Effect Of Oxygen Supply On Fermentation Production Of A Novel Anti-phytopathogenic Compound 2-heptyl-5-hexylfuran-3-carboxylic Acid

One Pseudomonas strain with antagonistic activity against rice sheath blight was isolated from the rhizosphere of the rice by our lab. The novel anti-phytopathogennic compound 2-heptyl-5-hexylfuran-3- carboxylic acid (HHCA) produced by this strain can inhibit the growth of Rhizoctonia solani. But its further application was limited due to its low production titer. In this work, the effects of initial volumetric oxygen transfer coefficient (K_La) on the cell growth, glycerol consumption and HHCA production were investigated both in flasks and bubble column bioreactors.In shake flask culture, the effect of initial K_La within the range of 2.1-18.9 h^-1 on HHCA production was investigated. As the results indicated, the cell growth and glycerol consumption were faster at a higher initial K_La value, but the maximum HHCA production (18.2 mg/L) was attained at the relatively low initial K_La value of 12.5 h^-1. The maximum HHCA production at initial K_La values of 2.1 h^-1, 12.5 h^-1, 14.6 h^-1 and 18.9 h^-1 was 8.9, 18.1, 10.0 and 9.0 mg/L as obtained at 96, 72, 96 and 96 h, respectively, and their corresponding productivity was 2.2, 6.0, 3.3 and 2.3 mg L-1 d-1. The oxygen supply information was further applied to a 2-L bubble column bioreactor (BCB) by varying initial K_La from 1.5 to 30.2 h^-1, and the hyperproduction of HHCA was achieved at a relatively low initial K_La around 5-10 h^-1, which was about 2-fold than those obtained in other cases.Oxygen supply was found to be a critical factor in Pseudomonas sp. SJT25 fermentaion process. The relatively low intial K_La is considered to be critical to enhance HHCA production, and the information obtained might be useful to production of the powerful new antibiotic on a large-scale.