Klebsiella pneumoniae – a useful pathogenic strain for biotechnological purposes: 1,3-propanediol biosynthesis

Abstract

Background Despite being a well-known human pathogen, Klebsiella pneumoniae plays a significant role in the biotechnology field, being considered as a microbial cell factory in terms of valuable chemicals biosynthesis. In fermentation processes, K. pneumoniae is mostly used to biosynthesize 1,3-propanediol (PDO), a very important intermediate compound utilized in the biodegradable bioplastics industry. This strain owns the ability to metabolize glycerol and to produce PDO under both aerobic and anaerobic circumstances, and under low oscillations of pH. Results In this work, we investigated the K. pneumoniae strain DSMZ 2026 in batch bioreactor cultivation. The bacterial strain was inoculated in 2 L culture broth containing 43.5 g·L- 1 main substrate and the pH was adjusted at 7 at the beginning of the process. After 12 h of batch cultivation, the pH values decreased to 4.77, and we obtained 51 g·L-1 wet biomass, 17 g·L-1 PDO, while the starting substrate reached 15 g·L- 1. The morphology of K. pneumoniae cells was analyzed on both solid and liquid media, by being identified large mucoid colonies on Columbia agar, and individual and grouped cells were observed by methyl blue staining. Conclusion From this study it can be concluded that K. pneumoniae can grow successfully in mineral broth under anaerobic environment and low decrease of pH, and can biosynthesize valuable chemicals like PDO.