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The health of biological life support systems
Adv. Space Res. Vol. 18, No. 12, Pp. (12)265-(12)268,1996
PII: SO273-1177(96)00121-4
Copyright 0 1996 COSPAR P&cd in Gent Britain. All rights nsavad 0273-I 177/96 $15.00 + 0.00
THE HEALTH OF BIOLOGICAL LIFE SUPPORT SYSTEMS N. S. Pechurkin,* L. A. Somova,* J. I. Gitelson* and R. C. Huttenbach** * Institute of Biophysics (Siberian Branch of Russian Academy of Sciences),
Krasnoyarsk, 660036, Russia ** Nelson Space Services Ltd, 90 London Road, London SE1 6LN, U.K.
ABSTRACT In developing diffcrcnt types of biological lift support systems for use in space or cxtrcme environments on Earth. researchers should pay attention to the long term health or functional state of such systems. The difficulty of the task is compounded by the complcsity of the links and structure to be found in biological systems. To solve the problem. a hierarchical approach mav be used to estimate and monitor the health of the system as a whole and its individual links. Three lcvcls in a typical hierarchy have been considered: a. the organismic b. populations
and communities
c. the ecosystem Special attention has been given to the interactions between macro- and microorganisms. are considered the most suitable indicators of a system’s health and its component links.
Microorganisms
Copyright 0 1996 COSPAR
INTRODUCTION The term ‘health’ is used vvidcly in medicine and vctcrinary science (less frcqucntly in plant physiology) to describe the normal functioning of organisms (man. animals and/or plants). One of the main indicators of health is stable functioning of the organism. most commonly the maintenance of homcostasis within specified limits. For man and animals, such limits may be monitor-cd by blood pressure, pulse rate, respiration rate or the ability to perform certain work. Mom complex paramctcrs include status of the immune system and the composition of blood or urine. For plants. health ma!’ bc determined by observing the concentration of chlorophyll in the biomass. measuring rates of photosynthesis and respiration, increases in the production of fruit and even immune status.
We bclicve it is more productive to consider the health of a LSS. a natural population or an ecosystem in terms of its function as a multi-organism. rather than to regard it as series of individual organisms. The reason for this, is that such systems can achicvc homcostasis (or more prcciselv. steady stat+ irrespective of the condition of individual components. The increasing impact of human activity on natural populations and the dcvclopment of new types of LSS gcncratca need for a precise knovvlcdgcof the limits of normal functioning of multi-organismic systems ix. their norm and their pathology,.
Man made biological lift support systems capable of simulating the functioning of an ecosystem with various clcments arranged in a hierarchy are an ideal vchiclc for studying the problem of system health. To develop a monitoring strategy. it is convcnicnt and suffrcicnt to single out three lcvcls that arc common to any type of system in which biotic tumovcr occurs. Thcsc arc: a. the lcvcl of the organism. b. the level of populations and communities performing the same trophic function. These include producers. consumers (predators and parasites). as well as reducers of biomass. (12)265
(12)266
N. S. Pechukin ct al.
c. the fcvcf of ccos!stcm
responsible for homcostasis or steady state of the LSS as a whofc.
Special emphasis should bc placed on anafysing the interactions between macro- and microorganisms on using microorganisms as the quickest and most cffcctivc indicator of health of the system. MAlN Methods
fNDICATORS
for monitoring
OF THE HEALTH
and
OF A LSS
the hcafth of humans arc wcff known.
Many arc also suitabfc for animals and
incfudc body temperature (though not for cold-blooded animals), pulse, respiration rates. as wvcff as needs for water and food. Marc comprchcnsive data on the state of hcafth can bc obtained by esamining the composition of blood and the diffcrcnt escrctions and secretions produced by the body. These include urine. facccs. saliva and sweat. An even more comprchcnsive indication of the hcafth of a macroorganism can bc obtained by estimating its immune status. This parameter is the most intcgratcd one and is of particular importance in dctcrmining the state and functional bchaviour of the organism. The immune rcsponsivcncss of a macroorganism measurmg. I I I: * total quantity of microorganisms * bactericidal
activity
can bc dctcrmined in a number of ways. These include
on an arca of skm
of the skin.
