Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

13
INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 5, No 5, 2015 © Copyright by the authors - Licensee IPA- Under Creative Commons license 3.0 Research article ISSN 0976 – 4402 Received on December2014 Published on March 2015 1030 Isolation and characterization of zinc resistant bacteria from a coil coating industrial wastewater treatment plant Joshua B. Owolabi and Melanie M. Hekeu Department of Biological Sciences, Microbiology Unit, School of Natural and Applied Sciences, College of Science and Technology, Covenant University, P.M.B. 1023 Ota, Ogun State, Nigeria. [email protected] doi: 10.6088/ijes.2014050100097 ABSTRACT Wastewater effluents from metal coil coating industry containing priority pollutants including chromium, cyanide, zinc, aluminum, cadmium, lead, nickel, selenium, tin, and mercury; oil and grease, or total suspended solids are often discharged with limited or no treatment into the environment thereby threatening microbial diversity and health of plants, animals and humans. This study was carried out to assess the incidence of Zn 2+ resistant bacteria from a coil coating industrial wastewater treatment plant in Ota, Southwest Nigeria. In this study, ten Zn 2+ resistant bacterial strains were recovered from treated wastewater samples on nutrient agar supplemented with 1mM concentration of zinc sulphate heptahydrate by the standard spread plate method. The isolates were studied based on their cultural, morphological and biochemical characteristics and were identified as strains of Bacillus azotoformans, Bacillus megaterium, Micrococcus varians, Serratia marcescens HM1, Serratia marcescens HM2, Proteus mirabilis, Aeromonas hydrophila HM3, Aeromonas hydrophila HM4, Aeromonas caviae and Citrobacter spp. Further testing of the bacterial isolates in nutrient agar supplemented with different concentrations (2, 4, 6, 8 and 10 mM) of hydrated zinc sulphate showed that eight of the isolates (80%) exhibited resistance to Zn 2+ concentration of 6 mM and above. Co-resistance of four bacterial isolates to Pb 2+ was studied and they showed high resistance to the heavy metal with minimum inhibitory concentration (MIC) in the range of 2 to 8 mM. Out of the ten bacterial strains, seven (70%) exhibited resistance to several antibiotics including amoxicillin, cotrimixazole, augmentin, nitrofurantoin and tetracycline, and intermediate or full sensitivity to ofloxacin, nalidixilic acid and gentamicin. The bacterial isolates obtained in the present study enrich studies on microbial diversity of zinc resistance and could be exploited for biotechnological remediation of zinc, lead and other heavy metal contaminated ecosystems. Keywords: Wastewater, heavy metal, resistance, antibiotics, bacteria 1. Introduction The metal coil surface coating industry includes any manufacturing facility engaged in the surface coating of metal coil mainly; aluminum, galvanized steel, and zinc/aluminum, and small quantities of brass (EPA, 1998). The coil coated metal is fabricated into end products after it is coated, thus eliminating the need for post-assembly painting. Most coil coating plants generate wastewater from wet section and quenching operations as well as clean-up activities. Biological and physical/chemical treatment technologies and upstream waste minimization activities are the building blocks in the development of industrial pollution

Transcript of Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

Page 1: Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

INTERNATIONAL JOURNAL OF ENVIRONMENTAL SCIENCES Volume 5, No 5, 2015

© Copyright by the authors - Licensee IPA- Under Creative Commons license 3.0

Research article ISSN 0976 – 4402

Received on December2014 Published on March 2015 1030

Isolation and characterization of zinc resistant bacteria from a coil coating

industrial wastewater treatment plant Joshua B. Owolabi and Melanie M. Hekeu

Department of Biological Sciences, Microbiology Unit, School of Natural and Applied

Sciences, College of Science and Technology, Covenant University,

P.M.B. 1023 Ota, Ogun State, Nigeria.

[email protected]

doi: 10.6088/ijes.2014050100097

ABSTRACT

Wastewater effluents from metal coil coating industry containing priority pollutants including

chromium, cyanide, zinc, aluminum, cadmium, lead, nickel, selenium, tin, and mercury; oil

and grease, or total suspended solids are often discharged with limited or no treatment into

the environment thereby threatening microbial diversity and health of plants, animals and

humans. This study was carried out to assess the incidence of Zn2+ resistant bacteria from a

coil coating industrial wastewater treatment plant in Ota, Southwest Nigeria. In this study, ten

Zn2+ resistant bacterial strains were recovered from treated wastewater samples on nutrient

agar supplemented with 1mM concentration of zinc sulphate heptahydrate by the standard

spread plate method. The isolates were studied based on their cultural, morphological and

biochemical characteristics and were identified as strains of Bacillus azotoformans, Bacillus

megaterium, Micrococcus varians, Serratia marcescens HM1, Serratia marcescens HM2,

Proteus mirabilis, Aeromonas hydrophila HM3, Aeromonas hydrophila HM4, Aeromonas

caviae and Citrobacter spp. Further testing of the bacterial isolates in nutrient agar

supplemented with different concentrations (2, 4, 6, 8 and 10 mM) of hydrated zinc sulphate

showed that eight of the isolates (80%) exhibited resistance to Zn2+ concentration of 6 mM

and above. Co-resistance of four bacterial isolates to Pb2+ was studied and they showed high

resistance to the heavy metal with minimum inhibitory concentration (MIC) in the range of 2

to 8 mM. Out of the ten bacterial strains, seven (70%) exhibited resistance to several

antibiotics including amoxicillin, cotrimixazole, augmentin, nitrofurantoin and tetracycline,

and intermediate or full sensitivity to ofloxacin, nalidixilic acid and gentamicin. The bacterial

isolates obtained in the present study enrich studies on microbial diversity of zinc resistance

and could be exploited for biotechnological remediation of zinc, lead and other heavy metal

contaminated ecosystems.

