Nutrient supplementation experiments with saltern microbial communities implicate utilization of DNA as a source of phosphorus
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For the 2015 NASA I (sup 2) Internship Program, I was selected to work in Dr. John Hogan's laboratory on a Human Nutrient Production in Space (Bio-Nutrients) Project involving Research & Development in advanced microbial strategies for the production of nutrients within crewed spacecraft and habitats. Long-term space missions encounter the hurdle of substantial degradation of certain nutrients in food and supplements with time, potentially resulting in nutrient deficiency and serious health problems. The goal of the Bio-Nutrients Project is to enable rapid, safe, and reliable in situ production of needed nutrients using minimal mass, power, and volume. A platform technology is being developed to employ hydratable single-use packets that contain an edible growth medium and a food microbe engineered to produce target human nutrients. In particular, we examined the production of the carotenoids lutein and zeaxanthin in a spore-forming strain of the yeast Saccharomyces cerevisiae. Carotenoids are important antioxidants required for ocular health, a problematic area for some astronauts on long-duration ISS missions...To meet the first-year milestones for the Bio-Nutrients project, my specific task was to design and run preliminary tests on a disposable bioreactor for in situ production of human nutrients in space.
A standard rodent diet for space flight must meet the unique conditions imposed by the space environment and must be nutritionally adequate since diet can influence the outcome of experiments. This paper evaluates the use of National Aeronautics and Space Administration (NASA) developed Foodbars as a standard space flight diet for rats. The Foodbar's semi-purified formulation permits criteria such as nutrient consistency, high nutrient bioavailability and flexibility of formulation to be met. Extrusion of the semi-purified diet produces Foodbars with the proper texture and a non-crumbing solid form for use in space. Treatment of Foodbar with 0.1% potassium sorbate prevents mold growth. Irradiation (15-25 kGy) prevents bacterial growth and in combination with sorbate-treatment provides added protection against mold for shelf-stability. However, during the development process, nutrient analyses indicated that extrusion and irradiation produced nutrient losses. Nutrients were adjusted accordingly to compensate for processing losses. Nutrient analysis of Foodbars continues to be performed routinely to monitor nutrient levels. It is important that the standard rodent diet provide nutrients that will prevent deficiency but also avoid excess that may mask physiological changes produced by space flight. All vitamins levels in the Foodbars, except for vitamin K conformed to or exceeded the current NRC (1995) recommendations. All indispensable amino acids in Foodbar conformed to or exceeded the NRC nutrient recommendation for mice growth and rat maintenance. However, some indispensable amino acids were slightly below recommendations for rat reproduction/growth. Short-term (18-20 d) animal feeding studies indicated that Foodbars were palatable, supported growth and maintained health in rats. Results indicated that NASA rodent Foodbars meet both the physical and nutritional criteria required to support rodents in the space environment and thus, may be used successfully as a standard diet for short-term space flight studies. However, nutritional adequacy of NASA Rodent Foodbars as a standard diet on longer duration (>20 d) space flight missions remains to be determined.
Abstract Excess nutrient pollution contributes to the formation of harmful algal blooms (HABs) that compromise fisheries and recreation and that can directly endanger human and animal health via cyanotoxins. Efforts to quantify the occurrence, drivers, and severity of HABs across large areas is difficult due to the resource intensive nature of field monitoring of lake nutrient and chlorophyll‐aconcentrations. To better characterize how nutrients interact with other environmental factors to produce algal blooms in freshwater systems, we used spatially explicit and temporally matched climate, landscape, in‐lake characteristic, and nutrient inventory data sets to predict nutrients and chlorophyll‐aacross the conterminous US (CONUS). Using a nested modeling approach, three random forest (RF) models were trained to explain the spatiotemporal variation in total nitrogen (TN), total phosphorus (TP), and chlorophyll‐aconcentrations across US EPA's National Lakes Assessment (n = 2,062). Concentrations of TN and TP were the most important predictors and, with other variables, the RF model accounted for 68% of variation in chlorophyll‐a. We then used these RF models to extrapolate lake TN and TP predictions to lakes without nutrient observations and predict chlorophyll‐afor ∼112,000 lakes across the CONUS. Risk for high chlorophyll‐aconcentrations is highest in the agriculturally dominated Midwest, but other areas of risk emerge in nutrient pollution hot spots across the country. These catchment and lake‐specific results can help managers identify potential nutrient pollution and chlorophyll‐ahot spots that may fuel blooms, prioritize at‐risk lakes for additional monitoring, and optimize management to protect human health and other environmental end goals.
