Enzymatic Process for the Carrageenolytic Bioconversion of Sulfated Polygalactans into ß-Neocarrabiose and 3,6-Anhydro-d-galactose.

Oligosaccharides and anhydro-sugars derived from carrageenan have great potential as functional foods and drugs showing various bioactivities, including antioxidant, anti-inflammatory, antiviral, antitumor, and cytotoxic activities. Although preparation of sulfated carrageenan oligosaccharides by chemical and enzymatic processes has been widely reported, preparation of nonsulfated ß-neocarrabiose (ß-NC2) and the rare sugar 3,6-anhydro-d-galactose (d-AHG) was not reported in the literature. Based on the carrageenan catabolic pathway in marine heterotrophic bacteria, an enzymatic process was designed and constructed with recombinant κ-carrageenase, GH127/GH129 α-1,3 anhydrogalactosidase, and cell-free extract from marine carrageenolytic bacteria Colwellia echini A3T. The process consisted of three successive steps, namely, (i) depolymerization, (ii) desulfation, and (iii) monomerization, by which carrageenan oligosaccharides, ß-NC2, and d-AHG were obtained from κ-carrageenan. Unlike the chemical process, enzymatic hydrolysis yields oligosaccharides with the desired degree of polymerization facilitates specific removal of sulfated groups, free of toxic byproducts, and avoids chemical modifications. The final optimized enzymatic process produced 0.52 g of ß-NC2 and 0.24 g of d-AHG from 1 g of κ-carrageenan. The carrageenolytic process designed for the enzymatic hydrolysis of κ-carrageenan can be scaled up for the mass production of bioactive carrageeno-oligosaccharides.

Aurantiacibacter sediminis sp. nov., a marine bacterium isolated from a tidal flat.

A yellow-coloured bacterium, designated as strain JGD-13T, was isolated from a tidal flat in the Republic of Korea. Cells were Gram-stain-negative, aerobic, non-flagellated and rod-shaped. Growth was observed at 4-42 °C (optimum, 30 °C), at pH 6.0-12.0 (pH 7.0-8.0) and at 1-7 % (w/v) NaCl concentration (3 %). The 16S rRNA gene sequence analysis indicated that strain JGD-13T was closely related to Aurantiacibacter gangjinensis K7-2T with a sequence similarity of 98.2 %, followed by Aurantiacibacter aquimixticola JSSK-14T (98.1 %), Aurantiacibacter atlanticus s21-N3T (97.6 %), Aurantiacibacter zhengii V18T (97.6 %) and Aurantiacibacter luteus KA37T (97.5 %). The average nucleotide identity and digital DNA-DNA hybridization values with related strains were 70.3-76.2 % and 18.5-20.3 %. The genomic DNA G+C content was 60.2 mol%. Phylogenetic analysis using the maximum-likelihood method showed that strain JGD-13T formed a clade with A. aquimixticola JSSK-14T and A. gangjinensis K7-2T. The major fatty acids were summed feature 8 (39.7 %) and C17 : 1 ω6c (14.4 %). The predominant respiratory quinone was ubiquinone-10. The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, one sphingoglycolipid and three unidentified lipids. On the basis of phylogenetic, phenotypic and chemotaxonomic characteristics, strain JGD-13T represents a novel species within the genus Aurantiacibacter, for which the name Aurantiacibacter sediminis JGD-13Tsp. nov. is proposed. The type strain is JGD-13T (=KCTC 72892T=KACC 21676T=JCM 33995T).

Metabolism perturbation Causedby the overexpression of carbon monoxide dehydrogenase/Acetyl-CoA synthase gene complex accelerated gas to acetate conversion rate ofEubacterium limosumKIST612.

