Water Quality With Reference to the Significance of Chemical and Microbial Pollution Indicator

7/31/2019 Water Quality With Reference to the Significance of Chemical and Microbial Pollution Indicator

1/9

ASSIGNMENT

Subject: Environmental Microbiology and Public Health

Course No: MIC-509

Submitted To: Dr.Tanveer Abbas

Submitted On: 13th

.Dec.2011

Seat No: B0819075

SUBMITTED BY:

TAYYABA MAJEED

CLASS: BS 3rd

YEAR

DEPARTMENT OF MICROBIOLOGY

UNIVERSITY OF KARACHI


2/9


3/9

1ndicators of Microbial and Chemical Water Quality

Tayyaba Majeed (B.S. 3RD YEAR) Page 2

1.1.3.1Process IndicatorA group of organisms that demonstrates the efficacy of a process

1.1.3.2Fecal Indicator:A group of organisms that indicates the presence of fecal contamination such asE. coli

1.1.3.3Index and Model OrganismsA group/or species indicative of human pathogen.

1.1.4 Fecal Coliforms as Index of Water Pollution

It is almost impossible to isolate from water the organisms responsible for water-borne

diseases so water quality bacteriologist have adopted the practices for certain indicator

bacteria normally found in the human intestinal tract.Few organisms are present and they do not multiply in water. The only safe method to

prevent waterborne disease is to condemn fecal polluted water as being unfit for human use,

as it may contain harmful organisms. Fecal pollution can be determined by examination of

water for colon bacilli (E. coli).E. coli is abundant in feces and not found outside intestinal

tract in nature. The E. coli in water indicates the presence of pathogenic microorganisms in

water, which may be responsible for a number of water-borne diseases. Hence, E. coli is

known as indicator organism. Water also contains bacteria that resemble E. coli but may or

may not be of fecal origin. These bacteria also ferment lactose with formation of gas like E.

coli. The other indicator organisms are Enterococci including Streptococcus faecalis.

1.1.5 Significance of Fecal ColiformsThe group of coliform bacteria as an indicator of other pathogenic micro-organisms,

specifically organisms of fecal origin, has had much emphasis in all countries. This is due

primarily to the fact that the coliform bacteria groups meets many of the criteria for a suitable

indicator organism, and are thus a sensitive indicator of fecal pollution:

They are abundant in feces approximately billions/g of feces. They can grow in water under certain conditions. They are generally found only in fecally polluted waters

They are easily detected by simple laboratory tests Can be detected in low concentrations in water The number of indicator bacteria seems to be correlated with the extent of

contamination.

It is important to remember, however, that not all coliforms originate from human feces as

they can originate from other mammalian species or from other environmental sources (e.g.,

bird droppings). When coliforms are discharged to the aquatic environment they will tend to

die at a rate which depends, amongst other things, on the temperature and turbidity of the

water and the depth to which solar radiation penetrates. Therefore, it is not safe to conclude

that the lack of coliforms in a water means that it has not been subject to fecal pollution. [3]

It is necessary to be familiar with a number of terms are as follows:


4/9



1.1.6 Total Coliforms and Fecal Coliforms

1.1.6.1 Coliforms

Coliform is not a taxonomic classification, rather it is a group of Gram-negative, facultative

anaerobic rod-shaped non-spore forming bacteria that ferment lactose to produce acid and gas

within 48 h at 35C.

Coliform bacteria are a commonly used bacterial indicator of sanitary quality of foods and

water. Coliforms can be found in the aquatic environment, in soil and on vegetation; they are

universally present in large numbers in the feces ofwarm-bloodedanimals.

By and large, coliforms are represented by four or five genera of the family

Enterobacteriaceae. Typical genera include:

Salmonella Shigella Proteus Citrobacter Enterobacter Hafnia Klebsiella Serratia Escherichia (Fecal coliform)

Coliform bacteria include genera that originate in feces (e.g. Escherichia) as well as genera

not of fecal origin in normal conditions (e.g. Enterobacter, Klebsiella, Salmonella,

Citrobacter). The assay is intended to be an indicator of fecal contamination; more

specifically ofE. coli which is an indicatormicroorganism for other pathogens that may be

present in feces.

