3D-Printed Microelectrodes for Biological Measurement.

Microelectrodes are useful electrochemical sensors that can provide spatial biological monitoring. Carbon fiber has been by far the most widely used microelectrode; however, a vast number of different materials and modification strategies have been developed to broaden the scope of microelectrodes. Carbon composite electrodes provide a simple approach to making microelectrodes with a wide range of materials, but manufacturing strategies are complex. 3D printing can provide the ability to make microelectrodes with high precision. We used fused filament fabrication to print single strands of carbon black/polylactic acid (CB/PLA) and multiwall carbon nanotube/polylactic acid (MWCNT/PLA), which were then made into microelectrodes. Microelectrodes ranged from 70 µm in diameter to 400 µm in diameter and were assessed using standard redox probes. MWCNT/PLA electrodes exhibited greater sensitivity, a lower limit of detection, and stability for the measurement of serotonin (5-HT). Both CB/PLA and MWCNT/PLA microelectrodes were able to monitor 5-HT overflow from the ex vivo ileum tissue. MWCNT/PLA microelectrodes were utilized to show differences in 5-HT overflow from ex vivo ileum and colon following exposure to odorants present in spices. These findings highlight that any conductive thermoplastic material can be fabricated into a microelectrode. This simple strategy can utilize a wide range of materials to make 3D-printed microelectrodes for a diverse range of applications.

Muricauda oceani sp. nov., isolated from the East Pacific Ocean.

A Gram-stain-negative bacterium, designated strain 501str8T, was isolated from a sediment sample collected from the East Pacific Ocean. 16S rRNA gene sequence analysis revealed that strain 501str8T belonged to the genus Muricauda, with closely related type strains Muricauda aquimarina SW-63T (98.5 %), Muricauda lutimaris SMK-108T (98.3 %) and Muricauda ruestringensis B1T (97.9 %). Up-to-date bacterial core gene set analysis revealed that strain 501str8T represented one independent lineage with M. aquimarina SW-63T. The average nucleotide identity values of strain 501str8T with M. aquimarina SW-63T and M. lutimaris SMK-108T were 80.2 and 81.3 %, respectively. In silico DNA-DNA hybridization values between strain 501str8T and M. aquimarina SW-63T and M. lutimaris SMK-108T were 22.8 and 32.9 %, respectively. The predominant isoprenoid quinone was menaquinone-6, and iso-C15 : 0, iso-C17 : 0 3-OH and iso-C15 : 1 G were the dominant cellular fatty acids. The G+C content of the genomic DNA was 42.8 mol%. Differential phylogenetic distinctiveness and chemotaxonomic differences, together with the phenotypic properties observed in this study, revealed that strain 501str8T could be differentiated from closely related species. Therefore, we propose that strain 501str8T represents a novel species of the genus Muricauda, for which the name Muricauda oceani sp. nov. is suggested. The type strain is 501str8T (=JCM 33902T=MCCC 1K04567T).

Jiella pacifica sp. nov., isolated from the West Pacific Ocean.

A Gram-stain-negative bacterium, designated strain 40Bstr34T, isolated from a sediment sample from the West Pacific Ocean, was taxonomically characterized by using a polyphasic approach. The strain was phylogenetically close to Jiella aquimaris LZB041T and Jiella endophytica CBS5Q-3T, with 16S rRNA gene sequence similarities of 98.5 and 97.1 %, respectively. The genome of strain 40Bstr34T featured a G+C content of 65.7 % for a 5.8 Mb chromosome. Up-to-date bacterial core gene set analysis revealed that strain 40Bstr34T represents one independent lineage with J.aquimaris LZB041T. In silico DNA-DNA hybridization values between strain 40Bstr34T and its phylogenetic neighbours ranged from 30.3-34.2 %, below the cutoff of 70 %. In addition, the corresponding average nucleotide identity values were between 81.8-83.7 %, which are lower than 95 % threshold. The predominant cellular fatty acids of strain 40Bstr34T were summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c), cyclo-C19 : 0 ω8c and iso-C17 : 0 3-OH, and ubiquinone-10 as the predominant respiratory quinone. The major polar lipids included phosphatidylethanolamine, phosphatidylmonomethylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, two unidentified aminolipids and two unidentified lipids. Based on the results of phenotypic, chemotaxonomic and genetic analyses, strain 40Bstr34T is identified as representing a novel species of the genus Jiella for which the name Jiella pacifica sp. nov. is proposed. The type strain is 40Bstr34T (=JCM 33903T=MCCC 1K04569T).

