ELUFISAN, T. O. | bioRxiv Science

bioRxiv2026

Stenotrophomonas oleivorans sp. nov. A polycyclic aromatic hydrocarbon-degrading strain isolated from crude oil contaminated soil

ASS1 was isolated as a motile Stenotrophomonas strain from crude oil-contaminated soils in Tabasco, Mexico. We characterized this strain using physiological and biochemical traits. ASS1 grew at temperature 25-37 (optimally at 37 {degrees} C) and at pH 6 to 8 (optimally at pH 7 to 8). The assembled genome has a total length of 4.56MB with a G + C content of 66.6%. The 16S rRNA gene sequence analysis confirmed that this strain belongs to the genus Stenotrophomonas. Based on the 16S rRNA analysis, Stenotrophomonas geniculata ATCC 19374 is the closest species, and it shares 99.86% similarity with ASS1. Similarly, a phylogenomic tree based on core genome sequence revealed that the closest species to ASS1 is Stenotrophomonas geniculata ATCC 19374. The major fatty acids in ASS1 are C16:0, antesio C15:0, iso C12:0, iso C15:0, iso C17:0 and C18:0. The genome of ASS1 consists of 4,373,402 bp. The Average Nucleotide Identity (ANI) values for ASS1 which it shared with its closest phylogenetic neighbors, are Stenotrophomonas geniculata ATCC 19374 = JCM 13324 [T] 92.66 %, Stenotrophomonas maltophilia 13637[T] 92.15%, Stenotrophomonas maltophilia K279a 92.13% Stenotrophomonas maltophilia R551-3 92.15% Stenotrophomonas maltophilia MTCC 434 [T] 92.08% and Pseudomonas hibisicicola ATCC [T] 91.66%. ASS1 possesses genes that are essential for the degradation of Polycyclic Aromatic hydrocarbon. Genes such as 1, 2 dihydroxyl 1, 2 dihydronaphthalene dehydrogenase; MG068 17425, homologous to 2 hydroxyl chromene 2 carboxylate isomerases; MG 18055, homologous to salicylaldehyde dehydrogenase and MG068 20095, homologous to naphthalene 1, 2 dioxygenases were identified in ASS1. The dDDH value between ASS1 and its closest neighbor Stenotrophomonas geniculata ATCC 19374 = JCM 13324 [T] is 50%, which is the highest for all the typed species and as such we proposed that ASS1 is a novel species with the name Stenotrophomonas oleivorans sp. nov. sp. nov. and ASS1T as the typed strain

microbiology↗

bioRxiv2024

Genes required for the formation of virulence-provoking bacterial sphingolipids

Sphingolipids are ubiquitous in membranes of eukaryotes and are associated with important cellular functions. Although sphingolipids occur scarcely in bacteria, for some of them they are essential and, in other bacteria, they contribute to fitness and stability of the outer membrane, such as in the well-studied -proteobacterium Caulobacter crescentus. We previously defined five structural genes for ceramide synthesis in C. crescentus. However, other mutants affected in genes of this same genomic region show cofitness with a mutant deficient in serine palmitoyltransferase. Here we show that at least two phospho-sphingolipids are produced in C. crescentus and that at least another six gene products are needed for the decoration of ceramide upon phospho-sphingolipid formation. All eleven genes participating in phospho-sphingolipid formation are also required in C. crescentus for membrane stability and for displaying sensitivity towards the antibiotic polymyxin B. The genes for the formation of complex phospho-sphingolipids are also required for C. crescentus virulence on Galleria mellonella insect larvae. Author SummarySphingolipids participate in the formation of biological membranes and molecular signaling in higher organisms. Many bacteria also accommodate sphingolipids in their membranes. Here we report that eleven genes participate in the synthesis of complex bacterial phospho-sphingolipids. Our data show that these lipids contribute to membrane stability, but also confer sensitivity towards certain antibiotics. The bacterium Caulobacter crescentus is widely distributed in fresh water lakes and streams and was considered to be non-virulent. However, we demonstrate that complex phospho-sphingolipids are the main virulence contributors in this bacterium.

microbiology↗