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Title page




Table of contents


1.0     Introduction

1.1     Scope of the Review


2.0     Space Environment

2.1     Earth’s Upper Environment

2.3     Outer Space Parameters

2.4     Survival of micro-organisms in outer space.


3.0     Role of gravity in basic biological processes

3.1     Facilities for studying gravity effects

3.2     cause and effect theories and mechanisms

3.3     Biological effectiveness of comic radiation

3.4     Role of the stratospheric ozone layer in protecting Earth’s    biosphere from UV radiation.

3.5     Interactions of micro-organisms in outer space


4.0     Facilities for exposing micro-organisms to outer space

4.1     Outer space as a test bed for assessing limit for survival of    microorganisms

4.2     Likelihood of interplanetary transport of microorganisms by          natural processes

4.3     Microorganisms in the spacecraft environment

4.4     Applied Aspects


5.0     Summary

5.1     Conclusion




The vast, cold, and radiation filled conditions of outer space present an environmental challenge for any form of life. One might think of space as a germ-free environment, but microbes can be carried to space inside human gut flora as well as in food and water and once up there, can be expelled by humans in alter breath. The weightless microgravity environment of space can alter bacteria as they grow. (Olsson-Francis et al., 2010).

Microorganisms exposed to outer space has been studied using both stimulated facilities and low earth orbit exposures. A large number of microorganisms have been selected and tested in outer space, these include; Bacillus cereus, Bacillus megaterium, Bacillus mycoides, Bacillus pumilus, clostridium botilinum, Clostridium cletatum, Zaxtobacillus plantarum, staphylococcus auneus, streptococcus mutans, xanthoria elegans etc.

Horneck, G. (2012) Rothschild et al., (2001. it is possible to classify these mlos into two groups; the human – borne, and the extremophiles. Studying the human – borne mlos is significant for human welfare and future manned missions in space, whilst the extremophiles are vital for studying the physiological requirements of survival in space (Olsson – Francis et al., 2010). The existence of extremophites has led to the speculation that mlos could survive the harsh conditions of extraterrestrial environments and be used as model organisms to understand the fate of biological systems in these environments. Because of their  ubiquity and resistance to space craft decontamination, bacterial spores are considered likely potential forward contaminants on robotic missions to mars (Nicholson, et al., 2012).

Studying microorganism in space and in simulated extraterrestrial environments is important for space exploration. A number of terrestrial microorganisms can survive in a stimulated mars environment when protected for solar UV radiation (Nicholson and Schuerger, 2005; cockle et al., 2005). Biotechnological processes that are successful used on earth could be employed in space. For example, bio-mining could be used to leach minerals from local materials such as basalt on mars or the moon, which is rich in industrially useful elements such as iron and magnesium. Mars simulated experiments have been conducted with both pure cultures and communities of microorganisms. Uv radiation has been shown to be the main factor in cell inactivation (Schuerger et al., 2003); Cockell et al., 2005).

Plants have been a valuable source of natural products for maintaining human health, especially in the last decade, with more intensive studies for natural therapies (Nascimento, 2000). Since 1926, the characteristics of the plants that inhibit microorganisms are important for human health have been researched in laboratories (Athamna, 2004). The development of new antimicrobial agent especially from the natural resources is based on the pharmacodynamic properties. These properties are very useful in rationalizing the determination of antimicrobial susceptibility plus preventing the emergence of resistance (matthew and Lavison, 2004). Therefore, pharmacodynamic properties have increasingly become the focus of investigations designed to determine optimal dosage regimens for antimicrobial agents (Basharat et al, 2010).

Recently, the world health organization estimated that 80 percent of people world-wide rely on herbal medicines for some aspect of their primary health care. It has been proposed that traditional medicines should be incorporated into the current medical curriculum as herbs are efficacious in the treatment of many ailments in Nigeria (Prof. Onyebuchi Chkwu, 2014). The use of plant as medicine to cure or prevent illness and to lubricate the wheels of social interaction at the interpersonal and group level is a behaviour that predates civilization. It is found in every society irrespective of its level of development and sophistication (Odungbemi, 2006). According to the history of Nigeria traditional medicine, thousands of plant species have been used for many years in the practice of herbalism (Akinmumi, et al 1986).

Interest in medicinal plant as a remerging health aid has been fuelled by the rising costs of prescription drugs in the maintenance of personal health and well-being and the bio-prospecting of new plant derive drugs. Based on current and research and financial investments, medicinal plants will seemingly, continue to play an important role as a health aid (Moerman, 1996). The use of medicinal plants constitutes an important part of traditional medicine, which is a part of African heritage, though, modern / orthodox medicine has improved the lot of many cultures. Modern medicine complements traditional practices as is obtainable in industrialized societies e.g china and India (Odugbemi, 2006). In these societies, herbal remedies have become more popular in the treatment of minor ailments and also account of the increasing costs of personal health maintenance. Indeed, the market and public demand have been so great, that there is a great risk that many medicinal plants today, face extinction or loss of genetic diversity. In Nigeria, the majority of citizens still use medicinal plants and visit traditional medicine practitioners for their health care needs (odugbemi, 2006).