This research involves the manipulation of the root-zone water potential for the purposes of discriminating the rate limiting step in the inorganic nutrient uptake mechanism utilized by higher plants. This reaction sequence includes the pathways controlled by the root-zone conditions such as water tension and gradient concentrations. Furthermore, plant based control mechanisms dictated by various protein productions are differentiated as well. For the nutrients limited by the environmental availability, the kinetics were modeled using convection and diffusion equations. Alternatively, for the nutrients dependent upon enzyme manipulations, the uptakes are modeled using Michaelis-Menten kinetics. In order to differentiate between these various mechanistic steps, an experimental apparatus known as the Porous Ceramic Tube - Nutrient Delivery System (PCT-NDS) was used. Manipulation of the applied suction pressure circulating a nutrient solution through this system imposes a change in the matric component of the water potential. This compensates for the different osmotic components of water potential dictated by nutrient concentration. By maintaining this control over the root-zone conditions, the rate limiting steps in the uptake of the essential nutrients into tomato plants (Lycopersicon esculentum cv. Cherry Elite) were differentiated. Results showed that the uptake of some nutrients were mass transfer limited while others were limited by the enzyme kinetics. Each of these were adequately modeled with calculations and discussions of the parameter estimations provided.
A system was developed in which nutrient flow to plant roots is controlled by a thin (0.98 or 1.18 mm) porous (0.2 or 0.5 microns) stainless steel sheet membrane. The flow of nutrient solution through the membrane is controlled by adjusting the relative negative pressure on the nutrient solution side of the membrane. Thus, the nutrient solution is contained by the membrane and cannot escape from the compartment even under microgravity conditions if the appropriate pressure gradient across the membrane is maintained. Plant roots grow directly on the top surface of the membrane and pull the nutrient solution through this membrane interface. The volume of nutrient solution required by this system for plant growth is relatively small, since the plenum, which contains the nutrient solution in contact with the membrane, needs only to be of sufficient size to provide for uniform flow to all parts of the membrane. Solution not passing through the membrane to the root zone is recirculated through a reservoir where pH and nutrient levels are controlled. The size of the solution reservoir depends on the sophistication of the replenishment system. The roots on the surface of the membrane are covered with a polyethylene film (white on top, black on bottom) to maintain a high relative humidity and also limit light to prevent algal growth. Seeds are sown directly on the stainless steel membrane under the holes in the polyethylene film that allow a pathway for the shoots.
The goal of this study was to understand biofilm formation under microgravity (µg), in support of biofilm mitigation efforts in exploration water recovery systems. The technical approach was to conduct a mass transfer and bacterial culture study under both simulated µg and ambient gravity. The aim was to correlate nutrient consumption to gene expression to better understand biofilm formation. A representative species of bacteria that is commonly cultured from the International Space Station (ISS) Water Processor Assembly (WPA) was cultured in a WPA influent water ersatz formulation that is tailored for microbiology studies. A mass transfer rate study was carried out using the ersatz WPA influent water by introducing a water-soluble dye to represent dissolved nutrients and nutrient particles. Imaging of dye diffusion over time allowed for the comparison of mass transport rates under a series of rotation per minute (RPM) speeds for the High Aspect Ratio Vessels (HARVs) on a Rotating Wall Vessel (RWV). This was done to determine the speed that will most accurately simulate the low convective rates experienced under actual µg conditions. Three biological replicates of the Burkholderia contaminans (B. contaminans) microbe were cultured under simulated µg with a rotating (R) control in the horizontal plane at the determined optimal RPM of 15, along with a stationary (S) reference culture. At T=0, and then at T=1,2,3 (in exponential phase) and T=4 (in S phase), the bacterial culture and ersatz were harvested for transcriptomic and nutrient content analysis, respectively. The experimental results illustrated that phosphate is a limiting nutrient in the WPA ersatz formula. Nutrient analysis illustrated that the µg treatment culture took up essential nutrients more rapidly than the R and S control cultures, yet non-essential nutrients remained higher in the µg treatment than in the controls at later timepoints. The rapid uptake and subsequent starvation of phosphate in the culture under µg conditions is further illustrated in the transcriptomic response when compared to that of the R control condition. The subsequent starvation response may serve as one element to explain a moderate enhancement of biofilm formation in the µg treatment. One implication of this work is that biofilm mitigation in the ISS environment could be supported by ensuring a steady flow of water as a vehicle for phosphate within the WPA to avoid complete phosphate consumption, which occurs in times of no flow and leads to undesired biofilm formation.
