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In this study, the phospholipid species [i.e., phosphatidylethanolamine (PE), phosphatidylcholine (PC), and sphingomyelin (SM)] in human milk (HM) were compared according to their fatty acid (FA) composition. 34 HM samples were collected and classified into three groups (A < B < C) according to their fat content. Stearic acid (C18:0) was the main FA in PE, PC, and SM. The highest concentrations of arachidonic acid (AA), eicosapentaenoic acid (EPA), and docosapentaenoic acid (DPA) were observed in PE, whereas docosahexaenoic acid (DHA) was predominant in SM. Although PC exhibited the highest total saturated FAs (SFAs) and PE contained the highest unsaturated FAs (UFAs), very long-chain SFAs and monounsaturated FAs (MUFAs) were preferentially distributed in SM. PC and SM had higher saturation compared to PE. Regarding the effect of the fat content of HM on the FA composition of the phospholipid species, a limited influence was observed on the composition of SFAs and MUFAs of PE, SM, and particularly PC. However, a more pronounced effect on the composition of polyunsaturated FAs (PUFAs) in phospholipids was observed, especially for linoleic acid (LA), α-linolenic acid (ALA), EPA, and DHA, indicating that the composition of FAs in the phospholipid species was probably affected by the maternal diet.

Odd chain fatty acids serve as anti-allergic, anti-inflammatory, and antifungal agents, and are useful for the production of biodiesel. Rhodococcus sp. YHY01 utilizes a wide range of carbon sources and accumulate lipids i.e. fructose (37% w/w dcw) glucose (56% w/w dcw), glycerol (50% w/w dcw), acetate (42% w/w dcw), butyrate (65% w/w dcw), lactate (56% w/w dcw), and propionate (62% w/w dcw). In this study, propionate was proved as the best carbon source and produced 69% odd chain fatty acids of total fatty acids, followed by glycerol (13% odd chain fatty acids of total fatty acids). A synthetic medium optimized with response surface design containing glycerol, propionate, and ammonium chloride (0.32%:0.76%:0.040% w/v) facilitated the production of total fatty acids 69% w/w of dcw, and odd chain fatty acids comprised 85% w/w of total fatty acids. Major odd chain fatty acids were in the order C17:0 > C15:0 > Cis-10-C17:1 > 10Me-C17:0 > C19:0 > Cis-10-C19:1., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Herein, we present a qualitative and quantitative analysis of the compositions of plasmalogens and phospholipids (PLs) in dried big head shrimp (Solenocera melantho), opossum shrimp (Neomysis awatschensis), mussel (Mytilus galloprovincialis), and sea cucumber (Apostichopus japonicus). We also analyze the fatty acid composition of the extracted lipids, phosphatidyl choline (PtdCho), and plasmalogen choline (PlsCho) from each sample. In big head shrimp, opossum shrimp, and mussel, phosphatidyl choline (PtdCho) was the most abundant PL at 1677.9, 1603, and 1661.6 mg/100 g of dried sample, respectively, whereas the most abundant PL in sea cucumber was PlsCho (206.9 mg/100 g of dried sample). In all four samples, plasmalogen ethanolamine (PlsEtn) was higher than phosphatidyl ethanolamine (PtdEtn). The content (mg/100 g of dried sample) of PlsCho was highest in mussel (379.0), and it was higher in big head shrimp (262.3) and opossum shrimp (245.6) than sea cucumber (206.9). The contents (mg/100 g of dried sample) of PlsEtn were in the order of mussel (675.4) > big head shrimp (629.5) > opossum shrimp (217.9) > sea cucumber (51.5). For analyzing the fatty acids at the sn-2 position of PlsCho, the consecutive treatment with phospholipase A1, solid phase extraction, thin-layer chromatography (TLC), and GC-FID were applied. The most abundant fatty acid was eicosapentaenoic acid (EPA, C20:5, n-3) in big head shrimp and sea cucumber, palmitoleic acid (C16:1, n-7) in opossum shrimp, and docosadienoic acid (C22:2, n-6) in mussel. [ABSTRACT FROM AUTHOR]

Psychrophilic bacteria, living at low and mild temperatures, can contribute significantly to our understanding of microbial responses to temperature, markedly occurring in the bacterial membrane. Here, a newly isolated strain, Pseudomonas sp. B14-6, was found to dynamically change its unsaturated fatty acid and cyclic fatty acid content depending on temperature which was revealed by phospholipid fatty acid (PLFA) analysis. Genome sequencing yielded the sequences of the genes Δ-9-fatty acid desaturase (desA) and cyclopropane-fatty acid-acyl-phospholipid synthase (cfa). Overexpression of desA in Escherichia coli led to an increase in the levels of unsaturated fatty acids, resulting in decreased membrane hydrophobicity and increased fluidity. Cfa proteins from different species were all found to promote bacterial growth, despite their sequence diversity. In conclusion, PLFA analysis and genome sequencing unraveled the temperature-related behavior of Pseudomonas sp. B14-6 and the functions of two membrane-related enzymes. Our results shed new light on temperature-dependent microbial behaviors and might allow to predict the consequences of global warming on microbial communities. [ABSTRACT FROM AUTHOR]

Methicillin-resistant Staphylococcus aureus (MRSA) strains are distinct from general Staphylococcus strains with respect to the composition of the membrane, ability to form a thicker biofilm, and, importantly, ability to modify the target of antibiotics to evade their activity. The agr gene is an accessory global regulator of gram-positive bacteria that governs virulence or resistant mechanisms and therefore an important target for the control of resistant strains. However, the mechanism by which agr impacts resistance to β-lactam antibiotics remains unclear. In the present study, we found the Δagr mutant strain having higher resistance to high concentrations of β-lactam antibiotics such as oxacillin and ampicillin. To determine the influence of variation in the microenvironment of cells between the parental and mutant strains, fatty acid analysis of the supernatant, total lipids, and phospholipid fatty acids were compared. The Δagr mutant strain tended to produce fewer fatty acids and retained lower amounts of C16, C18 fatty acids in the supernatant. Phospholipid analysis showed a dramatic increase in the hydrophobic longer-chain fatty acids in the membrane. To target membrane, we applied several surfactants and found that sorbitan monolaurate (Span20) had a synergistic effect with oxacillin by decreasing biofilm formation and growth. These findings indicate that agr deletion allows for MRSA to resist antibiotics via several changes including constant expression of mecA, fatty acid metabolism, and biofilm thickening. [ABSTRACT FROM AUTHOR]