Levels of some toxic elements and frequency of bacterial heavy metal resistance in sediment and sea water

Abstract

The Golden Horn Estuary located in the Istanbul region of Turkey has been thought to be a heavily polluted area since the 1950s: the concentration of the elements, which include heavy metals such as Cu2+, Mn2+, Ni2+, Zn2+, Pb2+, Cd2+, and Fe2+, was therefore investigated in sediment and water samples of the area. The resistance of Enterobacteriaceae members to some heavy metal salts was investigated to determine levels of metal-resistant bacteria in the Golden Horn Estuary after the environmental restoration project in 1998. The sediment samples were collected with an Ekman-Grab in the period from November 2002 to February 2004 from depths of 4-15 m and analyzed by means of an atomic absorption spectrophotometer. Analyses of average heavy metals of sediment samples yielded the following results: 131.5 ppm Cu, 405.5 ppm Mn, 46.5 ppm Ni, 191.2 ppm Zn, 81.5 ppm Pb and 27668 ppm Fe. As with water, Ni concentrations in sediment were found lower than that in limit values. Frequency of heavy metals resistance to Cu, Zn, Fe, Ni, Mn, Pb and Cd was detected as an average of 65.0%, 64.4%, 62.5%, 38.4%, 37.3%, 36.2% and 28.4%, respectively in a total of 192 strains isolated from sediment samples. It was observed that there was no statistically significant difference among the results of analyses with respect to sampling dates. Despite the environmental restoration project in 1998, our study results showed that heavy metal levels were still high in the sediment and this situation induced the tolerance of bacteria to some heavy metals.

A Bacillus sp. isolated from sediments of the Sarno River mouth, Gulf of Naples (Italy) produces a biofilm biosorbing Pb(II)

“…This suggests that this strain experiences frequent exposure to Pb in nature. A study conducted at the Golden Horn Estuary close to Istanbul (Turkey), known to be heavily polluted by heavy metals such as Pb(II), Cu(II), Mn(II), Ni(II), Zn(II), Cd(II), and Fe(II), showed average concentrations of these metals comparable to what found in this study and percentages of resistant bacterial strains ranging from 28% to 65% of total isolates, depending on the metal investigated (Altug and Balkis, 2009). This suggests that many bacteria can develop resistance and thrive even in the presence of such toxic metals.…”

A Gateway to Metal Resistance: Bacterial Response to Heavy Metal Toxicity in the Biological Environment

“…However, drug resistances have been found associated with heavy metal resistance factors in samples from sewage [107], polluted sites [108] and clinical sources [109,110]. In fact, resistance to heavy metals is virtually always found associated with resistance to antibiotics [111,112] and the frequency of heavy metal resistance is often the same as or higher than the frequency of drug resistance [113]. Resistant Bacillus populations have a greater frequency in sites polluted by mercury containing sewage sludge than in unpolluted sites, and ampicillin resistance follows the same pattern [114][115][116].…”

Time Scale Changes in the Water Quality of the Ganga River, India and Estimation of Suitability for Exotic and Hardy Fishes

“…Over the last two decades huge scale usage of chemicals in various human activities has grown very rapidly. In developing and underdeveloped countries, the industrial and domestic effluents are release directly or indirectly into the large water bodies [14,15].…”