Alteromonas profundi sp. nov., isolated from the Indian Ocean.

A Gram-staining-negative bacterium, designated 345S023T, was isolated from a sea water sample from the Indian Ocean. The results of 16S rRNA gene sequence analysis revealed that 345S023T represents a member of the genus Alteromonas, with closely related type strains Alteromonas fortis 1T (98.7 %), Alteromonas hispanica F-32T (98.6 %) and Alteromonas genovensis LMG 24078T (98.6 %). Up-to-date bacterial core gene set analysis revealed that 345S023T formed a phyletic lineage with Alteromonas australica H 17T. The case for 345S023T representing a novel species was supported by genomic results. Pairwise in silico DNA-DNA hybridization and average nucleotide identity values were much lower than the proposed and generally accepted species boundaries. Strain 345S023T contains ubiquinone-8 (Q-8) as the sole isoprenoid quinone, summed featured 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and C18 : 1ω7c as the dominant cellular fatty acids (>10 %), and phosphatidylglycerol and phosphatidylethanolamine as the major polar lipids. The genome of strain 345S023T consisted of a 4.4 Mb chromosome with a DNA G+C content of 44.4 %. On the basis of these genomic, chemotaxonomic and phenotypic characteristics, we propose a novel species: Alteromonas profundi sp. nov. The type strain is 345S023T(=JCM 33893T=MCCC 1K04570T).

Muricauda sediminis sp. nov., isolated from western Pacific Ocean sediment.

A Gram-stain-negative bacterium, designated strain 40Bstr401T, was isolated from a sediment sample collected from the western Pacific Ocean. Analysis of its 16S rRNA gene sequence revealed that strain 40Bstr401T belongs to the genus Muricauda and is closely related to type strains Muricauda antarctica Ar-22T (98.2 %), Muricauda taeanensis 105T (98.2 %) and Muricauda beolgyonensis BB-My12T (97.4 %). The average nucleotide identity values for 40Bstr401T with M. antarctica Ar-22T and M. taeanensis 105T are 79.3 % and 78.8 %, respectively. The in silico DNA-DNA hybridization values between strain 40Bstr401T and M. antarctica Ar-22T and M. taeanensis 105T are 26.7 and 26.6 %, respectively. The major isoprenoid quinone of 40Bstr401T is MK-6, and iso-C17 : 0 3-OH and iso-C15 : 0 are the dominant cellular fatty acids. The major polar lipids are phosphatidylethanolamine, four unidentified amino lipids and two unidentified lipids. The G+C content of the genomic DNA is 42.9 mol%. Its phylogenetic distinctiveness and chemotaxonomic differences, together with the phenotypic properties observed in this study, indicate that strain 40Bstr401T can be differentiated from closely related species. Therefore, we propose strain 40Bstr401T represents a novel species in the genus Muricauda, for which the name Muricauda sediminis sp. nov. is suggested. The type strain is 40Bstr401T (=MCCC 1K04568T=KCTC 82139T).

Carnobacterium antarcticum sp. nov., a psychrotolerant, alkaliphilic bacterium isolated from sandy soil in Antarctica.

A novel, alkaliphilic, psychrotolerant, facultative anaerobe, designated CP1T, was isolated from sandy soil near the Davis Station in Antarctica. The short-rod-shaped cells displayed Gram-positive staining and did not form spores. Strain CP1T was able to grow at temperatures between 4 and 36 °C, pH 6.0-9.5, and in the presence of up to 5.0 % (w/v) NaCl. 16S rRNA gene and multilocus (pheS, rpoA, and atpA) sequence analysis revealed Carnobacterium mobile DSM 4848T and Carnobacterium iners LMG 26642T as the closest relatives (97.4 and 97.1 % 16S rRNA gene sequence similarity, respectively). The genomic G+C content was 38.1 mol%, and DNA-DNA hybridization with DSM 4848T revealed 32.4±3.4 % similarity. The major fatty acid components were C14 : 0 and C16 : 1ω9c. The cell wall contained meso-diaminopimelic acid and was of peptidoglycan type A1γ. Based on physiological, genotypic and biochemical characteristics, strain CP1T represents a novel species of the genus Carnobacterium for which the name Carnobacterium antarcticum sp. nov. is proposed. The type strain is CP1T (=DSM 103363T=CGMCC 1.15643T).