Polar Lipids Research Articles

Improving lipid digestion by modulating interfacial structure of fat globule based on milk fat globule membrane and different phospholipids

Combining milk fat globule membrane (MFGM) and phospholipid (PL) could compensate for the low content of polar lipids in MFGM and supplement specific sphingomyelin, and ceramide lipids. This study investigated the effects of MFGM combined with PL from different sources (soy, egg yolk, and milk) as membrane components on the physicochemical properties, structure, and lipid digestion of simulated human milk fat globule (HMFG) emulsions for the first time. The emulsion prepared by MFGM with PL performed a larger and more uniform particle size distribution (1.25–1.77 μm), and an interface structure similar to the PL-protein membrane of human milk. Meanwhile, MFGM combined with milk PL simulated HMFG emulsion performed the highest stability. During gastric digestion, the MFGM combined with PL emulsions could better maintain the MFG structure and reduce the aggregation of proteins and lipids. This ultimately resulted in higher levels of lipolysis degree (65.86%–77.37%) and the release of free fatty acids. Overall, modulating the interfacial structure of MFG based on MFGM and PL could be an effective strategy to improve the stability and lipid digestion of simulated HMFG emulsion.

Archaea membranes in response to extreme acidic environments

Bipolar tetraether lipids (BTL), such as glycerol dialkyl calditol tetraether (GDNT) and glycerol dialkyl glycerol tetraether (GDGT), are the dominating lipid species in thermoacidophiles that inhabit at pH ≤ 4 and temperatures ≥65°C. BTL containing archaea membranes respond to environmental pH changes by varying the number of cyclopentane rings in the isoprenoids, the amount of GDNT relative to GDGT, the ratio of tetraethers to diethers, and the level of glycosylation in polar headgroups. These structural and compositional adjustments can alter the hydrogen bond networks in the membrane polar headgroup regions and the packing tightness and rigidity in the membrane hydrophobic core. It is likely that these changes in non-covalent interactions among archaea lipids are made to retain low membrane volume fluctuations and their low sensitivity to temperature, as illustrated in the case of liposomes made of the polar lipid fraction E (PLFE) of Sulfolobus acidocaldarius. As such, a low passive proton permeability and a near neutral intracellular pH can be maintained, and, as a result, optimal activities of soluble and membrane-bound proteins in thermoacidophiles can be retained in acidic growth conditions at elevated growth temperatures.

Nocardioides limicola sp. nov., an alkaliphilic alkane degrading bacterium isolated from oilfield alkali-saline soil.

A Gram-stain-positive, rod-shaped, non-spore-forming, alkane degrading bacterium, designated DJM-14T, was isolated from oilfield alkali-saline soil in Heilongjiang, Northeast China. On the basis of 16S rRNA gene sequencing, strain DJM-14T was shown to belong to the genus Nocardioides, and related most closely to Nocardioides terrigena KCTC 19,217T (95.53% 16S rRNA gene sequence similarity). Strain DJM-14T was observed to grow at 25-35°C, pH 7.0-11.0, in the presence of 0-6.0% (w/v) NaCl. The predominant respiratory quinone was MK-8 (H4) and LL-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. The major fatty acids were identified as iso-C16:0 and C18:1 ω9c. It contained diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol as the polar lipids. The genome (3,722,608bp), composed of 24 contigs, had a G + C content of 69.6mol%. Out of the 3667 predicted genes, 3618 were protein-coding genes, and 49 were ncRNAs. Digital DNA-DNA hybridization (dDDH) estimation and average nucleotide identity (ANI) of strain DJM-14T against genomes of the type strains of related species in the same family ranged between 18.7% and 20.0%; 68.8% and 73.6%, respectively. According to phenotypic, genotypic and phylogenetic data, strain DJM-14T represents a novel species in the genus Nocardioides, for which the name Nocardioides limicola sp. nov. is proposed and the type strain is DJM-14T (= CGMCC 4.7593T, =JCM 33,692T). In addition, novel strains were able to grow with n-alkane (C24-C36) as the sole carbon source. Multiple copies of alkane 1-monooxygenase (alkB) gene, as well as alcohol dehydrogenase gene and aldehyde dehydrogenase gene involved in the alkane assimilation were annotated in the genome of type strain DJM-14T.

