| Summary: | Arctic bacteria employ various mechanisms to survive harsh conditions, one of which is to accumulate carbon and energy inside the cell in the form of polyhydroxyalkanoate (PHA). Whole-genome sequencing of a new Arctic soil bacterium <i>Pseudomonas</i> sp. B14-6 revealed two PHA-production-related gene clusters containing four PHA synthase genes (<i>phaC</i>). <i>Pseudomonas</i> sp. B14-6 produced poly(6% 3-hydroxybutyrate-<i>co</i>-94% 3-hydroxyalkanoate) from various carbon sources, containing short-chain-length PHA (scl-PHA) and medium-chain-length PHA (mcl-PHA) composed of various monomers analyzed by GC-MS, such as 3-hydroxybutyrate, 3-hydroxyhexanoate, 3-hydroxyoctanoate, 3-hydroxydecanoate, 3-hydroxydodecenoic acid, 3-hydroxydodecanoic acid, and 3-hydroxytetradecanoic acid. By optimizing the PHA production media, we achieved 34.6% PHA content using 5% fructose, and 23.7% PHA content using 5% fructose syrup. Differential scanning calorimetry of the scl-<i>co</i>-mcl PHA determined a glass transition temperature (T<sub>g</sub>) of 15.3 °C, melting temperature of 112.8 °C, crystallization temperature of 86.8 °C, and 3.82% crystallinity. In addition, gel permeation chromatography revealed a number average molecular weight of 3.6 × 10<sup>4</sup>, weight average molecular weight of 9.1 × 10<sup>4</sup>, and polydispersity index value of 2.5. Overall, the novel <i>Pseudomonas</i> sp. B14-6 produced a polymer with high medium-chain-length content, low T<sub>g</sub>, and low crystallinity, indicating its potential use in medical applications.
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