Research in Biotechnology, 4(6): 21-29, 2013 ISSN: 2229-791X www.researchinbiotechnology.com Regular Article Effects of medium and culture conditions on folate production by Streptococcus thermophilus BAA-250 Seyed Sadegh Mousavi 1 , Hassan Moeini 2 , Rosfarizan Mohamad 1,2* , Mojdeh Dinarvand 1 , Arbakariya Ariff 1,2 , Foo Hooi Ling 1,2 and Abdul Rahim Raha 2, 3 1 Department of Bioprocess Technology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malatsiay, Selangor, Malaysia 2 Institute of Bioscience, Universiti Putra Malaysia, Selangor, Malaysia 3 Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Selangor, Malaysia *Corresponding author Email: farizan@biotech.upm.edu.my The present study was conducted to investigate the effects of culture conditions on folate production by Streptococcus thermophilus BAA-250. Lactose (3g/L) and yeast extract (20g/L) were found to be the more suitable carbon and nitrogen sources for folate production by S. thermophilus BAA-250. para-aminobenzoic acid (pABA) higher than 1 μM had no significant effect on folate biosynthesis. The optimum pH for folate production was shown to be 7.0 with a folate yield and productivity of 54.53 (μg/L) and 2.27 (μg/L.h), respectively. Optimum folate production obtained in the presence of lactose and yeast extract in a controlled pH of 7 during batch fermentation in bioreactor. Kinetic studies indicated that folate production by S. thermophilus is growth-associated process. Keywords: Folate, Lactic acid bacteria, Kinetic model, Streptococcus thermophilus. Folate is a water soluble group of B- vitamins with related biological activity which is synthesized from guanosine-5'- triphosphate (GTP), p-aminobenzoate (PABA), and glutamate (Basset et al., 2005; Wegkamp et al., 2007). Various green plants and some microorganisms produce folate. Numerous studies have shown that lactic acid bacteria (LAB) such as Lactococcus lactis, Lactobacillus bulgaricus and Streptococcus thermophilus have the ability to produce folate in fermented foods (Crittenden et al., 2003; LeBlanc et al., 2007; Lin & Young, 2000; Papastoyiannidis et al., 2006). There is limited information about the parameters that influence folate biosynthesis by LAB used for the production of dairy products (Crittenden et al., 2003; Lin & Young, 2000; Sybesma et al., 2003b). Therefore, the present study was conducted to investigate the effect of culture conditions, such as carbon and nitrogen sources, p-aminobenzoic (PABA) concentration, and pH on influence folate production by S. thermophilus BAA-250. In this work, kinetics models for folate production and the growth of the strain were also described.