Keywords: Wastewater, heavy metal, resistance, antibiotics, bacteria

1. Introduction

The metal coil surface coating industry includes any manufacturing facility engaged in the

surface coating of metal coil mainly; aluminum, galvanized steel, and zinc/aluminum, and

small quantities of brass (EPA, 1998). The coil coated metal is fabricated into end products

after it is coated, thus eliminating the need for post-assembly painting. Most coil coating

plants generate wastewater from wet section and quenching operations as well as clean-up

activities. Biological and physical/chemical treatment technologies and upstream waste

minimization activities are the building blocks in the development of industrial pollution

Page 2: Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

Isolation and characterization of zinc resistant bacteria from a coil coating industrial

wastewater treatment plant

Joshua B. Owolabi and Melanie M. Hekeu International Journal of Environmental Sciences Volume 5 No.5, 2015

1031

control strategies. In Nigeria, despite the issuance of guidelines and standards that relate to

environmental pollution control by the Nigerian Federal Environmental Protection Agency

(FEPA, 1991), these regulations are not strictly enforced nor followed (Okereke, 2007).

Following the chemical and pharmaceutical industrial sector, the second most polluting are

the basic metal manufacturing facilities engaged in steel manufacturing, metal fabrication,

aluminum extrusion and related categories. Majority of these industries discharge their

partially treated or untreated effluents into the environment (Oketola and Osibanjo, (2011);

out of the 14 industries examined in the study, only 29% had effluent treatment plant which

was operational, 36% had no effluent treatment plant while the remaining 36% operate dry

process in which effluent treatment plant was not applicable. This dismal conventional

effluent analysis is comparable to the status of the United States’ coil coating industry in the

early 1980’s when approximately 15% of coil coating companies reportedly had no

wastewater treatment in place (EPA, 1980). According to that report, just about a third to

half of coil coating companies with wastewater treatment conducted some aspects of the

treatment process such as filtering to remove zinc and aluminum particles, oil skimming for

oil removal, lime precipitation of metals, pH adjustment, hexavalent chromium reduction,

filtration of total suspended solids, membrane processes or ion exchange systems to remove

dissolved salts from wastewater, clarification, sludge evaporation and reclamation (EPA,

1980). Consequently, regulated pollutants for coil coating industry include chromium,

cyanide, zinc, aluminum, cadmium, lead, nickel, selenium, tin, and mercury; oil and grease,

total suspended solids, and pH; nutrients and volatile organic compounds (VOCs) such as

ammonia, nitrogen, phosphorus, chloroethane, 1,1,1-trichloroethane, dichloroethane, and

dichloroethylene (EPA, 1980). Untreated wastewater when released to the rivers downstream

of point sources constitute an important health risk for the population using this water for

other purposes such as agricultural land irrigation, cleaning, bathing or even drinking,

whereby heavy metals and other hazardous chemicals often make their way into the food

chain (Echiegu and Liberty, 2013; Osho et al., 2010).

Introduction of high concentrations of heavy metals into the environment kills the majority of

the microflora, thereby creating selective pressure for the emergence of a few strains with

resistance to the metals. Such resistant strains participate in the process of self-recovery of

the contaminated habitat through a variety of mechanisms such as differences in uptake

and/or transport of the toxic metal while in other cases, the metal may be enzymatically

transformed by oxidation, reduction, methylation or demethylation into chemical species

which may be less toxic or more volatile than the parent compound (Nies, 1999). These

mechanisms are sometimes encoded in plasmid genes in close proximity with antibiotic-

resistance genes thus facilitating the transfer of toxic metal resistance from one cell to another

(Nageswaran et al., 2012) and cross resistance to both heavy metals and antibiotics (Devika

et al., 2013).

Although, heavy metal resistant bacteria have been demonstrated to exhibit high metal

biosorption or bioaccumulation capacity in the laboratory setting (Yilmaz, 2003; Ansari and

Malik, 2007; Bautista-Hernández, 2012) and some heavy metal resistant strains have been

successfully applied in remediating contaminated sites elsewhere in the developed world

(Canstein et al., 1999; Okino et al., 2002; Nakamura et al., 1999), similar efforts are

presently scanty in Nigeria (Odokuma and Akponah, 2010; Sanuth et al., 2010). The

principal aim of the present study was to assess the potential occurrence of Zn2+ resistant

bacteria from a coil coating industrial wastewater effluent, evaluate the maximum heavy

metal tolerance as well as determine co-resistance against antibiotics; all initial steps in

capacity building for biosorption/bioaccumulation studies.

Page 3: Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

Isolation and characterization of zinc resistant bacteria from a coil coating industrial

wastewater treatment plant

Joshua B. Owolabi and Melanie M. Hekeu International Journal of Environmental Sciences Volume 5 No.5, 2015

1032

2. Materials and Methods

2.1 Study area and sample collection

Treated wastewater samples were collected from industrial wastewater treatment plant in a

coil coating company in Ota, the capital of the Ado-Odo/Ota Local Government Area of

Ogun State, Southwest, Nigeria. The coil coating facility is engaged in the production of a

variety of coated materials covering aluminum, galvanized steel and zinc/aluminum steel for

roofing applications. The wastewater treatment system receives wastewater from wet section

operations, quenching operations and clean-up activities. The following treatment activities

were in place at the treatment plant: oil skimming for oil removal, lime precipitation of

metals, clarification, sludge evaporation, sludge landfill or reclamation and effluent discharge.

