luna (ultraoligotrophy, very low pH, high ultraviolet radiation) most likely explained the differences in the dominant species composition and lower species richness compared to Lake El Sol. Herein, we provide for the first time a taxonomic list of the phytoplankton community of Lakes El Sol and La Luna. This information constitutes a baseline needed to use these HML as sentinels of global and climate change.

Prior exposure to weathered oil influences foraging of an ecologically important saltmarsh resident fish.

Estuarine ecosystem balance typically relies on strong food web interconnectedness dependent on a relatively low number of resident taxa, presenting a potential ecological vulnerability to extreme ecosystem disturbances. Following the Deepwater Horizon (DwH) oil spill disaster of the northern Gulf of Mexico (USA), numerous ecotoxicological studies showed severe species-level impacts of oil exposure on estuarine fish and invertebrates, yet post-spill surveys found little evidence for severe impacts to coastal populations, communities, or food webs. The acknowledgement that several confounding factors may have limited researchers’ abilities to detect negative ecosystem-level impacts following the DwH spill drives the need for direct testing of weathered oil exposure effects on estuarine residents with high trophic connectivity. Here, we describe an experiment that examined the influence of previous exposure to four weathered oil concentrations (control: 0.0 L oil m−2; low: 0.1 L oil m−2; moderate: 0.5–1 L oil m−2; high: 3.0 L oil m−2) on foraging rates of the ecologically important Gulf killifish (Fundulus grandis). Following exposure in oiled saltmarsh mesocosms, killifish were allowed to forage on grass shrimp (Palaeomonetes pugio) for up to 21 h. We found that previous exposure to the high oil treatment reduced killifish foraging rate by ~37% on average, compared with no oil control treatment. Previous exposure to the moderate oil treatment showed highly variable foraging rate responses, while low exposure treatment was similar to unexposed responses. Declining foraging rate responses to previous high weathered oil exposure suggests potential oil spill influence on energy transfer between saltmarsh and off-marsh systems. Additionally, foraging rate variability at the moderate level highlights the large degree of intraspecific variability for this sublethal response and indicates this concentration represents a potential threshold of oil exposure influence on killifish foraging. We also found that consumption of gravid vs non-gravid shrimp was not independent of prior oil exposure concentration, as high oil exposure treatment killifish consumed ~3× more gravid shrimp than expected. Our study findings highlight the sublethal effects of prior oil exposure on foraging abilities of ecologically valuable Gulf killifish at realistic oil exposure levels, suggesting that important trophic transfers of energy to off-marsh systems may have been impacted, at least in the short-term, by shoreline oiling at highly localized scales. This study provides support for further experimental testing of oil exposure effects on sublethal behavioral impacts of ecologically important estuarine species, due to the likelihood that some ecological ramifications of DwH on saltmarshes likely went undetected.

Global Assimilation of Remotely Sensed Leaf Area Index: The Impact of Updating More State Variables Within a Land Surface Model

As vegetation regulates water, carbon, and energy cycles from the local to the global scale, its accurate representation in land surface models is crucial. The assimilation of satellite-based vegetation observations in a land surface model has the potential to improve the estimation of global carbon and energy cycles, which in turn can enhance our ability to monitor and forecast extreme hydroclimatic events, ecosystem dynamics, and crop production. This work proposes the assimilation of a remotely sensed vegetation product (Leaf Area Index, LAI) within the Noah Multi-Parameterization land surface model using an Ensemble Kalman Filter technique. The impact of updating leaf mass along with LAI is also investigated. Results show that assimilating LAI data improves the estimation of transpiration and net ecosystem exchange, which is further enhanced by also updating the leaf mass. Specifically, transpiration anomaly correlation coefficients improve in about 77 and 66% of the global land area thanks to the assimilation of leaf area index with and without updating leaf mass, respectively. Random errors in transpiration are also reduced, with an improvement of the unbiased root mean square error in 70% (74%) of the total area without the update of leaf mass (with the update of leaf mass). Similarly, net ecosystem exchange anomaly correlation coefficients improve from 52 to 75% and random errors improve from 49 to 62% of the total pixels after the update of leaf mass. Better performances for both transpiration and net ecosystem exchange are observed across croplands, but the largest improvement is shown over forests and woodland. The global scope of this work makes it particularly important in data poor regions (e.g., Africa, South Asia), where ground observations are sparse or not available altogether but where an accurate estimation of carbon and energy variables can be critical to improve ecosystem and crop management.

Bacterial diversity, physicochemical and geothermometry of South Asian hot springs.