Microbial conversion of carbon monoxide (CO) to acetate is a promising upcycling strategy for carbon sequestration. Herein, we demonstrate that CO conversion and acetate production rates of Eubacterium limosum KIST612 strain can be improved by in silico prediction and in vivo assessment. The mimicked CO metabolic model of KIST612 predicted that overexpressing the CO dehydrogenase (CODH) increases CO conversion and acetate production rates. To validate the prediction, we constructed mutant strains overexpressing CODH gene cluster and measured their CO conversion and acetate production rates. A mutant strain (ELM031) co-overexpressing CODH, coenzyme CooC2 and ACS showed a 3.1 × increased specific CO oxidation rate as well as 1.4 × increased specific acetate production rate, compared to the wild type strain. The transcriptional and translational data with redox balance analysis showed that ELM031 has enhanced reducing potential from up-regulation of ferredoxin and related metabolism directly linked to energy conservation.

Novosphingobium aureum sp. nov., a marine bacterium isolated from salt flat sediment.

A Gram-stain-negative, aerobic, pale yellow-coloured, rod-shaped marine bacterium designated strain YJ-S2-02T was isolated from salt flat sediment sampled in Yongyu-do, Republic of Korea. Strain YJ-S2-02T grew at pH 6.0-9.0 (optimum, pH 7.0), 10-40 °C (optimum, 30 °C) and with optimum 1 % (w/v) NaCl. The 16S rRNA gene sequence analysis indicated that strain YJ-S2-02T was closely related to Novosphingobium naphthalenivorans NBRC 102051T (97.8 %) followed by Novosphingobium mathurense SM117T (97.5 %), Novosphingobium indicum H25T (97.3 %), Novosphingobium pentaromativorans US6-1T (96.8 %), Novosphingobium fontis STM-14T (96.6 %), Novosphingobium endophyticum EGI60015T (96.5 %), Novosphingobium naphthae D39T (96.5 %) and Novosphingobium malaysiense MUSC 273T (95.9 %). The average nucleotide identity and estimated DNA-DNA hybridization values between YJ-S2-02T and related type strains were 77.0-77.9 % and 19.1-24.0 %. Strain YJ-S2-02T was characterized as having Q-10 as the predominant respiratory quinone and the principal fatty acids (>10 %) were summed feature 8 (C18 : 1 ω6c/ω7c, 20.7 %), C18 : 3 ω6c (16.3 %) and C17 : 1 ω6c (11.8 %). The polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, sphingolipids and two unidentified lipids. The DNA G+C content of strain YJ-S2-02T was 65.6 mol%. On the basis of the polyphasic taxonomic evidence presented in this study, YJ-S2-02T should be classified as representing a novel species within the genus Novosphingobium, for which name Novosphingobium aureum is proposed, with the type strain YJ-S2-02T (=KACC 21677T =KCTC 72891T=JCM 33996T).

Marinobacter halodurans sp. nov., a halophilic bacterium isolated from sediment of a salt flat.

A Gram-staining-negative, aerobic, cream-coloured, marine bacterium, with rod-shaped cells, designated strain YJ-S3-2T, was isolated from salt flat sediment of Yongyu-do, Republic of Korea. YJ-S3-2T grew at pH 5.0-9.0 (optimum pH 7.0), 4-45 °C (optimum 30 °C) and with 1-18 % (w/v) NaCl (optimum 6 %). The results of 16S rRNA gene sequence analysis indicated that YJ-S3-2T was closely related to Marinobacter segnicrescens SS011B1-4T (97.0 %) followed by, 'Marinobacter nanhaiticus' D15-8W (96.7 %), Marinobacter bryozoorum 50-11T (96.7 %), Marinobacter koreensis DSMZ 179240T T (96.5 %) and Marinobacter bohaiensis T17T (96.5 %). The average nucleotide identity (ANI) and the genome to genome distance calculator (GGDC) estimate values between YJ-S3-2T and related type strains were 73.7-79.8 and 19.9-22.5 %, and also 73.5 and 20.7 % with Marinobacter hydrocarbonoclasticus. YJ-S3-2T was characterized as having Q-9 as the predominant respiratory quinone and the principal fatty acids (>10 %) were C16 : 0 (22.3 %), summed feature 9 (C17 : 1iso ω9c/C16 : 0 10-methyl, 13.8 %) and 3 (C16 : 1ω7c/C16 : 1ω6c, 11.9 %). The polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, two unidentified aminolipids and two unidentified phospholipids. The DNA G+C content of YJ-S3-2T is 60.9 mol%. On the basis of the polyphasic taxonomic evidence presented in this study, YJ-S3-2T should be classified as representing a novel species within the genus Marinobacter, for which name Marinobacter halodurans sp. nov. is proposed, with the type strain YJ-S3-2T (=KACC 19883T=KCTC 62937T=JCM 33109T).

