title: Enhanced butyric acid tolerance and bioproduction by Clostridium tyrobutyricum immobilized in a fibrous bed bioreactor.
abstract: Repeated fed-batch fermentation of glucose by Clostridium tyrobutyricum immobilized in a fibrous bed bioreactor (FBB) was successfully employed to produce butyric acid at a high final concentration as well as to adapt a butyric-acid-tolerant strain. At the end of the eighth fed-batch fermentation, the butyric acid concentration reached 86.9 ± 2.17 g/L, which to our knowledge is the highest butyric acid concentration ever produced in the traditional fermentation process. To understand the mechanism and factors contributing to the improved butyric acid production and enhanced acid tolerance, adapted strains were harvested from the FBB and characterized for their physiological properties, including specific growth rate, acid-forming enzymes, intracellular pH, membrane-bound ATPase and cell morphology. Compared with the original culture used to seed the bioreactor, the adapted culture showed significantly reduced inhibition effects of butyric acid on specific growth rate, cellular activities of butyric-acid-forming enzyme phosphotransbutyrylase (PTB) and ATPase, together with elevated intracellular pH, and elongated rod morphology.
authors.affiliation: School of Bioscience and Bioengineering, South China University of Technology, Guangzhou 510640, PR China.
authors.forename: Ling
authors.initials: L
authors.lastname: Jiang
authors.forename: Jufang
authors.initials: J
authors.lastname: Wang
authors.forename: Shizhong
authors.initials: S
authors.lastname: Liang
authors.forename: Jin
authors.initials: J
authors.lastname: Cai
authors.forename: Zhinan
authors.initials: Z
authors.lastname: Xu
authors.forename: Peilin
authors.initials: P
authors.lastname: Cen
authors.forename: Shangtian
authors.initials: S
authors.lastname: Yang
authors.forename: Shuang
authors.initials: S
authors.lastname: Li
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000378:metabolism / Q000633:toxicity; D019149:Bioreactors / Q000382:microbiology*; D020148:Butyric Acid / Q000378:metabolism* / Q000633:toxicity*; D002462:Cell Membrane / Q000201:enzymology; D018914:Cells, Immobilized / Q000187:drug effects* / Q000378:metabolism*; D048014:Clostridium tyrobutyricum / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D003600:Cytosol / Q000737:chemistry; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008853:Microscopy; D010709:Phosphate Acetyltransferase / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D020148:Butyric Acid; D010709:Phosphate Acetyltransferase; D000251:Adenosine Triphosphatases; D005947:Glucose