scholarly journals Influence of the polar light cycle on seasonal dynamics of an Antarctic lake microbial community

Microbiome ◽  
2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Pratibha Panwar ◽  
Michelle A. Allen ◽  
Timothy J. Williams ◽  
Alyce M. Hancock ◽  
Sarah Brazendale ◽  
...  
Keyword(s):  
Microbial Community ◽  
Carbon Fixation ◽  
Negative Impact ◽  
Green Sulfur Bacteria ◽  
Seasonal Abundance ◽  
Light Cycle ◽  
Video Footage ◽  
Cold Environments ◽  
Vestfold Hills ◽  
Global Biogeochemical Cycles

Abstract Background Cold environments dominate the Earth’s biosphere and microbial activity drives ecosystem processes thereby contributing greatly to global biogeochemical cycles. Polar environments differ to all other cold environments by experiencing 24-h sunlight in summer and no sunlight in winter. The Vestfold Hills in East Antarctica contains hundreds of lakes that have evolved from a marine origin only 3000–7000 years ago. Ace Lake is a meromictic (stratified) lake from this region that has been intensively studied since the 1970s. Here, a total of 120 metagenomes representing a seasonal cycle and four summers spanning a 10-year period were analyzed to determine the effects of the polar light cycle on microbial-driven nutrient cycles. Results The lake system is characterized by complex sulfur and hydrogen cycling, especially in the anoxic layers, with multiple mechanisms for the breakdown of biopolymers present throughout the water column. The two most abundant taxa are phototrophs (green sulfur bacteria and cyanobacteria) that are highly influenced by the seasonal availability of sunlight. The extent of the Chlorobium biomass thriving at the interface in summer was captured in underwater video footage. The Chlorobium abundance dropped from up to 83% in summer to 6% in winter and 1% in spring, before rebounding to high levels. Predicted Chlorobium viruses and cyanophage were also abundant, but their levels did not negatively correlate with their hosts. Conclusion Over-wintering expeditions in Antarctica are logistically challenging, meaning insight into winter processes has been inferred from limited data. Here, we found that in contrast to chemolithoautotrophic carbon fixation potential of Southern Ocean Thaumarchaeota, this marine-derived lake evolved a reliance on photosynthesis. While viruses associated with phototrophs also have high seasonal abundance, the negative impact of viral infection on host growth appeared to be limited. The microbial community as a whole appears to have developed a capacity to generate biomass and remineralize nutrients, sufficient to sustain itself between two rounds of sunlight-driven summer-activity. In addition, this unique metagenome dataset provides considerable opportunity for future interrogation of eukaryotes and their viruses, abundant uncharacterized taxa (i.e. dark matter), and for testing hypotheses about endemic species in polar aquatic ecosystems.

A peek in the micro-sized world: a review of design principles, engineering tools, and applications of engineered microbial community

2020 ◽  
Vol 48 (2) ◽  
pp. 399-409
Author(s):  
Baizhen Gao ◽  
Rushant Sabnis ◽  
Tommaso Costantini ◽  
Robert Jinkerson ◽  
Qing Sun
Keyword(s):  
Microbial Community ◽  
Microbial Communities ◽  
Environmental Remediation ◽  
Real Life ◽  
Design Principles ◽  
Microbial Interactions ◽  
Potential Applications ◽  
New Gene ◽  
Global Biogeochemical Cycles ◽  
Synthetic Microbial Communities

Microbial communities drive diverse processes that impact nearly everything on this planet, from global biogeochemical cycles to human health. Harnessing the power of these microorganisms could provide solutions to many of the challenges that face society. However, naturally occurring microbial communities are not optimized for anthropogenic use. An emerging area of research is focusing on engineering synthetic microbial communities to carry out predefined functions. Microbial community engineers are applying design principles like top-down and bottom-up approaches to create synthetic microbial communities having a myriad of real-life applications in health care, disease prevention, and environmental remediation. Multiple genetic engineering tools and delivery approaches can be used to ‘knock-in' new gene functions into microbial communities. A systematic study of the microbial interactions, community assembling principles, and engineering tools are necessary for us to understand the microbial community and to better utilize them. Continued analysis and effort are required to further the current and potential applications of synthetic microbial communities.

scholarly journals Disentangling Responses of the Subsurface Microbiome to Wetland Status and Implications for Indicating Ecosystem Functions

