Bacteriological and Physicochemical Analysis of Sachet Drinking Water in Makurdi, Benue State, Nigeria

Received 27 Feb, 2021

Accepted 05 Apr, 2021

Published 10 Jun, 2021

ABSTRACT

Background and Objectives: Packaged drinking water popularly known as “sachet and bottled water” serves a large percentage in increasing access to clean drinking water in Nigeria. This study was carried out to determine the bacteriological and physicochemical characteristics of sachet and bottled water sold in Makurdi metropolis. Materials and Methods: A cross sectional study was carried out with a total of one hundred and sixty-five samples collected. These comprised of triplicates of fifty sachet water and five bottled water brands purchased using simple random sampling from street vendors within Makurdi metropolis and analyzed using standard methods and results were compared with the recommended guidelines for water quality. Results: The pH, conductivity, total dissolved solids, dissolved oxygen and sodium chloride levels of sachet and bottled water brands ranged from 6.0 to 7.9 and 6.6 to 8.3; 8.4 to 188.4 μS/cm and 14 to 208.4 μS/cm; 4.2 to 94.2 mg/l and 7.5 to 108.1 mg/l; 0.08 to 0.16 mg/l and 0.08 to 0.11 mg/l; 0.0 to 0.4 and 0.0 to 0.4 respectively. The bacteriological quality of the samples was assessed based on the World Health Organization (WHO) classification system for drinking water and organisms isolated include; Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus sp., Klebsiella sp., Salmonella sp. and Shigella sp. Total coliform count was recorded as Most Probable Number (MPN) of coliform per 100 ml ranging from 0 – 1100 MPN/100 ml. Conclusion: The study revealed high bacteriological contamination which is an indication that portable drinking water was contaminated by sewage or animal waste. There is urgent need to intensify the monitoring of activities of this rapidly expanding industry and enforcing strict hygienic measures with a view to raising standards to improve packaged water quality.

INTRODUCTION

Humans are faced with a lot of challenges and health is about the most important. To keep a healthy life, all human beings need a qualitative water supply¹. Water is one of the six classes of food indispensable for the continued existence of man. The provision of potable water to the rural and urban population is necessary to prevent health hazards². Portable water has to comply with certain physical, chemical and microbiological standards which are designed to ensure its safety for drinking^2,3. WHO defines drinking water to be safe if it has no significant health risks during its lifespan and when it is consumed⁴.

It is expected that packaged water processing be carried out under aseptic conditions free from every possible source of contamination. In addition, packaged drinking water regardless of its source, has to be subjected to a form of treatment process intended to improve its safety and aesthetic quality⁴. In Nigeria, almost all villages, towns and cities consume packaged water in food grade polyethylene sachets popularly known as “pure water” designed for safe drinking^1,2,5. The source of the water depends on the manufacturers and ranges from available natural water including the rivers, lakes, oceans, pond, hand-dug wells, rainwater, underground water and sometimes pipe-borne water^2,5.

In Nigeria and many developing nations of the world, it is difficult for all producers of packaged water to strictly adhere to the rules of regulatory agents like World Health Organization (WHO), International Standard Organization (ISO), Standard Organization of Nigeria (SON) and National Agency for Food and Drug Administration and Control (NAFDAC)^1,6. Irrespective of the monitoring agents’ efforts, adherence to production and analytical standards are doubtful as most of the factories lack the appropriate technology for achieving these standards². Therefore, the packaged water could be contaminated from source or during collection, packaging and consumer handling. There is possible contamination of some water sources by surface runoff or leachate from sewage systems^2,4. Bacterial growth on a poorly maintained filter is also a possible source of contamination¹. More importantly, producers could be unhealthy at the time of production and could disseminate the pathogens to the products.

This study was carried out to determine the level of health risks associated with the drinking of sachet water produced within Makurdi metropolis. Information on bacterial load and physicochemical parameters of the water could improve the production and distribution line of the products thereby ensuring the safety of the consumers.

MATERIALS AND METHODS

Study Area: Benue State lies within the area bounded by latitude 6⁰30' and 8⁰15'N and longitudes 6⁰30' and 9⁰40'E. Makurdi the capital city of Benue State of Nigeria lies between latitudes 7⁰39' and 7⁰45'N and longitudes 8⁰33' and 8⁰35'E. River Benue, one of the two major rivers in Nigeria, traverses the State. The people in the area rely on such sources of water as borehole; hand dug well, streams, sachet water and River Benue. This work was carried out from May to June, 2014.