* the number of haemofytic
strains of microorganisms
on the skin
* prcscncc of IY. co/i in the mouth The main indicator of inhibited immune rcsponsivcncss is fowcrcd bactericidal activity, of the skin of the macroorganism. Bactericidal activity, can bc estimated by, applying a specific dosage of a test microbe to a portion of the skin. A sclcctivc nutrient medium is then applied some minutes later. If bactcricidaf activity is high (c.g. a hcafthy person). the test microbe will fail to grow and dies. (In a similar manner. J? co/i dies on the skin or in tfx mouth of hcafthy men and animals. Wflcn there is a fall in immune responsiveness, /Z coli is found both on the skin and in the mouth). Such a method is simple and quicker to USCthan other techniques /I/. Although the influcncc of plants on microorganisms has stiff to bc studied in detail, it is possible that this tcchniquc could bc cstcndcd to monitoring the hcafth of a biological LSS. It is common knowfcdgc that many’ saprophytic microorganisms grow actively on the dead cells of plants but cannot survive on the living cclfs of the same plant. Morcovcr, the hcafthicr the plant is. the more activcfy, it inhibits the growth of foreign ccffs and cvcn kills them. This is the bactcriostatic and bactericidal
cffccts of the macroorganism
- a manifestation
of its immunity
and conscquentfv.
its health.
Plants start to struggfc with microscopic particles (viruses. fungal spores, bacteria. etc.) as soon as they come into contact with their surface. As a rufc. tflc upper surfaces of plants arc covered with a waxy, noncellular layer known as cuticfc. This is a pofycstcr of fatty acids and oxy-acids (cg. stcaric acids) 121. This was prcscnts a physical barrier to microorganisms. vvflifst its water-rcpcffcnt propcrtics causes microbial cells to dry and die. The roots of plants on the other hand. have no cuticfc and release various compounds to protect themscivcs against invasion by microorganism and pathogen. Thcsc compounds may generate pH’s unfavourabfc to tflc microorganism or be dcficicnt in substances required by, pathogens, etc. Protection of this type is dctcrmincd by, and rcfatcd to the health of the plant. It is similar in many ways to the antimicrobial
activity
of animals and man.
In addition to immune rcsponsivcncss, it is ncccssary’ to idcntif? beneficial and concomitant microorganisms that can be used to indicate the state of the fife support system. Of particular importance are organisms that arc highly scnsitivc to the prcscncc of toxic compounds such as heavy metal salts. Both unicellular and small mufticcffufar organisms of phvtoplankton, zooplankton. zoobcnthos and periphyton can bc used for this purpose /3/. In the case of air. it may be uscfUf to monitor the total number of microorganisms and tfx presence of pathogens specific to man. These include sfrepfocncci spp and sfrrphylocctcci spp. as wclf as fungaf sports. The principal mechanism for monitoring microbial activity at the level of the population is rcfatcd to the growth strarcgies that the diffcrcnt types of microorganisms pursue in nature. There arc three such strategists 141:
Health ofBiologiul Life Support Systems * R-strategists
Thcsc include pserrdomonns, enrerobucleriu and fungi. Such microorganisms demonstrate balanced performance at high growth rates, flcsiblc metabolism, but die quickly in the absence of adequate nutrition.
* K-strategists
Thcsc include corynehcrcterio spp. lipomyces, prostecohacterin spp and organisms that have a high affmity for substrate metabolism when
(12)267
the supply of nutrients is scvcrcly limit& * L-strategists
Tbcsc include bacilli. fungi and other organisms capable of forming dormant cells. These are poor competitors, but can survive under estrcmcly unfavourablc conditions.
