Environmental Microbiology, Soil Microbiology & Microbial Biogeochemistry

Water Microbiology

Aquatic microbiology is the science that deals with microscopic living organisms in fresh or saltwater systems. While aquatic microbiology can encompass all microorganisms, including microscopic plants and animals, it more commonly refers to the study of bacteria, viruses, and fungi and their relation to other organisms in the aquatic environment.

Importance and Scope: Bacteria are quite diverse in nature. The scientific classification of bacteria divides them into 19 major groups based on their shape, cell structure, staining properties (used in the laboratory for identification), and metabolic functions. Bacteria occur in many sizes as well ranging from 0.1 micrometres to greater than 500 micrometres. Some are motile and have flagella, which are tail-like structures used for movement. Although soil is the most common habitat of fungi, they are also found in aquatic environments. Aquatic fungi are collectively called water moulds or aquatic Phycomycetes. They are found on the surface of decaying plant and animal matter in ponds and streams. Some fungi are parasitic and prey on algae and protozoa. Bacteria, viruses, and fungi are widely distributed throughout aquatic environments. They can be found in freshwater rivers, lakes, and streams, in the surface waters and sediments of the world's oceans, and even in hot springs. They have even been found supporting diverse communities at hydrothermal vents in the depths of the oceans. Microorganisms living in these diverse environments must deal with a wide range of physical conditions, and each has specific adaptations to live in the particular place it calls home. For example, some have adapted to live in fresh waters with very low salinity, while others live in the saltiest parts of the ocean. Some must deal with the harsh cold of arctic waters, while those in hot springs are subjected to intense heat. In addition, aquatic microorganisms can be found living in environments where there are extremes in other physical parameters such as pressure, sunlight, organic substances, dissolved gases, and water clarity. Aquatic microorganisms obtain nutrition in a variety of ways. For example, some bacteria living near the surface of either fresh or marine waters, where there is often abundant sunlight, are able to produce their own food through the process of photosynthesis. Bacteria living at hydrothermal vents on the ocean floor where there is no sunlight can produce their own food through a process known as chemosynthesis, which depends on preformed organic carbon as an energy source. Many other microorganisms are not able to produce their own food. Rather, they obtain necessary nutrition from the breakdown of organic matter such as dead organisms.