The water samples: Fifty sachet (transparent polyethylene bag) water brands (500 ml each) and five bottled water brands (75cl each) were randomly purchased in triplicate from markets, shop shelves and street vendors in Makurdi metropolis making it a total of one hundred and sixty-five samples of packaged water and were immediately transported to the Microbiology Laboratory (Food Section) for microbiological analysis.

Physicochemical Analysis: pH was determined using a pH meter (HANNA model HI76310, US), the temperature was determined with a (HANNA model HI11310, US) thermometer, conductivity meter (HANNA model HI2550, US) was used to determine the electrical conductivity and dissolved oxygen was determined using DO-meter (HANNA model HI9146, UK). Physicochemical parameters were examined in Benue State Water Board.

Determination of Colour and Odour: A 20 ml volume of each water sample was shaken vigorously in a clean glass beaker to check for any frothing and was allowed to settle. Thereafter, it was observed under a bright light for presence of any particulate matter and was then brought close to the nose to test for any odour present⁷.

Determination of Taste: A small volume of each sample was tasted with the tongue and was immediately rinsed with taste free distilled water after each sample.

Bacteriological Quality Analysis: The bacteriological quality of the drinking water samples was assessed using the multiple fermentation tube method as a presumptive test for total coliforms as indicators which was expressed using the Most Probable Number tables as MPN per 100 ml. While culture on selective media and biochemical methods were used as confirmatory test⁸.

Total coliform identification and enumeration: Serial dilutions of 10⁰, 10^-1, 10^-2 and 10^-3 were prepared for each water sample using sterile distilled water. One millilitre aliquot from appropriate dilutions was inoculated into three fermentation tubes containing 9 ml of MacConkey broth with inverted Durham tubes. The tubes were closed firmly, agitated slightly to distribute the sample evenly and was inverted gently to expel air from the Durham tubes. The set of fermentation tubes were incubated at 44⁰C for 24 hours to determine total coliforms growth. The tubes that showed a colour change, from purple to yellow with gas production in the Durham tubes after 24 and 48 hours were identified as positive and were quantified from the Most Probable Number tables as MPN per 100ml⁸.

Identification and Enumeration of Escherichia coli: E. coli was observed on EMB Agar and XLD Agar and was identified on the basis of cultural characteristics and biochemical tests. The number of positive test tubes with acid (yellow coloration) and gas production were matched with the MPN statistical table, and the MPN of coliforms present in 100 ml of each sample was thus determined⁸. For the confirmation test, a loopful of cultures from the presumptive test was inoculated into MacConkey broth containing Durham tubes and was incubated for 48 hours at 37⁰C. Gas production confirmed the presence of E. coli. Cultures were further inoculated into Eosin Methylene Blue medium and incubated at 37⁰C for 24 hours. A purple-green metallic sheen on the surfaces of the colonies indicated a positive test⁹.

Characterization and Identification of Isolates: This was done according to standard methods⁹. The methods involved Gram staining, morphological, culture and biochemical characteristics (catalase, coagulase, triple sugar iron test and oxidase).

Statistical Analysis: Statistical analysis was done using SPSS version 15.0 and presented in frequencies, percentages and charts.

RESULTS AND DISCUSSION

Physicochemical Characteristics of Sachet and Bottled Water: The result of this study indicated that no colour, taste and odour were present in both sachet and bottled water brands investigated (Table 1). This indicates that all the water brands were devoid of the presence of any particles and free from dissolved humic acids in them¹⁵. The Physicochemical properties of the various sachet and bottled water brands in (Table 2) and (Table 3) respectively shows that the pH values of the brands of sachet and bottled water ranged from 6.0 to 7.9 and 6.6 to 8.3. All the fifty brands of sachet drinking water had their pH values below the Standard Organization of Nigeria (SON) and the World Health Organization (WHO) upper permissible limit of 8.5 though five brands violated the lower permissible limit of 6.5. While all the five brands of bottled water met the pH range values of both SON and WHO.

