Symbiotic system of termite:
Symbiotic relationships are universal in nature and some symbiotic systems have functions related to the maintenance of homeostasis in ecological systems. The Termite has such a function related to decomposition of litter (wood) in a forest using enteric microorganisms as a symbiotic system. This function plays an important part in global material cycles. Litter is composed of lignocellulose that most living things cannot decompose. Termites and their symbionts are able to convert lignocellulose with high efficiency into hydrogen and other products used to fuel their metabolisms, however this mechanism have not been clearly revealed because the symbionts, like most symbionts, can not be cultured after they are isolated from the Termite symbiotic system. To make a breakthrough of this problem, we are trying to identify underlying mechanisms by observing the function of symbiotic systems without the cultivation of each symbiont.
In fact Termites do not always have the ability to decompose lignocellulose. Newborn and newly-molted termites do not have symbionts and cannot grow by eating litter. Instead they require nutrients provided by other termites and it is thought that in this manner that the intracellular symbiosis is established in these termites by horizontal infection. Through several molts termites repeat this cycle of symbiont loss with subsequent reacquisition. At the last instar, the symbiont community is re-constructed and becomes a fixed symbiosis. The study of this Termite symbiotic system- the “dynamic symbiosis” observed during the process of growing and the “static symbiosis”of the last instar, will provide important information for answering the question of “what is symbiosis” from the point of the view of the function of four hierarchical biological networks (microorganismal community network, gene expression network, protein network, metabolite network). In addition, the study of the special function of Termite symbiotic system will be helpful for the technological application of lignocellulose use.
1. Kumiko Kihara, Kotaro Mori, Shingo Suzuki, Naoaki Ono, Chikara Furusawa, Tetsuya Yomo; Global/temporal gene expression analysis of Escherichia coli in the early stages of symbiotic relationship development with the cellular slime mold Dictyostelium discoideum, Biosystems, 2009 May;96(2):141-64