Biosynthesis Of Indole-3-Acetic Acid By Bacillus cereus Immobilized Cells

Abstract. Four different strains of Bacillus cereus producing indole-3-acetic acid (IAA) were isolated from various rhizospheric soils and characterized biochemically. The isolates were screened for (IAA) production and BC-On strain was found to be the best IAA producer with 46.25 mg/l. Maximum IAA production was obtained in the stationary growth phase at 72h. Significant correlation was also observed between IAA production and growth of the B. cereus strains. Among the isolates, BC-On strain was further used for immobilization studies. Maximum IAA production was obtained at initial pH of 8.0 and temperature of 35 °C after 18 h of fermentation. The immobilized cells could be effectively reused thirteen times and the IAA concentration of 300 mg/l was determined during this period. Results showed that immobilized cells can be used in the continuous process for the production of IAA. The productivity obtained by immobilization was higher than the one obtained by submerged cultivation and immobilization reduced the fermentation time. Keywords: Indole-3-acetic acid, Rhizobacteria, Bacillus cereus, Immobilization Ozet. Indol-3-asetik asit (IAA) ureten dort farkli Bacillus cereus straini cesitli rizosfer topraklarindan izole edildi ve biyokimyasal olarak karakterize edilmistir. Izolatlar IAA uretimi icin taranmis ve BC-On straini 46.25  mg/l ile en iyi IAA ureticisi olarak bulunmustur. En fazla IAA uretimi 72. saatte duragan buyume fazinda elde edilmistir. B. cereus strainlerinin IAA uretimi ve buyume arasinda onemli bir iliski gozlenmistir. Izolatlar arasinda, BC-On straini immobilizasyon calismalarinda kullanilmistir. En fazla IAA uretimi 18 saatlik fermentasyon sonrasinda baslangic pH’si 8.0 ve 35 °C elde edilmistir. Immobilize edilmis hucreler etkili olarak on uc kez kullanilabilmis ve bu sure boyunca 300 mg/l IAA konsantrasyonu tespit edilmistir. Sonuclar immobilize hucrelerin IAA uretimi icin surekli bir islemde kullanilabilir oldugunu gostermistir. Immobilizasyon ile elde edilen verimlilik, derin fermentasyon ile elde edilenden daha yuksek oldugu bulunmus ve immobilizasyon fermentasyon suresini kisaltmistir. Anahtar Kelimeler: Indol-3-asetik asit, Rizobakteriler, Bacillus cereus, Immobilizasyon