Employing Response Surface Methodology for Optimization of Mercury Bioremediation by Vibrio parahaemolyticus PG02 in Coastal Sediments of Bushehr, Iran

Abstract

Three bacterial species of PG01, PG02, and PG03 were isolated from coastal sediments of Bushehr (Iran) as mercury‐resistant bacteria. According to 16S ribosomal DNA gene sequence, the strains were identified as Vibrio natriegens, Vibrio parahaemolyticus, and Oceanimonas baumannii, respectively. Minimum inhibitory concentration test in the presence of HgCl2 revealed that the strain PG02 was the most resistant one, which tolerated up to 45 mg L−1 Hg2+. Tracing the growth curves for the PG02 showed that when it is initially exposed to 5 mg L−1 Hg2+ in the medium, only 10% of its natural growth is reduced, while it simultaneously succeeds to remove 90% of mercury. However, initially 10 mg L−1 Hg2+ in the medium led to 30% growth inhibition and 80% mercury removal. According to a linear relationship between the growth inhibition percentage and the initial mercury concentrations, the median effective concentration was calculated as 21.84 mg L−1 for PG02. Central composite design under response surface methodology well proposed a model with high values of R2 = 0.999 and adjusted R2 = 0.998 which predicted the maximum mercury removal of 89.47% by PG02 under optimum pH of 7.2, temperature of 37.5°C and the initial mercury concentration of 5 mg L−1.

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Adsorption Study of Arsenic Removal by Novel Hybrid Copper Impregnated Tufa Adsorbents in a Batch System

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“…The coded and operational values of the selected variables are shown in Supporting Information Tab. S1, together with the experimental plan, which comprised 16 experimental runs plus six replicates on the central point . Each experiment (except the central point) was performed in duplicate.…”

Contaminated Aquatic Sediments

“…Metals Biodegradation. One of three bacterial species were isolated from coastal sediments of Bushehr (Iran) as the most mercury-resistant bacteria that removed 90% of mercury (Jafari et al, 2015). A proposed model with R 2 = 0.999 predicted the maximum mercury removal of 89.47% by the bacteria under optimum pH of 7.2, temperature of 37.5 °C and the initial mercury concentration of 5 mg L −1 .…”