(471g) Lactic Acid Fermentation by Rhizopus Oryzae with Activated Carbon Addition

Recently, the demand of lactic acid with high optical purity has increased more and more since it is useful as a raw material for polymer. The pure L-lactic acid is produced by fermentation method using lactic acid bacterium such as Lactobacillus rhamnosus or molds such as Rhizopus oryzae. Though there are many reports on L-lactic acid production using bacterium, it is not preferable to produce lactic acid for poly-lactic acid commercially as it requires expensive nitrogen sources such as yeast extract. On the other hand, R. oryzae can produce L-lactic acid from inexpensive medium consisted of glucose and minerals. Since the broth of fermentation using R. oryzae is relatively clear due to the simple medium, decolorized crude lactic acid solution can be obtained by activated carbon. It has been clarified that direct addition of activated carbon was inefficient in fermentation by bacterium but productivity and yield were improved in fermentation by R. oryzae. It might be due to that components required for growth and fermentation in ordinal fermentation, such as yeast extract, could not perform by adsorption on activated carbon, but in the case using R. oryzae the components adsorbed was not required as medium, and productivity might be improved by enhancing the cell activity like biological activated carbon in water treatment. Further, it was expected that inhibitors might be removed by activated carbon in fermentation from organic wastes. From these points of view, activated carbon addition was attempted in L-lactic acid fermentation by R. oryzae using crude glucose solution obtained by saccharification of wood waste and kitchen garbage as feeds, and productivity and yield could be improved remarkably.