Table 1: Colour, Taste and Odour parameters of packaged drinking water in Makurdi
Packaged drinking Water	Colour	Taste	Odour
Brands of Sachet Water	Colourless	Tasteless	Odourless
Brands of Bottled Water	Colourless	Tasteless	Odourless
WHO/SON	Colourless	Tasteless	Odourless

Table 2: Physicochemical parameters of sachet water produced in Makurdi metropolis.
Brands of sachet water	pH	EC (μS/cm)	TDS (mg/L)	DO (mg/L)	Temp (℃)	NaCl (%)
WF	7.0	59.1	30.0	0.08	29.6	0.0
GN	6.5	55.4	27.6	0.08	29.3	0.1
TG	7.1	78.5	39.2	0.09	29.3	0.2
ML	7.2	82.7	41.4	0.09	29.2	0.2
AN	7.2	96.4	48.2	0.08	29.0	0.2
ED	7.3	188.4	94.2	0.09	29.6	0.4
OG	7.4	80.2	40.1	0.10	29.2	0.2
DM	7.4	83.1	41.6	0.10	29.2	0.2
SE	7.5	78.5	39.2	0.10	29.3	0.2
LP	6.8	79.6	39.9	0.08	29.0	0.2
FL	7.0	53.3	26.6	0.08	29.1	0.1
UA	6.5	97.5	49.0	0.08	29.3	0.1
PA	7.0	89.4	44.8	0.09	29.1	0.1
SH	7.2	105.9	53.0	0.10	28.9	0.1
JO	7.1	86.2	42.9	0.11	29.1	0.1
DK	6.5	103.4	51.5	0.12	29.4	0.1
HE	6.8	81.6	40.6	0.11	29.2	0.1
OB	7.1	87.8	43.7	0.09	28.9	0.1
AQ	7.3	179.7	89.9	0.13	28.8	0.1
WD	6.6	12.1	5.9	0.09	28.9	0.1
OX	7.6	8.4	4.2	0.08	28.8	0.1
OC	6.7	92.2	46.4	0.10	29.1	0.1
PR	6.9	79.5	39.8	0.12	28.7	0.1
SC	7.1	95.6	47.9	0.13	28.8	0.1
KY	6.6	96.9	48.7	0.14	28.6	0.1
WHO/SON	6.5-8.5	1000	1000	Nil	25-30	<1.6
Brands of sachet water	pH	EC (μS/cm)	TDS (mg/L)	DO (mg/L)	Temp (℃)	NaCl (%)
SX	6.7	90.5	45.3	0.14	28.8	0.1
CN	7.0	82.9	41.5	0.13	28.5	0.1
JD	6.9	13.9	6.9	0.08	30.5	0.1
MV	7.2	93.6	46.8	0.14	28.5	0.1
MD	6.3	52.6	26.3	0.15	29.0	0.1
ES	6.6	56.4	28.2	0.14	28.7	0.1
RY	7.6	100.9	50.5	0.08	30.0	0.1
DS	6.6	88.4	44.2	0.14	28.6	0.1
RB	6.2	81.3	40.0	0.08	29.3	0.1
OU	6.8	75.0	37.5	0.15	28.6	0.1
VF	6.0	33.4	16.8	0.13	29.1	0.1
DU	6.3	81.9	40.3	0.15	28.8	0.1
FW	6.9	73.0	36.4	0.12	28.8	0.1
WL	6.7	96.2	48.1	0.11	28.7	0.1
OV	6.0	95.4	47.8	0.16	28.9	0.1
SB	6.4	86.3	43.2	0.14	28.8	0.1
DE	6.7	95.9	48.1	0.16	28.9	0.1
GB	6.6	98.7	49.4	0.14	28.6	0.1
WP	6.5	94.5	46.8	0.13	28.5	0.1
IL	6.6	175.1	87.6	0.12	28.4	0.1
DN	6.9	124.3	62.1	0.11	28.4	0.1
VC	7.0	99.4	49.7	0.13	28.2	0.1
DW	7.2	87.5	43.9	0.14	28.1	0.1
DI	7.9	82.3	41.5	0.13	28.6	0.1
SF	7.7	87.3	43.5	0.12	28.5	0.1
WHO/SON	6.5-8.5	1000	1000	Nil	25-30	<1.6

