Investigation of the production and dietary features of oyster mushrooms for a planned lunar farm.

In our previous work, we organized a project mainly to design a lunar mushroom farm. In this work, we proceeded to study the features of the production and consumption of oyster mushrooms in that project. Oyster mushrooms were grown in cultivation vessels containing a sterilized substrate. The fruit yield and mass of the spent substrate in the cultivation vessels were measured. A three-factor experiment was carried out with the subsequent application of the steep ascent method and correlation analysis in the R program. These factors included the density of the substrate in the cultivation vessel, its volume, and the number of harvesting flushes. The data obtained was used to calculate the process parameters: productivity, speed and degree of substrate decomposition, and biological efficiency. The consumption and dietary features of oyster mushrooms were modeled in Excel using the Solver Add-in. In the three-factor experiment, the highest productivity amounting to 272 g of fresh fruiting bodies/(m3*day) was obtained with a substrate density of 500 g/L, a cultivation vessel volume of 3 L, and two harvest flushes. The application of the method of steep ascent showed that it is possible to increase the productivity by increasing the substrate density and reducing the volume of the cultivation vessel. In production, there is a need to tally the substrate decomposition speed with the substrate decomposition degree and the biological efficiency of growing oyster mushrooms, since these process parameters have a negative correlation. Most of the nitrogen and phosphorus passed from the substrate into the fruiting bodies. These biogenic elements could limit the yield of oyster mushrooms. It is safe to set the daily intake of oyster mushrooms at 100-200 g while maintaining the antioxidant capacity of the food set.

Modeling a lunar base mushroom farm.

To calculate the equivalent system mass of mushrooms, a conceptual configuration of a mushroom farm as part of a bioregenerative life support system on an inhabited lunar base was designed. The mushroom farm consists of two connected modules. Each module is a double-shell rigid pipe-in-pipe aluminum structure. The first module is used to prepare and sterilize the substrate, while the mushrooms are sown and grown in the second module. Planned productivity of the mushroom farm is 28 kg of fresh mushrooms per one process cycle lasting 66 days for 14 consumers. Mushroom production can be increased using additional modules. The calculated equivalent system masses of the mushroom farm and the mushrooms produced therein is 88,432 kg and 31,550 kg per 1 kg of dry mushrooms in one process cycle, respectively. At that, the biggest contributor to the equivalent system mass of mushrooms is the total pressurized volume of the farm - 68%. The results obtained may be a prerequisite for performing trade-off studies between different configurations of mushroom farm and calculating a space diet using the equivalent system mass of mushrooms.

Bioregenerative life support space diet and nutrition requirements: still seeking accord.

The capability of "dish" and "ingredient in dish" modeling to reduce the number of nutrition imbalances in bioregenerative life support diet was compared. Masses of dishes were assumed to be the independent variables in the 'dish' model, while in the 'ingredient in dish' model the independent variables were the total masses of the ingredients in a one-day menu and masses of ingredients in the dishes. The objective function in both models was minimization of discrepancy between the calculated nutrition intakes and the daily nutrition requirements of NASA for long duration space missions. Comparing of two models was carried out for the case of a one-day diet containing 12 dishes and 32 ingredients. It was established that the diet simulation by 'dish' model brings 6 nutrition imbalances. The use of the 'ingredient in dish' modeling has helped to reduce the number of nutrition imbalances to 3, namely, an excess of iron, vitamin A and saturated fat. Obstacles to the fulfillment of all nutrition requirements were the nomenclature and masses of ingredients in the dish recipes.

Modeling snail breeding in a bioregenerative life support system.

The discrete-time model of snail breeding consists of two sequentially linked submodels: "Stoichiometry" and "Population". In both submodels, a snail population is split up into twelve age groups within one year of age. The first submodel is used to simulate the metabolism of a single snail in each age group via the stoichiometric equation; the second submodel is used to optimize the age structure and the size of the snail population. Daily intake of snail meat by crewmen is a guideline which specifies the population productivity. The mass exchange of the snail unit inhabited by land snails of Achatina fulica is given as an outcome of step-by-step modeling. All simulations are performed using Solver Add-In of Excel 2007.

Material balance and diet in bioregenerative life support systems: connection with coefficient of closure.

