| dc.description.abstract | There are several acts of antagonisms by bacteria toward phytopathogen and one of them is by
producing antimicrobial compounds such as antibiotics. In dual plate tests, Pseudomonadaceae
SH2a and Pantoea sp. MO22g showed ability to inhibit the growth of Xanthomonas oryzae pv.
oryzae (Xoo) which causes bacterial leaf blight disease of rice. These antagonistic bacteria have
been isolated from rice phyllospheres from Wonogiri and Sukoharjo Regency, Central Java,
Indonesia. This activity may suggest that those bacteria produce antibiotics as antimicrobial agents.
Therefore, extraction and identification of their bioactive compounds were conducted to confirm
the validity of antibiotics production. Stratified extraction based on polarity of solvents was
performed using n-hexane, ethyl acetate, and methanol. Furthermore, column chromatography
and UV-VIS spectrophotometer were used to classify groups of bioactive compounds. Disc diffusion
method was also used to determine anti-Xoo activity of bioactive compounds in each fraction. The
results showed that bioactive compounds from the methanol fraction of Pseudomonadaceae SH2a
showed greater inhibitory activity against Xoo than its crude extract and the n-hexane fraction of
Pantoea sp. MO22g. The Methanol fraction of Pseudomonadaceae SH2a contains bioactive
compounds such as polyketide (pyoluteorin and 2,4-diacetylphloroglucinol), phenazine,
pyrrolnitrin, peptides, terpenoids, alkaloids, and lipopeptide groups, while the n-hexane fraction of
Pantoea sp. MO22g contains bioactive compounds such as polyketide, terpenoids, and alkaloids
groups. | id |