The Salad Machine Research has continued to be a two path effort with the research at Marshall Space Flight Center (MSFC) focusing on the design, construction, and operation of a semiautomated system (Salad Machine) for the production of salad vegetables within a standard rack. Boeing Corporation in cooperation with NASA MSFC constructed a four drawer Salad Machine which was occasionally placed within the Space Station Freedom Mockup facility for view by selected visitors. Final outfitting of the Salad Machine is awaiting the arrival of parts for the nutrient delivery system. Research at the Alabama A&M facilities focused on compatibility of radish and lettuce plants when grown on the same nutrient solution. Lettuce fresh weight shoot yield was significantly enhanced when lettuce plants were grown on nutrient solution which was shared with radish. Radish tuber production was not significantly affected although there was a trend for radish from shared solutions to be heavier than those grown on separate nutrient solutions. The effect of sharing nutrient solutions on carbohydrate partitioning reflected the effect of sharing solution on fresh weight yield. Lettuce shoot dry weight was significantly greater for plants from shared solutions than from separate. There was no significant effect on sharing nutrient solution on radish tuber dry weight. Partitioning of nitrogen, calcium, magnesium, and potassium was not affected by sharing, there was, however, a disproportionate amount of potassium in the tissues, suggesting luxury consumption of potassium in all plants and tissues. It is concluded that lettuce plants benefit from sharing nutrient solution with radish and that radish is not harmed.
In the Brazilian Amazon, selective logging is second only to forest conversion in its extent. Conversion to pasture or agriculture tends to reduce soil nutrients and site productivity over time unless fertilizers are added. Logging removes nutrients in bole wood, enough that repeated logging could deplete essential nutrients over time. After a single logging event, nutrient losses are likely to be too small to observe in the large soil nutrient pools, but disturbances associated with logging also alter soil properties. Selective logging, particularly reduced-impact logging, results in consistent patterns of disturbance that may be associated with particular changes in soil properties. Soil bulk density, pH, carbon (C), nitrogen (N), phosphorus (P), calcium (Ca), magnesium (Mg), potassium (K), iron (Fe), aluminum (Al), delta(sup 3)C, delta(sup 15)N, and P fractionations were measured on the soils of four different types of loggingrelated disturbances: roads, decks, skids, and treefall gaps. Litter biomass and percent bare ground were also determined in these areas. To evaluate the importance of fresh foliage inputs from downed tree crowns in treefall gaps, foliar nutrients for mature forest trees were also determined and compared to that of fresh litterfall. The immediate impacts of logging on soil properties and how these might link to the longer-term estimated nutrient losses and the observed changes in soils were studied.
Food and nutrient databases are populated with data obtained from a variety of sources including USDA Reference Tables, scientific journals, food manufacturers and foreign food tables. The food and nutrient database maintained by the Nutrition Coordinating Center (NCC) at the University of Minnesota is continually updated with current nutrient data and continues to be expanded with additional nutrient fields to meet diverse research endeavors. Data are strictly evaluated for reliability and relevance before incorporation into the database; however, the values are obtained from various sources and food samples rather than from direct chemical analysis of specific foods. Precise nutrient values for specific foods are essential to the nutrition program at the National Aeronautics and Space Administration (NASA). Specific foods to be included in the menus of astronauts are chemically analyzed at the Johnson Space Center for selected nutrients. A request from NASA for a method to enter the chemically analyzed nutrient values for these space flight food items into the Nutrition Data System for Research (NDS-R) software resulted in modification of the database and interview system for use by NASA, with further modification to extend the method for related uses by more typical research studies.
The importance of nutrition in exploration has been documented repeatedly throughout history, where, for example, in the period between Columbus' voyage in 1492 and the invention of the steam engine, scurvy resulted in more sailor deaths than all other causes of death combined. Because nutrients are required for the structure and function of every cell and every system in the body, defining the nutrient requirements for spaceflight and ensuring provision and intake of those nutrients are primary issues for crew health and mission success. Unique aspects of nutrition during space travel include the overarching physiological adaptation to weightlessness, psychological adaptation to extreme and remote environments, and the ability of nutrition and nutrients to serve as countermeasures to ameliorate the negative effects of spaceflight on the human body. Key areas of clinical concern for long-duration spaceflight include loss of body mass (general inadequate food intake), bone and muscle loss, cardiovascular and immune system decrements, increased radiation exposure and oxidative stress, vision and ophthalmic changes, behavior and performance, nutrient supply during extravehicular activity, and general depletion of body nutrient stores because of inadequate food supply, inadequate food intake, increased metabolism, and/or irreversible loss of nutrients. These topics are reviewed herein, based on the current gap structure.