Bioregenerative life support systems (BLSS) with different coefficients of closure are considered. The 66.2% coefficient of closure achieved in "BIOS-3" facility experiments has been taken as a base value. The increase in coefficient of closure up to 72.6-93.0% is planned due to use of soil-like substrate (SLS) and concentrating of urine. Food values were estimated both in a base variant ("BIOS-3"), and with increases in the coefficient of closure. It is shown that food requirements will be more fully satisfied by internal crop production with an increase in the coefficient of closure of the BLSS. Changes of massflow rates on an 'input-output' and inside BLSS are considered. Equations of synthesis and degradation of organic substances in BLSS were examined using a stoichiometric model. The paper shows that at incomplete closure of BLSS containing SLS there is a problem of nitrogen balancing. To compensate for the removal of nitrogen from the system in urine and feces, it is necessary to introduce food and a nitrogen-containing additive.

Synthesis of biomass and utilization of plants wastes in a physical model of biological life-support system.

The paper considers problems of biosynthesis of higher plants' biomass and "biological incineration" of plant wastes in a working physical model of biological LSS. The plant wastes are "biologically incinerated" in a special heterotrophic block involving Californian worms, mushrooms and straw. The block processes plant wastes (straw, haulms) to produce soil-like substrate (SLS) on which plants (wheat, radish) are grown. Gas exchange in such a system consists of respiratory gas exchange of SLS and photosynthesis and respiration of plants. Specifics of gas exchange dynamics of high plants--SLS complex has been considered. Relationship between such a gas exchange and PAR irradiance and age of plants has been established. Nitrogen and iron were found to the first to limit plants' growth on SLS when process conditions are deranged. The SLS microflora has been found to have different kinds of ammonifying and denitrifying bacteria which is indicative of intensive transformation of nitrogen-containing compounds. The number of physiological groups of microorganisms in SLS was, on the whole, steady. As a result, organic substances--products of exchange of plants and microorganisms were not accumulated in the medium, but mineralized and assimilated by the biocenosis. Experiments showed that the developed model of a man-made ecosystem realized complete utilization of plant wastes and involved them into the intrasystem turnover.

Mass exchange in an experimental new-generation life support system model based on biological regeneration of environment.

An experimental model of a biological life support system was used to evaluate qualitative and quantitative parameters of the internal mass exchange. The photosynthesizing unit included the higher plant component (wheat and radish), and the heterotrophic unit consisted of a soil-like substrate, California worms, mushrooms and microbial microflora. The gas mass exchange involved evolution of oxygen by the photosynthesizing component and its uptake by the heterotroph component along with the formation and maintaining of the SLS structure, growth of mushrooms and California worms, human respiration, and some other processes. Human presence in the system in the form of "virtual human" that at regular intervals took part in the respirative gas exchange during the experiment. Experimental data demonstrated good oxygen/carbon dioxide balance, and the closure of the cycles of these gases was almost complete. The water cycle was nearly 100% closed. The main components in the water mass exchange were transpiration water and the watering solution with mineral elements. Human consumption of the edible plant biomass (grains and roots) was simulated by processing these products by a unique physicochemical method of oxidizing them to inorganic mineral compounds, which were then returned into the system and fully assimilated by the plants. The oxidation was achieved by "wet combustion" of organic biomass, using hydrogen peroxide following a special procedure, which does not require high temperature and pressure. Hydrogen peroxide is produced from the water inside the system. The closure of the cycle was estimated for individual elements and compounds. Stoichiometric proportions are given for the main components included in the experimental model of the system. Approaches to the mathematical modeling of the cycling processes are discussed, using the data of the experimental model. Nitrogen, as a representative of biogenic elements, shows an almost 100% closure of the cycle inside the system. The proposed experimental model of a biological system is discussed as a candidate for potential application in the investigations aimed at creating ecosystems with largely closed cycles of the internal mass exchange. The formation and maintenance of sustainable cycling of vitally important chemical elements and compounds in biological life support systems (BLSS) is an extremely pressing problem. To attain the stable functioning of biological life support systems (BLSS) and to maintain a high degree of closure of material cycles in than, it is essential to understand the character of mass exchange processes and stoichiometnc proportions of the initial and synthesized components of the system.

Light intensity and production parameters of phytocenoses cultivated on soil-like substrate under controlled [correction of controled] environment conditions.