Devosia lacusdianchii sp. nov., an attached bacterium inhibited by metabolites from its symbiotic Microcystis.

A novel alphaproteobacterial strain JXJ CY 41T was isolated from a culture mass of Microcystis, collected from Lake Dianchi, south-west, China. Strain JXJ CY 41T was gram-strain-negative, aerobic, motile, with rod-shaped cells (0.4-1.0 × 1.7-3.5μm). It was positive for catalase and starch hydrolysis, negative for oxidase and hydrolysis of Tweens (20, 40, and 80). Growth occurred at 10-44°C, pH 5.0-10.0, and 0-5.0% (w/v) NaCl. Major fatty acids included C16:0 (28.1%), 11-methyl C18:1 ω7c (36.7%) and C18:1 ω7c (20.8%). Q10 was the sole ubiquinone. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, glycolipid, and an unidentified lipid. The DNA G + C content was 63.1%. Its 16S rRNA gene sequence showed high similarities with Devosia oryziradicis G19T (99.5%; not validly published), D. yakushimensis Yak96BT (98.3%) and D. ginsengisoli Gsoil 520T (98.1%), and less than 98.1% similarities with other members of the genus Devosia. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain JXJ CY 41T and its 5 closest similar strains were 19.9-24.1% and 75.7-80.5%, respectively. Based on the data above, strain JXJ CY 41T was identified as a novel species of the genus Devosia, for which the epithet Devosia lacusdianchii sp. nov. was proposed. The type strain is JXJ CY 41T (= KCTC 72812T = CGMCC 1.17502T). Strain JXJ CY 41T exhibited different interactions with Microcystis aeruginosa FACHB-905 (Maf) under different conditions, and Maf could control the bacterial cellular density by secreting unknown specific chemical compounds according to its nutritional requirements.

Description of Nesterenkonia aerolata sp. nov., an actinobacterium isolated from air of manufacturing shop in a pharmaceutical factory.

During our studies on the microorganism diversity from air of manufacturing shop in a pharmaceutical factory in Shandong province, China, a Gram-stain-positive, aerobic, cocci-shaped bacterium, designated LY-0111T, was isolated from a settling dish. Strain LY-0111T grew at temperature of 10-42°C (optimum 35°C), pH of 5.0-10.0 (optimum pH 7.0) and NaCl concentration of 1-12% (optimum 0.5-3%, w/v). Based on the 16S rRNA gene sequence analysis, the strain shared the highest sequence similarities to Nesterenkonia halophila YIM 70179T (96.2%), and was placed within the radiation of Nesterenkonia species in the phylogenetic trees. The genome of the isolate was sequenced, which comprised 2,931,270bp with G + C content of 66.5%. A supermatrix tree based on the gene set bac120 indicated that LY-0111T was close related to Nesterenkonia xinjiangensis YIM 70097T (16S rRNA gene sequence similarity 95.3%). Chemotaxonomic analysis indicated that the main respiratory quinones were MK-7, MK-8, and MK-9, the predominant cellular fatty acids were anteiso-C15:0 and iso-C15:0, and the major polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylinositol. According to the phenotypic, chemotaxonomic and phylogenetic features, strain LY-0111T is considered to represent a novel species, for which the name Nesterenkonia aerolata sp. nov. is proposed. The type strain is LY-0111T (= JCM 36375T = GDMCC 1.3945T). In addition, Nesterenkonia jeotgali was proposed as a later synonym of Nesterenkonia sandarakina, according to the ANI (96.8%) and dDDH (72.9%) analysis between them.

