Halomonas elongate produces ectoine to protect itselt from environmental stresses. In this research, important factors in the production of ectoine were optimized using statistical methods to achieve the best production efficiency in bioreactor. Screening important variables (ectoine, hydroxyectoine, L-aspartic acid, and glutamate) on H. elongate growth showed that ectoine and L-aspartic acid directly affect ectoine production. Two nanostructures, multiwalled carbon nanotube (MWCNT) and iron oxide nanoparticle (Fe 2 O 3 NPs), were used to increase the availability of substrate for the microorganism. The results showed that Fe 2 O 3 nanoparticles and MWCNT could have a negative or positive effect on bacterial growth and ectoine production depending on the concentration of nanoparticles. At optimized conditions, the amounts of bacterial growth and ectoine production in fermenter were 10.4 g/L and 14.25 g/L, respectively. Therefore, it could be concluded that nanoparticles improve bacterial growth and ectoine production at optimized concentrations.

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