Kalai Chelvam Kalaivani, Yap Kien Pong, Chai Lay Ching, Thong Kwai Lin
Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.
PLoS One. 2015 May 6;10(5):e0126207. doi: 10.1371/journal.pone.0126207. eCollection 2015.
Salmonella enterica serovar Typhi (S. Typhi) is a foodborne pathogen that causes typhoid fever and infects only humans. The ability of S. Typhi to survive outside the human host remains unclear, particularly in human carrier strains. In this study, we have investigated the catabolic activity of a human carrier S. Typhi strain in both planktonic and biofilm cells using the high-throughput Biolog Phenotype MicroArray, Minimum Biofilm Eradication Concentration (MBEC) biofilm inoculator (96-well peg lid) and whole genome sequence data. Additional strains of S. Typhi were tested to further validate the variation of catabolism in selected carbon substrates in the different bacterial growth phases. The analyzes of the carbon utilization data indicated that planktonic cells of the carrier strain, S. Typhi CR0044 could utilize a broader range of carbon substrates compared to biofilm cells. Pyruvic acid and succinic acid which are related to energy metabolism were actively catabolised in the planktonic stage compared to biofilm stage. On the other hand, glycerol, L-fucose, L-rhamnose (carbohydrates) and D-threonine (amino acid) were more actively catabolised by biofilm cells compared to planktonic cells. Notably, dextrin and pectin could induce strong biofilm formation in the human carrier strain of S. Typhi. However, pectin could not induce formation of biofilm in the other S. Typhi strains. Phenome data showed the utilization of certain carbon substrates which was supported by the presence of the catabolism-associated genes in S. Typhi CR0044. In conclusion, the findings showed the differential carbon utilization between planktonic and biofilm cells of a S. Typhi human carrier strain. The differences found in the carbon utilization profiles suggested that S. Typhi uses substrates mainly found in the human biliary mucus glycoprotein, gallbladder, liver and cortex of the kidney of the human host. The observed diversity in the carbon catabolism profiles among different S. Typhi strains has suggested the possible involvement of various metabolic pathways that might be related to the virulence and pathogenesis of this host-restricted human pathogen. The data serve as a caveat for future in-vivo studies to investigate the carbon metabolic activity to the pathogenesis of S. Typhi.
伤寒沙门氏菌血清型伤寒杆菌（伤寒杆菌）是一种食源性病原体，可引起伤寒热，且仅感染人类。伤寒杆菌在人类宿主外存活的能力尚不清楚，尤其是在人类携带菌株中。在本研究中，我们使用高通量Biolog表型微阵列、最低生物膜根除浓度（MBEC）生物膜接种器（96孔钉盖）和全基因组序列数据，研究了一株人类携带的伤寒杆菌菌株在浮游细胞和生物膜细胞中的分解代谢活性。对其他伤寒杆菌菌株进行了测试，以进一步验证不同细菌生长阶段中选定碳底物分解代谢的变化。碳利用数据分析表明，与生物膜细胞相比，携带菌株伤寒杆菌CR0044的浮游细胞能够利用更广泛的碳底物。与生物膜阶段相比，在浮游阶段，与能量代谢相关的丙酮酸和琥珀酸被积极分解代谢。另一方面，与浮游细胞相比，生物膜细胞对甘油、L-岩藻糖、L-鼠李糖（碳水化合物）和D-苏氨酸（氨基酸）的分解代谢更为活跃。值得注意的是，糊精和果胶可在伤寒杆菌的人类携带菌株中诱导强烈的生物膜形成。然而，果胶不能在其他伤寒杆菌菌株中诱导生物膜形成。表型组数据显示了某些碳底物的利用情况，这得到了伤寒杆菌CR0044中与分解代谢相关基因存在的支持。总之，研究结果显示了伤寒杆菌人类携带菌株的浮游细胞和生物膜细胞之间碳利用的差异。碳利用谱中发现的差异表明，伤寒杆菌利用的底物主要存在于人类宿主的胆汁黏液糖蛋白、胆囊、肝脏和肾皮质中。在不同伤寒杆菌菌株中观察到的碳分解代谢谱的多样性表明，各种代谢途径可能参与其中，这可能与这种宿主受限的人类病原体的毒力和发病机制有关。这些数据为未来研究伤寒杆菌发病机制中的碳代谢活性的体内研究提供了警示。
