2-50: D-Lactic Acid Production from Xylose by a New Bacterium Found in Thailand

Abstract

 

            Lignocellulosic biomass is one of the most abundant renewable resources on earth, but conversion of biomass to ethanol has many challenges including pentose fermentation.  Pentose is usually a result of dilute-acid pretreatment, and the majority of the pentose generated is xylose.  Although, several organisms can convert xylose to ethanol but the conversion is still relatively inefficient.  However, xylose can also be converted to lactic acid, which is a building block of polylactic acid (PLA), a biodegradable plastic.  Our research team has found a new microbial isolate that can ferment xylose to D-lactic acid with the chiral purity greater than 95%.  The bacterium was isolated from manure samples from the farm in Northeastern part of Thailand.  Addition of poly D-lactic acid to the existing poly L-lactic acid will improve the thermal properties of the resulting polymer.  Nonetheless, lactic acid is not the only product produced by this isolate.  In this study, the xylose concentration, temperature and pH are varied in order to find the suitable conditions for D-lactic acid production by this isolated bacterial strain.