Pemanfaatan Substrat Molasses dan Urea Pada Produksi Biopestisida oleh Bakteri Endofit (Pseudomonas putida) Menggunakan Bioreaktor Kolom Gelembung

Abstract

The main constraint in the cultivation of nilam (patchouli) is the decrease its production after being harvested 3-4 times. This is due to disease attacks, particularly nematode-a type of disease called Pratylenchus brachyurus. Besides inhibiting the plant growth, an infection of P. brachyurus also decreases the chlorophyll content and oil content of patchouli. A biological control using endophytic bacteria is one alternative to overcome this problem. For the ease of application in the field, the bacteria should be formulated and propagated. The propagation formulation is done by modifying cultivation media. This research aimed to study the utilization of molases and urea on the growth media of endophytic bacteria (Pseudomonas putida) by using a bubble column bioreactor, to get the best cultivation media formulation to produce the highest biomass dry weight, and to measure bacterial filtrate toxicity as a result of cultivation against nematodes (target mortality rate). This study included an analysis of pre-cultivation, during the cultivation process and post cultivation using a completely randomized experimental design of one factor. The factor used was the molases content consisting of 3 levels (molases of 1%, 1.25% and 1.5%) and urea content of 1%. The cultivation was carried out in a bubble column bioreactor with temperature of 25-30ºC, initial pH of 6.8-7.3 and aeration of 0.5v/v/m. The observation was conducted every 6 hours for 48 hours. The result showed that the formulation of media influenced the changes in pH and biomass formation. A molases content of 1.5% and urea content of 1% had the highest dry weight biomass, namely 3.495 (g/l). The efficiency value of the highest substrate utilization in a molases concentration of 1.5% and urea of 1% was 72.10%, with the highest cultivation kinetic parameters in the form of μmax of 0.147/hrs and a td-x of 4.714 hours. The highest value of Yx/s occurred at the molases concentration of 1.5% and urea of 1% for 0.257±0.067 g biomass per g substrate. The highest nematode mortality was at the molases concentration of 1.5% and urea of 1%, which had a positive correlation with dry weight biomass.