Drewnowska Justyna M, Zambrzycka Monika, Kalska-Szostko Beata, Fiedoruk Krzysztof, Swiecicka Izabela
Department of Microbiology, Institute of Biology, University of Bialystok, Bialystok, Poland.
Department of Physicochemical Analysis, Institute of Chemistry, University of Bialystok, Bialystok, Poland.
PLoS One. 2015 Apr 24;10(4):e0125428. doi: 10.1371/journal.pone.0125428. eCollection 2015.
Although melanin is known for protecting living organisms from harmful physical and chemical factors, its synthesis is rarely observed among endospore-forming Bacillus cereus sensu lato. Here, for the first time, we reported that psychrotolerant Bacillus weihenstephanensis from Northeastern Poland can produce melanin-like pigment. We assessed physicochemical properties of the pigment and the mechanism of its synthesis in relation to B. weihenstephanensis genotypic and phenotypic characteristics. Electron paramagnetic resonance (EPR) spectroscopy displayed a stable free radical signal of the pigment from environmental isolates which are consistent with the commercial melanin. Fourier transform infrared spectroscopy (FT-IR) and physicochemical tests indicated the phenolic character of the pigment. Several biochemical tests showed that melanin-like pigment synthesis by B. weihenstephanensis was associated with laccase activity. The presence of the gene encoding laccase was confirmed by the next generation whole genome sequencing of one B. weihenstephanensis strain. Biochemical (API 20E and 50CHB tests) and genetic (Multi-locus Sequence Typing, 16S rRNA sequencing, and Pulsed-Field Gel Electrophoresis) characterization of the isolates revealed their close relation to the psychrotrophic B. weihenstephanensis DSMZ 11821 reference strain. The ability to synthesize melanin-like pigment by soil B. weihenstephanensis isolates and their psychrotrophic character seemed to be a local adaptation to a specific niche. Detailed genetic and biochemical analyses of melanin-positive environmental B. weihenstephanensis strains shed some light on the evolution and ecological adaptation of these bacteria. Moreover, our study raised new biotechnological possibilities for the use of water-soluble melanin-like pigment naturally produced by B. weihenstephanensis as an alternative to commercial non-soluble pigment.
尽管黑色素以保护生物体免受有害物理和化学因素影响而闻名，但在形成芽孢的蜡样芽孢杆菌复合群中很少观察到其合成。在此，我们首次报道来自波兰东北部的耐冷魏氏芽孢杆菌能够产生类黑色素。我们评估了该色素的物理化学性质及其合成机制与魏氏芽孢杆菌基因型和表型特征的关系。电子顺磁共振（EPR）光谱显示环境分离株中色素的稳定自由基信号，这与商业黑色素一致。傅里叶变换红外光谱（FT-IR）和物理化学测试表明该色素具有酚类特征。多项生化测试表明，魏氏芽孢杆菌合成类黑色素与漆酶活性有关。通过对一株魏氏芽孢杆菌菌株进行下一代全基因组测序，证实了漆酶编码基因的存在。分离株的生化（API 20E和50CHB测试）和遗传（多位点序列分型、16S rRNA测序和脉冲场凝胶电泳）特征表明它们与嗜冷的魏氏芽孢杆菌DSMZ 11821参考菌株密切相关。土壤中魏氏芽孢杆菌分离株合成类黑色素的能力及其嗜冷特性似乎是对特定生态位的局部适应。对黑色素阳性的环境魏氏芽孢杆菌菌株进行详细的遗传和生化分析，为这些细菌的进化和生态适应提供了一些线索。此外，我们的研究为利用魏氏芽孢杆菌天然产生的水溶性类黑色素替代商业非水溶性色素提出了新的生物技术可能性。
