[Show abstract][Hide abstract] ABSTRACT: Experimental devices for stimulating productivity of lactic acid fermentation were installed and a level meter was used to control the volume of fermentation broth. Experiments were carried out by means of continuous EDF with feed medium. It was verified that 175 g/L of glucose concentrations in the feed medium was the best value. In this case, the continuous EDF lasted for above 350 h and was stable for above 200 h. The maximum productivity, yield and conversion ratio were 8.18 g/L h, 68.8% and 71%, respectively. Compared with other EDFs, the continuous EDF with a level meter had the highest productivity and produced 2637 g of lactic acid from 4000 g of glucose. The amount of lactic acid produced was, due to the longest fermentation time and the highest productivity, about 19.5 times greater than that of the conventional EDF and was about 9.7 times greater than that of the intermittent EDF. The glucose, however, began to be excessive in fermentation broth after 200 h, resulting in a decrease of lactic acid production.
No preview · Article · Mar 2005 · PROCESS BIOCHEMISTRY
[Show abstract][Hide abstract] ABSTRACT: The extraction of lactic acid was investigated using a model aqueous solution. Extraction tests were carried out with tri-n-octylphosphine oxide (TOPO), tributyl phosphate (TBP), tri-n-octylamine (TOA), di-n-octylamine (DOA) and tri-n-octylmethylammonium chloride (TOMAC) as extractants, and butyl acetate and oleyl alcohol as diluents. Amongst these extractants, di-n-octylamine (DOA) had the highest extractive capacity. A possible mechanism for the extraction with DOA was proposed. DOA is protonated at the interface, where the protonated DOA extracts lactic acid by the formation of the protonated DOA complex with dissociated lactic acid. Finally, taken into account the influence of the fermentation media, the recovery of lactic acid from fermentation broth was investigated.
No preview · Article · Jan 2005 · Solvent Extraction Research and Development Japan
[Show abstract][Hide abstract] ABSTRACT: Batch fermentations of Rhizopus oryzae AHU 6537 in medium containing granular activated carbon from coal, powder activated carbon from coal or granular activated carbon from coconut were carried out in an airlift bioreactor. As a result, fermentation broths were decolorized by activated carbon, and clearer fermentation broths were obtained than in fermentation without activated carbon. With activated carbon from coal, the cells formed smaller pellets than in fermentation without activated carbon, and fermentation performance was improved. Productivity was further improved by increasing the amount of activated carbon from coal. Therefore, the productivity of lactic acid fermentation could be improved by selecting a suitable activated carbon and by controlling the amount of activated carbon.
No preview · Article · Nov 2004 · KAGAKU KOGAKU RONBUNSHU
[Show abstract][Hide abstract] ABSTRACT: An efficient process for producing l-lactic acid using an, EDF method is described. The results showed that intermittent EDF with continuous medium feed was the best one among the experiment methods employed. Comparing with the conventional EDF, intermittent EDF (seven on–off) with continuous medium feed indicated that the maximum value of o.d.660 was not increased, but productivity was 1.5 times higher. The yield increased by above 30% and glucose transport decreased to 1/10 (from 0.46 to 0.05).
No preview · Article · Oct 2004 · PROCESS BIOCHEMISTRY
[Show abstract][Hide abstract] ABSTRACT: The continuous fermentation of L-lactic acid by Rhizopus oryzae AHU6537 was attempted with dilution rate of 0.02 h(-1) and feed glucose rate of 2.0 kg/(m(3) (.) h) in an airlift bioreactor. As a result, stable operation could be carried out over a long time without immobilizing cells. When the optimum amount of yeast extract in batch culture was added to the starting medium, the cells formed spherical pellets, and the fermentation rate was improved. Further, to investigate the influence of glucose and lactic acid concentration, when the dilution rate and glucose concentration in feed medium were controlled in continuous fermentation, it was found that R. oryzea was strongly inhibited by the lactic acid produced. When the effect of lactic acid inhibition was analyzed according to a Michaelis-Menten mechanism with uncompetitive inhibition and the fermentation rate at the steady state was simulated, the calculated lines agreed well with experimental values.