Depending on the type of LSS and functional load. microbial populations can pursue any of the above strategies. Beneficial microflora (populations of photosynthesising organisms and rhizosphcric microbes, etc.) must pursue an R-strategy if they are to function in a biological life support system. Such activity will indicate the health of the link in the LSS as a whole. On the other hand. K-strategies will manifest themselves when the growth of microorganisms is restricted. This can bc controlled by, adjusting the residual concentration of limiting substances in the system. Methods to indicate the health of a lift support system at population lcvcl arc being dcvclopcd. New ideas are far from cshausted and for the moment. it will suffice to mention one - a technique rclatcd to developments in gent engineering. Indicator gcncs responsive to the specific condition of an environment or its population can be inserted into the genotype of a well studied microorganism. Thus for csamplc, it can be a relatively simple matter to insert and automate the mcasurcment of a propcrtvpsuch as autoluminescence. It may not bc too long before the health of a LSS will be monitored by such indicators. As mentioncci previously. a lift support system with the fcaturcs of a large organism can maintain true homeostasis for an indcfinitc period of time. A biological system will posses such intcgratcd properties as productivity. light utilisation. rclcasc and take-up of carbon dioxide, oxygen and vvatcrs. etc. Together with the dynamics of indicator microorganisms, such paramctcrs can bc us.4 to indicate the health of the system as a single whole. The producer link in the biological system carries the main load. generating oxygen and biomass for other component links. Fortunately, these paramctcrs are closely rclatcd to one another. and any increase in biomass can be monitored directly by measuring the rclcase of oxygen. This is a well dcvclopcd technology,, Additional information on the health of a trophic lcvcl can be obtained by using other variants such as the performance of mixed algal reactors and higher plants. In the first cast, the slightest dccrcase in the growth of cukaryotic algae causes a concomitant increase in the number of prokaryotic bacteria. This can be measured on-line simply by monitoring the ratio bctwecn green and yello~v pigments. In the second case, valuable information on the health of a system can bc obtained by monitoring the dynamics of moisture transpired by the lcavcs of higher plants, Another integrated factor can also indicate the health of a lift support system. This is the so-called phenomenon of autostabilisation of limiting factors 151. The concentration of components in an open biological system at steady state will remain constant over a period of time. When inflows change, these propertics will change and the system will bc brought to a new state of equilibrium. On the other hand, the level of the autostabiliscd factors will not change from their former values to new ones. Despite the great diversity of biological spccics and populations used in a LSS, limiting factors arc few in number. Examples include the concentration of nutrient elements, principally nitrogen and phosphorus and sometimes dissolved os)‘gcn or carbon diosidc in the atmosphere. Existing technologies can be used to measure and monitor all thcsc parameters automatically. CONCLUSIONS An analysis of the mechanisms used to estimate the health of a life support system should emphasise the steady functioning of a multi-organismic entity. This is based on the observation that a system containing a number of hierarchies has many opportunities to maintain homeostasis and health.
(12)268
N.S.Pcdwkhefal.
The limits to the health!, functioning of a complex ecosystem are much greater than the limits imposed by the esistcncc of its component clcmcnts. Although analysis shows the health vector to be multi-parametric, only a few key parameters arc nccdcd to mcasurc and monitor the health of the LSS. This inspires the hope that means for monitoring the health of qstcm can bc dcvclopcd in the war firturc. It seems certain that this knowledge can be applied cxtcnsivcly to human activity both in space and on Earth. REFERENCES 1.
N.N. Klcmparskaja. Autoflora as Indicator of Radiation Damage of Organisms. Mcditsina. Moscow, 1966. (in Russian).
2.
S.A.Y. Tarr. The Principles of Plant Patholog\r. Macmillan Press. London. 1972
3.
A.A. Bekker. T.B. Agacv. Protection against Environmental Pollution and its Control. Gidrometeoizdat. Leningrad, 1989. (in Russian).
4.
N.S. Panikov. Kinetic Microbiology. Nauka Press. Moscow. 1988. (in Russian).
5.
N.S. Pechurkin. On Fundamentals of Biosphcrics. Preprint N l78B, lnstitutc of Biophysics. Kholkin Press, Krasnoyarsk. 1992.
