Aurantiacibacter hainanensis sp. nov. and Qipengyuania zhejiangensis sp. nov., two novel Erythrobacteraceae species isolated from tidal flat sediments.

Two Gram-stain-negative, rod-shaped, non-motile, aerobic and carotenoid-producing strains, belonging to the family Erythrobacteraceae, designated as H149T and Z2T, were isolated from tidal flat sediment samples collected in Hainan and Zhejiang, PR China, respectively. Growth of strain H149T occurred at 15-42 °C, 0-10.0 % (w/v) NaCl, and pH 6.0-8.5, with the optima at 35-37 °C, 3.0-3.5 % (w/v) NaCl and pH 7.0. Strain Z2T grew at 15-37 °C, 0-6.0 % (w/v) NaCl, and pH 6.0-9.5, with the optima at 25-30 °C, 0.5-1.0 % (w/v) NaCl and pH 6.0-6.5. Ubiquinone-10 was the sole ubiquinone in two strains. The predominant cellular fatty acids of strain H149T were C16 : 0, summed feature 3 and summed feature 8, while those of strain Z2T were C17 : 1 ω6c, summed feature 3 and summed feature 8. Strains H149T and Z2T shared diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and sphingoglycolipid as major polar lipids. The 16S rRNA gene sequence identity analysis indicated that strain H149T had the highest sequence identity of 98.4 % with Aurantiacibacter odishensis KCTC 23981T, and strain Z2T had that of 98.2 % with Qipengyuania pacifica NZ-96T. Phylogenetic trees based on 16S rRNA gene and core-genome sequences revealed that strains H149T and Z2T formed two independent clades in the genera Aurantiacibacter and Qipengyuania, respectively. Strain H149T had average nucleotide identity values of 74.0-81.3 % and in silico DNA-DNA hybridization values of 18.5-23.1 % with Aurantiacibacter type strains, while strain Z2T had values of 73.3-78.7 % and 14.5-33.3 % with Qipengyuania type strains. The genomic DNA G+C contents of strains H149T and Z2T were 64.3 and 61.8 %, respectively. Based on the genetic, genomic, phylogenetic, physiological and chemotaxonomic results, strains H149T (=KCTC 8397T=MCCC 1K08920T) and Z2T (=KCTC 8396T=MCCC 1K08946T) are concluded to represent two novel Erythrobacteraceae species for which the names Aurantiacibacter hainanensis sp. nov. and Qipengyuania zhejiangensis sp. nov. are proposed, respectively.

Substrate stiffness affects neural network activity in an extracellular matrix proteins dependent manner.

Neuronal growth, differentiation, extension, branching and neural network activity are strongly influenced by the mechanical property of extracellular matrix (ECM). However, the mechanism by which substrate stiffness regulates a neural network activity, and the importance of ECM composition in conferring substrate stiffness sensing have not been explored. To address this question, the hippocampal neurons were seeded on the polydimethylsiloxane (PDMS) substrate with different stiffness, which were coated with fibronectin and laminin respectively. Our results show that voltage-gated Ca2+ channel currents are greater in neurons on the stiff substrate than on the soft substrate. In addition, the neurons exhibit a greater increase of Ca2+ currents on laminin-coated stiff substrate than on those coated with fibronectin, indicating that the composition of ECM can modulate responses to substrate stiffness of neurons. Paired patch-clamp recordings have shown that upregulation of neural effective synaptic connectivity is greater on the laminin-coated stiff substrate than on the fibronectin-coated ones. Consistently, laminin-coated stiff substrate enhances Ca2+ oscillations of neurons is greater that compared with the fibronectin-coated ones. Our study demonstrates that a direct role for substrate stiffness in regulating neuronal network activity and indicate that this modulation is dependent on a specific type of ECM protein, which should be taken into account for the design of biomaterials for neuronal tissue engineering.