Journal of the Indian Institute of Science最新文献

The architectural feats of termites and their farming capabilities have been admired by biologists, engineers and architects and have inspired writers including early natural historians. South India is endowed with termite mud castles; their seeming impregnability threw up intellectual challenges, initiating conversations between biologists and engineers. The biologists were interested in how termites kept their farmed basidiomycete fungus free from parasites and discovered experimentally that termites can sniff out parasitic ascomycete fungi, proceed to anoint them with broad-spectrum fungicides and bury them resulting in mortality-yielding anoxia. High levels of humidity and carbon dioxide inside soil nests are conducive to the growth of parasitic fungi whose density is likely actively supressed by eradication of incipient foci of parasite growth by the termite farmers. The engineers were interested in how the mound acquired its strength, stability and longevity while allowing gas exchange. They discovered that the safety factor of termite mounds is very high, that termite-manipulated soil achieves great strength and weathering resistance, that termites manipulate the water content of soil between its plastic and liquid limits and that mounds have a more porous exterior shell and a less porous core. Dialogues between biologists and engineers have enabled insights into the bio-engineering aspects of animal-built architecture. The natural biological constraints of the termite builders (e.g. size, load-carrying ability in relation to particle grain size, caste) and available material (red soil containing organic matter) in the presence of water have been realistically incorporated into modelling the greenhouses that harbour termites and their crops.

Discovering exoplanets and satellites in habitable zones within and beyond our solar system has sparked intrigue in planetary setting varieties that could support life. Based on our understanding of life on Earth, we can shed light on the origin, evolution, and future of Earth-like organisms in the galaxy and predict extinct or extant extraterrestrial life. Hence, extremophiles thriving in mimic outer space environments are particularly interesting as they exhibit traits that preponderate our comprehension regarding the possibility of life elsewhere and in situ life detection. Additionally, many extremophiles have been used for astrobiological research model organisms to unveil native alien life or possible life-produced metabolites outside Earth. Laboratory-based simulation chambers mimic this outer space condition, helping researchers study life beyond Earth in near identical conditions and understand molecular mechanisms for survival. This review summarizes relevant studies with isolated microorganisms from extreme analog Earth environments, harnessing them as promising astrobiological model candidates for pursuing life potentialities in other planetary bodies. We also highlight the necessity of environmental simulation chamber approaches for mimicking extraterrestrial habitats.

Understanding the habitability of both past and present Mars continues to evoke scientific interest, particularly now that there is growing evidence of previous, vastly available liquid water and a warmer Martian climate. While today the surface of the Red Planet is barren and dry, the presence of hydrated minerals like phyllosilicates and sulphate minerals may indicate that the planet was once much more conducive to the emergence of life. These observations are the driving force behind investigations into possible biomarkers and signs of extinct life in the context of Mars. While Mars orbiters, landers and rovers have significantly improved our understanding of the planet’s past, Earth-based experiments are necessary to support those missions technically and scientifically. Simulation facilities replicating the Mars climate are used to test instruments before flight and investigate interactions of biomarkers with the Martian environment. Here, we review some exemplary, modern ground-based facilities with a focus on sample species relevant to astrochemistry and astrobiology. The presented Mars simulation facilities utilize a variety of technical implementations and thus are capable of simulating all of the major environmental parameters on the Martian surface: atmosphere, temperature and electromagnetic solar radiation. Depending on the subject-specific requirements of each investigation, these setups integrate various simulation features and different measurement techniques. A few examples of particularly remarkable simulation facilities include: the Planetary Atmospheres and Surfaces Chamber and the MARTE Simulation Chamber at INTA's Centro de Astrobiologia, Spain, which are unique in terms of integrated measurement techniques and Martian dust simulation; the Mars Simulation Facility, one of several planetary simulation chambers based at the German aerospace center DLR, Germany, is specialized in humidity measurements and sample analysis using PAM fluorometry; the Mars Simulation Chamber/Planetary Atmosphere Chamber at the Kennedy Space Center, USA, integrates an optical filter system to simulate ultraviolet-light attenuation by Martian dust; the Mars Environmental Simulation Chamber at Aarhus University, Denmark, provides atmospheric cooling and the possibility to extract samples mid-experiment. Many state-of-the-art technologies used in Mars simulation chambers are also integral to space-based experimental platforms, such as the planned OREOcube/Exocube experiment on the International Space Station. In-situ space experiments are highly complementary to Martian simulations, particularly in providing supplementary knowledge about the influence of broad-range radiation exposure and the true solar spectrum.

