Removal of heavy metals from contaminated sites, using microorganisms is a cheaper alternative to chemical technologies, there is therefore a need to isolate identity and characterize  the fungal microorganisms that exist and interact in contaminated environment. Investigation were carried out to isolate fungal strains from the battery manufactured polluted soil at mechanic shop line, Mgbuka Obosi of Anambra State and to test their metal tolerance to lead (Pb), pure cultures were isolated, and characterized. The isolates UM1 to UM4 are greenish in colour while UM5 blackish in colour. UM1 to UM5 were identified as Aspergillus except UM3 which was identified as both Aspergillus and Penicillum. Different diameters of the isolates was measured at four different point. Determination of minimum inhibitory concentration (MIC) range of 100g/ml- 2000g/ml with lead nitrate and was found that all the isolates exhibit high resistance to lead. It has also been noticed that the intracellular accumulation of lead (Pb) changes the color of colonies grown on media with lead, isolates at 100g/ml of um1 shows maximal diameter while 2000g /ml of um1 shows minimal diameter (0.45cm). After isolation, the 5 pure cultures of the fungal strains were characterized. Data indicated that the isolated fungi are highly tolerant to lead.





1.0 Introduction

Lead (Pb) is non-bioessential persistent and hazardous heavy metal pollutant of environmental concern. Bioremediation has, become a potential alternate to the existing technologies for the removal and recovery of toxic lead from motor battery dumping area. (Amini et al., 2008).

Environmental contamination by toxic metals, is a serious problem worldwide due to their incremental accumulation in the food chain and continued persistence in the ecosystem. Conventional technologies, such as ion exchange or line precipitation, are often ineffective and or expensive particularly for the removal of heavy metal ions. The use of microorganisms to destroy, or reduce the concentration of, hazardous waste on a contaminated site is called bioremediation (Amini et al.,2008).  Indigenous microbial specie that has high resistance to lead have been isolated from the waste water sample, which was characterized and identified as Staphylococcus species. Maximum lead tolerance up to 100mg/ml was evidenced by isolated Staphylococcus species, effect on pH on lead degradation by Staphylococcus shows the rate of lead removal was maximum at pH6, optimum temperature of 30oc and incubation time at 48 hours. Effect of initial metal concentration on lead degradation by Staphylococcus shows the rate of lead degradation was constantly high until 300mg/l and then after it decreased. Under optimum process conditions Staphylococcus is able to degrade lead up to 83% in 48 hours, (Amini, et al., 2008). In microbiology, the  term isolation refers to the separation of a strain from a  natural, mixed population of living  microbes as present  in the environment, for example in soil flora water, or  from living being  with skin flora, oral flora or gut flora, in order to identify the microbes of interest. Historically, the laboratory techniques of isolation first developed on the field of bacteriology and Parastiology (during the 19th century before those in virology during the 20th century. Methods of microbial isolation have drastically changed over the past 50 years from a labor perspective with increasing mechanization and in regard to the technology involved. Environmental biotechnology strategies must address and  solve in a long-term perspective, the formidable environmental problem facing the world, such  as soil contamination with pesticides, metals or hydrocarbon, disposal of animal manures, treatment of waste  waters  or recovery of revisable products and energy from wastes (Singh et al., 2010).

There is therefore a need to isolate, identify and characterize the microorganisms that exist and interact in contaminated environment. (Singh et al., 2010).


  • Aim of the Study

To isolate and characterize highly lead tolerant microorganism.

To determine the lead content of soil samples.

To determine the pH (acidity and alkalinity) of the soil samples.