Samples of wastewater from the treated effluent at the point of discharge to the environment

were aseptically collected in sterile screw-capped bottles and transported immediately to the

laboratory for analysis.

2.2 Enrichment, isolation and identification of metal resistant bacteria

For the isolation of heterotrophic bacteria, 1 ml of treated wastewater effluent was inoculated

into 9 ml of nutrient broth and incubated for 24 h at 370C with shaking at 100 rpm. Ten-fold

serial dilutions of the overnight cultures were prepared. An aliquot (0.1 ml) of the diluted

samples was spread on sterile nutrient agar plates amended with 1 mM of zinc heptahydrate.

The plates were incubated at 370C for 48 h. After the incubation period, the plates were

observed for growth on the media. The isolated and distinct colonies on the media were sub-

cultured repeatedly on the same media for purification. The purified isolates were grown in

nutrient agar slants 370C for 24 h and kept in storage at 40C. The isolates were identified on

the basis of their morphology and biochemical characteristics following the schemes

described (Madigan et al., 2009; Hemraj et al., 2013) and comparison with Bergey’s Manual

of Determinative Bacteriology (Holt et al., 1994).

2.3 Determination of maximum tolerated concentrations (MTCs) of heavy metals

The MTCs were determined for the bacterial isolates on nutrient agar medium in presence of

each of zinc and lead separately. The isolates were inoculated on nutrient agar plates

containing singly Zn2+ and Pb2+ at concentrations of 2, 4, 6, 8, 10 mM. The organisms were

incubated at 370C for 72 h. The MTC was noted when the isolate failed to show growth on

the plates after the three days of incubation. All experimental set-ups were prepared in

duplicate.

2.4 Determination of antibiotic susceptibility

The bacterial isolates were tested for susceptibility to 8 different antibiotics by the disc

diffusion method on Mueller Hinton agar (Oyetibo et al., 2010). The antibiotics tested were

ofloxacin 5 µg (OFL), amoxicillin 20 µg (AMX), cotrimixazole 25 µg (COT), nitrofurantoin

300 µg (NIT), nalidixilic acid 30 µg (NAL), augmentin 30 µg (AUG), tetracycline 30 µg

(TET) and gentamicin 10 µg (GEN). The antibiotics discs were placed on Mueller Hinton

agar plates previously seeded with cell suspension with a turbidity of 0.5 McFarland

standards. The plates were incubated at 370C for 24 h and observed for zones of inhibition.

Page 4: Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

Isolation and characterization of zinc resistant bacteria from a coil coating industrial

wastewater treatment plant

Joshua B. Owolabi and Melanie M. Hekeu International Journal of Environmental Sciences Volume 5 No.5, 2015

1033

3. Results

Samples of treated wastewater from a coil coating industrial effluent examined in this study

contained heavy metal resistant bacteria. A total of 10 different, Gram negative (70%) and

Gram positive (30%), bacterial strains were isolated from the treated wastewater effluent

samples on nutrient agar – supplemented with 1 mM zinc sulphate heptahydrate by the

standard spread plate method. The Zn2+ resistant bacterial isolates were identified by

comparing their cellular and colonial morphological characteristics and the results from

biochemical tests with Bergey’s Manual of Determinative Bacteriology (Holt et al., 1994).

The results shown in Table 1 indicate the putative identity of the bacterial strains as follows:

Bacillus azotoformans, Bacillus megaterium, Micrococcus varians, Serratia marcescens

HM1, Serratia marcescens HM2, Proteus mirabilis, Aeromonas hydrophila HM3,

Aeromonas hydrophila HM4, Aeromonas caviae and Citrobacter spp.

Table 1: Zinc resistant bacterial isolates from treated wastewater effluent

Isolate G

R

CM Cat Cit Ind MR VP Oxi Sta Glu Lac Man Putative Identity

A + Rods - + - + - + - - + + Bacillus

azotoformans

B - Rods + - - + + - - + + + Serratia

marcescens HM1

C + Rods + + - + - - + + + + Bacillus

megaterium

D - Rods + + - + - - - + - + Proteus mirabilis

E - Rods + + - + + - - + - + Serratia

marcescens HM2

F - Rods + - - + - + - - - - Aeromonas

hydrophila HM3

G - Rods + - - + - + - + - + Aeromonas

caviae

H + Cocci + - - + - - - + + - Micrococcus

varians

I - Rods + - - + - + - + - - Aeromonas

hydrophila HM4

J - Rods + + + + - - - + + + Citrobacter spp.

GR: Gram reaction, CM: Cell Morphology, Cat: Catalase production, Cit: Citrate utilization,

Ind: Indole production, MR: Methyl Red, VP: Voges_Proskauer reaction, Oxi: Oxidase

activity, Sta: Starch hydrolysis, Glu: Glucose fermentation, Lac: Lactose fermentation, Man:

Mannitol fermentation, +: Positive, -: Negative

Maximum tolerance concentrations of Zn2+ were determined for each of the ten Zn2+ resistant

bacterial isolates by gradually increasing the concentrations of Zn2+ by 2 mM, on nutrient

agar until the strains failed to give colonies on plates. Table 2 presents the results of Zn2+

tolerance tests on nutrient agar. The results show a decline in the growth of the selected Zn2+

resistant bacterial isolates as the concentrations of Zn2+ increased. Strains of Serratia

marcescens HM1, Aeromonas caviae, Micrococcus varians and Aeromonas hydrophila HM4

were able to grow at up to 8 mM concentration of Zn2+. Bacillus azotoformans, Proteus

mirabilis and Citrobacter spp. exhibited tolerance of Zn2+ at up to 6 mM; Bacillus

megaterium tolerated up to 4 mM while Aeromonas hydrophila HM3 strain did not grow at

any of the Zn2+ (2, 4, 6, 8 and 10 mM) concentrations tested.