1.1.6.2 Fecal Coliforms

Fecal coliform, first defined based on the works of Eijkman. They are facultatively-

anaerobic, rod-shaped, gram-negative, non-sporulating bacteria capable of growth in the

presence ofbile salts or similar surface agents, are oxidase negative, that grow and ferment

lactose at elevated incubation temperature at 44.5 to 45.5C, hence also referred to as

thermotolerant coliforms.

The fecal coliform group consists mostly ofE. coli but some other enterics such as Klebsiellacan also ferment lactose at these temperatures and therefore, be considered as fecal coliforms.

Escherichia coli(E. coli), a rod-shaped member of the coliform group, can be distinguished

from most other coliforms by its ability to ferment lactose at 45.5C in the fecal coliform test,

and by its growth and color reaction on certain types of culture media. When cultured on an

EMB plate, a positive result forE. coli is metallic greencolonies on a dark purple media.

Unlike the general coliform group, E. coli are almost exclusively of fecal origin and their

presence is thus an effective confirmation of fecal contamination. Rarely causing problems, it

has theretofore been used as a marker to indicate the contamination of water or food with

human feces, and hence the potential dangers that might accompany the presence of human
http://en.wikipedia.org/wiki/Bacteriahttp://en.wikipedia.org/wiki/Enterobacterhttp://en.wikipedia.org/wiki/Enterobacterhttp://en.wikipedia.org/wiki/Hafnia_%28bacterium%29http://en.wikipedia.org/wiki/Hafnia_%28bacterium%29http://en.wikipedia.org/wiki/Klebsiellahttp://en.wikipedia.org/wiki/Klebsiellahttp://en.wikipedia.org/wiki/Serratiahttp://en.wikipedia.org/wiki/Serratiahttp://en.wikipedia.org/wiki/Escherichiahttp://en.wikipedia.org/wiki/Fecal_coliformhttp://en.wikipedia.org/wiki/Coliform_bacteriahttp://en.wikipedia.org/wiki/Generahttp://en.wikipedia.org/wiki/Feceshttp://en.wikipedia.org/wiki/Escherichiahttp://en.wikipedia.org/wiki/Enterobacterhttp://en.wikipedia.org/wiki/Klebsiellahttp://en.wikipedia.org/wiki/Citrobacterhttp://en.wikipedia.org/wiki/Citrobacterhttp://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Pathogenhttp://en.wikipedia.org/wiki/Facultative_anaerobic_organismhttp://en.wikipedia.org/wiki/Facultative_anaerobic_organismhttp://en.wikipedia.org/wiki/Bacillushttp://en.wikipedia.org/wiki/Gram-negativehttp://en.wikipedia.org/wiki/Sporehttp://en.wikipedia.org/wiki/Bilehttp://en.wikipedia.org/wiki/Oxidasehttp://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Fecal_coliformhttp://en.wikipedia.org/wiki/Fecal_coliformhttp://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Oxidasehttp://en.wikipedia.org/wiki/Bilehttp://en.wikipedia.org/wiki/Sporehttp://en.wikipedia.org/wiki/Gram-negativehttp://en.wikipedia.org/wiki/Bacillushttp://en.wikipedia.org/wiki/Facultative_anaerobic_organismhttp://en.wikipedia.org/wiki/Facultative_anaerobic_organismhttp://en.wikipedia.org/wiki/Pathogenhttp://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Citrobacterhttp://en.wikipedia.org/wiki/Klebsiellahttp://en.wikipedia.org/wiki/Enterobacterhttp://en.wikipedia.org/wiki/Escherichiahttp://en.wikipedia.org/wiki/Feceshttp://en.wikipedia.org/wiki/Generahttp://en.wikipedia.org/wiki/Coliform_bacteriahttp://en.wikipedia.org/wiki/Fecal_coliformhttp://en.wikipedia.org/wiki/Escherichiahttp://en.wikipedia.org/wiki/Serratiahttp://en.wikipedia.org/wiki/Klebsiellahttp://en.wikipedia.org/wiki/Hafnia_%28bacterium%29http://en.wikipedia.org/wiki/Enterobacterhttp://en.wikipedia.org/wiki/Bacteria


5/9



feces in our food and water supply. Some strains of E. coli can cause serious illness in

humans.

