Isolation and characterisation of lactic acid bacterium for effective fermentation of cellobiose into optically pure homo L-(+)-lactic acid.
Effective utilisation of cellulosic biomasses for economical lactic acid production requires a microorganism with potential ability to utilise efficiently its major components, glucose and cellobiose. Amongst 631 strains isolated from different environmental samples, strain QU 25 produced high yields of l-(+)-lactic acid of high optical purity from cellobiose. The QU 25 strain was identified as Enterococcus mundtii based on its sugar fermentation pattern and 16S rDNA sequence. The production of lactate by fermentation was optimised for the E. mundtii QU25 strain. The optimal pH and temperature for batch culturing were found to be 7.0°C and 43°C, respectively. E. mundtii QU 25 was able to metabolise a mixture of glucose and cellobiose simultaneously without apparent carbon catabolite repression. Moreover, under the optimised culture conditions, production of optically pure l-lactic acid (99.9%) increased with increasing cellobiose concentrations. This indicates that E. mundtii QU 25 is a potential candidate for effective lactic acid production from cellulosic hydrolysate materials.
Laboratory of Microbial Technology, Division of Applied Molecular Microbiology and Biomass Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, 6-10-1 Hakozaki, Higashi-ku Fukuoka 812-8581, Japan.
Mohamed Ali
MA
Abdel-Rahman
Yukihiro
Y
Tashiro
Takeshi
T
Zendo
Keisuke
K
Shibata
Kenji
K
Sonomoto
D015373:Bacterial Typing Techniques; D002475:Cellobiose / Q000378:metabolism*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D016983:Enterococcus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D004783:Environmental Microbiology; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000378:metabolism*; D008969:Molecular Sequence Data; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013696:Temperature
D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D002475:Cellobiose; D019344:Lactic Acid; D005947:Glucose