1.2 Outline of the Microcosm
The term microcosm is derived from the Greek words for “small” (mikrós) and
“universe” (kósmos); it denotes a system in which a population of a single species or
a community, a group of populations of two or more species, is cultured in a
container under controlled conditions. A large number of microcosms have hitherto
been created to elucidate microbial interactions and their mechanisms, as well as to
assess the effects of hazardous chemical substances and foreign microbes on ecosystems from the perspectives of microbial ecology and environmental science.
These microcosms are classified into three types by size: (1) real-world scale
(mesocosm), (2) pilot plant (pilot site) scale, and (3) flask scale. Furthermore, they
can be divided into three types according to their population compositions: (1) gnotobiotic, in which the species composition is fully known, the population sizes of
each species can be measured, and the traits of each species can be analyzed in
isolation; (2) stress-selected, in which a natural community is cultured under specific
conditions to promote natural selection in an effort to maintain and develop a specific
biological community; and (3) naturally derived, in which a real-world community is
maintained without varying any conditions. Among these, the concept of the gnotobiotic and the stress-selected types is used in the same sense as a standardized
aquatic microcosm and abstract model ecosystem, respectively. Because the abstract
model ecosystem (i.e., stress-selected microcosm) can be steadily sustained with
repeated subculturing, it is well-suited to repetitive experiments and has been used in
both theoretical ecology and applied ecology. It has also recently begun to be used as
a test for assessing environmental impacts. The microcosm in our research model
consists of producers, consumers, and decomposers. It can be considered to fall
under the abstract model ecosystem category with respect to its properties and under
the standardized aquatic microcosm category with respect to its structure.
The microcosm in this experiment is not merely a system for microbial cultures.
The system is characterized by its ability to replicate the target phenomena at an
ecosystem level, as it includes the physical, chemical, and biological factors of an
ecosystem and some of their interactions, which substantiate four relationships:
proliferation, consumption, production, and inhibition. Therefore, when applying
outcomes obtained through a simple experimental system in a laboratory to the
interpretation of real-world phenomena, the phenomena observed in a microcosm
are expected to play an intermediary role, linking laboratory and natural conditions
and responses.
This manual presents microcosms (N-systems) that were originally developed
from water in a natural environment at Tohoku University, Japan, by Prof. Yasushi
Kurihara (1926–2005) through the process of natural selection and that were subsequently followed and modified by the National Institute for Environmental Studies
(NIES), Japan. They were subcultured as stable ecosystems at the Bio-Eco Engineering Research Institute in the Foundation for Advancement of International
Science (FAIS), the Chiba Institute of Technology, and the Yokohama National
University, Japan. These microcosms are aquatic, microbial model ecosystems that
1 Introduction
3
The term microcosm is derived from the Greek words for “small” (mikrós) and
“universe” (kósmos); it denotes a system in which a population of a single species or
a community, a group of populations of two or more species, is cultured in a
container under controlled conditions. A large number of microcosms have hitherto
been created to elucidate microbial interactions and their mechanisms, as well as to
assess the effects of hazardous chemical substances and foreign microbes on ecosystems from the perspectives of microbial ecology and environmental science.
These microcosms are classified into three types by size: (1) real-world scale
(mesocosm), (2) pilot plant (pilot site) scale, and (3) flask scale. Furthermore, they
can be divided into three types according to their population compositions: (1) gnotobiotic, in which the species composition is fully known, the population sizes of
each species can be measured, and the traits of each species can be analyzed in
isolation; (2) stress-selected, in which a natural community is cultured under specific
conditions to promote natural selection in an effort to maintain and develop a specific
biological community; and (3) naturally derived, in which a real-world community is
maintained without varying any conditions. Among these, the concept of the gnotobiotic and the stress-selected types is used in the same sense as a standardized
aquatic microcosm and abstract model ecosystem, respectively. Because the abstract
model ecosystem (i.e., stress-selected microcosm) can be steadily sustained with
repeated subculturing, it is well-suited to repetitive experiments and has been used in
both theoretical ecology and applied ecology. It has also recently begun to be used as
a test for assessing environmental impacts. The microcosm in our research model
consists of producers, consumers, and decomposers. It can be considered to fall
under the abstract model ecosystem category with respect to its properties and under
the standardized aquatic microcosm category with respect to its structure.
The microcosm in this experiment is not merely a system for microbial cultures.
The system is characterized by its ability to replicate the target phenomena at an
ecosystem level, as it includes the physical, chemical, and biological factors of an
ecosystem and some of their interactions, which substantiate four relationships:
proliferation, consumption, production, and inhibition. Therefore, when applying
outcomes obtained through a simple experimental system in a laboratory to the
interpretation of real-world phenomena, the phenomena observed in a microcosm
are expected to play an intermediary role, linking laboratory and natural conditions
and responses.
This manual presents microcosms (N-systems) that were originally developed
from water in a natural environment at Tohoku University, Japan, by Prof. Yasushi
Kurihara (1926–2005) through the process of natural selection and that were subsequently followed and modified by the National Institute for Environmental Studies
(NIES), Japan. They were subcultured as stable ecosystems at the Bio-Eco Engineering Research Institute in the Foundation for Advancement of International
Science (FAIS), the Chiba Institute of Technology, and the Yokohama National
University, Japan. These microcosms are aquatic, microbial model ecosystems that
1 Introduction
3