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N.K. Udaya Prakash1, V. Subha Shree2, S. Revathy2, K. Tara Devi Sharma2, K. Mohammed Yasar3, A. Mohamed Azaruddin3, J. Aswin3, D. Santhosh3, S. Aruna Devi4, M. Priyadharshini4 and S. Bhuvaneswari5*
1Department of Biotechnology, Vels Institute of Science, Technology and Advanced Studies, Pallavaram, Chennai 600117. 2Department of Zoology, University of Madras, Guindy Campus, Chennai 600025. 3Department of Chemistry, The New College, Royapettah, Chennai 600014. 4R and D, Marina Labs, 14, Kavya Gardens, N.T. Patel Road, Nerkundram, Chennai 600107. 5 Department of Botany, Bharathi Women’s College, Broadway, Chennai 600108.
e-mail: drsbhuvaneswari8@gmail.com
*For correspondence
Abstract
The study was conducted to know the microbial quality of potable waters in Chennai city during summer, 2019 when there was acute shortage of drinking water. A total of 27 water samples were collected in Chennai from different water sources (well water, bore water, metro water supplied through pipe lines and through tankers). Samples were tested for their microbial quality through enumeration of total bacteria, coliform and Vibrio as microbial indicators. The bacterial colonies were enumerated by serial dilution method using Nutrient agar, MacConkey agar and TCBS agar for total bacteria, Coliforms and Vibrio respectively. An average of 16,177 CFU/ml of total bacteria was recorded from the water samples. An average count of 216.2 CFU/ml and 44.9 CFU/ml of coliforms and vibrio were recorded respectively. Bacteria and coliforms were high in well waters and Vibrio was recorded maximum in the water sample supplied through Tankers. The study strongly recommends continuous monitoring of potable waters for microbial presence of drinking water supplied.
Introduction
Water is a vital commodity for life next to oxygen. Though 71% of earth’s surface is covered with water, availability of safe drinking water to human population is becoming scarce. India being the most second populated country in the world suffers water scarcity because of improper water management, inadequate harvesting and saving of rain water, urbanization and failing monsoons. India, suffers to an extent where it loses 3.4 million children every year due to unavailability and scarcity of clean and potable drinking water (WHO, 2003). According to UNICEF (2005) assessment, contaminated water leads to 4000 deaths in children each day and states that we can decrease disease burden all over the world by 4% by improving the water quality. Under-five years’ age group, Diarrhoea is the third most common cause of death in children and contributes to 13% of death, killing 300,000 children world over each year in India alone. Sadly, Indian population which has access to more mobile phones than those who have access to safe drinking water, which is of utmost importance, to maintain good health of the community (Malathy et.al, 2017).
Water borne diseases are spread mainly through drinking, washing, bathing in contaminated water or by eating food prepared with contaminated water. The general symptom of water borne diseases includes acute fever, chillness, vomiting, diarrhoea, nausea and headache. Waterborne diseases in the household of Chennai were found to be 12.2% (Dhanasekar et al., 2017). The disease risk associated with drinking water in developing countries is due to pathogens, which include viruses, bacteria, and protozoans that spread either via oral or fecal route. Campylobacter jejuni, Microsporidia sp., Yersinia enterocolitica, Cyclospora sp., and environmental bacteria like Mycobacterium sp., Aeromonas sp., Legionella pneumophila are serious water borne pathogens causing illness. The continuous disease outbreaks every year are due to these pathogens spread through water sources and interfuse directly through food and water. The main distribution of many water-borne pathogens varies substantially from one country to another. Some pathogens such as Vibrio cholerae, Hepatitis E virus, and the disease Schistosomiasis are restricted to certain tropical countries; others, such as Cryptosporidiosis and Campylobacteriosis, are probably widespread (Devipriya and Kalaivani, 2012).
