Semi-continuous L-lactate fermentation of garbage without sterile condition and analysis of the microbial structure.
In order to develop a simple L-lactate fermentation of organic wastes, acidogenic fermentation was investigated in semi-continuous culture at 55 degrees C with using unsterilized artificial garbage as feedstock. And, sludge from a thermophilic acidification reactor was inoculated at the start of the fermentation. The effects of pH and hydraulic retention time (HRT) on performance of L-lactate production were discussed in a series of operational conditions with regard to long-term stability. The best operational conditions for L-lactate fermentation are proposed to be 55 degrees C, pH 6 and HRT of 10 days to get the highest yield of lactate based on initial carbohydrate in the feedstock. The yield of 0.74 and produced L-lactate optical purity of 96.7% were obtained on these operational conditions. Another L-lactate fermentation, which were semi-continuous and batch mode operations, were conducted to present reproducibility of the fermentation. Microbial structures in the semi-continuous fermentations were analyzed with using 16S rDNA libraries, and Bacillus coagulans was shown to be the most predominant species in the L-lactate fermented cultural broth.
Akao
S
S
Department of Social Systems Engineering, Faculty of Engineering, Tottori University, 4-101, KoyamaMinami, Tottori 680-8552, Japan. akao@sse.tottori-u.ac.jp
Tsuno
H
H
Cheon
J
J
D001407:Bacillus / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D003247:Conservation of Natural Resources; D004269:DNA, Bacterial / Q000032:analysis; D005285:Fermentation; D005735:Garbage; D019344:Lactic Acid / Q000032:analysis / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013242:Sterilization
D004269:DNA, Bacterial; D019344:Lactic Acid