Extreme ecosystems with enormous arrays of physicochemical or biological physiognomies serve as an important indicator of various processes occurred and/or occurring in and on the Earth. Among extreme habitats, hot springs represent geothermal features which are complex systems with a well-defined plumbing system. Besides geological tectonic based hypsography and orology annotations, the hot springs have served as hot spots for ages where there is an amalgamation of nature, religion, faith, health, and science. Thus, there remains an escalating scope to study these hot springs all over the world. The Himalayan Geothermal Belt (HGB) banquets three densely demographic countries i.e. Pakistan, India and China, that hosts numerous hot springs. Studies on the hot springs distributed over these countries reveal Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria as the predominant bacterial phyla. The bacterial diversity shows a significant positive correlation with physicochemical parameters like temperature, pH, Na+, HCO3 -, etc. Physicochemical analyses of these hot springs indicate the water mainly as Na-Cl, Na-HCO3, SO4-Cl, and mixed type, with temperature ranging approximately between 100-250°C as predicted by various geothermometers. Numerous studies although done, not much of a comprehensive database of the analysis are provided on the hot springs harboured by the HGB. This review aims to give a cumulative illustration on comparative facets of various characteristic features of hot springs distributed over the HGB. These are found to be of great importance with respect to the exploitation of geothermal energy and microflora in various sectors of industries and biotechnology. They are also important sources in terms of socio-economic perspective, and routes to eco-medical tourism.

АНАЛИЗ КОНТАМИНИРОВАННОСТИ ОДЕЖДЫ И ОБОРУДОВАНИЯ МИКРОСКОПИЧЕСКИМИ ГРИБАМИ ПОСЛЕ ПОСЕЩЕНИЯ ПЕЩЕР КИНДЕРЛИНСКАЯ И ШУЛЬГАН-ТАШ

Caves are extreme ecosystems whose microbiomes are very sensitive to invasion by extraneous microbial species. The entry of such organisms from one cave into another can occur due to anthropogenic transfer, which makes it possible to bypass natural barriers. The article presents materials on the analysis of microscopic fungi contamination of clothing and equipment after working in caves. It is shown that after visiting the cave Kinderlinskaya and Shulgan-Tash, a significant number of micromycete species settle on clothes and equipment. Twenty-one species of microscopic fungi were found, as well as yeast, light and dark-colored sterile forms. The isolated species correspond to the typical species composition of fungi in a particular cave. Gloves turned out to be the most contaminated. Washing made it possible to significantly reduce the number and species richness of micromycetes on clothes. Thus, following simple rules can significantly reduce the risk of anthropogenic transfer of microorganisms between caves.

Characterization of Some Bacteria in the Waters of Chott of A&amp;#239;n El-Beida in the South of Algeria

Hypersaline environments, represented by the chotts, the Sebkhas and the saline soils, etc., are a typical example of extreme environment harboring a particularly interesting microbial flara. In this context, the aim of this word is to try to make a characterization of the bacteria in the waters of the chott of Aïn El-Beida in the region of Ouargla (South Algeria). The water samples taken are characterized by a pH between 6.6 and 8.39, the water is neutral to alkaline water, with a temperature between 8˚C to 10˚C, and an electrical conductivity between 2.4 to 6 ds/m reflecting extremely salty water. These characteristics enabled us to select a microflora specific to this environment. The microbiological analsis of these samples revealed fifteen isolated strains, including the following species: Escherichia coli 2, Flavobacterium meningosepticum, Shigella sp, Aeromonas salmonicida, with a bacterial density that varied between 0.27 × 104 to 2.236 × 104, which may explain why the water in this ecosystem is rich in specific important microflora. The results of NaCl tolerance have revealed to us that certain isolated strains tolerate a NaCl concentration up to 35%, these are euryhaline bacteria. With regard to the antagonist test, the strains (S8) have a strong antifungal capacity, which can be explained by the fact that latter has a significant competitive power against Aspergillus carbonarius and Penicillium sp. The microbial exploration of this specific extreme ecosystem proved successful, as we were able to detect significant specific microbial diversity.

Hypersaline environments as natural sources of microbes with potential applications in biotechnology: The case of solar evaporation systems to produce salt in Alicante County (Spain).

