In the present work, we undertaken to find strategies for improving the volumetric productivity of P(3HB-co-3HV) by Yangia sp. ND199 using molasses as the carbon source. For this, two-step fed-batch fermentation was designed to attain both high cell density and high P(3HB-co-3HV) content. | TAP CHI SINH HOC 2015,process 37(3): for 325-331 A fed-batch fermentation poly DOI: A FED-BATCH FERMENTATION PROCESS FOR POLY (3-HYDROXYBUTYRATE-co-3-HYDROXYVALERATE) PRODUCTION BY Yangia sp. ND199 USING MOLASSES AS SUBSTRATE Doan Van Thuoc1*, Tran Huu Phong1, Dang Minh Khuong2 1 Hanoi National University of Education, *thuocdv@ 2 Bao Yen 2 High School ABSTRACT: A locally isolated halophilic bacterium, Yangia sp. ND199 was able to use molasses as substrate for copolymers poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] production. Cell dry weight (CDW) of g/l, P(3HB-co-3HV) content of wt% and P(3HB-co3HV) concentration of g/l were obtained by Yangia sp. after 60 h of cultivation in flask. In a batch cultivation mode in a fermentor, the CDW was increased to g/l but P(3HB-co-3HV) content was decreased to 37 wt%. Fed-batch fermentation with two different nutrient feeding strategies was used. High CDW of g/l was obtained after 54 h of cultivation but P(3HB-co-3HV) content was still low ( wt%). Two-step fed-batch fermentation with two different nutrient feeding strategies was then designed. High CDW of 50 g/l and P(3HB-co-3HV) content of wt% were obtained after 54 h of cultivation. The two-step fed-batch process designed here for the production of P(3HBco-3HV) by Yangia sp. ND199 can be developed and used for further studies. Keywords: Yangia, fed-batch fermentation, molasses, P(3HB-co-3HV). INTRODUCTION Polyhydroxyalkanoates (PHAs) are a group of biodegradable polyesters of biological origin, PHAs accumulate intracellularly as carbon and energy storage materials in many microorganisms, usually when grown under the limitation of a nutrient, such as oxygen, nitrogen, phosphate, sulphur, or magnesium and in the presence of excess carbon [1, 14]. The properties of PHAs are similar to those of common petrochemical-based synthetic thermoplastics and can hence potentially replace them .
