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Growth of Pseudomonas Spp. Capable of Degrading Chlorinated Pesticides

SYEDA MAHRUH BARNINI
Department of Microbiology, University of Dhaka, Dhaka-1000, Bangladesh

MAHMUDA YASMIN
Department of Microbiology, University of Dhaka, Dhaka-1000, Bangladesh

ANOWARA BEGUM
Department of Microbiology, University of Dhaka, Dhaka-1000, Bangladesh

MAJIBAR RAHMANI
Department of Microbiology, University of Dhaka, Dhaka-1000, Bangladesh

Abstract/ Executive Summary:

The present study attempted to isolate and identify bacteria that were capable of degrading the chlorinated pesticide, dichloroacetic acid (DCA). Three different species of Pseudomonas such as, P. pud ita, P. aerugenosa and P. fluorescens were isolated from the soil samples by growing them in mineral media (MM) containing DCA as the sole carbon and energy sources . The bacteria were found to grow well in MM and maximum growth was obtained after 48 h of incubation. Dehalogenase activity of the three strains were also assessed. Maximal enzyme activity was found after 48 h which correlated well with the growth of these strains.

Keywords: Pseudomonas spp., Pesticide, Dehalogenase

Location: Botanical garden of Dhaka University

Start Date:

End Date:

Program Area: Pest Management

Commodity: Becteriocides

Objectives:

To isolate and identify the bacteria that were capable of degrading chlorinated pesticides.

Methodology:

Soil samples were collected from the Botanical garden of Dhaka University. After collection of samples, one gram of soil was mixed with dichloroacetic acid (a representative chlorinated pesticide) as per recommended dose (0.5 g C/l). The sample was then serially diluted and 0.1 ml was inoculated on nutrient agar and cetrimide agar plates by spread plate technique and incubated at 37°C for 18 - 24 h. After incubation, twenty different colonies were isolated . Out of 20, three were identified (named as PD-1, PD-2 and PD-3) according to Bergey's Manual of Systematic Bacteriology (9th ed.). A single colony from nutrient agar plate was inoculated in 10.0 ml nutrient broth and incubated overnight at 150 rpm and 37°C in a temperature controlled orbital shaker. After incubation, again 1.0 ml of bacterial suspension was inoculated in 100.0 ml nutrient broth and were incubated in an orbital shaker at 150 rpm at 37°C. At the log phase of growth, recommended dose of DCA was added as a carbon source. The release of chloride ions were determined according to the method of Bergmann and Sanik after addition of pesticide and since then measurement of chloride ions was made every 6 h of growth. Concentration of chloride ions in the medium indicates whether the strain is utilizing the pesticide or not. Chloride ions were released into the medium as a result of breakdown of the pesticide. Indirectly, release of chloride ions indicates the presence of dehalogenase activity of the bacteria. Dehalogenase activity was assessed according to the method of Slater et al.

Source of Information: Dhaka Univ. J. Biol. Sci. 10(2): 191-195, 2001 (July)

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The bacteria were found to grow well in MM and maximum growth was obtained after 48 h of incubation. Dehalogenase activity of the three strains were also assessed. Maximal enzyme activity was found after 48 h which correlated well with the growth of these strains.

Knowledge Management: Journal