Simplicispira sedimenti sp. nov., isolated from a sediment of drainage ditch in winery.

A Gram-stain-negative, motile (by single polar flagellum) and rod-shaped bacterium, designated W1-6T, was isolated from a sediment of drainage ditch in winery in Guiyang, south-western China. Strain W1-6T showed the highest 16S rRNA gene sequence similarities with the type strain of Acidovorax wautersii (98.1%) and Simplicispira lacusdiani (97.9%). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain W1-6T was placed adjacent to the members of the genus Simplicispira and formed a separat subclade. Cells showed oxidase and catalase negative reactions. The only respiratory quinone detected was ubiquinone-8 (Q-8). Summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), C16:0 and summed feature 8 (C18:1 ω7c and/or C18:1 ω6c) were predominant cellular fatty acids (> 10%) of strain W1-6T. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and five unidentified phospholipids were found in the polar lipid extraction. The genomic DNA G + C content was 65.6%. Strain W1-6T shared the highest digital DNA-DNA hybridization [dDDH, (27.6%)] and average nucleotide identity [ANI (84.3%)] values with the type strain of S. lacusdiani. The dDDH and ANI values were below the cutoff level (dDDH 70%; ANI 95-96%) for species delineation. The polyphasic characteristics indicated that the strain W1-6T represents a novel species of the genus Simplicispira, for which the name Simplicispira sedimenti sp. nov. is proposed. The type strain is W1-6T (= CGMCC 1.16274T = NBRC 115624T).

Milk fat globule membrane and its polar lipids: reviewing preclinical and clinical trials on cognition.

In most parts of the world, life expectancy is increasing thanks to improved healthcare, public health policies, nutrition, and treatment. This increase in lifespan is often not accompanied by an increase in health span, which severely affects people as they age. One notable consequence of this is the increasing prevalence of neurodegenerative diseases such as mild cognitive impairment, dementia, and Alzheimer's disease. Therefore, dietary and pharmaceutical measures must be taken to reduce the burden of such pathologies. Among the different types of nutrients found in the diet, lipids and especially polar lipids are very important for cognition due to their abundance in the brain. Amid the most studied sources of polar lipids, milk fat globule membrane (MFGM) stands out as it is abundant in industrial by-products such as buttermilk. In this narrative review, we discuss the latest, i.e. less than five years old, scientific evidence on the use of MFGM and its polar lipids in cognitive neurodevelopment in early life and their potential effect in preventing neurodegeneration in old age. We conclude that MFGM is an interesting, abundant and exploitable source of relatively inexpensive bioactive molecules that could be properly formulated and utilized in the areas of neurodevelopment and cognitive decline. Sufficiently large randomized controlled trials are required before health-related statements can be made. However, research in this area is progressing rapidly and the evidence gathered points to biological, health-promoting effects.

Липидный анализ слезной жидкости в диагностике дисфункции мейбомиевых желез

The tear film lipid layer plays a crucial role in maintaining ocular surface homeostasis by preventing excessive evaporation of the aqueous layer and reducing heat transfer from the corneal and conjunctival surface. The lipid composition of the tear film is unique and consists of two main layers: the outer (nonpolar lipids) and the inner (polar lipids). The thick outer layer of the tear film is composed of non-polar lipids that lack internal distributed charge, while the thin inner layer is formed by polar lipids with positive and negative charges at the ends of the molecule. Both types of lipids are synthesized in the meibomian glands (MG) and contribute to tear film stability. Meibomian gland dysfunction (MGD) alters the composition and physical properties of lipids, leading to pathological changes in both the MG and tear film. In meibomian gland dysfunction (MGD), the meibum thickens and acquires a higher melting point than normal. This leads to a decrease in the amount of nonpolar and amphiphilic lipids in the meibomian gland secretion and tear film. Consequently, the protective effect of the tear lipid layer is impaired, and its stability is compromised. Lipid mapping analyzes the lipid composition of biological samples, such as tear fluid, to study the mechanisms of the development and progression of various ocular surface diseases, including dry eye syndrome, MGD, and recurrent blepharoconjunctivitis. This method provides fundamental data on the properties of the tear film in various ocular surface diseases. It has the potential to establish hallmarks of disease course and develop personalized treatment approaches for specific clinical cases. KEYWORDS: tear, tear film lipids, ocular surface, meibomian gland dysfunction, lipid analysis. FOR CITATION: Takhauova L.R., Guseva A.A., Krylova A.A., Krivosheina O.I. Lipid analysis of tear fluid as a diagnostic tool for meibomian gland dysfunction. Russian Journal of Clinical Ophthalmology. 2024;24(2):83–87 (in Russ.). DOI: 10.32364/2311-7729-2024-24-2-7.

