Haematococcus pluvialis Whole Cell Biosensor for Heavy Metal Detection

Suzan, Nakayiza (2017) Haematococcus pluvialis Whole Cell Biosensor for Heavy Metal Detection. Other thesis, INTI International University.

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Abstract

Tonnes of heavy metals are deposited onto the environment every year causing high water contamination which has become a major concern for health regulatory bodies world-wide. So there is need to develop screening methods for rapid and accurate detection of heavy metals. Hence a novel Haematococcus pluvialis whole cell biosensor was developed utilizing astaxanthin as a bio-reporter for detection of presence of heavy metals Cd, Pb and Ni. Haematococcus pluvialis cells were immobilized with agarose and exposed to heavy metals cadmium, lead and nickel. The astaxanthin response was detected spectrophotometrically at wavelength 482nm. The biosensor produced the highest absorbance response with cell immobilized at day 3 with a density of 5 x 10 cells/ cuvette. pH was found to affect the response of biosensor, with the highest response produced at pH 5. The biosensor was able to detect presence of both Cd and Pb with in a linear range of 0.001 to 1.00 mg/L for both Cd and Pb while the linear detection range for Ni was found to be with 0.001-5.00 mg/L range. The results showed that astaxanthin is naturally present in Haematococcus pluvialis at low concentration but can be induced due to oxidative stress from increased reactive oxygen species induced by the heavy metals in the cells which triggers increased biosynthesis of astaxanthin. Astaxanthin is an antioxidant and acts a defense mechanism to protect the cell against oxidative damage. Additionally, Haematococcus pluvialis biosensor produced a high and rapid response within 15 minutes on exposure to heavy metal hence the designed biosensor, showed good potential for detection of heavy metals for environmental toxicity monitoring.

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