Discovery

Escherichia coli, (fig I-1) originally known as Bacterium coli commune, was identified in1885 by the German pediatrician, Theodor Escherich.

In 1892, Shardinger proposed the use of E. coli as an indicator of fecal contamination. This

was based on the premise that E. coli is abundant in human and animal feces and not usually

found in other niches. Hence, the presence of E. coli in food or water became accepted as

indicative of recent fecal contamination.

Fig 1-1 Escherichia coli

Distribution

E. coli is widely distributed in the intestine of humans and warm-blooded animals and is the

predominant facultative anaerobe in the bowel and part of the essential intestinal flora that

maintains the physiology of the healthy host.

E. coli is a member of the familyEnterobacteriaceae, which includes many genera, including

known pathogens such as Salmonella, Shigella, and Yersinia. Although most strains ofE. coli

are not regarded as pathogens, they can be opportunistic pathogens that cause infections inimmunocompromised hosts. There are also pathogenic strains ofE. coli that when ingested,

causes gastrointestinal illness in healthy humans.

In practice not all such coliforms are fecal in origin although most (> 95%) are Escherichia

coli (E. coli). This bacterium is a particular member of the fecal coliform group of bacteria;

this organism in water indicates the presence of fecal contamination. E. coli reside in human

intestinal tracts. They are excreted in large numbers in feces, averaging about 50 million per

gram. Whereas untreated domestic wastewater generally contains 5 to 10 million coliforms

per 100 ml. Perhaps the biggest drawback to using coliforms as indicators is that they can

grow in water under certain conditions. [4][5][6]


6/9



1.1.7 Fecal Streptococci

This group of bacteria includes several species or varieties of streptococci and the normal

habitat of these bacteria is the intestines of humans and animals. Examples include

Streptococcus faecalis which represents bacteria of humans.

So Escherichia coli (E. coli) and enterococci are used as indicators of microbial fecal

pollution with reference to the water quality standards.

1.1.8 Waterborne Gastroenteritis Caused By E. coli (Diarrheagenic E. coli)

Foodborne gastroenteritis occurs from the consumption of food (and water) contaminated

with pathogenic E. coli.

1.1.8.1 The Recognized Virulent Groups

Based on disease syndromes and characteristics, and also on their effect on certain cellcultures and serological groupings, five virulence groups ofE. coli are recognized which are

as follows;

Enteroaggregative (EAggEC) Enterohemorrhagic (EHEC) Enteroinvasive (EIEC) Enteropathogenic (EPEC) Enterotoxigenic (ETEC)

PROPERTIES/

SYMPTOMS EAggEC EHEC EIEC EPEC ETEC

TOXIN ST

SHIGA/

VERO TOXIN - - LT & ST

STOOL

WATERY,

BLOODY

WATERY,

VERY BLOODY

MUCOID,

BLOODY

WATERY,

BLOODY WATERY

FEVER + - + + LOW

INTESTINE

INVOLVED

SMALL COLON

COLON,

LOWER

SMALL

SMALL SMALL

SEROLOGY VARIOUS 0157:H7,026

OTHERS

0124:B17 &

OTHERS

026,O11 &

OTHERS

VARIOUS

INFECTIVE DOSE HIGH LOW LOW HIGH HIGH

DISEASEPERSISTENTDIARRHEA

BLOODYDIARRHEA &

HUS

BLOODYDIARRHEA

BLOODYDIARRHEA

TRAVLERS'DIARRHEA

Table 1-1The Recognized Virulent Groups of E. coli
http://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Enterococcihttp://en.wikipedia.org/wiki/Enterococcihttp://en.wikipedia.org/wiki/Escherichia_coli


7/9



1.1.9 Detection and Enumeration

The examination of water for the presence, types, and numbers of microorganisms and/or

their products is basic to food microbiology. In spite of the importance of this, none of the

methods in common use permits the determination of exact numbers of microorganisms in a

in water. Although some methods of analysis are better than others, every method has certaininherent limitations associated with its use.

The four basic methods employed for total numbers are as follows:

Standard plate counts (SPC) or aerobic plate counts (APC) for viable cells or colonyforming units (cfu).

The most probable numbers (MPN) method as a statistical determination of viablecells.

Dye reduction techniques to estimate numbers of viable cells that possess reducingcapacities.

