Development of a noble method for utilization of organic waste resources, open lactic acid fermentation of kitchen refuse is a good model of it

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In order to show new direction for investigation of economical transformation of organic waste, we set three subjects in the none-sterilizing lactic acid(LA) fermentation of garbage ; analyses of microbes by FISH, mixed culture reactor system with plural substrates, and high-viscous, suspended fermentation system.(1)Quantitative fluorescent In Situ hybridization(FISH) using group- and species- specific probes has established, and selective LA accumulation in the pH-swing control fermentation was found to be caused by L.plantarun, which also resulted decrease of optical purity of LA. On the other hand, inoculation of thermophilic L-LA producing bacteria at 55℃ was effective to accumulation of L-LA. FISH analysis demonstrated well the relationship between LA purity and populations of mesophilic and thermophilic LA bacteria.(2)To determine conditions for supporting growth of a specific microorganism, a new co-culture system with three microfiltration modules, fermentors, and a mixing vess … More el was developed. The co-culture system allowed the cultivation of the individual microorganism in each fermentor with the successful exchange of medium. Efficient production of LA from mixture of xylose and glucose by co-culture with two microorganisms also succeeded. In a simultaneous saccharification and fermentation of unsterile defatted rice bran, a LA bacterium could grow specifically by keeping the pH acidic, with selective LA production.(3)In LA fermentation by Rhizopus oryzae, the high viscosity-suspension system was examined by reducing the water content, however, oxygen supply required for the fermentation was not enough and the LA yield lowered. Product inhibition is strong in the continuous fermentation of glucose. Although starch did not inhibit the fermentation, there was a limit in concentration due to its viscosity. As a result, addition of equivalent water was desirable in kitchen refuse fermentation. Also, it was considered that the substrate containing starch highly should be supplied in batch to the system. Less