Abstract:
Microcystin –LR (MC-LR) is considered to be the most dominant type of cyanobacterial toxins present in water
bodies. The present study focuses on using cellular extracts of Bacillus cereus in removal of MC-LR in water.
Bacterial cell extracts were prepared using overnight grown fresh cultures of B. cereus which was previously
recorded as a potent MC-LR degrading bacterium. Bacterial cell disruption was performed by bead beating on
a micro-mini bead beater. Cell debris was removed by centrifugation at 13000 rpm, 20 min. Subsequently, a
series of concentrations of cellular extract (100%, 75%, 50% and 25%) was prepared. These cell extracts were
separately incubated at 280C with 100μg ml-1 of MC-LR for a period of 4 days. 1ml aliquots were removed at
24 hour intervals for four days and frozen at (-20) 0C. Then frozen samples were freeze-dried and subjected to
Photo diode array- High Performance Liquid Chromatography (PDA-HPLC) analysis to detect the remaining
MC-LR concentrations of the samples. At the end of fourth day, 81.1 μgml-1 of MC-LR was removed when 100%
of cell extract was used. When 75 % of cell extract was used, 77.6 μgml-1 of MC-LR removal was evident at the
end of fourth day. Whereas when 50 % and 25% of cell extract were used only 40.7 μgml-1 and 25.7 μgml-1 of
MC-LR removal was detected respectively. The results of the present study indicate that bacterial cell extracts of
B. cereus has the ability to remove MC-LR by an enzyme mediated mechanism.