Table 3: Physicochemical parameters of bottled water produced in Makurdi metropolis.
Brands of bottled water	pH	EC (μS/cm)	TDS (mg/L)	DO (mg/L)	Temp (℃)	NaCl (%)
WF	7.4	60.1	34.6	0.08	29.5	0.0
GN	7.7	54.5	28.3	0.08	29.3	0.0
ED	8.3	208.4	108.1	0.09	29.6	0.4
JD	6.6	14.2	7.5	0.08	28.9	0.0
WD	7.5	87.3	45.4	0.11	29.0	0.1
WHO/SON	6.5-8.5	1000	1000	Nil	25-30	<1.6
NB: These brand samples of sachet and bottled water were identified through pseudonyms based on their respective initials.

pH value is a good indicator of identifying whether water is hard or soft. The pH of pure water is 7. In general, water with a pH levels less than 7 is considered acidic and may cause severe corrosion of metals, a pH greater than 7 is considered basic while at pH 8, there is a progressive decrease in the efficiency of chlorine disinfection process causing a bitter taste to the water⁶. The normal range for pH in surface water systems is 6.5 to 8.5, and the pH range for groundwater systems is between 6 and 8.5⁶. Alkalinity is a measure of the capacity of the water to resist a change in pH that would tend to make the water more acidic¹⁰. pH affects various water treatment processes that contribute to the removal of viruses, bacteria and other harmful organisms; it could be claimed that pH has an ill-effect on health³.

Electrical Conductivity measurements ranged from 8.4 μS/cm to 188.4 μS/cm for sachet water and 14.2 μS/cm to 208.4 μS/cm for bottled water. These values obtained for both sachet and bottled water investigated were within the range of WHO/SON standard conductivity (0-1000μs/cm). The electrical conductivity of water measures the capacity of water to conduct electrical current and it is directly related to the concentration of ions in water. These conductive ions come from dissolved salts and inorganic compounds¹². Compounds that dissolve into ions are called electrolytes. The more ions that are present, the higher the conductivity of water. Likewise, the fewer ions that are in the water, the less conductive it is. Therefore, all these dissolved salts or ions are also known as the total dissolved solids (TDS)¹². The average conductivity of the bottled water 82.1 μS/cm analyzed is lower than 85.9 μS/cm of sachet water. This might be that the bottled waters analyzed contain fewer amounts of dissolved ions or salts than the sachet water brands.

Total dissolved solids for sachet and bottled water ranged from 4.2 mg/l to 94.2 mg/l and 7.5 mg/l to 108.1 mg/l respectively. The concentration of total dissolved solids (TDS) indicated that all the brands of packaged water contained varied concentrations of dissolved mineral elements but they were far below the permissible level of total dissolved solids (TDS) value (1000 mg/l) of WHO/SON for the mineral nutrition of consumers. The source of TDS in drinking water is attributed to natural sources, domestic wastewaters, municipal runoffs and industrial wastewaters¹⁰. Water containing TDS concentrations below 1000 mg/l is usually acceptable to consumers, although acceptability may vary according to circumstances. However, the presence of high levels of TDS in water may be objectionable to consumers owing to the resulting taste and to excessive scaling in water pipes, heaters, boilers, and household appliances. Water with extremely low concentrations of TDS may also be unacceptable to consumers because of its flat and flavourless taste⁶. High TDS values may be an indication of the presence of excessive concentrations of some specific substances⁶. Relatively, the low TDS recorded for packaged water brands also indicated that they were soft drinking waters.

Dissolved oxygen is an important indicator of water quality. This is due to its importance as a respiratory gas, and its use in biological and chemical reactions. Dissolved oxygen levels in this study ranged between 0.08 mg/l to 0.16 mg/l for brands of sachet water and 0.08 mg/l to 0.11 mg/l for brands of bottled water. The presence of dissolved oxygen in drinking water adds taste and it is a highly variable factor in water³. Dissolved oxygen in water primarily affects oxidation-reduction reactions involving iron, manganese, copper and compounds containing nitrogen and sulphur¹². The dissolved oxygen content of water depends on its source, temperature, chemical and biological processes taking place in the water distribution system¹². However, large declines in dissolved oxygen in water could indicate high levels of microbiological activity, and should trigger further sampling for microorganisms. No guideline value is recommended because the acceptability of low levels of dissolved oxygen depends on the presence of other water constituents¹².

