An overview of the structure and function of microbial biofilms, with special emphasis on heterotrophic aquatic microbial communities

Abstract

An overview is presented of the formation, structure and development of biofilms, and of the roles and functions of heterotrophic microbial communities in streambeds, in order to stimulate interest and research in this field in Africa. Microbial biolfilms are of major ecological significance. Exopolymeric substances (EPS) in biofilms attach microorganisms to each other, enabling them to exist in environments where individual organisms cannot. The EPS enhances access by cells to nutrients and the removal of toxic materials from the environment through binding, degradation, or by transformation to non-toxic substances. As a food resource, streambed biofilms are intensively grazed by protozoans and macrobenthos, their quality as a food source for grazing organisms affecting the diversity, abundance and distribution of macrobenthic invertebrates. Biofilms are indicators of environmental quality and are active sites for species evolution. Laser scanning microscopy and microelectrode techniques are the most suitable techniques for studying intact biofilms in various environments. The potential of biofilms as environmental health bioindicators requires investigation. Little information is currently available on biofilms in the tropics, especially in sub-Saharan Africa.

Keywords::

• aquatic environments
• bacteria
• exopolymeric substances
• microorganisms
• organic matter
• sediments
• streams