title: Improved vitamin B(12) production by step-wise reduction of oxygen uptake rate under dissolved oxygen limiting level during fermentation process.
abstract: Effects of different oxygen transfer rates (OTR) on the cell growth and vitamin B(12) biosynthesis of Pseudomonas denitrificans were first investigated under dissolved oxygen limiting conditions. The results demonstrated that high OTR accelerated cell growth and initial vitamin B(12) biosynthesis rate, while lower OTR was critical for higher productivity in the late fermentation process. The oxygen uptake rates (OUR) corresponded well with OTR. Based on the metabolic intermediate analysis, a step-wise OUR control strategy was proposed. The strategy was successfully implemented in scale-up to an industrial fermenter (120,000 l). A stable maximum vitamin B(12) production of 208 + or - 2.5 mg/l was achieved, which was increased by 17.3% compared with the control. Furthermore, the glucose consumption coefficient to vitamin B(12) was 34.4% lower than that of the control. An efficient and economical fermentation process based on OUR criterion was established for industrial vitamin B(12) fermentation by P. denitrificans.
authors.affiliation: State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, People's Republic of China.
authors.forename: Ze-Jian
authors.initials: ZJ
authors.lastname: Wang
authors.forename: Hui-Yuan
authors.initials: HY
authors.lastname: Wang
authors.forename: Yong-Liang
authors.initials: YL
authors.lastname: Li
authors.forename: Ju
authors.initials: J
authors.lastname: Chu
authors.forename: Ming-Zhi
authors.initials: MZ
authors.lastname: Huang
authors.forename: Ying-Ping
authors.initials: YP
authors.lastname: Zhuang
authors.forename: Si-Liang
authors.initials: SL
authors.lastname: Zhang
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D000622:Aminolevulinic Acid / Q000378:metabolism; D019149:Bioreactors; D001709:Biotechnology / Q000379:methods*; D002245:Carbon Dioxide / Q000378:metabolism; D005285:Fermentation; D010100:Oxygen / Q000378:metabolism*; D011549:Pseudomonas / Q000378:metabolism*; D014805:Vitamin B 12 / Q000096:biosynthesis*
chemical_list: D000596:Amino Acids; D002245:Carbon Dioxide; D000622:Aminolevulinic Acid; D014805:Vitamin B 12; D010100:Oxygen