2021 ◽  
Vol 9 (2) ◽  
pp. 211
Author(s):  
Jie Gao ◽  
Miao Liu ◽  
Sixue Shi ◽  
Ying Liu ◽  
Yu Duan ◽  
...  
Keyword(s):  
Microbial Community ◽  
High Throughput Sequencing ◽  
Carbon Fixation ◽  
Microbial Community Composition ◽  
Ecosystem Functions ◽  
Microbial Composition ◽  
Wetland Ecosystems ◽  
Soil Microbial ◽  
Geochemical Properties ◽  
Microbial Groups

In this study, we analyzed microbial community composition and the functional capacities of degraded sites and restored/natural sites in two typical wetlands of Northeast China—the Phragmites marsh and the Carex marsh, respectively. The degradation of these wetlands, caused by grazing or land drainage for irrigation, alters microbial community components and functional structures, in addition to changing the aboveground vegetation and soil geochemical properties. Bacterial and fungal diversity at the degraded sites were significantly lower than those at restored/natural sites, indicating that soil microbial groups were sensitive to disturbances in wetland ecosystems. Further, a combined analysis using high-throughput sequencing and GeoChip arrays showed that the abundance of carbon fixation and degradation, and ~95% genes involved in nitrogen cycling were increased in abundance at grazed Phragmites sites, likely due to the stimulating impact of urine and dung deposition. In contrast, the abundance of genes involved in methane cycling was significantly increased in restored wetlands. Particularly, we found that microbial composition and activity gradually shifts according to the hierarchical marsh sites. Altogether, this study demonstrated that microbial communities as a whole could respond to wetland changes and revealed the functional potential of microbes in regulating biogeochemical cycles.

scholarly journals Ecophysiological Distinctions of Haloarchaea from a Hypersaline Antarctic Lake as Determined by Metaproteomics

2016 ◽  
Vol 82 (11) ◽  
pp. 3165-3173 ◽  
Author(s):  
Bernhard Tschitschko ◽  
Timothy J. Williams ◽  
Michelle A. Allen ◽  
Ling Zhong ◽  
Mark J. Raftery ◽  
...  
Keyword(s):  
Low Complexity ◽  
Abundant Species ◽  
Specific Protein ◽  
Organic Substrates ◽  
Deep Lake ◽  
Nitrogen And Phosphorus ◽  
Content Type ◽  
Cold Environments ◽  
Vestfold Hills ◽  
Life On Earth

ABSTRACTDeep Lake in the Vestfold Hills is hypersaline and the coldest system in Antarctica known to support microbial growth (temperatures as low as −20°C). It represents a strong experimental model because the lake supports a low-complexity community of haloarchaea, with the three most abundant species totaling ∼72%. Moreover, the dominant haloarchaea are cultivatable, and their genomes are sequenced. Here we use metaproteomics linked to metagenome data and the genome sequences of the isolates to characterize the main pathways, trophic strategies, and interactions associated with resource utilization. The dominance of the most abundant member,Halohasta litchfieldiae, appears to be predicated on competitive utilization of substrates (e.g., starch, glycerol, and dihydroxyacetone) produced byDunaliella, the lake's primary producer, while also possessing diverse mechanisms for acquiring nitrogen and phosphorus. The second most abundant member, strain DL31, is proficient in degrading complex proteinaceous matter.Hht. litchfieldiaeand DL31 are inferred to release labile substrates that are utilized byHalorubrum lacusprofundi, the third most abundant haloarchaeon in Deep Lake. The study also linked genome variation to specific protein variants or distinct genetic capacities, thereby identifying strain-level variation indicative of specialization. Overall, metaproteomics revealed that rather than functional differences occurring at different lake depths or through size partitioning, the main lake genera possess major trophic distinctions, and phylotypes (e.g., strains ofHht. litchfieldiae) exhibit a more subtle level of specialization. This study highlights the extent to which the lake supports a relatively uniform distribution of taxa that collectively possess the genetic capacity to effectively exploit available nutrients throughout the lake.IMPORTANCELife on Earth has evolved to colonize a broad range of temperatures, but most of the biosphere (∼85%) exists at low temperatures (≤5°C). By performing unique roles in biogeochemical cycles, environmental microorganisms perform functions that are critical for the rest of life on Earth to survive. Cold environments therefore make a particularly important contribution to maintaining healthy, stable ecosystems. Here we describe the main physiological traits of the dominant microorganisms that inhabit Deep Lake in Antarctica, the coldest aquatic environment known to support life. The hypersaline system enables the growth of halophilic members of theArchaea: haloarchaea. By analyzing proteins of samples collected from the water column, we determined the functions that the haloarchaea were likely to perform. This study showed that the dominant haloarchaea possessed distinct lifestyles yet formed a uniform community throughout the lake that was collectively adept at using available light energy and diverse organic substrates for growth.

