Mercury is one of the major pollutant in the environment which is highly toxic. Bioremediation strategies using bacteria have been proposed as an attractive alternative because this is effective, less expensive and more efficient to remove mercury. Brevundimonas sp. HgP1 and Brevundimonas sp. HgP2 were two highly mercury resistant bacteria isolated from a gold mine in Pongkor village with MIC of 575 ppm. The purposes of the research were to study the effect of mercury on bacterial growth and morphological changes of bacterial colony and to measure the ability of bacterial isolates to accumulate Hg 2+ . The growth was monitored by measuring optical density at 600 nm, whereas accumulation of Hg 2+ was measured by mercury vaporation unit. This present studies revealed that the addition of 50 and 100 ppm HgCl 2 in Brevundimonas sp. HgP1 resulted in the decreasing of growth rate and the elongation of lag phase in 8 and 16 hours, respectively. The addition of HgCl 2 also affected morphological appearance of the bacterial colony to black. Brevundimonas sp. HgP1 accumulated Hg 2+ up to 1.09 and 2.7 mg/g dry weight of cells and removed 64.38 and 57.10% Hg 2+ from the medium containing 50 and 100 ppm HgCl 2 , respectively.

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Detection of rhodamine B concentration in distilled water can be conducted without direct contact between the sensor probe and the sample using fiber bundle as a sensor probe and concave mirror as a sample container. e fiber bundle used is a concentric and a pair bundle probe. e working mechanism of the sensor is based on the displacement sensor and absorption of rhodamine B on laser light at a wavelength of 543 nm. e concentration of rhodamine B was detected through the valley and the peak voltage resulting from the displacement of the sensor probe to the sample surface. e best performance is shown by a sensor that uses a concentric bundle as a probe with a detection range of 0-20 ppm with a resolution of 0.6 ppm.

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