23-07-2012, 02:29 PM
bacterial diversity
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INTRODUCTION
The biological contamination in water is major problem of public health in developing world. WHO estimate that about 1.1 billion people globally drink unsafe water and vast majority of diarrhoeal disease in the world (88%) is attributable to unsafe water ,sanitation and hygiene (WHO, 2003). The most common and wide spread health risk associated in drinking water in developing countriesare of biological origin. Looking at 20 leading risk factors for health burden in developing region unsafe water,sanitation and poor hygenes are 3rd, behind underweight or practicing unsafe sex (WHO) . Ten major water born diseases are responsible for over 28 billions disease episodes annually in developing countries (WALSH 1990). Of these diarrhoeal diseases are big killers specially in infants . According to the WHO estimation more than 3 billion children below age 5 die annually form diarrhoeal disease contracted through drinking water in developing world. None the less ,the inadequate availability of water , poor quality at source , ill- maintained water pipe lines and sewer lines , unsafe disposing of human ,animals and household waste ,unawareness about good sanitation and personal hygienic practices etc are some key factors are responsible for poor drinking water quality in rural areas of india.Also infectious diseases caused by pathogenic bacteria , viruses ,and parasites (eg:- Protozoa and Helminthes) are the most common and wide spread helth risks associated with drinking water in rural habitations .
The quality of drinking water may be ascertained by its microbiological examination. The greatest risks from microbes in water is associated with consumption of drinking water that is contaminated with human and animal excreta ,all though other sources and routs of exposer may also be significant .The Colliforms bacterial group may occur in water due to fecal contamination, that is discharge of fecal by human and other animal in water. Colliforms includes the member of the family enterobacteriaceae , eg:- Escherichia colli(E.colli). Enterobacter aerogenes ,Salmonela and klebsiella .These enteropathogenic bacteria in water are responsible for variety of diseases like Collera ,Typhoid,Dysenteries,Bacillary dysentery,etc in human and live stock(Ashbolt,2004) .The fecal indicator bacterium (E.colli) has been considered as a bioindicator of fecal contamination of drinking water. It is excreted in the feaces of all warm-blooded animal and some reptiles (Enriquez et al. 2001).The major pathogenic bacteria responsible for water-borne diseases are spread by the fecal-oral rout in which water may play an intermediate role. The public health burden is determined by the severity of the illnesses associated with pathogen , their infectivity and population exposed. There has ,therefore been an increasing interest in the application of quantitative risk assessment for microbial load in drinking water source.
Water is more suitable habitat for microbial growth . Water is necessary for microbial metabolism. These microorganisms are able to grow atlow nutrient concentration. Most aquatic microbes are motile by means of either flagella or other mechanism. Water quality is the physical, biological and chemical characteristics of water. It is measure of condition of water relative to the requirements of one or more biotic species and or to any human need or purpose . It is most frequently used by reference to a set of standards against which complains can be assessed. The most common standard used to assesses water quality relate to health of ecosystem and safety of human contact and drinking water.
[b]Physical properties of water:-[/b]
Each fresh water body has an individual pattern of physical and chemical characterstics which are determined largely by the climatic ,geomorphological and geochemical condition prevailing in the drainage basin and the underlying aquifer . Summary characterstics, such as total dissolve solids ,conductivity ,and redox potential ,provide a general classification of water bodies of a similar nature .Mineral content determined by the total dissolve solids present ,is an essential feature of the quality of any water body resulting from the balance between dissolution and precipitation oxygen content is another vital feature of any water body because it greating influences the solubility of metals and its essential for all forms of biological life.
Chemical properties of water:-
The chemical quality of the aquatic environment where is according to local geology , the climate ,the distance from the ocean and the amount of soil cover ,etc.If surface water were totally unaffected by human activities up to 90 to 99% of global fresh water ,depending on the variable of interest would have natural chemical concentration suitable for aquatic life and human uses .Rare(between 1and 10%and between 90 and 99% of the global distribution)and very rare (<1%and >99%of the glbal distribution) chemicall conditions in fresh water , such as in occur in salt lakes, hydrothermal water ,acid ,volcanic lakes ,peat bogs ,etc., usually make the water unsafe for human use. None the less, a range of aquatic organism have adapted to these extereme environment. In many region ground water concentration of total dissolve salts , fluoride , arsenic , etc., may also naturally exceed maximum allowable concentration(MAC) .
Particulate matter (PM) is key factor in water quality , regulating adsorption –desorption processes . These processes depends on :-
The amount of PM in contact with a unit water volume .
The type and character of the PM ( eg:-whether organic or inorganic)
The contact time between the water and PM.
The time variability of dissolved and particulate matter content in water bodies results mainly from the interaction between hydrodynamic variability, mineral solubility ,PM characterstics and the nature and intensity of biological activity.
Biological characterstics:-
The development of biota (flora and fauna ) in surface waters is governed by a variety of environmental conditions which determined the selection of species as well as the physiological performance of individual organisms.
The primary production of organic matter ,in the form of phytoplankton and macrophytes,is most intensive in lakes and reservoirs and usually more limited in rivers.The degradation of organic substances and the associated bacterial production can be a long term process which can be important in ground water and deep lake water which are not directly exposed to sunlight.
In contrast to the chemical quality of water bodies which can be measured by suitable analytical methods , the description of the biological quality of a water body is a combination of qualitative and quantitative characterization. Biological monitoring can generally be carried out 2 different levels:
The response of individual species to changes in their environment .
The response of biological community to change in their environment
Water quality classification system based upon biological characterstics have been developed for various water bodies .Where the chemical analysis of selected of selected species (eg:-mussels and aquatic mosses) and /or selected body tissues (eg :- muscle or liver) for contaminants can be considered as a combination of chemical and biological monitory. Biological quality , including the chemical analysis of biota ,has a much longer time dimention then the chemical quality of water since biota can be effected by chemaical and /or hydrological events that may have lasted only a fue days , some months or even years before the monitoring was carried out.
Water microorganism:-
Water microbiology is concerned with the microorganisms that livein water, or can be transported from one habitat to another by water. Water can support the growth of many types of microorganisms. This can be advantageous. For example, the chemical activities of certain strains of yeasts provide us with beer and bread. As well, the growth of some bacteria in contaminated water can help digest the poisons from the water.