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Heterotrophic Activities in Eutrophic Lake Sediment by Indigenous Bacterium Bacillus Firmus

Md. Abdul Karim
Laboratory of Microbiology, Department of Botany, University of Dhaka, Dhaka-1000, Bangladesh

Sirajul Hoque
Department of Soil, Water and Environment, University of Dhaka, Dhaka 1000, Bangladesh

Nazneen Akhter
Laboratory of Microbiology, Department of Botany, University of Dhaka, Dhaka-1000, Bangladesh

Abstract/ Executive Summary:

Bacterial isolates, Bacillus firmus (LS-31) were collected from eutrophic Gulshan lake, Dhaka sediments and introduced to stimulate inorganic nutrient regeneration in the laboratory. The bacteria stimulated net regeneration of dissolved inorganic nitrogen and inorganic phosphorus in the water by about two folds at both the incubation temperatures (26°C and 30°C). These results suggest that the application of B. firmus would be promising for the stimulation of inorganic nutrient regeneration at the eutrophic environment.

Keywords: Bacillus firmus, Heterotrophic activity, Eutrophic environment

Location: Gulshan lake, Dhaka

Start Date: 26-09-2009

End Date: 02-10-2009

Program Area: Resource Development and Management

Non-commodity: Performance

Objectives:

1. Present work was undertaken to assses the role of a bacterial isolate to improve the water quality of an europhic lake by enhancing decomposition of organic pollutants.

Methodology:

Isolation and selection of bacteria: For isolation of effective bacteria that might be active at high temperature, surface water and sediment sample were collected twice (September 26 and October 2, 2009) from the Gulshan lake during summer when the temperature was between 26°C-30°C. After returning to the laboratory, 1 g of sediment sample was added to 100 ml of sterile distilled water and mixed it well and from which 1 ml of sediment suspension was inoculated into each of 10 test tubes containing 10 ml of nutrient broth medium and incubated at 37ºC for 48 hours. One ml of bacterial culture from each inoculated tube was transferred into new nutrient broth medium. It was continued until 4 times to enrich the bacteria. Finally, 0.1 ml of bacterial culture from each tube was inoculated onto nutrient agar plates, and incubated at 37ºC. Eighty fast growing bacterial isolates were isolated from the surface sediment of the study sites. Considering growth pattern, high metabolic activities and colony morphology, bacterial isolate LS-31 was selected to use in the present experiment. Inocula preparation and incubation: Bacterial broth culture was centrifuged at 10,000 rpm (Himac CR 21E, Hitachi) for 10 minutes at 10ºC. The supernatant was discarded and bacterial cells plate was gently rinsed with sterilized water at least five times in order to remove associated nutrients and re-suspended with the same sterilized water by pipetting. Five ml of bacterial cell re-suspension was used as inocula and it was inoculated into the water sample containing treatment glass bottle. The glass bottles were incubated in a light condition in situ (in duplicate) at 26ºC temperature during September 2010 and at 30ºC during October 2010 for 15 days without any shaking to estimate bacterial activities. Bacterial activities were evaluated by the changes of inorganic nutrient regeneration into the water during incubation with or without adding bacteria. Sub-sampling and nutrient analysis: Just after adding bacteria two glass bottles where one for control and another with bacteria (in duplicate) were taken at the beginning of the incubation (0-day). At 5 days interval up to 15 days, two glass bottles (in duplicate) were taken without any disturbance of the system and analyzed for chemical changes. For chemical analysis, water samples were passed through the filter paper (Whatman No. 42, England) to eliminate suspended solid particles. The concentrations of inorganic form of nitrogen (DIN) ammonium, nitrate and nitrite and phosphorus (DIP) were measured by the following standard methods. Morphological, cultural, physiological and biochemical studies of the isolate: Important morphological, physiological and biochemical characteristics were studied for the identification of the selected isolate. Morphological studies were performed by simple, gram and spore staining and observed under phase contrast microscope at 10X to 100X. Different biochemical tests were carried out following by standard methods.

Source of Information: Bangladesh J. Zool. 41(1): 73-78, 2013

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The results of the present experiment demonstrate that organic as well as inorganic pollutants of the fresh water many be reduced by decomposing the utilizing effective bacterial isolate.

Knowledge Management: Journal