Related Experiment Videos
Xylooligosaccharide fermentation with Leuconostoc lactis.
Hitomi Ohara1, Michiko Owaki, Kenji Sonomoto
1Laboratory of Microbial Technology, Division of Microbial Science and Technology, Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Higashi-ku, Fukuoka, Japan.
Journal of Bioscience and Bioengineering
|June 20, 2006
Summary
Leuconostoc lactis strains SHO-47 and SHO-54 efficiently produce D-lactic acid from hydrolyzed birch wood xylan. These strains utilize xylooligosaccharides more effectively than xylose for enhanced poly(D-lactic acid) production.
Area of Science:
- Biotechnology
- Microbiology
- Polymer Science
Background:
- Hydrolyzed birch wood xylan serves as a unique carbon source for lactic acid bacteria.
- NAD-specific 6-phosphoglucanate dehydrogenase is a clinically useful enzyme produced by Leuconostoc lactis.
- Poly(D-lactic acid) is a biodegradable polymer with diverse applications.
Purpose of the Study:
- To evaluate the potential of Leuconostoc lactis strains SHO-47 and SHO-54 in producing D-lactic acid from hydrolyzed birch wood xylan.
- To compare the xylose and xylooligosaccharide utilization capabilities of strains SHO-47 and SHO-54 with Lactococcus lactis IO-1.
- To investigate the induction and localization of xylosidase activity in these bacterial strains.
Main Methods:
- Cultivation of Leuconostoc lactis SHO-47, Le. lactis SHO-54, and Lactococcus lactis IO-1 using hydrolyzed birch wood xylan as the sole carbon source.
- Fermentation monitoring for lactic acid production and quantification.
- Analysis of carbohydrate utilization patterns, including xylose and various xylooligosaccharides.
- Enzyme activity assays to determine xylosidase induction and localization.
Main Results:
- Strains SHO-47 and SHO-54 produced 2.3 g/l and 2.2 g/l of lactic acid, respectively, within 12 hours from 8.5 g/l hydrolyzed xylan.
- These strains demonstrated more rapid utilization of xylooligosaccharides (xylobiose to xylohexose) compared to xylose.
- Lactococcus lactis IO-1 showed slower lactic acid production (1.3 g/l in 21 hours) and temporary xylose accumulation.
- Xylosidase activity in all tested strains was induced by xylose or specific xylooligosaccharides and was found to be cytoplasmic.
Conclusions:
- Leuconostoc lactis strains SHO-47 and SHO-54 are promising candidates for the efficient production of D-lactic acid from hemicellulosic biomass.
- The ability to utilize a range of xylooligosaccharides contributes to the high lactic acid yield from xylan.
- Understanding xylosidase activity and localization provides insights into the metabolic pathways for xylan degradation in these bacteria.