Genomic and phenotypic comparison of polyhydroxyalkanoates producing strains of genus Caldimonas/Schlegelella.

Polyhydroxyalkanoates (PHAs) have emerged as an environmentally friendly alternative to conventional polyesters. In this study, we present a comprehensive analysis of the genomic and phenotypic characteristics of three non-model thermophilic bacteria known for their ability to produce PHAs: Schlegelella aquatica LMG 23380T, Caldimonas thermodepolymerans DSM 15264, and C. thermodepolymerans LMG 21645 and the results were compared with the type strain C. thermodepolymerans DSM 15344T. We have assembled the first complete genomes of these three bacteria and performed the structural and functional annotation. This analysis has provided valuable insights into the biosynthesis of PHAs and has allowed us to propose a comprehensive scheme of carbohydrate metabolism in the studied bacteria. Through phylogenomic analysis, we have confirmed the synonymity between Caldimonas and Schlegelella genera, and further demonstrated that S. aquatica and S. koreensis, currently classified as orphan species, belong to the Caldimonas genus.

Complete Genome Sequence of the Type Strain Tepidimonas taiwanensis LMG 22826T, a Thermophilic Alkaline Protease and Polyhydroxyalkanoate Producer.

Tepidimonas taiwanensis is a moderately thermophilic, Gram-negative, rod-shaped, chemoorganoheterotrophic, motile bacterium. The alkaline protease producing type strain T. taiwanensis LMG 22826T was recently reported to also be a promising producer of polyhydroxyalkanoates (PHAs)-renewable and biodegradable polymers representing an alternative to conventional plastics. Here, we present its first complete genome sequence which is also the first complete genome sequence of the whole species. The genome consists of a single 2,915,587-bp-long circular chromosome with GC content of 68.75%. Genome annotation identified 2,764 genes in total while 2,634 open reading frames belonged to protein-coding genes. Although functional annotation of the genome and division of genes into Clusters of Orthologous Groups (COGs) revealed a relatively high number of 694 genes with unknown function or unknown COG, the majority of genes were assigned a function. Most of the genes, 406 in total, were involved in energy production and conversion, and amino acid transport and metabolism. Moreover, particular key genes involved in the metabolism of PHA were identified. Knowledge of the genome in connection with the recently reported ability to produce bioplastics from the waste stream of wine production makes T. taiwanensis LMG 22826T, an ideal candidate for further genome engineering as a bacterium with high biotechnological potential.