Space travel has been shown to affect various physiological and psychological processes in humans including the composition and function of the gut microbiome. In addition to the unique conditions of space, space travel is associated with changes in diet, circadian and diurnal rhythms, and physical activity, all of which can impact the gut microbiome. Additionally, the microgravity and radiation exposure encountered during space travel may have direct effects on gut microbiome composition and function. In this short review, we summarize the current state of knowledge on the effect of space travel on the human gut microbiome, including research designs that include animals (rodents), humans, and novel simulations. Experiments were conducted under conditions of spaceflight, ground-based, and analogous flight simulation.

Microbes are important decomposers of organic waste. By decomposing organic waste and using it for their growth, microbes play an important role in maintaining ecosystem's carbon and nitrogen cycles. An ecosystem's microbial shift may disturb it's carbon/nitrogen cycle as a result of any climate change or humanitarian factors, but heat produced by various instruments and greenhouse gases contribute significantly to global warming which in turn may be related to microbial shift of ecosystems. To reduce greenhouse gas emissions and global warming, innovative clean energy production methods must be employed to develop fuels with minimal greenhouse effect. Biofuels, such as bioethanol, provide clean energy with less carbon dioxide emissions. For the production of bioethanol, it is always recommended to use microbes that are capable of decomposing complex organic matter (cellulose, lignin, hemicellulose). Some microbes can efficiently decompose complex organic matter due to the presence of genetic machinery that produces cellulases and β-glucosidase. The membrane transporters are also important for microbes in uptake of simple sugars for metabolism and ethanol production. Microbial technologies are addressing the future needs for not only organic waste management but also clean energy/bioethanol production. However, the role of these technologies on space missions and extraterrestrial settings needs to be explored to improve long term space missions.

The history of agriculture on Earth has spanned thousands of years marked by great innovations needed to meet the challenges of the day. The space environment presents new challenges for growing plants from partial gravity to recycling plant and human waste in a closed environment. Regolith plays an important role in research for developing agricultural systems on planetary surfaces such as the moon and Mars. This work reviews the history of growing plants in space and regolith-based agriculture including the challenges faced and the solutions attempted. Though many solutions have been developed, significant knowledge gaps remain which provide great opportunities for the future of off-world agricultural research and great returns for creating more sustainable practices for terrestrial agriculture.

The topic of extra-terrestrial habitats for humans is becoming more and more relevant with progress in space technology. For developing human colonies on moon or other planets, processes should be focussed around the utilisation of in situ resources so as to minimise the need of intra-terrestrial transportation of desired resources. Here we discuss how microbes can lend themselves to in situ resource utilisation on the moon and Mars.

Due to their extraordinary genetic and phenotypic plasticity, yeast and yeast-like fungi have been able to adapt and colonize a wide range of ecological niches. Pigmented and nonpigmented extremophilic yeasts have been discovered in areas on Earth characterized by physical and chemical conditions similar to those found in extraterrestrial environments. Thus, these "simple" eukaryotic life forms have evolved unique genetic, metabolic, and phenotypic characteristics for coping with extreme conditions, existing in both natural (polar continents, deep sea, stratosphere, etc.) and manmade environments such as the cleanrooms where spacecraft are built. This makes them ideal test organisms for astrobiology research. All of the results from the numerous experiments in which they have been tested are helping us to understand what to look for and where in space missions searching for signs of present and/or past life. Meanwhile, we must continue to explore the most inhospitable places on Earth to discover new promising extremophiles that could be used as model organisms for astrobiology research.

Plants are crucial to human existence. They provide a source of sustenance, nutrient recycling, atmospheric replenishment, water cycling, and physiological health for life on Earth as well as in space. The human spaceflight realm poses unique challenges for engineers who develop facilities to conduct plant experiments, grow crops, and design biology-based life support systems for off-Earth habitation. Fractional or microgravity strongly influences fluid and thermal management directly and indirectly in both the organisms themselves and their engineered life support facilities. Scarce resources such as mass, volume, power, crew involvement, and data must be minimized through all mission phases. The current spaceflight facilities vary in complexity from simple Petri dishes to closed-loop feedback-controlled chambers that regulate biologically relevant parameters such as photosynthetic illumination intensity and quality, diurnal cycle, temperature, relative humidity, moisture, atmospheric constituency, and even fractional gravity. Learning how to grow plants efficiently and effectively will become increasingly relevant as humans journey farther and farther out into the solar system.