PII: SO273-1177(96)00121-4
Copyright 0 1996 COSPAR P&cd in Gent Britain. All rights nsavad 0273-I 177/96 $15.00 + 0.00
THE HEALTH OF BIOLOGICAL LIFE SUPPORT SYSTEMS N. S. Pechurkin,* L. A. Somova,* J. I. Gitelson* and R. C. Huttenbach** * Institute of Biophysics (Siberian Branch of Russian Academy of Sciences),
Krasnoyarsk, 660036, Russia ** Nelson Space Services Ltd, 90 London Road, London SE1 6LN, U.K.
ABSTRACT In developing diffcrcnt types of biological lift support systems for use in space or cxtrcme environments on Earth. researchers should pay attention to the long term health or functional state of such systems. The difficulty of the task is compounded by the complcsity of the links and structure to be found in biological systems. To solve the problem. a hierarchical approach mav be used to estimate and monitor the health of the system as a whole and its individual links. Three lcvcls in a typical hierarchy have been considered: a. the organismic b. populations
and communities
c. the ecosystem Special attention has been given to the interactions between macro- and microorganisms. are considered the most suitable indicators of a system’s health and its component links.
Microorganisms
Copyright 0 1996 COSPAR
INTRODUCTION The term ‘health’ is used vvidcly in medicine and vctcrinary science (less frcqucntly in plant physiology) to describe the normal functioning of organisms (man. animals and/or plants). One of the main indicators of health is stable functioning of the organism. most commonly the maintenance of homcostasis within specified limits. For man and animals, such limits may be monitor-cd by blood pressure, pulse rate, respiration rate or the ability to perform certain work. Mom complex paramctcrs include status of the immune system and the composition of blood or urine. For plants. health ma!’ bc determined by observing the concentration of chlorophyll in the biomass. measuring rates of photosynthesis and respiration, increases in the production of fruit and even immune status.
We bclicve it is more productive to consider the health of a LSS. a natural population or an ecosystem in terms of its function as a multi-organism. rather than to regard it as series of individual organisms. The reason for this, is that such systems can achicvc homcostasis (or more prcciselv. steady stat+ irrespective of the condition of individual components. The increasing impact of human activity on natural populations and the dcvclopment of new types of LSS gcncratca need for a precise knovvlcdgcof the limits of normal functioning of multi-organismic systems ix. their norm and their pathology,.
Man made biological lift support systems capable of simulating the functioning of an ecosystem with various clcments arranged in a hierarchy are an ideal vchiclc for studying the problem of system health. To develop a monitoring strategy. it is convcnicnt and suffrcicnt to single out three lcvcls that arc common to any type of system in which biotic tumovcr occurs. Thcsc arc: a. the lcvcl of the organism. b. the level of populations and communities performing the same trophic function. These include producers. consumers (predators and parasites). as well as reducers of biomass. (12)265
(12)266
N. S. Pechukin ct al.
c. the fcvcf of ccos!stcm
responsible for homcostasis or steady state of the LSS as a whofc.
Special emphasis should bc placed on anafysing the interactions between macro- and microorganisms on using microorganisms as the quickest and most cffcctivc indicator of health of the system. MAlN Methods
fNDICATORS
for monitoring
OF THE HEALTH
and
OF A LSS
the hcafth of humans arc wcff known.
Many arc also suitabfc for animals and
incfudc body temperature (though not for cold-blooded animals), pulse, respiration rates. as wvcff as needs for water and food. Marc comprchcnsive data on the state of hcafth can bc obtained by esamining the composition of blood and the diffcrcnt escrctions and secretions produced by the body. These include urine. facccs. saliva and sweat. An even more comprchcnsive indication of the hcafth of a macroorganism can bc obtained by estimating its immune status. This parameter is the most intcgratcd one and is of particular importance in dctcrmining the state and functional bchaviour of the organism. The immune rcsponsivcncss of a macroorganism measurmg. I I I: * total quantity of microorganisms * bactericidal
activity
can bc dctcrmined in a number of ways. These include
on an arca of skm
of the skin.