Extremophilic microbes show a unique metabolism due to the adaptations they display to deal with extreme environmental parameters characterizing the extreme ecosystems that they inhabit (high salt concentration, high temperatures, and extreme pH values, high exposure to solar radiation etc.). Halophilic microorganisms characterised and isolated from saltmarshes, brines, salted ponds, salty lagoons etc. have recently attracted attention due to their potential biotechnological applications (as whole cells used for different purposes like wastewater treatments, or their biomolecules: enzymes, antibiotics, carotenoids, bioplastics). Alicante county (southeast of Spain) accounts for a significant number of salty environments like coastal or inland salty ponds from where sodium chloride (NaCl)is obtained, marshes, salty lagoons, etc. The best system characterised so far from a microbiological point of view is "Salinas de Santa Pola", also termed "Salinas Bras del Port". However, there are many other salty environments to be explored, like the natural park of Torrevieja and la Mata lagoons, salty lagoon located in Calpe city or inland salted ponds like those located in the northwest of the county. This review summarises the most relevant biotechnological applications of halophilic microbes described up to now. In addition, special attention is focused on ecosystems such as the lagoons of Torrevieja or inland salt marshes as natural environments whose microbial biodiversity is worthy of being studied in search of new strains and species with the aim to analyze their potential biotechnological applications (pharmaceutical, food industry, biomedicine, etc.).

Diatom of the Bacillariophyceae Class in Thermophilic Microbial Mats Present in Sulphurous Hot Springs and their Possible Biotechnological Application

The diversity of diatoms in the hot springs of the Comanjilla geothermal zone in northern Guanajuato, Mexico was studied. Hot springs are extreme ecosystems that, despite having high temperatures, constitute an environment for many thermophilic microorganisms (bacteria, cyanobacteria, and diatoms). The thermal water studied is classified as hyperthermal water (45°C to 100°C), of deep origin, and with low mineralization, are of type sulfuric sodium chloride, since the dissolved content of hydrogen sulfide (H2S) is found in concentrations higher than 1mg/L, and its smell is similar to the one of rotten eggs, presents a pH of 7.6 to 9.1 that represents neutrophilic to alkaliphilic environments, with a variable electrical conductivity (EC) (658-698 µs / cm) and total dissolved solids (TDS) (314-24 ppm). In the same way, these hot springs present microbial mats that consist of several stratified layers of green and orange color of 100 cm2, each one, which are dominated by specific types of microorganisms such as bacteria, cyanobacteria, but mainly diatoms, the latter were studied applying the scanning electron microscope and the optical microscope. The morphological characteristics observed in the optical microscope and in the scanning electron microscopy indicate the presence of diatoms of the Bacillariophyceae class, represented by Sellaphora disjuncta (55%), Achnanthes brevipes var. intermedia (45%). This diatom present in thermophilic microbial mats in the sulphurous geothermal zone of Comanjilla represents: a) the first report of said microorganisms in the study area and Mexico; b) an ecosystem of great interest from the biotechnological and industrial point of view; c) an important taxon in terms of diversity and technology; d) an applications in biofuels, environmental monitoring, wastewater treatment, manufacture of fertilizers, production of secondary metabolites, medical compounds, energy sources and food industry and within nanotechnology. It is important to mention that the physical and chemical characteristics of thermal water such as temperature, pH, dissolved solids, electrical conductivity, hardness, alkalinity and silica concentrations, were the major environmental factors influencing the distribution of diatoms in sulphurous hot springs.

Evaluation of antimicrobial activity of the extract of Streptomyces euryhalinus isolated from the Indian Sundarbans.

The discovery of new antimicrobials is the prime target in the fight against antimicrobial resistance. The continuous search for new lead compounds from bacteria of untapped and extreme ecosystems such as mangroves is currently being undertaken. This study describes the metabolite profiling of the Streptomyces euryhalinus culture extract. Previously, Streptomyces euryhalinus was isolated from the mangrove forest of Indian Sundarbans as a novel microorganism. The antimicrobial mechanism of action of Streptomyces euryhalinus culture extract against bacteria and fungi has been analyzed in this study. The gas chromatography-mass spectrometry profile of the ethyl acetate extract bacterial culture displayed the presence of several bioactive compounds with antibacterial, antifungal and antioxidant properties. The bacterial extract showed significant antimicrobial activity in terms of zone of inhibition, minimum inhibitory concentration, minimum bactericidal concentration, and minimum fungicidal concentration. Moreover, substantial capacity to alter or damage the inner membrane as well as the outer membrane of the gram-positive and gram-negative bacteria was exhibited by the bacterial extract. This membrane alteration or damaging potential of the extract is the mechanism of action. Biofilm formation inhibition property of the extract also signified its antimicrobial action, and possible use against resistant bacteria. The extract has shown notable activity against the virulence factors like prevention of hemolysis in bacteria and inhibition of secreted aspartyl proteinase in fungi. These functions of the bacterial extract have revealed the extent of its action in the prevention of infection by terminating the secretory virulence factors and by damaging the tissue.