Medicinal plants have been identified and used throughout human history. The use of plants as medicines predates written human history. In 2001 compounds use in modern medicine which were derived from “ethnomedical” plant sources; 80% of these have had an ethnomedical use identical or related to the current use of the active elements of the plant (Fabricant Ds, et al. 2001). Many of the pharmaceuticals currently available to physicians have a long history of use as herbal remedies, including aspirin, digitalis, quinine and opium. Many of the herbs and species used by humans to season food also yield useful medicinal compounds (Tapsell, et al. 2006). Studies shown that in tropical climates where pathogens are the most abundant, recipes are the most highly spices. Further, the spices with the most potent antimicrobial activity tend to be selected (Billing, et al. 1998). Medicinal plant substances are present in different parts of the plants like root, leaf, stem, bark, fruit, seed and also plant exudates. These medicinal substances are separated by different processes; the most common being extraction (Kurup et al 1979).

Extraction, as the term is used pharmaceutically, involves the separation of medicinally active portions of plant or animal tissues from the inactive or inert components by using selective solvents in standard extraction procedures. The ethanolic extract of the aerial plant of Euphorbia hirta exhibits a board spectrum of antimicrobial activity, particularly against Escherichia coli (Enteropathogen), proteus vulgaris, Pseudomonas aeruginosa and staphylococcus aureus (Sudhaka, M., et al. 2006). Euphorbia hirta have curative properties due to presence of various complex chemical substance of different composition, which are found as secondary plant metabolites in one or more parts of these plants (Kumar et al, 2010). These plant metabolites according to their composition are grouped as alkaloids, glycosides, corticosteroids, essential oils etc.

Euphorbia hirta, is an herb found in many parts of the world (patil, et al, 2009; ogueke, et al., 2007). Euphorbia hirta belongs to the family Euphorbiaceae. The common name is ‘Asthma weed’ and to the Ibibio tribe, it is locally known as ‘Adia ke garri’. E hirta is a small annual herb common to tropical countries (Soforows, 1982). E hirta contains antimicrobial properties which makes it effective in treating a wide variety of diseases. In East and West Africa extracts of the plant are used in treatment of asthma, respiratory tract inflammations, dysentery etc (Igolietal, 2005).

The basic concept of the time-kill kinetic study is establishment of the rate at which a microorganism is killed by a product as a function of survival data recorded at enough exposure time points such that a graph can be constructed at enough exposure time points such that a graph can be constructed modeling the decline in population over time to a point of extinction. In general and unofficially, the 3log10 reduction is considered the minimum level of performance that would indicate a product has substantive killing activity versus a particular microorganism. Anything less indicates that relatively huge numbers of the microorganisms remain viable after treatment with the product for example, a 1 log10 reduction in a population of one million bacteria (a small number, where bacteria contamination is concerned) means that 100,000 bacteria remain.

Haemolysins are lipids and proteins that cause lysis of red blood cells by destroying their cell membrane. Many haemolysins produced by pathogens do not cause significant destruction of red blood cells during infection. Although haemolysins are capable of doing this for red blood cells in vitro (Stipcevic T, 2005). Many bacteria produce haemolysins that can be detected in the laboratory. Haemolysins can be identified by their ability to lyse red blood cells in vitro. One way haemolysin lyses erythrocyte is by forming pores in phospholipids bilayers (Chalmeau, et al. 2011). Haemolysin can be segregated by many different kinds of bacteria such as Escherichia Coli, staphylococcus aureus or Listeria monocytogenes among other pathogens. Escherichia coli strains are often isolated from patients with extraintestinal infections such as urinary tract infections, bacteremia, and septicemia (Braun V, et al. 1987). Staphylococcus aureus is frequently isolated from urine samples obtained from long-term care patients. Listeria monocytogenes is an important food-borne pathogen and is widely tested for in food and clinical samples.


1.1     Objectives

  • Presenting medicinal plants as therapy in treatment of some diseases.
  • To evaluate the time kill kinetics of Euphorbia hirta against haemolysin producing bacteria strains in vitro


This review covers the primary aspect of space microbiology that have been studied to date. Emphasis is placed on recent findings that have not yet been dealt with in a critical review, especially those that are of relevance to future space exploration programs. The fields covered include:

  1. The use of the space environment for understanding basic biological mechanisms, such as the role of gravity at the cellular, subcellular levels, biological eff3cts of the radiation field in space, survival factors in the upper boundary of Earth’s biosphere, and the likelihood of interplanetary transport of microorganisms via meteorites; and
  2. Application oriented aspects, such as the use of microorganisms, in bioregenerative life support systems, the monitoring, characterization, and control of space craft microflora, and associated microbial crew health concerns.

While all of these factors have scientific importance, the latter, applied topics will be of paramount importance in future space exploration activities and will pose high demands on the microbiological research community. By providing a comprehensive review of these some what disparate research disciplines, we hope to convey the complexity of characterizing and analyzing microbial responses to various space environment stressors and also to recognize that the potential for synergistic effects must be considered as well.

Experiments in space have also been complemented by studies using terrestrial laboratory facilities designed to stimulate selected parameters of outer space, such as microgravity via clinorotation, space vacuum and thermal extremes in hypobaric chambers, and certain qualities of radiation in space, studied by use of heavy ion accelerators to simulate cosmic rays or polychromatic UV sources to simulate solar extraterrestrial UV radiation. In order to first familiarize the reader with the experimental conditions of relevance to space microbiology, this review starts with a short introduction describing the primary parameters encountered in the outer space environment that govern microbial growth and behaviour or affect survival. A categorical review of the literature pertaining to microgravity, radiation, and atmospheric effects on microorganisms follows, including an overview of the novel types of facilities and payloads used to conduct the studies.




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