Page 5: Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

Isolation and characterization of zinc resistant bacteria from a coil coating industrial

wastewater treatment plant

Joshua B. Owolabi and Melanie M. Hekeu International Journal of Environmental Sciences Volume 5 No.5, 2015

1034

Table 2: Zinc tolerance test of bacterial isolates on Nutrient agar

Zinc concentrations in mM

Bacterial isolates 2 4 6 8 10

Bacillus azotoformans

Serratia marcescens HM1

Bacillus megaterium

Proteus mirabilis

Serratia marcescens HM2

Aeromonas hydrophila HM3

Aeromonas caviae

Micrococcus varians

Aeromonas hydrophila HM4

Citrobacter spp.

+++

+++

++

+++

++

-

+++

+++

+++

+++

++

++

++

++

++

-

+++

+++

+++

++

++

++

-

+

+

-

++

++

++

+

-

+

-

-

-

+

+

+

-

-

-

-

-

Key: -: No growth; +: Scanty growth; ++: Moderate growth; +++: Heavy growth

Four of the highly zinc resistant strains were further tested for growth in the presence of

increasing Pb2+ concentrations (2, 4, 6, 8 and 10 mM) on nutrient agar. Table 3 shows that

Serratia marcescens HM1, Aeromonas caviae and Citrobacter spp. exhibited tolerance for

Pb2+ at up to 8 mM while Micrococcus varians could only grow at 2 mM concentration of

this heavy metal.

Table 3: Lead tolerance test on selected bacterial isolates on Nutrient agar

Lead concentrations in mM

Bacterial isolates 2 4 6 8 10

Serratia marcescens HM1

Aeromonas caviae

Micrococcus varians

Citrobacter spp

++

+++

++

+++

+

+++

-

++

+

+++

++

+

++

++

-

-

-

Key: -: No growth; +: Scanty growth; ++: Moderate growth; +++: Heavy growth

The results of antibiotic sensitivity tests as shown in Table 4 indicate that seven (70%) of the

ten Zn2+ resistant bacterial strains exhibited resistance to several antibiotics including

amoxicillin, cotrimixazole, augmentin, nitrofurantoin and tetracycline, and intermediate or

full sensitivity to ofloxacin, nalidixilic acid and gentamicin. Both Aeromonas caviae and

Aeromonas hydrophila HM4 appeared to be resistant to most number of antibiotics (75%)

while Bacillus megaterium and Proteus mirabilis were resistant to three (37.5%) and

sensitive to five antibiotics. All ten zinc resistant bacterial isolates were sensitive to ofloxacin.

Page 6: Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

Isolation and characterization of zinc resistant bacteria from a coil coating industrial

wastewater treatment plant

Joshua B. Owolabi and Melanie M. Hekeu International Journal of Environmental Sciences Volume 5 No.5, 2015

1035

Table 4: Antibiotic sensitivity pattern of zinc resistant bacteria from treated wastewater

effluent

Bacterial Isolates OFL AMX COT NIT NAL AUG TET GEN

Bacillus azotoformans S R R R S R R I

Serratia marcescens HM1 S R R R S R R I

Bacillus megaterium S R R S S R S I

Proteus mirabilis S R R S S R S I

Serratia marcescens HM2 S R R R S R R I

Aeromonas hydrophila

HM3

S R R R I R R I

Aeromonas caviae S R R R S R R R

Micrococcus varians S R R R R R S S

Aeromonas hydrophila

HM4

S R R R I R R R

Citrobacter spp. S R R R I S R I

Key: OFL = 5 µg ofloxacin, AMX = 20 µg amoxicillin, COT = 25 µg cotrimixazole, NIT =

300 µg nitrofurantoin, NAL = 30 µg nalidixilic acid, AUG = 30 µg augmentin, TET = 30 µg

tetracycline, GEN = 10 µg gentamicin. S = Susceptible to antibiotic effect, R = Resistant to

antibiotic effect, I: Intermediate

4. Discussion

This study was carried out to assess the incidence of Zn2+ resistant bacteria from a coil

coating industrial wastewater treatment plant in Ota, Southwest Nigeria. Ten Zn2+ resistant

bacterial isolates recovered from the treated wastewater samples were putatively identified as

strains of Bacillus azotoformans, Bacillus megaterium, Micrococcus varians, Serratia

marcescens HM1, Serratia marcescens HM2, Proteus mirabilis, Aeromonas hydrophila HM3,

Aeromonas hydrophila HM4, Aeromonas caviae and Citrobacter spp on the basis of their

cultural, morphological and biochemical characteristics. Similar findings of occurrence of

Zn2+ metal resistant bacteria in contaminated soils, wastewater effluents, river water and fish

have been reported (Ahemad and Malik, 2012; Bhadra et al., 2007; Akinbowale et al., 2007;

Jackson et al., 2012; Mgbemena et al., 2012). Ahemad and Malik (2012) characterized and

identified five Zn2+ resistant Bacillus spp. from Indian agricultural soils irrigated with metal

polluted wastewater. Aeromonas species, Proteus species and Micrococcus species isolated

from Otamiri River, Imo State, Nigeria were demonstrated by Mgbemena et al. (2012) to

tolerate the presence of Zn2+ at high concentrations. Jafarzade et al. (2012) also described

Serratia spp. isolated from a marine environment in Malaysia that was highly resistant to

Zn2+. Some members of the genus Citrobacter isolated from heavy metal-contaminated sites

have been found with the ability to resist and accumulate Zn2+ (Jeong and Macaskie, 1995).