Immune Control of Gut Microbiota Prevents Obesity and the Effect of Antibiotic on Microbial Population

Gut microbiota have gained increasing recognition for their vital role in human health, particularly in their interactions with the immune system, including their involvement in obesity prevention through the production of IgA antibodies. These microbiotas are instrumental in lipid breakdown, utilizing lipases to break down phospholipids and triglycerides into polar head groups and free lipids. The loss of these beneficial microbes has been suggested as a potential cause for disruptions in various homeostatic mechanisms within our bodies. Factors contributing to this loss may encompass antibiotic usage, heightened sanitation practices, and low-fiber diets. Obesity, more prevalent in developed nations, is linked to the diminished regulatory immune responses associated with specific beneficial microbial species. This review article aims to provide a comprehensive exploration of how gut microbiota influence lipid metabolism, considering T-cell-mediated regulation, and examines the effects of antibiotics on the gut microbial population.

Parachitinimonas caeni gen. nov., sp. nov., a novel member of family Burkholderiaceae isolated from activated sludge collected in Shenzhen, PR China.

A Gram-stain-negative, strictly aerobic and filamentous bacterial strain, designated as DQS-5T, was isolated from the activated sludge of a municipal sewage treatment plant in Shenzhen, PR China. Optimal growth was observed at 28 °C and pH 7.5. Catalase and oxidase activities were detected. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain DQS-5T was most closely related to the genera Chitinimonas and Chitinivorax (91.0-93.4 % and 92.5 % 16S rRNA gene sequence similarity, respectively) and was close to the member of the family Burkholderiaceae. The complete genome sequence of strain DQS-5T contains 5 653 844 bp and 57.3 mol% G+C. The average nucleotide identity, digital DNA-DNA hybridization and average amino acid identity values between the genome of strain DQS-5T and those of its close relatives were 75.9-77.2, 19.0-20.3 and 57.2-61.8 %, respectively. Chemotaxonomic analysis of strain DQS-5T indicated that the sole respiratory quinone was ubiquinone-8, the predominant cellular fatty acids were C16 : 0 and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), and the major polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, aminophospholipid and aminolipid. The phylogenetic, genotypic, phenotypic and chemotaxonomic data demonstrate that strain DQS-5T represents a novel species in a novel genus within the family Burkholderiaceae, for which the name Parachitinimonas caeni gen. nov., sp. nov., is proposed. Strain DQS-5T (=KCTC 92788T=CCTCC AB 2022320T) is the type and only strain of P. caeni.

Lipid Composition, Cytotoxic and Acetylcholinesterase Inhibition Effects of Two Brown Algae Species Lobophora tsengii and Lobophora australis.

