Heavy metal degradable halophilic bacteria isolation from soil in Samut Sakhon, Thailand

Abstract

This research was conducted to select halophilic microorganisms that can reduce heavy metals in water to be used in wastewater treatment. Halophilic bacteria from salt field soil were isolated in nutrient broth containing 5 heavy metals compound (Zn, Co, Cr, Hg, and Cu). 20 isolates which growth in heavy metal containing media were screened. After that, experiment was conducted to determine the maximum concentration of heavy metals that the isolated could growth. The concentration of heavy metals was obtained from 50-500 mg/L. In media which add Zn, Co, Cr and Cu compound, the isolated were found to be able to grow at concentrations of 450-500 mg/L but they did not grow in media which add Hg (50-500 mg/L). To check the heavy metal degrading ability, the isolates were cultured in nutrient broth which add the most concentrated of heavy metal that they could grow and incubated at 37 ° C for 15 days. Measured the remaining heavy metals and counted the number of microorganisms on days 3, 5,7,10 and 15 were done. It was found that microorganisms were capable to reduce two heavy metals, Cr and Co. Cr reduced by the isolated HL7 and 10-20. Co reduced by the isolated HL1, 3, 4, 5, 7, 8, 10, 11 and 15. Zn and Cu decreased at the decimal level, which were not significant. The results of this research showed that the isolated of halophilic bacteria which isolated from soil in Samut Sakhon had the ability to reduce some heavy metals, which can be applied in wastewater treatment.