Direct microscopic counts (DMC) for both viable and nonviable cells.A large number of methods have been developed for the detection and enumeration of E.

coli and coliforms. Almost all the methods used to detect E. coli, total coliforms or fecal

coliforms are enumeration methods that are based on lactose fermentation. [14] Some

commonly used methods are as follows;

Conventional Method for coliforms, fecal coliforms and E. colio The Most Probable Number (MPN) methodo Solid medium methodo Membrane Filtration (MF) Method

Fast Detections Using Chromogenic Substances Application of Antibodies

o IMS/Culture and Other Rapid Culture-Based Methodso Gene Sequence-Based Methods

1.1.10 Water Quality Standards for Bacteria

1.1.10.1 Drinking Water Standards

World Health OrganizationGuidelines for Drinking Water Quality state that as an indicator

organismEscherichia coliprovides conclusive evidence of recent fecal pollution and shouldnotbe present in water meant for human consumption. In the U.S., the EPA total coliform

rule states that a water system is out of compliance if more than 5% of its monthly water

samples contain coliforms.

1.1.10.2 Recreational Standards

Early studies showed that individuals who swam in waters with geometric mean coliform

densities above 2300/100 mL for three days had higher illness rates. In the 1960s, these

numbers were converted to fecal coliform concentrations assuming 18% of total coliforms

were fecal. Consequently, the National Technical Advisory Committee (NTAC) in the US

recommended the following standard for recreational waters in 1968: 10 % of total samplesduring any 30-day period should not exceed 400 fecal coliforms/100 mL or a log mean of
http://en.wikipedia.org/wiki/World_Health_Organizationhttp://en.wikipedia.org/wiki/World_Health_Organizationhttp://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/Water_pollutionhttp://en.wikipedia.org/wiki/Water_pollutionhttp://en.wikipedia.org/wiki/Escherichia_colihttp://en.wikipedia.org/wiki/World_Health_Organization


8/9



200/100 mL (based on a minimum of 5 samples taken over not more than a 30-day period).

Despite criticism, the US Environmental Protection Agency (EPA) recommended this

criterion again in 1976, however, numerous studies were initiated by the EPA in the 1970s

and 80s to overcome the weaknesses of the earlier studies. In 1986, the EPA revised its

bacteriological ambient water quality criteria recommendations to include E. coli and

enterococci. [7]

1.2 CHEMICAL POLLUTION INDICATORCommon chemical water quality pollution indicators include;

Dissolved Oxygen Ph Toxic Organic Compounds Biochemical Oxygen Demand (BOD) Chemical 0xygen Demand (COD) Heavy Metals Nutrients

1.2.1 Dissolved OxygenThe amount of molecular oxygen dissolved in water is an important measure of habitat

availability for aquatic organisms. Low levels of oxygen result from the introduction of

organic waste pollution which increases the rate of eutrophication and decreases the

suitability for aquatic animal life. Sources include: agricultural runoff, urban runoff, and

wastewater treatment plants.

1.2.2 pHBecause humans and aquatic organisms are dependent on water with pH levels within a range

near neutral, pH is a crucial water quality indicator.

The pH test, one of the most common and easily performed water quality tests, measures the

concentration of hydrogen ions, which then allows us to infer the strength of the acid or base.

Pollution from burning fossil fuels increases the amounts of sulfur and nitrogen oxides

introduced into the water, thereby increasing the overall acidity.

1.2.3 Toxic Organic CompoundsThere are many chemicals that have the capacity to travel throughout a waterway like

pesticides including herbicides and insecticides. They have deleterious effects on human

health if consumed so proper testing is necessary to ensure the standard quality of water.