To increase the degree of closure of biological life support systems of a new generation, we used vermicomposting to involve inedible phytomass in the intra-system mass exchange. The resulting product was a soil-like substrate, which was quite suitable for growing plants (Manukovsky et al. 1996, 1997). However, the soil like substrate can be regarded as a candidate for inclusion in a system only after a comprehensive examination of its physical, chemical, and other characteristics. An important criterion is the ability of the soil-like substrate to supply the necessary mineral elements to the photosynthesizing component under the chosen cultivation conditions. Thus, the purpose of this work was to study the feasibility of enhancing the production activity of wheat and radish crops by varying the intensity of photosynthetically active radiation, without decreasing the harvest index. The increase of light intensity from 920 to 1150 micromoles m-2 s-1 decreased the intensity of apparent photosynthesis of the wheat crops and slightly increased the apparent photosynthesis of the radish crops The maximum total and grain productivity (kg/m2) of the wheat crops was attained at the irradiance of 920 micromoles m-2 s-1. Light intensity of 1150 micromoles m-2 s-1 decreased the productivity of wheat plants and had no significant effect on the productivity of the radish crops (kg/m2) as compared to 920 micromoles m-2 s-1. The qualitative and quantitative composition of microflora of the watering solution and substrate was determined by the condition of plants, developmental phase and light intensity. By the end of wheat growth under 1150 micromoles m-2 s-1 the numbers of bacteria of the coliform family and phytopathogenic bacteria in the watering solution and substrate were an order of magnitude larger than under other illumination conditions. The obtained data suggest that the cultivation of plants in a life support system on soil-like substrate from composts has a number of advantages over the cultivation on neutral substrates, which require continual replenishment of the plant nutrient solution from the system's store to complement the macro- and micro-elements. Yet, a number of problems arise, including those related to the controlling of the production activity of the plants by the intensity of photosynthetically active radiation. It is essential to understand why the intensity of production processes is limited at higher irradiation levels and to overcome the factors responsible for this, so that the soil-like substrate could have an even better chance in the competition for the best plant cultivation technology to be used in biological life support systems.

Two-stage biohumus production from inedible potato biomass.

The feasibility of a two-stage bioconversion of inedible potato biomass into biohumus by oyster mushroom followed by worms was tested. As a raw material for biohumus production the inedible potato biomass in certain properties ranked below wheat straw. The most feasible method to convert the potato wastes into biohumus was to mix them with wheat straw at the mass ratio of 1:3 and then treat with mushrooms followed by worms. This gave a good yield of mushrooms. The biohumus produced from the mixture was suitable for use as a plant growth medium.

Waste bioregeneration in life support CES: development of soil organic substrate.

An experimental model of matter turnover in the biotic cycle: plants (plant biomass) --> mushrooms (residual substrate + mushroom fruit bodies) --> worms (biohumus) --> microorganisms (soillike substrate) --> plants is presented. The initial mass of soillike substrate was produced from wheat plants grown in a hydroponic system. Three cycles of matter turnover in the biotic cycle were carried out. Grain productivity on soillike substrate was 21.87 g/m2 day. The results obtained were used for designing a CES containing man, plants, soillike substrate, bioregeneration module and aquaculture. It was shown, that the circulating dry mass of the CES is 756 kg. The main part (88%) of the circulating mass accumulates in the soillike substrate and bioregeneration module.

Biological-physical-chemical aspects of a human life support system for a lunar base.

To create a life support system based on biological and physical-chemical processes is the optimum solution providing full-valued conditions for existence and efficient work of people at a lunar base. Long-standing experience in experimental research or closed ecosystems and their components allows us to suggest a realistic functional structure of the lunar base and to estimate qualitatively its parameters. The original restrictions are as follows: 1) the basic source of energy to support the biological processes has to be the solar radiation; 2) the initial amount of basic biological elements forming the turnover of substances (C, O, H, P, K, N) has to be delivered from Earth; 3). Moon materials are not to be used in the biological turnover inside the base; 4) the base is to supply the crew fully with atmosphere and water, and with 90% (A scenario) or 40% (B scenario) of food. Experimental data about the plant productivity under the "Moon" rhythm of light and darkness allow us to suggest that the A scenario requires per one human: plant area--40 m2 irradiated during the lunar day by 250-300 W/m2 PAR producing 1250 g of dry biomass a terrestrial day; a heterotrophic component of "biological incineration" of inedible plant biomass (800 g/day) including the aquaculture of fish to produce animal products and contaminating the environment less than birds and mammals, and the culture of edible mushrooms; a component of physical-chemical correction for the LSS environment including the subsystems of: deep oxidation of organic impurities in the atmosphere and of water, organic wastes of human activity and that biological components (420 g/day) CO2 concentration in "Moon" nights, damping O2 in "Moon" days, etc. The stock of prestored or delivered from Earth substances (food additions, seeds, etc.) to be involved in biological turnover is to be about 50 kg/year per man. Increase of the mass of prestored substances per man up to 220 kg/year would reduce twice the plant area and consumed amount of radiant energy to exclude the components of "biological incineration" and physical-chemical destruction of organic wastes.