scholarly journals Perspectives on the microbial carbon pump with special reference to microbial respiration and ecosystem efficiency in large estuarine systems

2014 ◽  
Vol 11 (14) ◽  
pp. 3887-3898 ◽  
Author(s):  
H. Dang ◽  
N. Jiao
Keyword(s):  
Dissolved Oxygen ◽  
Carbon Fixation ◽  
Negative Impact ◽  
Energy Transduction ◽  
Metabolic Energy ◽  
Transduction Efficiency ◽  
Estuarine Ecosystems ◽  
Carbon Pump ◽  
Microbial Carbon ◽  
Microbial Carbon Pump

Abstract. Although respiration-based oxidation of reduced carbon releases CO2 into the environment, it provides an ecosystem with the metabolic energy for essential biogeochemical processes, including the newly proposed microbial carbon pump (MCP). The efficiency of MCP in heterotrophic microorganisms is related to the mechanisms of energy transduction employed and hence is related to the form of respiration utilized. Anaerobic organisms typically have lower efficiencies of energy transduction and hence lower efficiencies of energy-dependent carbon transformation. This leads to a lower MCP efficiency on a per-cell basis. Substantial input of terrigenous nutrients and organic matter into estuarine ecosystems typically results in elevated heterotrophic respiration that rapidly consumes dissolved oxygen, potentially producing hypoxic and anoxic zones in the water column. The lowered availability of dissolved oxygen and the excessive supply of nutrients such as nitrate from river discharge lead to enhanced anaerobic respiration processes such as denitrification and dissimilatory nitrate reduction to ammonium. Thus, some nutrients may be consumed through anaerobic heterotrophs, instead of being utilized by phytoplankton for autotrophic carbon fixation. In this manner, eutrophied estuarine ecosystems become largely fueled by anaerobic respiratory pathways and their efficiency is less due to lowered ecosystem productivity when compared to healthy and balanced estuarine ecosystems. This situation may have a negative impact on the ecological function and efficiency of the MCP which depends on the supply of both organic carbon and metabolic energy. This review presents our current understanding of the MCP mechanisms from the view point of ecosystem energy transduction efficiency, which has not been discussed in previous literature.

Seasonal abundance and size variation in Antarctic populations of the Cladoceran Daphniopsis studeri

1995 ◽  
Vol 7 (4) ◽  
pp. 393-394 ◽  
Author(s):  
P.R. Bayliss ◽  
J. Laybourn-Parry
Keyword(s):  
Life Cycle ◽  
Size Variation ◽  
Personal Communication ◽  
Resting Eggs ◽  
Sexual Cycle ◽  
Seasonal Abundance ◽  
Preliminary Survey ◽  
Freshwater Lakes ◽  
Subantarctic Islands ◽  
Vestfold Hills

Continental freshwater lakes of Antarctica are characterized by species-poor biota (Heywood 1977). The plankton is dominated by algae, bacteria and protozoa (Koob & Leister 1972, Parker et al. 1982, Laybourn-Parry et al. 1991). Three species of micro-crustacea have been reported from Eastern Antarctica, the cladoceron Daphniopsis studeri, Ruhe and two copepods, Acanthocyclops mirnyi, Borutsky & Vinogradov, and Boeckella poppei, Mrazek (Borutsky & Vinogradov 1957, Akatova 1964, Bayley & Burton 1993). The origin of D. studeri in lakes of the Vestfold Hills has been documented (Laybourn-Parry & Marchant 1992) and it is generally thought that populations are derived from subantarctic islands and mainland South America. Populations of D. studeri from three freshwater lakes of the Vestfold Hills, have been studied in more detail in a preliminary survey of its occurrence and basic life cycle (Laybourn-Parry & Marchant 1992) during which it was observed that the population consisted entirely of parthenogenic females appearing to produce only subitaneous eggs. Herbert (1981) reported that some Arctic and Antarctic cladocerans were capable of producing ephippial (wintering) eggs asexually. D. studeri also occurs in some of the brackish lakes of the Vestfold Hills with salinities of <4 ppt. These populations were found to possess male individuals (J. Gibson, personal communication 1991) suggesting a sexual cycle and production of resting eggs. There is no evidence of this in the freshwater lakes of the region.

