Isolation of bacteria utilizing glycerol as a sole carbon source for potential production of 1,3-propanediol

Abstract

Glycerol is a by-product waste from biodiesel production, which can be converted by bacteria to other value-added products. One of these products is 1,3-propanediol (1,3-PDO), an important substrate for synthesis of biopolymer and many others. This research aims to isolate bacteria that can utilize glycerol as a sole carbon source and examine the 1,3-PDO production ability of these isolates using glycerol as a substrate. Bacterial isolates were obtained from soil near biodiesel plant by culturing in mineral salt medium containing glycerol. Growth of selected isolates in a medium containing glycerol as a sole carbon source were monitored and compared with reference bacterial strains. It was observed that 2 isolates grew better than reference strains according to optical density value at 600 nm. Both isolates were identified as Klebsiella pneumoniae by 16S rRNA gene sequencing. The isolate 5-3, renamed as K. pneumoniae KKU5 (Kp KKU5) was used for further study. The dhaT gene of Kp KKU5 shared 99% identity with those of K. pneumoniae (CP025630.1). To examine the ability of Kp KKU5 as a 1,3-PDO producer, its fermentation broth containing glycerol was analyzed by high-performance liquid chromatography. Under batch fermentation conditions with 20 g/L initial glycerol, Kp KKU5 produced 0.375 g/L of 1,3-PDO after 7 days. Despite its low production of 1,3-propanediol, we have demonstrated that Kp KKU5 was able to utilize glycerol as a sole carbon source. This study might provide some useful information to contribute in the research area of 1,3-PDO production, that adds value to glycerol waste from biodiesel production.