Contaminated drinking water is believed to be the cause of various diseases which is on raise during summer (Loganathan et. al., 2011). Also, consumption of contaminated water in India has led to frequent outbreaks of waterborne diseases such as cholera, typhoid, and hepatitis A and E (Joseph et. al., 2018). The supply of drinking water to residents of the Chennai is controlled by Chennai Metropolitan Water Supply and Sewage Board (Metro Water). As of 2012, it supplies about 830 million liters of water every day through pipelines. Chennai with a population of 8.24 million as per 2011 census, suffers from water stress since, the entire plain is dependent on rainfall. Thus, the study was conducted to know the quality of water samples for the bacterial presence, through counts of total bacteria, coliforms and vibrio in potable waters of Chennai city during summer, 2019 where there was acute shortage of drinking water.
Materials and Methods
A total of 27 water samples were collected in Chennai from different water sources such as well water, deep bore well water, metro water supplied through pipe lines and through tankers (Fig. 1) during the month of May 2019 using sterile containers. For the sake of comparison one Industry packaged drinking water samples available in the market was also taken into the study. The collected water samples were processed immediately for microbial analysis. The sampling sites are shown in Fig. 2.
Fig. 1. Type and number of samples collected in Chennai for enumeration of microbial quality
Microbial analysis
Water samples were serially diluted to detect the total count of bacteria, coliforms and Vibrio present. One ml of water sample was serially diluted to 1:10; 1:100; 1:1000 and further diluted if required using sterile distilled water. One ml of serially diluted sample (1:100), was added with Nutrient agar (Himedia, Bombay) and incubated at 37 ± 2oC for 24 hours for enumeration of total bacteria. Similarly, 1 ml of diluted sample (1:10) was mixed with MacConkey Agar (Himedia, Bombay) and incubated at 37 ± 2oC for 24 hours for the growth and enumeration of coliform bacteria. For the enumeration of Vibrio, 1ml of sample was directly added without dilution to a sterile petridish and mixed with Thiosulfate Citrate Bile salts Sucrose agar (TCBS) (Himedia, Bombay) and was incubated at 37 ± 2oC for 24 hours. The plates were maintained in triplicates and the average values were recorded.
Fig. 2. Map showing water sampling locations in Chennai.
The growth rate experiments were done for isolated algal species at temperature of 28˚C with cycles of light: dark (12:12h) illumination, measuring cell density at constant intervals using Spectrophotometer (Hitachi U 2900) at wavelength of 680nm and their dry weights were estimated. Effluents were treated with selected algal cultures in BBM with different ratios such as 100:400, 200:300, 250:250, 300:200 and 400:100 v/v respectively. The same experiment was repeated with combination of algal mixture in equal volume to determine the effectiveness of consortium in treatment of pharma effluents.
Presentation of data
The data was expressed as colony forming units (CFU) per ml of sample and calculated using the formula given below.
RESULTS
A total of 27 samples were analyzed for presence of total count of bacteria, coliforms and Vibrio in potable water collected from different sources during the month of May 2019. An average of 16,177 CFU/ml of total bacteria, 216.2 CFU/ml of coliforms and 44.9 CFU/ml of Vibrio were enumerated from samples collected.
The total bacterial count ranged from minimum of 1250 CFU/ml in Bisleri to maximum of 87900 CFU/ml for well water taken from Royapettah I. Total coliform counts ranged from absence of colonies to 826.5 CFU/ml. The highest number of coliforms were recorded from the pipe water supplied by Chennai metro in Saidapet II. Similarly, Vibrio ranged from 0 to 333 CFU/ml. The high number of Vibrio was recorded for the sample collected from Tankers supplied by Chennai metro. The sample number, place of collection, average count of total bacteria, coliforms and Vibrio in water samples from different sampling sites in Chennai is provided in the following Table.
Well water samples had maximum bacterial average of 50400 CFU/ml followed by water supplied through Tankers of Chennai metro containing 24637 CFU/ml. The least count of bacteria was observed in Industry packed Bisleri water (Figure 3). Similarly, maximum counts of coliforms were found in well water followed by water supplied through Tankers and pipes of Chennai metro. (Figure 4). Water supplied through Tankers of Chennai metro contained maximum Vibrio, followed by well water samples (Figure 5).