The standard temperature of drinking water according to WHO/SON is 25–30°C. Temperature is a measure of the average thermal energy of a substance¹³. The sachet water analyzed has 28.1 and 30.5°C as the lowest and highest temperature respectively. The average temperature of the fifty sachet water analyzed is 28.9°C which is significantly higher than the WHO/SON standard value for quality water. Similarly, the temperature of the bottled water analyzed ranged from 28.7 to 29.6°C with an average of 29.1°C. This was also significantly higher than the WHO/SON standard value for quality water.

This could be due to high temperature of 28 to 35°C in Makurdi during the period of this study. However, these temperatures for both sachet and bottled drinking water fell within the optimal growth temperature (20–45°C) for mesophilic bacteria. The microbiological characteristics of drinking water are related to temperature through its effects on water-treatment processes and its effects on both growth and survival of microorganisms¹¹. This result is similar to that of Danso-Boateng and Frimpong¹⁴ who reported 28.94°C and 28.81°C respectively for average temperatures of plastic sachet and bottled water brands produced and/or sold in Kumasi, Ghana. According to Onweluzo and Akuabgazie¹⁵, temperatures within this range are favourable for maximum growth of mesophyll bacteria such as Staphylococcus aureus, Escherichia coli and Streptococcus sp. This phenomenon has the tendency to promote the development of undesirable taste and odour in water with time¹⁵. However, the survival rate of cysts and ova of parasitic worms such as schistosoma ova in water is shortened by the higher temperatures (29 to 32°C)¹¹. All samples met the permissible value <1.6 of NaCl.

Bacteriological Characteristics of Sachet Water: The results obtained in this study indicated that sachet water produced in Makurdi Metropolis are contaminated with bacteria as shown in (Table 5).

Table 4: Total coliform (TC) count using the Most Probable Number (MPN) based on the presumptive positive bottles
BSW	TC (MPN/100 ml)	BSW	TC (MPN/100 ml)
WF	0	SX	150
GN	0	CN	9.4
TG	0	JD	3
ML	6.2	MV	93
AN	3	MD	7.4
ED	3	ES	20
OG	3	RY	6.1
DM	9.4	DS	210
SE	7.4	RB	20
LP	3	OU	16
FL	3	VF	3
UA	0	DU	43
PA	3	FW	3
SH	21	WL	3
JO	3	OV	23
DK	35	SB	3
HE	7.4	DE	150
OB	29	GB	28
AQ	1100	WP	21
WD	0	IL	160
OX	3	DN	120
OC	3	VC	9.2
PR	7.2	DW	240
SC	9.2	DI	93
KY	3.6	SF	150
TC: Total Coliform; BSW: Brands of Sachet Water; MPN: Most Probable Number; Faecal Coliform (FC)

Forty five (90%) sachet water brands tested positive for the presence of total coliforms which means going by the zero tolerance levels stipulated by the regulatory agencies for coliforms in drinking water, 5 (10%) out of the 50 sachet water brands sampled met the standards of quality water. The WHO bacterial risk level classification based on MPN/100 ml of total coliforms was used to grade the samples as “Excellent” (<2MPN/100), “Satisfactory” (2-3MPN/100 ml), “Suspicious” (4-10MPN/100 ml) and “Unsatisfactory” (>10MPN/100 ml)^6,16. Few of the samples (10%) were excellent, with 28% and 22% as satisfactory and suspicious respectively. Majority of the samples (40%) however, were unsatisfactory (Fig. 1).

Fig. 1: Grading of sachet water brands based on total coliforms

Although the sachet water samples collected for this study were presumptively treated by the manufacturer, 90% of the sachet water brands tested positive for total coliforms which is indicative of the risk associated with their consumption.

Table 5: Total Coliform (TC) count of bottled water brands
Brands of bottled water	TC (MPN/100 ml)
WF	0
GN	0
ED	0
JD	0
FW	0
WL	0

All bottled water brands produced and/or sold in various part of the Makurdi Metropolis are free from microbiological contaminants, as shown in (Table 6). This clearly indicated that all bottled water produced in Makurdi are of good microbiological quality, and thus suitable for human consumption.

Table 6: Characterization and Identification of Bacterial Isolates

Gram Reaction

Cell Shape

Cell Arrangement

Oxidase

Catalase

Coagulase

Citrate

Indole

TSI

MSA

EMB

XLD

Bacterial Isolates

+

C

S

-

+

+

+

-

-

+

-

-

S. aureus

-

R

SS

-

+

-

-

-

+

+

+

+

Salmonella sp.