Microbial exposure to heavy metals selects and maintains microbial variants able to tolerate

the harmful effects of metals. Varied and efficient metal resistance mechanisms have been

Page 7: Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

Isolation and characterization of zinc resistant bacteria from a coil coating industrial

wastewater treatment plant

Joshua B. Owolabi and Melanie M. Hekeu International Journal of Environmental Sciences Volume 5 No.5, 2015

1036

identified in diverse species of bacteria (Nies, 1999; Dopson et al., 2003; Issazadeh, 2013).

Some of the Zn2+ resistant bacterial isolates characterized in this study also showed resistance

to Pb2+. In the study by Ahemad and Malik (2012), the zinc resistant bacteria (Pseudomonas

isolate SN7, Pseudomonas isolate SN28 and Pseudomonas isolate SN30) exhibited co-

resistance against Cu2+, Hg2+, Cd2+, Ni2+, Pb2+, Cr3+ and Cr6+ in addition to Zn2+. Efflux

transporters belonging to the P1B-type subfamily of ATPases are thought to play a key role

in heavy metal homeostasis of essential metals such as Cu2+, Co2+, and Zn2+, as well as

mediating resistance to toxic metals Pb2+, Cd2+ and Ag2+ (Axelsen and Palmgren,1998). An

alternative resistance mechanism of Zn2+ and Pb2+ dependent upon metabolic energy of

microorganisms is the bioaccumulation of both heavy metals (Augusto da Costa and Duta,

2001). It remains to be determined which mechanism(s) accounted for bacterial resistance to

both zinc and lead in the bacterial isolates in this study.

The MTCs for Zn2+ and Pb2+ in this study ranged, respectively, between 1 and 8 mM, and 2

and 8mM, depending on the bacterial strains. The methodologies employed for the

determination of maximum tolerated concentrations of heavy metals for resistant bacteria

have been inconsistent from study to study; while some have used liquid media (Hassen et al.,

1998), most have conducted the determinations in solid media (Kermanshahi et al., 2007;

Bautista-Hernández et al., 2012; Xu et al., 2014) as was done in the present study. It is

generally considered that heavy metals are more toxic in liquid than in solid media due to

more dispersion in the culture (Haferburg et al., 2007).

The Zn2+ and Pb2+ resistant bacterial isolates identified in this study may be considered to fall

into three categories on the basis of tolerance to these metals; high (8 mM), medium (4-6

mM) and low at 1-2 mM concentrations. Thus Serratia marcescens HM1 and Aeromonas

caviae are considered to be highly tolerant of Zn2+ or Pb2+ given their growth on solid media

at up to 8 mM concentration of either metal. Micrococcus varians and Aeromonas hydrophila

HM4 also demonstrated high tolerance to Zn2+ at 8 mM. Bacillus azotoformans, Bacillus

megaterium, Proteus mirabilis and Citrobacter spp. exhibited moderate tolerance to Zn2+ at 4

to 6 mM concentrations. Aeromonas hydrophila HM3 strain grew on solid media at 1 mM

Zn2+ concentration. Interestingly, Citrobacter spp. exhibited high tolerance for Pb2+ at up to 8

mM while Micrococcus varians could only grow at 2 mM concentration of this heavy metal.

The range of maximum tolerated concentrations of Zn2+ metal observed for Serratia

marcescens HM1, Aeromonas caviae, Micrococcus varians, Aeromonas hydrophila HM4 and

Citrobacter spp. are comparable to the minimum inhibitory concentrations of up to 10 mM

Zn2+ ions previously reported for Pseudomonas aeruginosa HMRI and P. aureginosa HMR2

(Bhojiya and Joshi, 2012) or P. putida strain 06909 (Lee et al., 2001). Similarly, the

maximum concentration of Pb2+ tolerated by Serratia marcescens HM1, Aeromonas caviae

and Citrobacter spp compares favorably to the MTC of up to 10 mM for a Pseudomonas sp.

(Owolabi and Hekeu, 2014). Like some isolates in this study; Aeromonas hydrophila HM3

and Micrococcus varians, Devika et al. (2013) have demonstrated the minimum inhibitory

concentration of Zn2+ and Pb2+ ions up to 2-3 mM for an Enterobacter sp.

In the present study, seven out of the ten (70%) heavy metal resistant bacterial strains

exhibited resistance to several antibiotics including amoxicillin, cotrimixazole, augmentin,

nitrofurantoin and tetracycline, and intermediate or full sensitivity to ofloxacin, nalidixilic

acid and gentamicin. Our data indicate co-occurrence of heavy metal resistance with

antibiotic resistance. Similar results have been reported previously (Bahig et al., 2008;

Oyetibo et al., 2010; Owolabi and Hekeu, 2014; Jafarzade et al., 2014). In the study by Bahig

Page 8: Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

Isolation and characterization of zinc resistant bacteria from a coil coating industrial

wastewater treatment plant

Joshua B. Owolabi and Melanie M. Hekeu International Journal of Environmental Sciences Volume 5 No.5, 2015

1037

et al. (2008), 33% to 60% of the heavy metal resistant bacterial isolates from soils irrigated

with canal water or wastewater showed resistance to ampicillin, kanamycin and tetracycline.

