en Pharmaceutical Biotechnology Pharmaceutical Biotechnology مقاله کامل Full Length/Original Article <strong>Background:</strong> Levan or fructan, a polysaccharide of fructose, is widely used in various commercial industries. Levan could be produced by many organisms, including plants and bacteria. The cloning of the gene from <em>Bacillus licheniformis</em>, which expressed levansucrase in <em>Escherichia coli</em> host, was carried out successfully. In the present study, we performed the <em>in vitro </em>production of levan and analyzed its potential application as antibacterial and antioxidant agents. <strong>Methods:</strong> <em>In vitro</em> levan production catalyzed by heterologous-expressed levansucrase Lsbl-bk1 and Lsbl-bk2 was optimized with Box-Wilson design. The antibacterial activity of the produced levan was carried out using agar well diffusion method, while its antioxidant activity was tested by free radical scavenging assays. <strong>Results: </strong>The optimum conditions for levan production were observed at 36 &deg;C and pH 7 in 12% (w/v) sucrose for levansucrase Lsbl-bk1, while the optimum catalysis of levansucrase Lsbl-bk2 was obtained at 32 ^oC and pH 8 in the same sucrose concentration. The <em>in vitro</em> synthesized levan showed an antibacterial activity within a concentration range of 10-20% (w/v) against <em>Staphylococcus aureus</em>, <em>E. coli</em>, and <em>Pseudomonas aeruginosa</em>. The same levan was also able to inhibit the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity with the antioxidant strength of 75% compared to ascorbic acid inhibition. <strong>Conclusion: </strong>Our study, therefore, shows that the optimized heterologous expression of levansucrases encoded by Lsbl-bk1 and Lsbl-bk2 could open the way for industrial levan production as an antibacterial and antioxidant agent. Antioxidants, Fructans, In vitro technique, Levan 202 212 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-3966-1&slc_lang=en&sid=1 Rukman Hertadi capa.journal115@klinikjurnal.com 0000-0002-4352-5830 Yes Biochemistry Research Division, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology Nur Permatasari nur_permatasari@yahoo.com 0000-0001-6597-9510 No Chemistry Department, Faculty of Mathematics and Natural Sciences, Hasanuddin University Enny Ratnaningsih enny.ratnaningsih01@yahoo.com 0000-0001-9114-2167 No Biochemistry Research Division, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology