The limited number of well-characterised model bacteria cannot address all the challenges in a circular bioeconomy. Therefore, there is a growing demand for new production strains with enhanced resistance to extreme conditions, versatile metabolic capabilities and the ability to utilise cost-effective renewable resources while efficiently generating attractive biobased products. Particular thermophilic microorganisms fulfil these requirements. Non-virulent Gram-negative Caldimonas thermodepolymerans DSM15344 is one such attractive thermophile that efficiently converts a spectrum of plant biomass sugars into high quantities of polyhydroxyalkanoates (PHA)-a fully biodegradable substitutes for synthetic plastics. However, to enhance its biotechnological potential, the bacterium needs to be 'domesticated'. In this study, we established effective homologous recombination and transposon-based genome editing systems for C. thermodepolymerans. By optimising the electroporation protocol and refining counterselection methods, we achieved significant improvements in genetic manipulation and constructed the AI01 chassis strain with improved transformation efficiency and a ΔphaC mutant that will be used to study the importance of PHA synthesis in Caldimonas. The advances described herein highlight the need for tailored approaches when working with thermophilic bacteria and provide a springboard for further genetic and metabolic engineering of C. thermodepolymerans, which can be considered the first model of thermophilic PHA producer.

• Klíčová slova
• Caldimonas thermodepolymerans, gene deletion, genetic engineering, polyhydroxyalkanoates, thermophiles,
• MeSH
• editace genu * metody   MeSH
• elektroporace MeSH
• genom bakteriální MeSH
• homologní rekombinace MeSH
• metabolické inženýrství metody   MeSH
• polyhydroxyalkanoáty * biosyntéza   metabolismus   MeSH
• transpozibilní elementy DNA MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• polyhydroxyalkanoáty * MeSH
• transpozibilní elementy DNA MeSH

In recent years, extremophilic microorganisms have been employed as producers of the microbial bioplastics polyhydroxyalkanoates (PHA), which are of great biotechnological value. Nevertheless, cold-loving or psychrophilic (cryophilic) bacteria have been neglected in this regard. Here, we present an investigation of the Arctic glacier-derived PHA producer Acidovorax sp. A1169. Biolog GEN III Microplates were used as a screening tool to identify the most suitable carbon substrate concerning PHA synthesis. The strain produced homopolymer poly(3-hydroxybutyrate) (PHB) most efficiently (2 g/L) at a temperature of 15 °C when supplied with fructose or mannitol as carbon sources with a substantial decrease of PHB biosynthesis at 17.5 °C. The PHB yield did not increase considerably or even decreased when carbon source concentration exceeded 10 g/L hinting that the strain is oligotrophic in nature. The strain was also capable of introducing 3-hydroxyvalerate (3HV) into the polymer structure, which is known to improve PHA thermoplastic properties. This is the first investigation providing insight into a PHA biosynthesis process by means of a true psychrophile, offering guidelines on polar-region bacteria cultivation, production of PHA and also on the methodology for genetic engineering of psychrophiles.

• Klíčová slova
• Arctic, Bioplastics, Extremophile, Low-temperature biotechnology, Oligotrophy,
• MeSH
• Comamonadaceae * genetika   MeSH
• genetické inženýrství MeSH
• polyhydroxyalkanoáty * MeSH
• teplota MeSH
• uhlík MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• polyhydroxyalkanoáty * MeSH
• uhlík MeSH