Water microbiology is another area where microbiological studies play important roles to man and his environment. Study of micro-organisms and their communities in water environment is called Aquatic microbiology, while Water microbiology relates to the study of micro-organisms in potable water.
The scope of Aquatic Microbiology is wide and includes the habitats like planktons, benthos, microbial mats and biofilm which may be found in lakes, rivers, streams, seas, groundwater, rain, snow and hail.
Planktons are the collection of free living and drifting micro- organisms in ponds, lakes and oceans. Algae and cyanobacteria are phytoplanktons while protozoans and microbes are zooplanktons.
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1. Drinking Water Microbiology
In EHS 309 (Hydrology and Sanitation), water treatment was done to an extent that you can boast of knowing this section without much problems. Drinking or potable water is water that is free from pathogens and chemicals that are dangerous to human health.
Any taste, odor and color must be absent from the water to be palatable. Raw water may contain many contaminants derived from sewage and nearby industries. Many enteric pathogens are water borne.
Therefore, water is treated and disinfected to remove chemicals and pathogens respectively. The raw waste is stored in reservoirs where the oxidisable organic materials are stabilized and discrete particles settle.
The collected water or impounded water in the reservoir irrespective of its source contains sufficient nutrients for growth of algae which require only minerals and sunlight. Many phototrophic and chemolithotrophic bacteria grow in the dilute environment.
Heteroptrophs flourish on the organic matter of dead autotrophs. Some organic matter is introduced by wind, rain or soil with runoff water.
Various algae, protozoans and iron bacteria impart bad taste and odours. Some produce slime causing clogging of pipes. Iron bacteria include sheathed and stalked bacteria that are typical water organisms. They are aerobic, widely distributed in nature esp. in stagnant water such as reservoir for potable water supply.
Siderocapsa, Sphaerotilus, Clonothrix, Leptothrix, Crenothrix, Caulobacter and Gallionella are some common filamentous iron bacteria. Sulfur and sulfate reducing bacteria also contribute to fouling of impounded waters. A closer look at waterborne diseases is deemed necessary at this juncture.
2. Water-Borne Diseases
An important aspect of Water Microbiology is numerous disease causing micro-organisms spread through water. Many bacteria, viruses, fungi and protozoa are responsible for waterborne diseases.
The recurrence of waterborne illness has led to the improvement in water purification. Some common water borne diseases are listed in the table below. You can also refer to EHS 309 for more details.
Table: Common Water-borne Pathogens
|Hepatitis A virus
|Other Salmonella spp
|Shigellosis (bacillary dysentery)
|Vibrio parahaemolyti cus
|Cryptospori dium parvum
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