Factors affecting the fermentative lactic acid production from renewable resources1

Homolactate Fermentation by Metabolically Engineered Escherichia coli Strains

“…Samples were centrifuged (twice at 10,000 ϫ g for 10 min), and the supernatant was mixed with a 33% volume of deuterium dioxide (D 2 O) and filtered for nuclear magnetic resonance (NMR) analysis. Proton-decoupled 13 C NMR spectra (300 NMR spectroscopy; Varian Inc., Palo Alto, CA) at 75.4 MHz were obtained with the following spectral parameters: 45°p ulses, 18.1-kHz spectral width, and 4.5-s relaxation delay. Field stabilization was achieved by locking on the D 2 O frequency.…”

“…The absence of uniformly labeled succinate, however, demonstrated that glyoxylate did not reenter the tricarboxylic acid cycle via oxaloacetate. By minimizing the residual acetate at the time that the production phase commenced, the process with ALS974 achieved 138 g/liter lactate (1.55 M, 97% of the carbon products), with a yield of 0.99 g/g and a productivity of 6.3 g/liter · h during the anaerobic phase.Lactic acid (lactate) and its derivatives have a wide range of applications in the food, pharmaceutical, leather, and textile industries (13,27). Recently, polylactic acid has been developed as a renewable, biodegradable, and environmentally friendly polymer (16,28).…”

“…Lactic acid (lactate) and its derivatives have a wide range of applications in the food, pharmaceutical, leather, and textile industries (13,27). Recently, polylactic acid has been developed as a renewable, biodegradable, and environmentally friendly polymer (16,28).…”

“…Although several microorganisms can produce lactate by fermentation of glucose and other renewable resources (13), Escherichia coli has many advantages, including rapid growth and simple nutritional requirements. Moreover, the ease of genetic manipulation of E. coli makes possible metabolic engineering strategies for improving lactate accumulation in E. coli (6).…”

“…After part of the chromosomal ldhA coding region was replaced with Pediococcus acidilactici ldhL, encoding L-LDH, the new strain (SZ85) generated 50 g/liter L-lactate at a 95% yield, with a productivity of 0.42 g/liter · h (34). Recent results indicate that some characteristics of E. coli compare favorably with those of lactic acid bacteria, which often attain yields surpassing 90% (13).…”