1.2.4 Biochemical Oxygen Demand (BOD)Biochemical oxygen demand or B.O.D. is the amount ofdissolved oxygen needed by aerobic

biological organisms in a body of water to break down organic material present in a given

water sample at certain temperature over a specific time period. BOD can be used as a gauge

of the effectiveness of water treatment plants. It is listed as a conventional pollutant in the

U.S. Clean Water Act.
http://en.wikipedia.org/wiki/US_Environmental_Protection_Agencyhttp://tycho.knowlton.ohio-state.edu/gloss.html#eutrophicationhttp://tycho.knowlton.ohio-state.edu/gloss.html#oxideshttp://en.wikipedia.org/wiki/Oxygenation_%28environmental%29http://en.wikipedia.org/wiki/Sewage_treatmenthttp://en.wikipedia.org/wiki/Conventional_pollutanthttp://en.wikipedia.org/wiki/Clean_Water_Acthttp://en.wikipedia.org/wiki/Clean_Water_Acthttp://en.wikipedia.org/wiki/Conventional_pollutanthttp://en.wikipedia.org/wiki/Sewage_treatmenthttp://en.wikipedia.org/wiki/Oxygenation_%28environmental%29http://tycho.knowlton.ohio-state.edu/gloss.html#oxideshttp://tycho.knowlton.ohio-state.edu/gloss.html#eutrophicationhttp://en.wikipedia.org/wiki/US_Environmental_Protection_Agency


9/9



1.2.5 Chemical 0xygen Demand (COD)The chemical oxygen demand (COD) test is commonly used to indirectly measure the

amount oforganic compounds in water. Most applications of COD determine the amount of

organic pollutants found in surface water (e.g. lakes and rivers) or wastewater, making COD

a useful measure ofwater quality.

1.2.6 Heavy MetalsIndustrial effluents are major sources of heavy metals, and aquatic environments are

extremely sensitive to even the smallest concentrations of these materials. Serious

abnormalities have been reported in many aquatic organisms. Arsenic and mercury are two

common examples of heavy metals, but other similar substances and compounds can also

have significant effects on an aquatic community.

1.2.7 NutrientsAdditional nutrients, such as phosphorus and nitrogen, are added to streams by many

avenues, but primarily through human sewage, animal waste, fertilizers and erosion. This

area of water quality monitoring is greatly affected by both urban and agricultural human

practices.

Although these chemical variables are useful to monitor impacts, they only provide a short-

term picture of water quality at a sampled site and each can only represent a portion of a

complete assessment. A couple disadvantages of using only chemical indicators include:

Effects of certain isolated chemicals in a laboratory setting can be dramaticallydifferent than its interactive effects with other variables

Chemical testing is extremely expensive and labor intensive and not practical formonitoring non-point pollution sites such as urban and agricultural run-off

Chemical testing is much more applicable for point source pollution where industrial

contamination is suspected. [8]

REFERENCES

[1][2][3] Indicators of microbial water quality by Nicholas J. Ashbolt, Willie O.K. Grabow

and Mario Snozzi[4] Fundamental Food Microbiology by Bibek Ray, 3

rdEdition CRC Press.

[5] Modern Food Microbiology by James M. Jay, Martin J. Loessner and David A.

Golden 7th

Edition, Food Science Text Series.

[6] Coliforms and Fecal Coliforms, Wikipedia.

[7] http://en.wikipedia.org/wiki/Indicator_bacteria

[8] http://tycho.knowlton.ohio-state.edu/chem.html(Traditional Water Quality Indicators)
http://en.wikipedia.org/wiki/Organic_compoundhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Organic_compoundhttp://en.wikipedia.org/wiki/Pollutanthttp://en.wikipedia.org/wiki/Surface_waterhttp://en.wikipedia.org/wiki/Lakehttp://en.wikipedia.org/wiki/Riverhttp://en.wikipedia.org/wiki/Wastewaterhttp://en.wikipedia.org/wiki/Water_qualityhttp://tycho.knowlton.ohio-state.edu/chem.htmlhttp://tycho.knowlton.ohio-state.edu/chem.htmlhttp://en.wikipedia.org/wiki/Water_qualityhttp://en.wikipedia.org/wiki/Wastewaterhttp://en.wikipedia.org/wiki/Riverhttp://en.wikipedia.org/wiki/Lakehttp://en.wikipedia.org/wiki/Surface_waterhttp://en.wikipedia.org/wiki/Pollutanthttp://en.wikipedia.org/wiki/Organic_compoundhttp://en.wikipedia.org/wiki/Waterhttp://en.wikipedia.org/wiki/Organic_compound

Water Quality With Reference to the Significance of Chemical and Microbial Pollution Indicator

Documents

Transcript of Water Quality With Reference to the Significance of Chemical and Microbial Pollution Indicator