Efficient and economical recovery of poly(3-hydroxybutyrate) from recombinant Escherichia coli by simple digestion with chemicals

A simple method for the recovery of microbial poly(3-hydroxybutyrate) [P(3H B)] from recombinant Escherichia coli harboring the Ralstonia eutropha PHA biosynthesis genes was developed. Various acids (HCl, H2SO4), alkalies (NaO H, KOH, and NH4OH), and surfactants (dioctylsulfosuccinate sodium salt [AOT ], hexadecyltrimethylammonium bromide [CTAB], sodium dodecylsulfate [SDS], polyoxyethylene-p-tert-octylphenol [Triton X-100], and polyoxyethylene(20)s orbitan monolaurate [Tween 20]) were examined for their ability to digest n on-P(3HB) cellular materials (NPCM). Even though SDS was an efficient chemi cal for P(3HB) recovery from recombinant E. coli, it is expensive and has w aste disposal problem. NaOH and KOH were also efficient and economical for the recovery of P(3HB), and therefore, were used to optimize digestion cond ition. When 50 g DCW/L of recombinant E. coli cells having the P(3HB) conte nt of 77% was treated with 0.2 N NaOH at 30 degrees C for 1 h, P(3HB) was r ecovered with purity of 98.5%. Using this simple recovery method, the effec t of recovery method on the final production cost of P(3HB) was examined. P rocesses for the production of P(3HB) by recombinant E. coil from glucose w ith two different recovery methods, surfactant-hypochlorite digestion and s imple digestion with NaOH, were designed and analyzed. By employing the fer mentation process that resulted in P(3HB) concentration, P(3HB) content and P(3HB) productivity of 157 g/L, 77%, and 3.2 P(3HB) g/L-h, respectively, c oupled with the recovery method of NaOH digestion, the production cost of P (3HB) was US$ 3.66/kg P(3HB), which was 25% less than that obtained by empl oying the surfactant-hypochlorite digestion method. (C) 1999 John Wiley & S ons, Inc.