In this paper, the lipid classes, compositions of the neutral lipids, phospholipids and fatty acids, acetylcholinesterase inhibition and cytotoxic activity of two brown algae Lobophora tsengii D. Tien & Z. Sun and Lobophora australis Z. Sun, F. C. Gurgel & H. Kawai have been investigated. The polar lipid class had the highest content in total lipid (TL) (43.47% in L. tsengii and 48.95% in L. australis). Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were the main components in the phospholipids of two studied brown algae with contents varied from 32.27% to 52.33%. Total lipids were rich in PUFA (42.54% of total fatty acids for L. australis and 32.98% for L. tsengii), with EPA (11.46%, 14.30%) and AA (8.0%, 11.96%). L. tsengii methanol extract inhibited acetylcholinesterase (AChE) in in vitro assay with an IC50 value of 25.45 µg/mL. Both Lobophora methanol extracts display cytotoxic effects against four human cancer cell lines (KB, MCF7, HepG2 and A549) with IC50 in the range of 21.11-83.61 µg/mL. Especially, L. australis extract showed a strong cytotoxicity against KB cell lines with IC50 value of 21.11±0.39 µg/mL.

High-Throughput Lipidomic and Metabolomic Profiling for Brain Tissue and Biofluid Samples in Neurodegenerative Disorders.

Recent research has revealed the potential of lipidomics and metabolomics in identifying new biomarkers and mechanistic insights for neurodegenerative disorders. To contribute to this promising area, we present a detailed protocol for conducting an integrated lipidomic and metabolomic profiling of brain tissue and biofluid samples. In this method, a single-phase methanol extraction is employed for extracting both nonpolar and highly polar lipids and metabolites from each biological sample. The extracted samples are then subjected to liquid chromatography-mass spectrometry-based assays to provide relative or semiquantitative measurements for hundreds of selected lipids and metabolites per sample. This high-throughput approach enables the generation of new hypotheses regarding the mechanistic and functional significance of lipid and metabolite alterations in neurodegenerative disorders while also facilitating the discovery of new biomarkers to support drug development.

Fontisubflavum oceani gen. nov., sp. nov., isolated from the deep-sea cold seep water of South China Sea.

In this study, we report a Gram-stain-negative, rod-shaped, atrichous and aerobic bacterial strain named CSW1921T, which was isolated from the deep-sea water of a cold seep in South China Sea. Growth of strain CSW1921T occurred at 10.0-35.0 °C (optimum, 30 °C), pH 5.0-10.0 (optimum, pH 8.0-9.0) and with 0-9.0 % (w/v) NaCl (optimum, 1.0-2.0 %). Phylogenetic tree analysis based on 16S rRNA gene sequence or the genomic sequence indicated that strain CSW1921T belonged to the family Rhodobacteraceae and was closely related to Rhodophyticola porphyridii MA-7-27T (97.5 % sequence similarity). Genomic analysis indicated that strain CSW1921T contains a circular chromosome of 3 592 879 bp with G+C content of 60.5 mol%. The predominant respiratory quinone of CSW1921T was ubiquinone-10. The polar lipids of CSW1921T contained phosphatidylglycerol, three unidentified aminolipids, two unidentified phospholipids and two unidentified lipids. The major fatty acids of strain CSW1921T contained C16 : 0, C18 : 1 ω7c 11-methyl and summed feature 8 (C18 : 1 ω7c). The average nucleotide identity, DNA-DNA hybridization and average amino acid identity values between strain CSW1921T and members of its related species were 68.02-69.08 %, 12.7-12.9 % and 46.87-48.08 %, respectively, which were lower than the recommended threshold values for bacterial species or genus delineation. Phylogenetic, physiological, biochemical and morphological analyses suggested that strain CSW1921T represents a novel genus and a novel species of the family Rhodobacteraceae, and the name Fontisubflavum oceani gen. nov., sp. nov. is proposed with the type strain CSW1921T (=MCCC 1K08371T=KCTC 92834T).

Variations of intact phospholipid compositions in the digestive system of Antarctic krill, Euphausia superba, between summer and autumn.