Harnessing rhizosphere processes offers a valuable opportunity to optimize nutrient use efficiency in agroecosystems. In nutrient-limited soils, plants discharge part of photosynthate surplus via root exudation, including carboxylates, which may enhance mineral dissolution and nutrient mobilization. We aimed to assess how plant responses to nutrient limitation translated into changes in exudate profiles, and how these exudates, in turn, drive bioweathering processes across soils of contrasting mineralogy and weathering degree. We conducted a hydroponic experiment with Lupinus albus grown under five phosphorus (P) concentrations (5, 10, 20, 30, and 50 µM) over seven weeks. We measured plant biomass and root traits, performed a metabolomics analysis and quantified seven carboxylates in root exudates using gas chromatography-mass spectrometry. To assess bioweathering processes across contrasted soil domains, we conducted batch dissolution tests with exudates using three soil horizons—35 each with distinct physicochemical properties: enriched in organic matter, iron oxides, or primary silicates. At the intermediate level of P supply, shoot biomass was comparable to that under high P, but plants produced more root biomass and a higher total carboxylate exudation rate. Despite low carboxylate concentrations (<100 ppb), exudates promoted the dissolution of Ca, Mg, Si, Fe, P and K in all horizons. Yet, the degree of element released varied among horizons. These findings highlight the importance of root exudates in enhancing mineral dissolution, with effects dependent on soil physicochemical properties. The results suggest that managing agroecosystems under moderate nutrient limitation could be a sustainable strategy to increase root-to-shoot ratios, enhance bioweathering processes and nutrient release in soil solution.
It is problematic that geochemical estimates of new production - that fraction of total primary production in surface waters fueled by externally supplied nutrients - in oligotrophic waters of the open ocean surpass that which can be sustained by the traditionally accepted mechanisms of nutrient supply. In the case of the Sargasso Sea, for example, these mechanisms account for less than half of the annual nutrient requirement indicated by new production estimates based on three independent transient-tracer techniques. Specifically, approximately one-quarter to one-third of the annual nutrient requirement can be supplied by entrainment into the mixed layer during wintertime convection, with minor contributions from mixing in the thermocline and wind-driven transport (the potentially important role of nitrogen fixation - for which estimates vary by an order of magnitude in this region - is excluded from this budget). Here we present four lines of evidence - eddy-resolving model simulations, high-resolution observations from moored instrumentation, shipboard surveys, and satellite data - which suggest that the vertical flux of nutrients induced by the dynamics of mesoscale eddies is sufficient to balance the nutrient budget in the Sargasso Sea. Additional information is contained in the original extended abstract.
It is problematic that geochemical estimates of new production, that fraction of total primary production in surface waters fueled by externally supplied nutrients, in oligotrophic waters of the open ocean surpass that which can be sustained by the traditionally accepted mechanisms of nutrient supply. In the cam of the Sargasso Sea, for example, these mechanisms account for less than half of the annual nutrient requirement indicated by new production estimates based on three independent transient-tracer techniques. Specifically, approximately one-quarter to one-third of the annual nutrient requirement can be supplied by entrainment into the mixed layer during wintertime convection, with minor contributions from mixing in the thermocline and wind-driven transport (the potentially important role of nitrogen fixation- for which estimates vary by an order of magnitude in this region- is excluded from this budget). Here we present four lines of evidence-eddy-resolving model simulations, high-resolution observations from moored instrumentation, shipboard surveys and satellite data-which suggest that the vertical flux of nutrients induced by the dynamics of mesoscale eddies is sufficient to balance the nutrient budget in the Sargasso Sea.
The construction of a permanently manned space station will provide the opportunity to grow plants for weeks or months in orbit for experiments or food production. With this opportunity comes the need for a method to provide plants with a continuous supply of water and nutrients in microgravity. The Capillary Effect Root Environment System (CERES) uses capillary forces to maintain control of circulating plant nutrient solution in the weightless environment of an orbiting spacecraft. The nutrient solution is maintained at a pressure slightly less than the ambient air pressure while it flows on one side of a porous membrane. The root, on the other side of the membrane, is surrounded by a thin film of nutrient solution where it contacts the moist surface of the membrane. The root is provided with water, nutrients and air simultaneously. Air bubbles in the nutrient solution are removed using a hydrophobic/hydrophilic membrane system. A model scaled to the size necessary for flight hardware to test CERES in the space shuttle was constructed.