Relevance of Interface with Surface Property, Adhesion, and Activity of Microorganisms

Abstract

A microorganism is as small as colloidal dimension ca. 1μm. So, it has a large specific surface area: surface area per unit mass of a microbe seems to be ca. 100, 000 times larger than that of man. This makes the microbe more sensitive to its environment. In the natural ecosystem many microbes are adsorbed on interfaces formed by various materials. In this situation the environment for the microbe is the interface formed by the material on which the microbe is adsorbed. Thus, it is very important to clarify the relation between interface and the microbe for understanding microorganisms in the natural ecosystem. However, we know little about the effect of interface on microbe. This is due to the complexity of this system: the property of the microbe as a colloidal particle is changing every moment as a result of its living activity and the property of interface is also affected by the materials produced by the living microbe.In this review I introduce a way to investigate this complex system by clarifying, at first, the force operating between interface and microorganisms by using the term of surface and interfacial tension. Secondly, hydrophobic interaction is discussed in connection with microbial adhesion and activity, since this interaction has been noticed as one of the key factors operating at interface. Though the phenomenon in this system is very complex, the key factor controlling the interaction between interface and the microbe seems to be relatively simple. I expect that the consideration of the interaction by the physico-chemical term will become a clue to solve the complex phenomena at interface.