Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Brussels, Belgium.
Faculty of Sciences, Botany and Microbiology Department, Damanhour University, Damanhour, Egypt.
Environ Microbiol Rep. 2024 Jun;16(3):e13260. doi: 10.1111/1758-2229.13260.
As part of ongoing efforts to discover novel polyhydroxyalkanoate-producing bacterial species, we embarked on characterizing the thermotolerant species, Paracoccus kondratievae, for biopolymer synthesis. Using traditional chemical and thermal characterization techniques, we found that P. kondratievae accumulates poly(3-hydroxybutyrate) (PHB), reaching up to 46.8% of the cell's dry weight after a 24-h incubation at 42°C. Although P. kondratievae is phylogenetically related to the prototypical polyhydroxyalkanoate producer, Paracoccus denitrificans, we observed significant differences in the PHB production dynamics between these two Paracoccus species. Notably, P. kondratievae can grow and produce PHB at elevated temperatures ranging from 42 to 47°C. Furthermore, P. kondratievae reaches its peak PHB content during the early stationary growth phase, specifically after 24 h of growth in a flask culture. This is then followed by a decline in the later stages of the stationary growth phase. The depolymerization observed in this growth phase is facilitated by the abundant presence of the PhaZ depolymerase enzyme associated with PHB granules. We observed the highest PHB levels when the cells were cultivated in a medium with glycerol as the sole carbon source and a carbon-to-nitrogen ratio of 10. Finally, we found that PHB production is induced as an osmotic stress response, similar to other polyhydroxyalkanoate-producing species.
作为发现新型聚羟基烷酸酯生产细菌物种的持续努力的一部分，我们着手对耐热物种副球菌（Paracoccus kondratievae）进行生物聚合物合成的特性描述。使用传统的化学和热特性分析技术，我们发现 P. kondratievae 积累聚（3-羟基丁酸酯）（PHB），在 42°C 孵育 24 小时后，细胞干重的 PHB 积累量最高可达 46.8%。尽管 P. kondratievae 在系统发育上与典型的聚羟基烷酸酯生产者副球菌（Paracoccus denitrificans）有关，但我们观察到这两个副球菌物种在 PHB 生产动力学方面存在显著差异。值得注意的是，P. kondratievae 可以在 42 到 47°C 的升高温度下生长和生产 PHB。此外，P. kondratievae 在早期的静止生长阶段达到其 PHB 含量的峰值，特别是在摇瓶培养中生长 24 小时后。然后，在静止生长阶段的后期，PHB 含量会下降。在这个生长阶段观察到的解聚是由与 PHB 颗粒相关的丰富 PhaZ 解聚酶促进的。当细胞在以甘油为唯一碳源且碳氮比为 10 的培养基中培养时，我们观察到最高的 PHB 水平。最后，我们发现 PHB 生产是作为渗透压应激反应诱导的，类似于其他生产聚羟基烷酸酯的物种。