scholarly journals The Bloom-Forming Dinoflagellate Karenia mikimotoi Adopts Different Growth Modes When Exposed to Short or Long Period of Seawater Acidification

Toxins ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 629
Author(s):  
Yuanyuan Li ◽  
Zhengli Zhou ◽  
Yijun Li ◽  
Yanqun Wang ◽  
Mengxue Xu ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Carbon Fixation ◽  
Negative Impact ◽  
Growth Patterns ◽  
Apoptotic Pathway ◽  
Karenia Mikimotoi ◽  
Seawater Acidification ◽  
Photosynthetic Carbon Fixation ◽  
Photosynthetic Carbon ◽  
Short Time

Impacts of ocean acidification (OA) on noncalcifying organisms and the possibly responsible mechanism have aroused great research interests with the intensification of global warming. The present study focused on a noxious, noncalcifying, bloom-forming dinoflagellate, Karenia mikimotoi (K. mikimotoi), and its variation of growth patterns exposed to different periods of seawater acidification with stressing gradients was discussed. The dinoflagellates under short-time acidifying stress (2d) with different levels of CO2 presented significant growth inhibition (p < 0.05). The cell cycle was obviously inhibited at S phase, and the photosynthetic carbon fixation was also greatly suppressed (p < 0.05). Apoptosis was observed and the apoptotic rate increased with the increment of pCO2. Similar tendencies were observed in the key components of mitochondrial apoptotic pathway (the mitochondrial membrane potential (MMP), Caspase-3 and -9, and Bax/Bcl-2 ratio). However, under prolonged stressing time (8 d and 15 d), the growth of dinoflagellates was recovered or even stimulated, the photosynthetic carbon fixation was significantly increased (p < 0.05), the cell cycle of division presented little difference with those in the control, and no apoptosis was observed (p > 0.05). Besides, acidification adjusted by HCl addition and CO2 enrichment resulted in different growth performances, while the latter had a more negative impact. The results of present study indicated that (1) the short-time exposure to acidified seawater led to reduced growth performance via inducing apoptosis, blocking of cell cycle, and the alteration in photosynthetic carbon fixation. (2) K. mikimotoi had undergone adaptive changes under long-term exposure to CO2 induced seawater acidification. This further demonstrated that K. mikimotoi has strong adaptability in the face of seawater acidification, and this may be one of the reasons for the frequent outbreak of red tide. (3) Ions that dissociated by the dissolved CO2, instead of H+ itself, were more important for the impacts induced by the acidification. This work thus provides a new perspective and a possible explanation for the dominance of K. mikimotoi during the occurrence of HABs.

scholarly journals Tea Plants With Gray Blight Have Altered Root Exudates That Recruit a Beneficial Rhizosphere Microbiome to Prime Immunity Against Aboveground Pathogen Infection

2021 ◽  
Vol 12 ◽  
Author(s):  
Qiaomei Wang ◽  
Ruijuan Yang ◽  
Wenshu Peng ◽  
Yanmei Yang ◽  
Xiaoling Ma ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Microbial Community ◽  
Phenolic Acids ◽  
Root Exudates ◽  
Negative Impact ◽  
Control Measures ◽  
Soil Microbiome ◽  
Tea Plants ◽  
Blight Disease ◽  
Rhizosphere Microbial Community

