Saturday, 15 July 2006

Identification and Antimicrobial Activity of 2-Aminobenzoic Acid from Pantoea spp. Strain HB-22.

Hwangbo Hoon Sr., Jin Rong De, Cho Min Young, Na Sang su, Lim Hyoung Woo, Kim Kil Yong, and Kim Yong Woong. Division of Applied BioScience and Biotechnology, College of Agriculture and Life Science, Chonnam National Univ, 300, Yong Bong Dong, Buk Ku, Gwangju, South Korea

A phosphate solubilizing bacterium, HB-22 having a strong antimicrobial activity was isolated from cropland soil. Based on DNA sequence of a conserved partial 16S rRNA gene, was identified as Pantoea spp. To isolate antifungal compounds from culture filtrates of HB-22, the culture broth was extracted with ethyl acetate (EtOAc) and partitioned with a NaHCO3 buffer solution. Gram-positive bacterium, Staphylococcus aureus and Gram-negative bacterium Escherichia coli were used as the indicator for antimicrobial activity. The EtOAc-soluble acidic fraction showed strong antimicrobial activity against S. aureus and E. coli compared to EtOAc-soluble neutral fraction. The EtOAc-soluble acidic fraction (2.82 g) was subjected to silica gel adsorption column and then eluted with EtOAc-MeOH. The fraction (0.84 g) of 100% EtOAc eluate had a strong antimicrobial activity compared to other fractons. Chromatography on Sephadex LH-20 produced activity with a ratio for Ve/Vt (elution volume/total volume) of 1.06-1.08 eluate (150.1 mg). Purification through ODS, using a MeOH-H2O as the mobile phase, gave an active fraction at 100% MeOH eluate (41.35 mg). The active fraction purified by HPLC on an ODS column yielded a white powder (tR 13.06 min, 12.6 mg) with antimicrobial activity. The purified compound was identified, as 2-aminobenzoic acid using GC-EI-MS, which strongly inhibited Pythium ultimum and P. capsici on PDA medium supplemented with 100 to 300 g l-1. Scanning electron microscopic observation demonstrated that 2-aminobenzoic acid caused extensive hyphal deforming and destruction of R. solani.

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