Muricauda ochracea sp. nov., isolated from a tidal flat in the Republic of Korea.

A yellowish-brown-coloured bacterium, designated strain JGD-17T, was isolated from a tidal flat of Janggu-do, Garorim bay, Taean-gun, Chungcheongbuk-do, Republic of Korea. Cells were Gram-stain-negative, aerobic, non-flagellated and long-rod-shaped. Growth was observed at 20-45 °C (optimum, 25-30 °C), at pH 6.0-10.0 (9.0) and with 1-5 % (w/v) NaCl (1-3 %). Results of 16S rRNA gene sequence analysis indicated that strain JGD-17T was closely related to Muricauda nanhaiensis SM1704T (96.1 %), Muricauda olearia CL-SS4T (95.0 %), Muricauda beolgyonensis BB-My12T (94.9 %), Muricauda marina H19-56T (94.7 %) and Muricauda indica 3PC125-7T (94.5 %). The ranges of values for the average nucleotide identity and digital DNA-DNA hybridization analyses with related strains were 71.3-74.1 % and 16.9-18.2 %. The genomic DNA G+C content was 41.1 mol%. Phylogenetic analysis using the neighbour-joining method showed that strain JGD-17T formed a clade with Muricauda nanhaiensis SM1704T, Muricauda lutaonensis CC-HSB-11T, Muricauda lutea CSW06T and Muricauda pacifica SM027T. The major fatty acids were iso-C15 : 0 (26.9 %), iso-C15 : 1 G (19.5 %) and iso-C17 : 0 3-OH (12.7 %). The predominant respiratory quinone was menaquinone-6. The polar lipids were phosphatidylethanolamine, an unidentified aminolipid, an unidentified phospholipid and two unidentified lipids. On the basis of phylogenetic, phenotypic and chemotaxonomic characteristics, strain JGD-17T represents a novel species within the genus Muricauda, for which the name Muricauda ochracea sp. nov. is proposed. The type strain is JGD-17T (=KCTC 72732T=KACC 21486T=JCM 33817T).

Olfactory receptor 544 reduces adiposity by steering fuel preference toward fats.

Olfactory receptors (ORs) are present in tissues outside the olfactory system; however, the function of these receptors remains relatively unknown. Here, we determined that olfactory receptor 544 (Olfr544) is highly expressed in the liver and adipose tissue of mice and regulates cellular energy metabolism and obesity. Azelaic acid (AzA), an Olfr544 ligand, specifically induced PKA-dependent lipolysis in adipocytes and promoted fatty acid oxidation (FAO) and ketogenesis in liver, thus shifting the fuel preference to fats. After 6 weeks of administration, mice fed a high-fat diet (HFD) exhibited a marked reduction in adiposity. AzA treatment induced expression of PPAR-α and genes required for FAO in the liver and induced the expression of PPAR-γ coactivator 1-α (Ppargc1a) and uncoupling protein-1 (Ucp1) genes in brown adipose tissue (BAT). Moreover, treatment with AzA increased insulin sensitivity and ketone body levels. This led to a reduction in the respiratory quotient and an increase in the FAO rate, as indicated by indirect calorimetry. AzA treatment had similar antiobesogenic effects in HFD-fed ob/ob mice. Importantly, AzA-associated metabolic changes were completely abrogated in HFD-fed Olfr544-/- mice. To our knowledge, this is the first report to show that Olfr544 orchestrates the metabolic interplay between the liver and adipose tissue, mobilizing stored fats from adipose tissue and shifting the fuel preference to fats in the liver and BAT.