Tea gray blight disease and its existing control measures have had a negative impact on the sustainable development of tea gardens. However, our knowledge of safe and effective biological control measures is limited. It is critical to explore beneficial microbial communities in the tea rhizosphere for the control of tea gray blight. In this study, we prepared conditioned soil by inoculating Pseudopestalotiopsis camelliae-sinensis on tea seedling leaves. Thereafter, we examined the growth performance and disease resistance of fresh tea seedlings grown in conditioned and control soils. Next, the rhizosphere microbial community and root exudates of tea seedlings infected by the pathogen were analyzed. In addition, we also evaluated the effects of the rhizosphere microbial community and root exudates induced by pathogens on the performance of tea seedlings. The results showed that tea seedlings grown in conditioned soil had lower disease index values and higher growth vigor. Soil microbiome analysis revealed that the fungal and bacterial communities of the rhizosphere were altered upon infection with Ps. camelliae-sinensis. Genus-level analysis showed that the abundance of the fungi Trichoderma, Penicillium, and Gliocladiopsis and the bacteria Pseudomonas, Streptomyces, Bacillus, and Burkholderia were significantly (p &lt; 0.05) increased in the conditioned soil. Through isolation, culture, and inoculation tests, we found that most isolates from the induced microbial genera could inhibit the infection of tea gray blight pathogen and promote tea seedling growth. The results of root exudate analysis showed that infected tea seedlings exhibited significantly higher exudate levels of phenolic acids and flavonoids and lower exudate levels of amino acids and organic acids. Exogenously applied phenolic acids and flavonoids suppressed gray blight disease by regulating the rhizosphere microbial community. In summary, our findings suggest that tea plants with gray blight can recruit beneficial rhizosphere microorganisms by altering their root exudates, thereby improving the disease resistance of tea plants growing in the same soil.

scholarly journals Production of lipids from psychrophilic microalgae present in antarctic glaciers for the synthesis of biofuel

2019 ◽  
Vol 4 (1) ◽  
Author(s):  
Geovanny Huilca ◽  
L Licto ◽  
Ronny Flores
Keyword(s):  
Sensory Quality ◽  
Negative Impact ◽  
Chemistry Laboratory ◽  
Sustainable Chemistry ◽  
Lipid Concentration ◽  
Cold Environments ◽  
Chlorella Sp ◽  
A Value ◽  
Different Temperatures ◽  
Made In

Microalgae had a negative impact on the overall sensory quality. Psychrophilic microalgae live in extremely cold environments, their growth increases because they have enzymes in their structure that only adapt to temperatures below 0 ° C. For this reason, the Sustainable Chemistry Laboratory of the Central University of Ecuador, together with the Ecuadorian Antarctic Institute (INAE), made an expedition in the Greenwich, Roberts, Dee, Barrientos and Antarctic Towers where several microalgae consortia were collected, where 15 samples from Greenwich Island and Roberts were analyzed at 21 days at different temperatures, from which the genera Chlorella sp, Chlorococcum sp and Stichococcus sp. Subsequently, isolation was made in Petri dishes to obtain monoalgal cultures. Each of the isolated genera was massified in a volume of 5 mL until reaching a volume of 250 mL in modified M1 medium at a temperature of 4 ° C and 24 ° C, 5000 lux and a photoperiod of 12:12 hours. The Bligh & Dyer method was used for the extraction of lipids. The values of the lipid concentration showed that the genus Chlorella sp is the highest concentration with a value of 0.2802 mg / mL at 4 ° C and a value of 2.6704 mg / mL at 24 ° C on the 22nd day of its exponential phase in comparison with the genera Chlorococcum and Stichococcus sp.

scholarly journals Combined Effect of Platform Edge Doors and Level Access on Boarding and Alighting Process in London Underground

2017 ◽  
Vol 2648 (1) ◽  
pp. 60-67 ◽  
Author(s):  
Sebastián Seriani ◽  
Gonzalo de Ana Rodríguez ◽  
Catherine Holloway
Keyword(s):  
Negative Impact ◽  
Important Influence ◽  
Combined Effect ◽  
Behavior Patterns ◽  
Free Access ◽  
Video Footage ◽  
Passenger Safety ◽  
London Underground ◽  
Passenger Behavior ◽  
The Impact

Platform edge doors (PEDs) are used in metro stations to improve passenger safety and comfort, while step-free access with a minimum gap between the train and the platform is desirable on the grounds of accessibility. There is little research on the effect of PEDs on boarding and alighting time (BAT) and passenger behavior patterns. Many authors, however, have examined the impact of vertical and horizontal gaps in passengers’ boarding and alighting. On the London Underground, there is always step-free access between the train and the platform when there are PEDs; but even at some platforms without PEDs, level access may be provided by platform humps. This study examined the combined effect of PEDs and level access on the boarding and alighting process. Two London Underground platforms, both with level access, one with PEDs and one without PEDs, were compared by analyzing bespoke video footage. The results showed that PEDs on their own had no overall negative impact on BAT and that, in most situations, they encouraged passengers to wait beside the doors. It was also found that demand (number of boarders, alighters, and passengers on the train) was a more important influence on BAT and passenger behaviors than was the presence of PEDs.

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