Five heavy metal resistant strains; Pseudomonas aeruginosa, Actinomyces turicensis,

Acinetobacter junni, Nocardia sp., and Micrococcus sp., isolated from soils obtained from

Ikeja industrial estate, Lagos, Nigeria resisted all the 18 antibiotics evaluated (Oyetibo et al.,

2010). In the study reported by Jafarzade et al. (2012), three strains of Serratia spp. isolated

from marine environment were highly resistant to penicillin, ampicillin and tetracycline but

sensitive to nalidixic acid, streptomycin, kanamycin and gentamicin.

Samples of treated wastewater from a coil coating industrial effluent in Ota, examined in this

study contained diverse bacterial isolates that are moderately to highly resistant to heavy

metals and antibiotics. Dual resistant organisms would have the capacity to compete well

with antibiotic-producing flora in the polluted environment and may also help to overcome

the inhibition that heavy metals exert on the biodegradation of organic pollutants (Sandrin

and Maier, 2003). Further research is warranted at the molecular level to determine the

mechanism of these dual properties and their close association with one another. The

biosorption capacity of these bacterial strains remains to be assessed experimentally as an

important requisite for their potential use in practical bioremediation of heavy metal

accumulation in wastewater and soils.

5. Acknowledgement

The authors would like to acknowledge the Management of Covenant University for

providing research infrastructure and support systems that made this work possible.

6. References

1. Ahemad, M. (2012), Implications of bacterial resistance against heavy metals in

bioremediation: A review, IIOAB Journal 3, pp 39-46.

2. Ahemad, M. and Malik A. (2012), Bioaccumulation of heavy metals by zinc resistant

bacteria isolated from agricultural soils irrigated with wastewater. Bacteriology Journal,

2, pp 12-21.

3. Akinbowale, O. L., Peng H., Grant P., Bartona, M. D. (2007), Antibiotic and heavy metal

resistance in motile Aeromonads and Pseudomonads from rainbow trout (Oncorhynchus

mykiss) farms in Australia. International Journal of Antimicrobial Agents, 30, pp 177–

182.

4. Ali, S., Sardar, K., Hameed, S., Afzal, S., Fatima, S., Shakoor, B. M., Bharwana, S. A.

and Tauqeer, H. M. (2013), Heavy metals contamination and what are the impacts on

living organisms? Greener Journal of Environmental Management and Public Safety, 2,

pp 172-179.

5. Augusto da Costa, A. C. and Duta, F. P. (2001), Bioaccumulation of copper, zinc,

cadmium and lead by Bacillus sp., Bacillus cereus, Bacillus sphaericus and Bacillus

subtilis. Brazilian Journal of Microbiology, 32, pp 1-5.

Page 9: Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

Isolation and characterization of zinc resistant bacteria from a coil coating industrial

wastewater treatment plant

Joshua B. Owolabi and Melanie M. Hekeu International Journal of Environmental Sciences Volume 5 No.5, 2015

1038

6. Ansari, M. I. and A. Malik, A. (2007), Biosorption of Nickel and Cadmium by metal

resistant bacterial isolates from agricultural soil irrigated with industrial wastewater. Bio-

Resource Technology 98, pp 3149- 3153.

7. Anyakora, C., Ehianeta, T. and Umukoro, O. (2013), Heavy metal levels in soil samples

from highly industrialized Lagos environment. African Journal of Environmental Science

and Technology, 7, pp 919-924.

8. Arikpo, G.E., Eja, M.E., Enyi-Idoh, K.H., Etim, S.E. and Ikpeme, E.M. (2010), Heavy

metal uptake potentials of Pseudomonas aeruginosa and Micrococcus luteus. African

Journal Online 8.

9. Axelsen, K. B., and Palmgren, M. G. (1998), Evolution of substrate specificities in the P-

type ATPase superfamily. Journal of Molecular Evolution, 46, pp 84–101.

10. Bahig A. E., Aly E. A., Khaled A. A. and Amel K. A. (2008), Isolation, characterization

and application of bacterial population from agricultural soil at Sohag Province, Egypt.

Malaysian Journal of Microbiology, 4, pp 42- 50.

11. Bautista-Hernández, D A., Ramírez-Burgos, L. I., Duran-Páramo, E., Fernández-Linares,

L. (2012), Zinc and Lead biosorption by Delftia tsuruhatensis: A bacterial strain resistant

to metals isolated from mine tailings. Journal of Water Resource and Protection, 4, pp

207-216.

12. Bhadra B., Nanda, A. K. and Chakraborty, R. (2007), Fluctuation in recoverable nickel

and zinc resistant copiotrophic bacteria explained by the varying zinc ion content of Torsa

River in different months. Arch Microbiology, 188, pp 215–224.

13. Bhojiya A. A. and Joshi H. (2012), Isolation and characterization of zinc tolerant bacteria

from Zawar Mines Udaipur, India. International Journal of Environmental Engineering

and Management, 3, pp 239-242.

14. Canstein, V.H., Y. Li, K.N. Timmis, W.D. Deckwer and Wagner-Dobler, I. (1999),

Removal of mercury from chloralkali electrolysis wastewater by a mercury-resistant

Pseudomonas putida strain, Applied Environmental Microbiology, 65, pp 5279-5284.

15. Devika, L., Rajaram R. and Mathivanan, K. (2013), Multiple heavy metal and antibiotic

tolerance bacteria isolated from equatorial Indian Ocean. International Journal of

Microbiological Research, 4, pp 212-218.

16. Dopson M., Baker-Austin, C., Koppineedi, R. D. and Bond, L. P. (2003), Growth in

sulfidic mineral environments: Metal resistance mechanisms in acidophilic micro-

organisms. Microbiology, 149, pp 1959-1970.

