Aktivitas Kitinolitik Bakteri Diazotrof Isolat Rhizosfer Kelapa Sawit Terhadap Ganoderma boninense, Pat

Abstract

Diazotrophs are microorganisms that are able to fix nitrogen from atmosphere and sometimes used as biological control agents of fungal pathogens such as Ganoderma boninense. As biological control agent, dizotroph bacteria may produce the chitinolytic enzymes to lysis fungal cell wall. The aims of this study were to obtain of chitinolytic diazotrophic bacteria from rhizosphere of oil palm, screening their antagonistic activity against G. boninense and tested of selected isolates to the lysis activity their chitinase enzymes agaist cell walls of G. boninense. The diazotrophs bacteria were isolated from the rhizosphere of oil palm farm of Universitas Sumatera Utara. Firstly, chitinolytic bacteria was isolated from rhizosphere samples with chitin agar medium. Then, the positive chitinolytic bacteria were inoculated to Ashby’s agar medium to confirmation that isolated bacteria were diazotrophs. The chitinolytic diazotroph bacteria were characterized the morphology and Gram type. Antagonistic activity of diazotrophics bacteria were tested by dual culture assay toward G. boninense. The chitinolytics activity of diazotrophic bacteria was determined qualitatively. The potential isolates of bacteria with chitinolytic and antagonistic activity were tested for their enzyme activity to lysis of G. boninense cell wall. About 12 isolates of chitinolytic diazotrophic bacteria were obtain in this research. All of bacteria was Gram negative and have chitinolytic activity in the range index between 1.50 until 3.73. The antagonistic test obtained five potential isolates with percentage of inhibition activity against G. boninense was ranged from 4.1% to 20.2%. Isolates bacteria with the highest chitinolytic activity To 07 were able to lysis of G. boninense cell wall and released of N-acetyl glucosamine in the medium.