ECTOINE PRODUCTION BY HALOMONAS ELONGATA BK-AG25: TWO-STEP OPTIMIZATION USING THE RESPONSE SURFACE METHODOLOGYI PUTU PARWATA, DEANA WAHYUNINGRUM, SONY SUHANDONO AND RUKMAN HERTADIAbstract This study is aimed to optimize ectoine production by Halomonas elongata BK-AG25 with a twostep cultivation method. First, the bacteria were cultivated in MM63 media containing a moderate level of salt to obtain optimal biomass, followed by cultivation using the same media with a higher level of salt to gain maximum ectoine production. The level of nutrients in MM63 media and the incubation temperature were optimized using the response surface methodology (RSM). Using a central composite design to attain the optimal conditions for biomass level and ectoine production. The RSM model predicted a maximum biomass level of about 5.04 mg/mL when the bacteria were first cultivated at 37.4 oC in MM63 media. The model also predicted that a maximum ectoine production will reach about 186.4 mg/g of cell dry weight after the second cultivation in MM63 media with an NaCl level of 18% [w/v] at 33 °C. The experimental result following this two-step cultivation obtained a biomass level of 4.92 mg/mL and ectoine production of 179.9 mg/g of cell dry weight. The results showed that two-step cultivation was an effective method for elevating both the biomass level and ectoine productions. |