The biochemical composition of Antarctic krill, Euphausia superba, is largely determined by their feeding behaviour. As they supply energy for animals of a higher trophic level and are also commercialized for human consumption, the interest in research on the species is high. Lipids, especially phospholipids, make up a high proportion of dry weight in krill. Seasonal changes are well documented in the fingerprint of free fatty acids analysed after hydrolysis of phospholipids, but the underlying intact polar lipids are rarely considered. In this study, we evaluated the compositions of intact phospholipids (IPLs) in the stomach, digestive gland and hind gut of Antarctic krill caught in summer and autumn at the Antarctic Peninsula region. Using high-resolution mass spectrometry, the fatty acid composition of 179 intact phospholipids could be resolved. Most IPLs were phosphatidylcholines, followed by phosphatidylethanolamines. Several very long chain polyunsaturated fatty acids up to 38:8, which have not been reported in krill before, were identified. The composition shifted to higher molecular weight IPLs with a higher degree of unsaturation for summer samples, especially for samples of the digestive gland. The data supplied in this paper provides new insights into lipid dynamics between summer and autumn usually described by free fatty acid biomarkers.

A novel UV-resistant bacterium Sphingomonas endolithica sp. nov., and genomic analysis, isolated from the north slope of Mount Everest.

Gram-stain-negative, aerobic, rod-shaped, non-motile bacterium strain ZFBP2030T was isolated from a rock on the North slope of Mount Everest. This strain contained a unique ubiquinone-10 (Q-10) as a predominant respiratory quinone. Among the tested fatty acids, the strain contained summed feature 8, C14:0 2OH, and C16:0, as major cellular fatty acids. The polar lipid profile contained phosphatidyl glycerol, phosphatidyl ethanolamine, three unidentified phospholipids, two unidentified aminolipids, and six unidentified lipids. The cell-wall peptidoglycan was a meso-diaminopimelic acid, and cell-wall sugars were ribose and galactose. Phylogenetic analyses based on 16S rRNA gene sequence revealed that strain ZFBP2030T was a member of the genus Sphingomonas, exhibiting high sequence similarity to the 16S rRNA gene sequences of Sphingomonas aliaeris DH-S5T (97.9%), Sphingomonas alpina DSM 22537T (97.3%) and Sphingomonas hylomeconis CCTCC AB 2013304T (97.0%). The 16S rRNA gene sequence similarity between ZFBP2030T and other typical strains was less than 97.0%. The average amino acid identity values, average nucleotide identity, and digital DNA-DNA hybridization values between strain ZFBP2030T and its highest sequence similarity strains were 56.9-79.9%, 65.1-82.2%, and 19.3-25.8%, respectively. The whole-genome size of the novel strain ZFBP2030T was 4.1 Mbp, annotated with 3838 protein-coding genes and 54 RNA genes. Moreover, DNA G + C content was 64.7mol%. Stress-related functions predicted in the subsystem classification of the strain ZFBP2030T genome included osmotic, oxidative, cold/heat shock, detoxification, and periplasmic stress responses. The overall results of this study clearly showed that strain ZFBP2030T is a novel species of the genus Sphingomonas, for which the name Sphingomonas endolithica sp. nov. is proposed. The type of strain is ZFBP2030T (= EE 013T = GDMCC 1.3123T = JCM 35386T).

Moraxella haemolytica sp. nov., isolated from a goat with respiratory disease.

