High production of poly-β-hydroxybutyrate (PHB) by an Azotobacter vinelandii mutant altered in PHB regulation using a fed-batch fermentation process

Strategies for Large-scale Production of Polyhydroxyalkanoates

“…Exponential feeding of substrate was combined with pulse addition in a mixed fermentation strategy involving sucrose and yeast extract for increased P(3HB) production. 59 As a result, an improvement in the overall P(3HB) concentration by 7-fold was achieved as compared to batch cultivation (see Table 1). In yet another interesting approach, feeding was controlled by a decrease in the stirring speed, which resulted from exhaustion of the carbon source in the medium.…”

“…Pulse feeding of substrate, i.e., addition of small known amounts of substrate when the substrate is at low concentration in the bioreactor, has been a widely used fed-batch strategy for P(3HB) production. [59][60][61][62][63] This could be mainly attributed to the ease of operation of this strategy, which essentially involves measurement of residual substrate in the bioreactor at several periods during cultivation, and subsequent addition of concentrated substrate to the bioreactor when it falls below a limiting value. This addition helps to avoid limitation of substrate in the fermentation medium, thereby allowing continued microbial growth and product formation.…”

“…As can be seen from Table 1, poly-3-hydroxybutyrate (P(3HB) remains the most widely investigated PHA by batch fermentation, accounting for one-third of the literature reports. However, quite interestingly, there have been only few reports on the utilization of pure or refined substrates (sugars) for P(3HB) production, [27][28][29][30] while different types of inexpensive carbon sources such as agro-industrial wastes including cane molasses, sugar beet juice, rice straw hydrolysate, grass biomass hydrolysate, plant oils e.g., coconut oil, have been largely investigated. [31][32][33][34][35][36][37][38] Alcaligenes and Bacillus sp.…”

“…These include fed-batch with pulse addition of substrate, constant feed rate, linearly increasing feed rate, exponentially increasing/decreasing feed rate, pseudo-steady state of substrate(s), high cell density with highly concentrated feed, and 2-stage fed-batch. 26,59 As is the case with batch fermentation, P(3HB) has been the most investigated biopolymer by fedbatch fermentation. Pulse feeding of substrate, i.e., addition of small known amounts of substrate when the substrate is at low concentration in the bioreactor, has been a widely used fed-batch strategy for P(3HB) production.…”

A novel method for the determination of diffusion coefficients in amorphous poly(3-hydroxybutyrate)

“…Among microbial polyesters, poly(3-hydroxybutyrate) (PHB) gained considerable attention mainly because numerous fermentation techniques offer rather simple and cost efficient ways to produce it with recombinant E. coli strains [1][2][3][4]. Using it in medical and generally in vivo applications [5][6][7][8][9][10][11][12][13] seems to be obvious, since the polymer yields only nontoxic metabolites [14][15][16][17].…”