Shafeeq Sulman, Pannanusorn Srisuda, Elsharabasy Youssef, Ramírez-Zavala Bernardo, Morschhäuser Joachim, Römling Ute
Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-17165, Stockholm, Sweden.
Department of Biotechnology, Faculty of Science and Technology, Thammasat University, 12120, Bangkok, Thailand.
FEMS Yeast Res. 2019 Sep 1;19(6). doi: 10.1093/femsyr/foz057.
The commensal species Candida parapsilosis is an emerging human pathogen that has the ability to form biofilms. In this study, we explored the impact of the divalent cations cobalt (Co2+), copper (Cu2+), iron (Fe3+), manganese (Mn2+), nickel (Ni2+) and zinc (Zn2+) on biofilm formation of clinical isolates of C. parapsilosis with no, low and high biofilm forming abilities at 30 and 37°C. All strains besides one isolate showed a concentration-dependent enhancement of biofilm formation at 30°C in the presence of Mn2+ with a maximum at 2 mM. The biofilm forming ability of no and low biofilm forming isolates was >2-fold enhanced in the presence of 2 mM Mn2+, while the effect in high biofilm forming isolate was significantly less pronounced. Of note, cells in the biofilms of no and low biofilm forming strains differentiated into yeast and pseudohyphal cells similar in morphology to high biofilm formers. The biofilm transcriptional activator BCR1 has a dual developmental role in the absence and presence of 2 mM Mn2+ as it promoted biofilm formation of no biofilm forming strains, and, surprisingly, suppressed cells of no biofilm forming strains to develop into pseudohyphae and/or hyphae. Thus, environmental conditions can significantly affect the amount of biofilm formation and cell morphology of C. parapsilosis with Mn2+ to overcome developmental blocks to trigger biofilm formation and to partially relieve BCR1 suppressed cell differentiation.
共生菌近平滑念珠菌是一种新兴的人类病原体，具有形成生物膜的能力。在本研究中，我们探究了二价阳离子钴（Co2+）、铜（Cu2+）、铁（Fe3+）、锰（Mn2+）、镍（Ni2+）和锌（Zn2+）在30℃和37℃时对具有无、低和高生物膜形成能力的近平滑念珠菌临床分离株生物膜形成的影响。除一株分离株外，所有菌株在30℃下于Mn2+存在时均表现出生物膜形成的浓度依赖性增强，在2 mM时达到最大值。在2 mM Mn2+存在下，无生物膜形成能力和低生物膜形成能力的分离株的生物膜形成能力提高了2倍以上，而在高生物膜形成能力的分离株中，这种影响明显较弱。值得注意的是，无生物膜形成能力和低生物膜形成能力菌株生物膜中的细胞分化为酵母细胞和假菌丝细胞，其形态与高生物膜形成能力菌株相似。生物膜转录激活因子BCR1在不存在和存在2 mM Mn2+时具有双重发育作用，因为它促进了无生物膜形成能力菌株的生物膜形成，而且令人惊讶的是，它抑制了无生物膜形成能力菌株的细胞发育为假菌丝和/或菌丝。因此，环境条件可显著影响近平滑念珠菌的生物膜形成量和细胞形态，锰离子可克服发育障碍以触发生物膜形成并部分缓解BCR1抑制的细胞分化。