An aerobic, haemolytic, Gram-negative and rod-shaped bacterial strain ZY171148T was isolated from the lung of a dead goat with respiratory disease in Southwest China. The strain grew at 24-39°C, at pH 6.0-9.0 and in the presence of 0.5-2.0% (w/v) NaCl. Phylogenetic analysis of 16S rRNA gene sequences showed that the strain belongs to the genus Moraxella. The nucleotide sequence similarity analysis of the 16S rRNA gene showed that the strain has the highest similarity of 98.1% to Moraxella (M.) caprae ATCC 700019T. Phylogenomic analysis of 800 single-copy protein sequences indicated that the strain is a member of the genus Moraxella and forms a separated branch on the Moraxella phylogenetic tree. The strain exhibited the highest orthologous average nucleotide identity (OrthoANI) and average amino acid identity (AAI) values of 77.0 and 77.9% to M. nasibovis CCUG 75921T and M. ovis CCUG 354T, respectively. The strain shared the highest digital DNA-DNA hybridization (dDDH) value of 26.2% to M. osloensis CCUG 350T. The genome G + C content of strain ZY171148T was 42.6mol%. The strain had C18:1 ω9c (41.7%), C18:0 (11.2%), C16:0 (14.1%) and C12:0 3OH (9.7%) as the predominant fatty acids and CoQ-8 as the major respiratory quinone. The strain contained phosphatidylglycerol, phosphatidylethanolamine, cardiolipin, dilysocardiolipin, monolysocardiolipin and phosphatidic acid as the major polar lipids. β-haemolysis was observed on Columbia blood agar. All results confirmed that strain ZY171148T represents a novel species of the genus Moraxella, for which the name Moraxella haemolytica sp. nov. is proposed, with strain ZY171148T = CCTCC AB 2021471T = CCUG 75920T as the type strain.

Ochrobactrum chromiisoli sp. nov., Isolated from Chromium-Contaminated Soil.

A Gram-stain-negative, non-spore-forming, flagellated, motile, aerobic, rod-shaped bacteria strain, designated YY2XT, was isolated from chromium-contaminated soil. Phylogenetic analysis based on 16S rRNA gene, recA gene, and whole genome indicated that the strain represented a new member of the genus Ochrobactrum, family Brucellaceae, class Alphaproteobacteria. The phylogenetic trees based on 16s rRNA gene, revealed that Falsochrobactrum ovis DSM26720T (96.7%), Ochrobactrum gallinifaecis DSM15295T (96.2%), and Pseudochrobactrum asaccharolyticum DSM25619T (96.2%) are the most closely related phylogenetic neighbors of strain YY2XT. The draft genome of YY2XT was approximately 4,650,646bp in size with a G + C content of 53.0mol%. Average nucleotide identity and digital DNA-DNA hybridization values among strain YY2XT and the selected Brucellaceae species were 71.4-83.1% and 13.5-42.7%, which are below the recommended cut-off values for species delineation. Growth of strain YY2XT occurred within pH 5-10 (optimum, pH 7-8), 4℃-42°C (optimum, 30°C), and NaCl concentrations of 0.0-6.0% (optimum, 1.0%). Major quinone system was ubiquinone 10, the major fatty acids were C16:0, C18:1ω7c, and C16:1ω7c and the major polyamines were spermidine and putrescine. Major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine, phosphatidylmonomethylethanolamine, phosphatidylethanolamine, and four undefined lipids. On the basis of the phenotypic, genotypic and chemotaxonomic traits, strain YY2XT was considered to represent a novel species of the genus Ochrobactrum, for which the name Ochrobactrum chromiisoli sp. nov. is proposed. The type strain is YY2XT (= CCTCC AB 2023035T = JCM 36000T).

Micrococcus lacusdianchii sp. nov., an attached bacterium inhibited by metabolites from its symbiotic algae.