DISCUSSION
According to the World Health Organisation, diarrhoeal diseases account for an estimated 4.1% of the total daily global burden and are responsible for the deaths of 1.8 million people every year. It was estimated that 88% of that burden is attributed to unsafe water supply, sanitation and hygiene (Hatami, 2013). Bacterial values of less than 100 CFU/ml were considered to be normal. Values from 100 to 500 CFU/ml is anticipated during seasonal increases or at certain locations in the system (dead end, low residual) which would suggest a need for flushing. In other cases, 5 to 10 fold increases over normal levels were set as a guideline to prompt an investigation (US EPA, 1984). In our study, none of the samples analyzed met this condition of being potable water. Maximum of 87,900 CFU/ml of bacteria was recorded in the well water sample collected from Royapettah followed 42100 CFU/ml in water supplied through Tankers in the same locality.
Increased number of coliform in water samples will become a reason for epidemic outbreak of typhoid, dysentery, and other complications. The popular coliform, Salmonella is known to cause deadly typhoid and gastroenteritis. The group of species of Salmonella typhi and Salmonella paratyphi, is the cause of the enteric fevers, typhoid and paratyphoid. Another group, consisting of over 2000 serotypes of what is now considered to be one species, Salmonella enterica, causes gastroenteritis. In the present study, none of the samples except that of Nerkundrum recorded negative for coliforms. The CFU ranged from 34.5/ml in bore water collected from Chetpet and the maximum of 826.5 CFU/ml was recorded from the water supplied through pipeline by Chennai metro. On an average the coliforms was found to be dominant in well water followed by water supplied through Tankers by Chennai metro. The reason for recording more number of coliforms in well water can be attributed to an open area of well and the seepage of nearby drainages, thus contaminating the well water.
A standard potable drinking water should be totally free from coliforms and vibrio population. The genus vibrio comprises of diverse species out of which three species are known to cause disease, Vibrio cholerae, the causative agent of cholera, V. parahaemolyticus and V. vulnificus, which together are responsible for most cases of fatal poisoning (Janelle et.al., 2004). The results obtained from TCBS agar plates showed that, out of 27 samples, seven samples including industrial sample recorded negative and remaining samples showed the presence of vibrios. The presence of vibrio in water is of major concern as there may be an outbreak of cholera at times.
The reason for large bloom of coliforms and vibrios might be due to formation of biofilm layers on tankers, pipelines and in the storage containers. Broken pipes, leaking sewer lines and inadequate maintenance of old pipe networks are the primary causes of contamination. It is noticed that a single lorry supplying contaminated water can easily spread infections in many areas.
The study underlines the importance of following a) Check point for Municipality water Tankers and private to continuously monitor the water turbidity and quality. Apart from microbial contamination, waters should also be checked for total dissolved solvents and other heavy metals regularly to dispense safe water to public. b) Creation of awareness among rural and urban areas about microbial contamination of water leading to disease. c) Proper treatment and release of effluents and domestic sewage. d) Encouragement of toilet usage and awareness among rural areas to avoid any feacal contamination in potable waters. e) Maintenance of proper infrastructure for harvesting rainwater. f) During rainy seasons and disease outbreaks water should be boiled and filtered before drinking.
Although, the study possesses limited number of samples, we recommend continuous monitoring of potable waters for microbial presence and expanded parameters to monitor presence of Salmonella, Shigella, Pseudomonas and other pathogens. Although, majority of residents purchase packed drinking water (mineral water) for cooking and drinking, this should be kept in mind that whose genuineness again is not monitored (Malathy et.al 2017).
DISCUSSION
The research fund was supported by R & D, Marina Labs, Chennai (Grant Number: ML-2019-RD004).
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