PENENTUAN WAKTU OPTIMUM PRODUKSI ANTIMIKROBA DAN UJI FITOKIMIA EKSTRAK KASAR FERMENTASI BAKTERI ENDOFIT Pseudomonas sp. DARI UMBI TANAMAN DAHLIA (Dahlia variabilis)

Abstract

Dahlia’s tuber have been known to be potential as the sources ofsecondary metabolite compound as antimicrobial. Some of endophytescould produced certain phytochemicals originally characteristic of thehost. A total number of four endophyte bacteria Pseudomonas stutzeriLBKURCC53, Pseudomonas stutzeri LBKURCC44, Pseudomonascepacia LBKURCC47, and Pseudomonas stutzeri or Pseudomonascepacia LBKURCC50 were isolated from Dahlia’s tuber in Padang Luar,West Sumatera. Optimization time of fermentation is necessary to obtainoptimum products of antimicrobial compound. Therefore, the study wasconducted to determine the effect of bacterial growth time on theproduction of antimicrobial compounds by endophyte bacteria.Antimicrobial activity examination was carried out through agar diffusionmethod by measuring inhibition zone growth against two pathogenbacteria, Escherichia coli and Staphylococcus aureus and then thephytochemicals were qualitatively estimated. The research resultsindicated that two of the endophyte bacterial isolates, Pseudomonasstutzeri LBKURCC44 and Pseudomonas cepacia LBKURCC47 haveantibacterial activity. Optimum time of fermentation for production ofantimicrobial compounds by Pseudomonas stutzeri LBKURCC44, andPseudomonas cepacia LBKURCC47 was obtained at 72 hours. Theinhibition zone of this compounds against Escherichia coli were (9,16 ±0,28) mm and (8,73 ± 0,17) mm, and Staphylococcus aureus were (9,66± 0,28) mm and (8,63 ± 0,33) mm. The qualitative phytochemicalsidentification of antibacterial compounds produced by endophyte bacteriaPseudomonas stutzeri LBKURCC44 and Pseudomonas cepaciaLBKURCC47 showed positive result for saponin.