A novel actinobacterial strain, designated as JXJ CY 30 T, was isolated from the phycosphere of Microcystis aeruginosa FACHB-905 (Maf) collected from Lake Dianchi, China. The strain was a Gram-stain-positive, aerobic and coccus-shaped actinobacterium. It had alanine, glutamic acid, aspartic acid, and lysine in the peptidoglycan, and mannose, ribose and arabinose in its cell wall sugars, anteiso-C15:0 and iso-C15:0 as the main cellular fatty acids, MK-7 and MK-8 as the major respiratory quinones, and phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, glycolipid, and an unidentified phospholipid as the polar lipids. The DNA G + C content was 73.08%. Its 16 S rRNA gene sequence shared 99.14%, and 98.75% similarities with Micrococcus flavus DSM 19079 T and M. porci KD337-16T, respectively, and ≤98.41% similarities with other type strains of the genus Micrococcus. It formed independent clade with M. flavus DSM 19079 T on the phylogenetic trees. The digital DNA-DNA hybridization and average nucleotide identity values between strain JXJ CY 30 T and M. flavus DSM 19079 T and M. porci KD337-16T were 48.0% and 92.1%, 25.5% and 83.2%, respectively. These data above indicated that strain JXJ CY 30 T represented a new species of the genus Micrococcus, and the species epithet is proposed as Micrococcus lacusdianchii sp. nov. (type strain JXJ CY 30 T = KCTC 49378 T = CGMCC 1.17508 T). Strain JXJ CY 30 T can potentially provide Maf with various nutrients such as available phosphorus and nitrogen, plant hormones, various vitamins and carotenoids for growth, while it was inhibited by metabolites from its symbiotic algae Maf.

Roseomonas populi sp. nov., an acetate-degrading bacteria isolated from the stem of Populus tomentosa.

Strain CN29T, isolated from the stem of 5- to 6-year-old Populus tomentosa in Shandong, China, was characterized using a polyphasic taxonomic approach. Cells of CN29T were Gram-stain negative, aerobic, nonspore-forming, and nonmotile coccoid. Growth occurred at 20-37°C, pH 4.0-9.0 (optimum, pH 6.0), and with 0-1% NaCl (optimum, 1%). Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain CN29T was closely related to members of the genus Roseomonas and closest to Roseomonas pecuniae N75T (96.6%). This classification was further supported by phylogenetic analysis using additional core genes. The average nucleotide identity and digital DNA‒DNA hybridization values between strain CN29T and Roseomonas populi CN29T were 82.7% and 27.8%, respectively. The genome size of strain CN29T was 5.87Mb, with a G + C content of 70.9%. The major cellular fatty acids included summed feature 8 (C18:1 ω7c/C18:1 ω6c), C19:0 cyclo ω8c and C16:0. The major respiratory quinone was Q-10. The polar lipids were phosphatidylcholine, aminolipid, phosphatidylglycerol, and diphosphatidylglycerol. Strain CN29T can utilize acetate as a carbon source for growth and metabolism. Additionally, it contains acid phosphatase (2-naphthyl phosphate), which catalyzes the hydrolysis of phosphoric monoesters. The CN29T strain contains several genes, including maeB, gdhB, and cysJ, involved in carbon, nitrogen, and sulfur cycling. These findings suggest that the strain may actively participate in ecosystem cycling, leading to soil improvement and promoting the growth of poplar trees. Based on the phylogenetic, phenotypic, and genotypic characteristics, strain CN29T is concluded to represent a novel species of the genus Roseomonas, for which the name Roseomonas populi sp. nov. is proposed. The type strain is CN29T (= JCM 35579T = GDMCC 1.3267T).

Lipidomic and proteomic profiling identifies the milk fat globule membrane composition of milk from cows and camels

This study was designed to detect lipidomic and proteomic differences in the milk fat globule membrane (MFGM) fractions of cow and camel milk samples. In total, 353 lipid species were detected in these analyses, including 77 PEs, 30 PCs, 28 PIs, 59 SMs, 54 Cers, 13 LPCs, 14 LPEs, 20 PSs, and 4 PGs. These included 54 polar lipid species that differed significantly in abundance between cow and camel milk. Glycerophospholipid metabolism was identified as a core metabolic pathway associated with camel milk composition. Furthermore, 547 proteins exhibiting differential abundance were identified by a label-free proteomics methodology when comparing samples of MFGMfrom camels and cows. Of these proteins, those that differed most in expression between these groups were associated with metabolic pathways, including endoplasmic reticulum activity, endocytosis, and PI3K-Akt signaling. In conclusion, our findings provide a more thorough understanding of the composition of MFGM and its physiological significance, hence offering robust evidence for the potential utilization of camel milk as a nutritional resource in future developments.