Trimethylornithine Membrane Lipids: Discovered in Planctomycetes and Identified in Diverse Environments

Abstract

Intact polar membrane lipids (IPLs) are the building blocks of all cell membranes. There is a wide range of phosphorus-free IPL structures, including amino acid containing IPLs, that can be taxonomically specific. Trimethylornithine membrane lipids (TMOs) were discovered in northern wetland Planctomycete species that were isolated and described in the last decade. The trimethylated terminal nitrogen moiety of the ornithine amino acid in the TMO structure gives the lipid a charged polar head group, similar to certain phospholipids. Since their discovery, TMOs have been identified in various other recently described northern latitude Planctomycete species, and in diverse environments including tundra soil, a boreal eutrophic lake, meso-oligotrophic lakes, and hot springs. The majority of environments or enrichment cultures in which TMOs have been observed include predominately heterotrophic microbial communities involved in the degradation of recalcitrant material and/or low oxygen methanogenic conditions at primarily northern latitudes. Other ecosystems occupied with microbial communities that possess similar metabolic pathways, such as tropical peatlands or coastal salt marshes, may include TMO producing Planctomycetes as well, further allowing these lipids to potentially be used to understand microbial community responses to environmental change in a wide range of systems. The occurrence of TMOs in hot springs indicates that these unique lipids could have broad environmental distribution with different specialized functions. Opportunities also exist to investigate the application of TMOs in microbiome studies, including forensic necrobiomes. Further environmental and microbiome lipidomics research involving TMOs will help reveal the evolution, functions, and applications of these unique membrane lipids.

Polyunsaturated fatty acids and fatty acid-derived lipid mediators: Recent advances in the understanding of their biosynthesis, structures, and functions

“…Structurally ( Fig. 9 ), they are composed of a 3-FAHFA bound to the amine group of an amino acid(lysine [ 286 ], glycine [ 287 ], ornithine [ 288 , 289 ], di- and tri-methylated ornithine [ 290 ]) or dipeptide such as in flavolipin (a serine-glycine polar head and a omega-1 methyl group on both fatty chains)[ 267 ] or cerilipin [ 286 , 291 ].…”

Environmental micro‐niche filtering shapes bacterial pioneer communities during primary colonization of a Himalayas' glacier forefield

“…Betaine lipids, typical of lower plants and of some cyanobacteria (Klug & Benning, 2001 ; Řezanka et al, 2004 ), were abundant at all sites, representing up to 30% of total IPLs (Figure 2C ). High relative levels of ornithine lipids, particularly trimethyl ornithine lipids that are exclusive bacterial markers (López‐Lara & Geiger, 2017 ; Moore, 2021 ), were observed in BSCs of sites 2, 3 and 6 (relative abundance range, 2%–3.8%). Even though eukaryotic biomass (e.g., mosses, lichens and bryophytes) was not visible in BSCs, the detection of sterols revealed its presence.…”

“…On the contrary, DLs were enriched in Actinobacteria, Proteobacteria and Acidobacteria phyla which are among the most abundant taxa inhabiting bare soils of cold deserts worldwide (Bourquin et al, 2022;Leung et al, 2020) and were found in other Himalayan forefields (Srinivas et al, 2011). The limited dispersion and homogenous selection resulted in being the main ecological processes in the assembly of microbial communities in BSC and DL, suggesting that bacteria had a life-death dynamics that allowed community composition to drift apart due to spatial isolation between sites (Fodelianakis et al, 2020;2021), as it was also observed in permafrost-associated microbiomes in Alaskan forests (Bottos et al, 2018). The rejection of the neutral community model for both BSC and DL and of the source-sink hypotheses support that bacterial community assembly is mainly deterministic rather than stochastic and it is driven by environmental factors and microbial species interactions.…”

“…Besides phototrophs, representatives of the Firmicutes, Alphaproteobacteria and Gammaproteobacteria , are also capable of synthesizing glycolipids (Hölzl & Dörmann, 2007 ). While the abundant presence of trimethyl ornithine lipids can be most likely assigned to Planctomycetes in both the BSCs and DLs (Moore, 2021 ), the overall high levels of glycolipids and aminolipids suggest some nutrient limitation, especially of phosphorus (Schubotz et al, 2018 ; Van Mooy & Fredricks, 2010 ).…”

Composition, structure, and functional shifts of prokaryotic communities in response to co-composting of various nitrogenous green feedstocks

“…Nucleoside and Nucleotide biosynthesis, cofactor, carrier and vitamin biosynthesis, Amino acid biosynthesis, and Fatty acid and lipid biosynthesis were shown as critical pathways responsible for microbial proliferation and buildup in compost. The Nucleosides and Nucleotides are required for cell growth and replication pathways, while amino acids, fatty acids, and lipids are building blocks for microbial cell structure [ 60 – 62 ]. Cofactors, carriers, and vitamins play a critical role in microbial enzymatic functions, ultimately directly influencing nutrient cycling through catabolic and anabolic processes within the available pool of nutrients in the compost environment [ 63 – 65 ].…”