* the number of haemofytic
strains of microorganisms
on the skin
* prcscncc of IY. co/i in the mouth The main indicator of inhibited immune rcsponsivcncss is fowcrcd bactericidal activity, of the skin of the macroorganism. Bactericidal activity, can bc estimated by, applying a specific dosage of a test microbe to a portion of the skin. A sclcctivc nutrient medium is then applied some minutes later. If bactcricidaf activity is high (c.g. a hcafthy person). the test microbe will fail to grow and dies. (In a similar manner. J? co/i dies on the skin or in tfx mouth of hcafthy men and animals. Wflcn there is a fall in immune responsiveness, /Z coli is found both on the skin and in the mouth). Such a method is simple and quicker to USCthan other techniques /I/. Although the influcncc of plants on microorganisms has stiff to bc studied in detail, it is possible that this tcchniquc could bc cstcndcd to monitoring the hcafth of a biological LSS. It is common knowfcdgc that many’ saprophytic microorganisms grow actively on the dead cells of plants but cannot survive on the living cclfs of the same plant. Morcovcr, the hcafthicr the plant is. the more activcfy, it inhibits the growth of foreign ccffs and cvcn kills them. This is the bactcriostatic and bactericidal
cffccts of the macroorganism
- a manifestation
of its immunity
and conscquentfv.
its health.
Plants start to struggfc with microscopic particles (viruses. fungal spores, bacteria. etc.) as soon as they come into contact with their surface. As a rufc. tflc upper surfaces of plants arc covered with a waxy, noncellular layer known as cuticfc. This is a pofycstcr of fatty acids and oxy-acids (cg. stcaric acids) 121. This was prcscnts a physical barrier to microorganisms. vvflifst its water-rcpcffcnt propcrtics causes microbial cells to dry and die. The roots of plants on the other hand. have no cuticfc and release various compounds to protect themscivcs against invasion by microorganism and pathogen. Thcsc compounds may generate pH’s unfavourabfc to tflc microorganism or be dcficicnt in substances required by, pathogens, etc. Protection of this type is dctcrmincd by, and rcfatcd to the health of the plant. It is similar in many ways to the antimicrobial
activity
of animals and man.
In addition to immune rcsponsivcncss, it is ncccssary’ to idcntif? beneficial and concomitant microorganisms that can be used to indicate the state of the fife support system. Of particular importance are organisms that arc highly scnsitivc to the prcscncc of toxic compounds such as heavy metal salts. Both unicellular and small mufticcffufar organisms of phvtoplankton, zooplankton. zoobcnthos and periphyton can bc used for this purpose /3/. In the case of air. it may be uscfUf to monitor the total number of microorganisms and tfx presence of pathogens specific to man. These include sfrepfocncci spp and sfrrphylocctcci spp. as wclf as fungaf sports. The principal mechanism for monitoring microbial activity at the level of the population is rcfatcd to the growth strarcgies that the diffcrcnt types of microorganisms pursue in nature. There arc three such strategists 141:
Health ofBiologiul Life Support Systems * R-strategists
Thcsc include pserrdomonns, enrerobucleriu and fungi. Such microorganisms demonstrate balanced performance at high growth rates, flcsiblc metabolism, but die quickly in the absence of adequate nutrition.
* K-strategists
Thcsc include corynehcrcterio spp. lipomyces, prostecohacterin spp and organisms that have a high affmity for substrate metabolism when
(12)267
the supply of nutrients is scvcrcly limit& * L-strategists
Tbcsc include bacilli. fungi and other organisms capable of forming dormant cells. These are poor competitors, but can survive under estrcmcly unfavourablc conditions.