-

R

CL

-

+

-

-

+

+

+

+

+

E. coli

-

R

S

-

+

-

+

-

+

+

+

+

Klebsiella sp.

-

R

S

+

+

-

+

-

-

+

+

+

P. aeruginosa

-

R

S

-

+

-

-

V

+

+

-

+

Shigella sp.

+

C

CH

-

-

-

-

-

-

-

+

-

S. faecalis

C: Cocci; R: Rods; S: Single; SS: Slander and Scattered; CL: Cluster; CH: Chains; V: Variable, +: Positive; -: Negative; TSI: Triple Sugar Iron; MSA: Mannitol Salt Agar; EMB: Eosin Methylene Blue; XLD: Xylose Lysine Deoxycholate Agar.

Organisms isolated in sachet drinking water were Escherichia coli, Staphylococcus aureus, Salmonella species, Pseudomonas aeruginosa, Streptococcus sp, Shigella species, Klebsiella species as shown in (Fig. 2).

The presence of E. coli, a faecal coliform in drinking water is a strong indicator of recent sewage, faeces of human or animal waste contamination. Treated water should therefore not contain this organism because it is also an indicator microorganism in drinking water¹⁷.

The presence of Staphylococcus aureus of sample water brands suggests human contamination as the organism is a commensal on the skin and nostrils of humans or poor personal hygiene of handlers.

The presence of Pseudomonas aeruginosa of the sample water brands suggest contamination of the water either through decay or improper sanitization or sterilization of the factory equipment or instrument used in the production processes. It can also result from the use of unsterile polyethene which is used for the packaging of the water product.

The presence of Salmonella sp., Shigella sp. and Klebsiella sp. in the sachet water brands suggest a serious pathogenic waterborne threat, liable for causing serious disease to the consumer of those sample water brand. This could be as a result of serious microbial pollution of the factory equipment or from an infected worker, working under unhygienic practices.

Fig. 2: Graphical representation of bacterial isolates from sachet water brands in percentage

The high bacteriological contamination of sachet water could be attributed to inadequate treatment of water samples by the producers, improper use of filters, poor sanitary conditions and post-production contamination¹⁶. When water supplies contain coliform bacteria in levels greater than one per 100 ml of water, the water may also contain pathogens that cause acute intestinal illness. While normally regarded as discomfort to health, these infections may be lethal to infants, the elderly and the infirm¹⁸.

The presence of these contaminating bacteria could account for the incidence of diarrhoea, food poisoning, gastroenteritis, dysentery and typhoid. The absence of faecal indicator bacteria in some brands of sachet water could be attributed to effective treatment processes employed in addition to the remoteness of sewage facilities from factories compared to the sachet water producing factories. Others include the use of personal protective equipment (PPE) and improved and hygienic filling system⁵.

It was reported that the National Agency for Food and Drug Administration and Control (NAFDAC) and Standard Organization of Nigeria (SON), who are the main regulators of drinking water quality, have intensified their inspections, which should have put recalcitrant producers on the alert, but improvement is not forthcoming. Lack of information has made it difficult for consumers to identify the contaminated brands of sachet water to avoid patronizing them.

CONCLUSION

The physicochemical properties of sachet water sold in Makurdi metropolis are generally satisfactory. However, the bacteriological analysis of this study showed bacterial contamination of packaged water from coliforms and other bacteria found naturally in water, soil, or vegetation which indicates a problem with the overall quality of water production which could be due to no or inadequate treatment and also contamination with sewage or animal waste as evidenced by the presence of faecal coliforms,Salmonella, and Shigella. It is therefore desirable that efforts should be intensified in the monitoring of activities in this rapidly expanding industry with a view to raising standards.

SIGNIFICANCE STATEMENT

This study revealed that sachet water sold in Makurdi metropolis is contaminated with bacteria. This has increase the information base on the portability of sachet water sold in Nigeria and also provides baseline data for regulatory bodies who ensure standards are kept in the production of drinking water.

ACKNOWLEDGEMENT

We highly thank the Benue State Water Board for granting us access to use their instruments for physicochemical analysis and Department of Microbiology, University of Agriculture, Makurdi for their material support during laboratory work. We would also like to extend our appreciation to staff for their technical and administrative support.

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