17. Echiegu, E. A. and Liberty, J. T. (2013), Effluents characteristics of some selected food

processingindustries in Enugu and Anambra States of Nigeria. Journal of Environment

and Earth Science, 3, pp 46-54.

Page 10: Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

Isolation and characterization of zinc resistant bacteria from a coil coating industrial

wastewater treatment plant

Joshua B. Owolabi and Melanie M. Hekeu International Journal of Environmental Sciences Volume 5 No.5, 2015

1039

18. Fagade, O. E. and Adetutu E. M. (1999), Lead solubilization and accumulation by two

strains of Pseudomonas species obtained from a battery manufacturing factory effluent.

Nigeria Journal of Miccrobiology, 13, pp 39-46.

19. Federal Environmental Protection Agency (FEPA) (1991), Guidelines and Standard for

Environmental Control in Nigeria. Federal Environmental Protection Agency (FEPA).

Government Printer, Lagos.

20. Haferburg, G., Reinicke, M., Merten, D., Buchel G. and Kothe E. (2007), Microbes

adapted to acidic mine drainage as source for strain active in retention of aluminum or

uranium. Journal of Geochemical Exploration, 92, pp 196-204.

21. Hassen, A., Saidi, N., Cherif, M. and Boudabous, A. (1998), Resistance of environmental

bacteria to heavy metals. Bio-resource Technology, 64, pp 7-15.

22. Hemraj, V., Diksha, S. and Avneet, G. (2013), A review on commonly used biochemical

tests for bacteria. Innovare Journal of Life Science, 1, 1-7.

23. Holt, J. G., Kreig, P. H. A., Sneath, J. T., Staley, T. and. Williams, S. T. (1994), Bergey’s

Manual of Determinative Bacteriology, 9th edition, Lippincott V. Williams and Wilkins,

Baltimore, USA.

24. Huddleston J. R., Zak J. C., and Jeter R. M. (2006), Antimicrobial susceptibilities of

Aeromonas spp. isolated from environmental sources. Applied and Environmental

Microbiology 72, pp 7036–7042.

25. Issazadeh, K., Jahanpour, N., Pourghorbanali, F., Raeisi, G. and Faekhondeh, J. (2013),

Heavy metal resistance by bacterial strains. Annals of Biological Research, 4, pp 60-63.

26. Jackson, V. A, Paulse A. N., Odendaal J. P., Khan S. and Khan W. (2012), Identification

of metal-tolerant organisms isolated from the Plankenburg River, Western Cape, South

Africa. Water SA, 38, pp 29-38.

27. Jafarzade, M., Mohamad S., Usup, G. and Ahmad, A. (2012), Heavy-metal tolerance and

antibiotic susceptibility of red pigmented bacteria isolated from marine environment.

Natural Resources, 3, pp 171-174.

28. Jeong, B. C and Macaskie, L. E. (1995), PhoN-type acid phosphatases of a heavy metal-

accumulating Citrobacter sp.: Resistance to heavy metals and affinity towards

phosphomonoester substrates. FEMS Microbiology Letters, 130, pp 211–214.

29. Kermanshahi, R. K., Ghazifard, A. and Tavakoli, A. (2007), Identification of bacteria

resistant to heavy metals in the soils of Isfahan province. Iranian Journal of Science &

Technology, Transaction A. 31, pp 7-16.

30. Kumar, A., Bisht, B. S. and Joshi, V. D. (2011), Bioremediation potential of three

acclimated bacteria with reference to heavy metal removal from waste. International

Journal of Environmental Sciences, 2, pp 896-908.

Page 11: Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

Isolation and characterization of zinc resistant bacteria from a coil coating industrial

wastewater treatment plant

Joshua B. Owolabi and Melanie M. Hekeu International Journal of Environmental Sciences Volume 5 No.5, 2015

1040

31. Lee, S. W., Glickmann, E., and Cooksey, D. A. (2001), Chromosomal locus for cadmium

resistance in Pseudomonas putida consisting of a cadmium-transporting ATPase and a

MerR family response regulator. Applied Environmental Microbiology, 67, pp 1437-

1444.

32. Leung, W. C., Wong, M-F, Chua, H., Lo, W., Yu, P. H. and Leung, C. K. (2000),

Removal and recovery of heavy metals by bacteria isolated from activated sludge treating

industrial effluents and municipal wastewater. Water Science & Technology 41, pp 233–

240.

33. Madigan, M. T., Martinko, J. M., Dunlap, P. V. and Clark, D. P. (2009), Brock Biology

of Microorganisms (12th ed.). Pearson Benjamin Cummings. ISBN 0-132-32460-1 pp 27-

28.

34. Mgbemena, C. I., Nnokwe, J. C., Adjeroh L.A. and Onyemekara N. N. (2012), Resistance

of bacteria isolated from Otamiri River to heavy metals and some selected antibiotics.

Current Research Journal of Biological Sciences, 4, pp 551-556.

35. Nageswaran, N., Ramteke, P. W., Verma O. P. amd Pandey A. (2012), Antibiotic

susceptibility and heavy metal tolerance pattern of Serratia marcesens isolated from soil

and water. Bioremediation and Biodegradation, 3, pp 158-167.

36. Nakamura K., Hagimine M., Sakai M. and Furukawa K. (1999), Removal of mercury

from mercury- contaminated sediments using a combined method of chemical leaching

and volatilization of mercury by bacteria. Biodegradation, 10, pp 443-447.

37. Nies, D. H., (1999), Microbial heavy-metal resistance. Applied Microbiology and

Biotechnology, 51, pp 730-750.