Depending on the type of LSS and functional load. microbial populations can pursue any of the above strategies. Beneficial microflora (populations of photosynthesising organisms and rhizosphcric microbes, etc.) must pursue an R-strategy if they are to function in a biological life support system. Such activity will indicate the health of the link in the LSS as a whole. On the other hand. K-strategies will manifest themselves when the growth of microorganisms is restricted. This can bc controlled by, adjusting the residual concentration of limiting substances in the system. Methods to indicate the health of a lift support system at population lcvcl arc being dcvclopcd. New ideas are far from cshausted and for the moment. it will suffice to mention one - a technique rclatcd to developments in gent engineering. Indicator gcncs responsive to the specific condition of an environment or its population can be inserted into the genotype of a well studied microorganism. Thus for csamplc, it can be a relatively simple matter to insert and automate the mcasurcment of a propcrtvpsuch as autoluminescence. It may not bc too long before the health of a LSS will be monitored by such indicators. As mentioncci previously. a lift support system with the fcaturcs of a large organism can maintain true homeostasis for an indcfinitc period of time. A biological system will posses such intcgratcd properties as productivity. light utilisation. rclcasc and take-up of carbon dioxide, oxygen and vvatcrs. etc. Together with the dynamics of indicator microorganisms, such paramctcrs can bc us.4 to indicate the health of the system as a single whole. The producer link in the biological system carries the main load. generating oxygen and biomass for other component links. Fortunately, these paramctcrs are closely rclatcd to one another. and any increase in biomass can be monitored directly by measuring the rclcase of oxygen. This is a well dcvclopcd technology,, Additional information on the health of a trophic lcvcl can be obtained by using other variants such as the performance of mixed algal reactors and higher plants. In the first cast, the slightest dccrcase in the growth of cukaryotic algae causes a concomitant increase in the number of prokaryotic bacteria. This can be measured on-line simply by monitoring the ratio bctwecn green and yello~v pigments. In the second case, valuable information on the health of a system can bc obtained by monitoring the dynamics of moisture transpired by the lcavcs of higher plants, Another integrated factor can also indicate the health of a lift support system. This is the so-called phenomenon of autostabilisation of limiting factors 151. The concentration of components in an open biological system at steady state will remain constant over a period of time. When inflows change, these propertics will change and the system will bc brought to a new state of equilibrium. On the other hand, the level of the autostabiliscd factors will not change from their former values to new ones. Despite the great diversity of biological spccics and populations used in a LSS, limiting factors arc few in number. Examples include the concentration of nutrient elements, principally nitrogen and phosphorus and sometimes dissolved os)‘gcn or carbon diosidc in the atmosphere. Existing technologies can be used to measure and monitor all thcsc parameters automatically. CONCLUSIONS An analysis of the mechanisms used to estimate the health of a life support system should emphasise the steady functioning of a multi-organismic entity. This is based on the observation that a system containing a number of hierarchies has many opportunities to maintain homeostasis and health.
(12)268
N.S.Pcdwkhefal.
The limits to the health!, functioning of a complex ecosystem are much greater than the limits imposed by the esistcncc of its component clcmcnts. Although analysis shows the health vector to be multi-parametric, only a few key parameters arc nccdcd to mcasurc and monitor the health of the LSS. This inspires the hope that means for monitoring the health of qstcm can bc dcvclopcd in the war firturc. It seems certain that this knowledge can be applied cxtcnsivcly to human activity both in space and on Earth. REFERENCES 1.
N.N. Klcmparskaja. Autoflora as Indicator of Radiation Damage of Organisms. Mcditsina. Moscow, 1966. (in Russian).
2.
S.A.Y. Tarr. The Principles of Plant Patholog\r. Macmillan Press. London. 1972
3.
A.A. Bekker. T.B. Agacv. Protection against Environmental Pollution and its Control. Gidrometeoizdat. Leningrad, 1989. (in Russian).
4.
N.S. Panikov. Kinetic Microbiology. Nauka Press. Moscow. 1988. (in Russian).
5.
N.S. Pechurkin. On Fundamentals of Biosphcrics. Preprint N l78B, lnstitutc of Biophysics. Kholkin Press, Krasnoyarsk. 1992.