Screening of insecticide (carbofuran) degrading bacteria from soil

Abstract

Biodegradation by microflora in soil was very important since intensive pollutions occurred such as pesticide residues in soil and other pollutants. The aims of this study were to isolate the bacteria from the soil samples and to identify bacteria degrading carbofuran in soil. Soil collection was done at tobacco farms that had been investigated for the histories of carbofuran treatments situated in Merang, Terengganu. Soil pH and temperature were determined at the collection sites which are 30 °C and pH 5.75. Serial dilution and pour plate method in order to isolate bacteria from soil were conducted. Sum of three isolates finally being selected for treatment with carbofuran in enrichment cultures. Two controls were prepared which were Control A (trace element + carbofuran, no bacteria inserted) and Control B (bacteria + trace element, without carbofuran) in order to monitor and compare the growth of the tested bacteria. The growths of isolated bacteria were monitored by Optical Density (OD) 600 nm reading and plate count method in 2-days interval for 12 days. The graphs showed negative result of carbofuran degrading growth curves for all of the three isolates tested. Isolate 1, 2 and 3 showed decreasing growth of bacteria number in 12 days compared to bacteria number in control medium cultures and most of the growth graphs of isolates almost imitated the pattern of control graphs.