38. Nwaugo V. O., Onyeagba, R. A., Akubugwo, E. I. and Ugbogu, O. (2008), Soil bacterial

flora and enzymatic activities in zinc and lead contaminated soil. Biokemstri, 20, pp 77-

84.

39. Odokuma, L. O. and Akponah, E. (2010), Effect of nutrient supplementation on

biodegradation and metal uptake by three bacteria in crude oil impacted fresh and

brackish waters of the Niger Delta. Journal of Cell and Animal Biology, 4, pp 001-018.

40. Olukoya, D. K., Smith, S. I. and Ilori M. O. (1997), Isolation and characterization of

heavy metals resistant bacteria from Lagos Lagoon. Folia Microbiologica, 42, pp 441-

444.

41. Oketola, A. and Osibanjo, O. (2011), Assessment of industrial pollution load in Lagos,

Nigeria by industrial pollution project system (IPPS) versus effluent analysis,

environmental management in practice. Dr Elzbieta Broniewicz (Ed), ISBN: 978-953-

307-358-3. InTech, Available from:http://www.intechopen.com/books/environmental-

management-in-practice/assessment-of-industrial-pollutionload- in-lagos-nigeria-by-industrial-

pollution-projection-system, accessed during February 2015.

42. Okereke, C. D. (2007), Environmental Pollution Control. 1st Edition. Barloz Publication,

Owerri, Nigeria.

Page 12: Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

Isolation and characterization of zinc resistant bacteria from a coil coating industrial

wastewater treatment plant

Joshua B. Owolabi and Melanie M. Hekeu International Journal of Environmental Sciences Volume 5 No.5, 2015

1041

43. Okino, S., Iwasaki, K., Yagi, O. and Tanaka, H. (2002), Removal of mercuric chloride by

immobilized cells of genetically engineered mercury-volatilizing bacterium Pseudomonas

putida Pp Y101/pS134. Bill. Environmental Contamination and Toxicology, 68, pp 712-

719.

44. Olukoya D. K., Smith S. I. and M. O. Ilori (1997), Isolation and characterization of heavy

metals resistant bacteria from Lagos Lagoon. Folia Microbiologica (Praha). 42, pp 441-

444.

45. Osho, A., Mabekoje, O. O. and Bello, O. O. (2010), Preliminary evaluation of wastewater

effluents from two food companies in Nigeria. African Journal of Microbiology Research,

4, pp 1395-1399.

46. Oyetibo, G. O., Ilori, M. O., Adebusoye, S. A., Obayori, O. S. and Amund O. O. (2010),

Bacteria with dual resistance to elevated concentrations of heavy metals and antibiotics in

Nigeria in contaminated systems. Environmental Monitoring Assessment 168, pp 305-

314.

47. Sandrin, T. R. and Maier, R. M. (2003), Impact of metals on the biodegradation of

organic pollutants. Environmental Health Perspectives, 111, pp 1093–1101.

48. Sanuth H. A., Ogunjobi, A. A. and Fagade, O. E. (2010), The growth and survival of lead

solubilizing strains of Pseudomonas in the presence of carbon and nitrogen supplements

in a lead culture medium. Au Journal of Technology, 14, pp 88 - 96.

49. Sinha, K. R., Valani, D., Sinha, S., Singh, S. and Herat, S. (2009), Bioremediation of

contaminated sites: A low-cost nature biotechnology for environmental clean-up by

versatile microbes, plants and earthworms. In: Solid waste management and

environmental remediation. Timo Faerber and Johann Herzog. ISBN: 978-1-60741-761-

3.

50. Tamtam, F.,Van Oort, F., Lebot, B., Dinh, T., Mompelat, S., Chevreuil, M., Lamy, L.and

Thiry, M. (2011), Assessing the fate of antibiotic contaminants in metal contaminated

soils four years after cessation of long term waste water irrigation. Science of the Total

Environment, 405, pp 540-547.

51. U.S. Environmental Protection Agency (EPA) (1980), Development Document for the

Coil Coating Point Source Category. Effluent Guidelines Division. Office of Water and

Waste Management, Washington, D. C.

52. U.S. Environmental Protection Agency (EPA) (1998), Preliminary Industry

Characterization Metal Coil Surface Coating Industry.

53. U.S. Environmental Protection Agency (EPA) (2000), National Emission Standards for

Hazardous Air Pollutants: Metal Coil Surface Coating Industry Background Information

for Proposed Standards. Publication No. EPA-453/P-00-001 Research Triangle Park, NC.

Page 13: Isolation and characterization of zinc resistant bacteria from a coil coating wastetreatment plant

Isolation and characterization of zinc resistant bacteria from a coil coating industrial

wastewater treatment plant

Joshua B. Owolabi and Melanie M. Hekeu International Journal of Environmental Sciences Volume 5 No.5, 2015

1042

54. Xu, Y., Ruan, J., Hou, M., Zhao, X., Zheng, L., Zhou S. and Yuan B. (2014), Stress of

five heavy metals on the resistance of isolates from swine wastewater to four antibiotics.

Hydrology Current Research, 5, pp 1-5.

55. Yamina B, Tahar B, and Marie Laure F. (2012), Isolation and screening of heavy metal

resistant bacteria from wastewater: A study of heavy metal co-resistance and antibiotics

resistance. Water Science and Technology, 66, pp 2041-2048.

56. Yilmaz, E. I. (2003), Metal tolerance and biosorption capacity of Bacillus circulans strain

EB1. Research in Microbiology, 154, pp 409–415.