| Summary: | Chlorinated herbicides especially dichlorophenoxyaceticacid (2,4-D) are one
of the synthetic pesticides still being used in Indonesia for agricultural intensification.
These herbicides are belonged to the class of organochlorines, recalcitrant and
persistent in the soil for about one month.. Only a few types of microbes, especially
bacteria were able to degrade the herbicide residues. These studies focused on the
biodegradation of dichlorophenoxyaceticacid (2,4-D) herbicides which are most
widely applied in the agricultural sector. The purpose of this study was to get the best
bacteria able to degradate 2,4-D, to analyze the mechanism of biodegradation of 2,4-
D by selected bacterial and to identify these bacteria.
These studies used seven types of indigenous soil bacterial isolates (strain
BLM 5-3, BLM 6-1, BLM 6-2, BLM 6-3, BLM 6-4, BLM 6-5 and BLM 6-6) from
volcanic soil around the slopes of Mount Merapi, Yogyakarta. The first step of the
research was to purify all isolates by single cell culture techniques. Their ability to
grow in liquid medium containing 2,4-D was determined through the growth
experiment. incubated at room temperature for 48 hours. At certain interval of time (1
hour), the isolates growth was measured by spectrophotometry (A600 nm), their
activity was determined based on the number of chlorine ions released in the medium
using Argentometry method (the titration), isolates that showed the highest activity of
chlorine release ion selected and partially identified using standard methods
(Bergey�s Manual of Determinative Bacteria). The results showed that all isolat could
grow on liquid medium, but only isolate of BLM 6-6 was able to degrade 2,4-D
within seven days and release chlorine ions up to 48 %. The results of the
identification of the isolate figured out its characteristic resembled to Pseudomonas
sp. the colony was circulair, translucent, baccil, gram negative and able to reduce
nitrate.
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