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

Abstract

A simple method for the recovery of microbial poly(3‐hydroxybutyrate) [P(3HB)] from recombinant Escherichia coli harboring the Ralstonia eutropha PHA biosynthesis genes was developed. Various acids (HCl, H2SO4), alkalies (NaOH, 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)sorbitan monolaurate [Tween 20]) were examined for their ability to digest non‐P(3HB) cellular materials (NPCM). Even though SDS was an efficient chemical for P(3HB) recovery from recombinant E. coli, it is expensive and has waste disposal problem. NaOH and KOH were also efficient and economical for the recovery of P(3HB), and therefore, were used to optimize digestion condition. When 50 g DCW/L of recombinant E. coli cells having the P(3HB) content of 77% was treated with 0.2 N NaOH at 30°C for 1 h, P(3HB) was recovered with purity of 98.5%. Using this simple recovery method, the effect of recovery method on the final production cost of P(3HB) was examined. Processes for the production of P(3HB) by recombinant E. coli from glucose with two different recovery methods, surfactant‐hypochlorite digestion and simple digestion with NaOH, were designed and analyzed. By employing the fermentation 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, coupled 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 employing the surfactant‐hypochlorite digestion method. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 62: 546–553, 1999.

Effects of Granule-Associated Protein PhaP on Glycerol-Dependent Growth and Polymer Production in Poly(3-Hydroxybutyrate)-Producing Escherichia coli

“…For qualitative detection of PHB inclusion bodies, cells were observed by fluorescence microscopy after staining with the basic oxazine Nile Blue A as previously described (17). PHB content in flask cultures was determined gravimetrically after alkaline treatment with 0.2 N NaOH as described previously (5). PHB content in bioreactor cultures was quantitatively determined by gas chromatography using a slight modification of the method described by Braunegg et al (4,16).…”

Isolation and recovery of microbial polyhydroxyalkanoates

“…The proposed recovery process of PHA is more economical as the costly freeze drying step could be avoided. [54][55]. The cell wall strength of these microorganisms could be compromised by modifying the composition of the growth medium.…”

Can Bio-plastics Replace Non-Biodegradable Plastics?

“…Since PHAs are completely biodegradable and have thermoplastic or elastomeric properties, they could offer an excellent alternative to nonbiodegradable petrochemical based plastics [2]. However, the production cost of biodegradable plastics is comparatively very high that limits its industrial production.…”