Draft Genome of Proteus mirabilis Serogroup O18 Elaborating Phosphocholine-Decorated O Antigen

Unraveling the genome of Proteus mirabilis strain representing the O78 serogroup: Insights into the unique features of the O-antigen biosynthesis gene cluster

Lipopolysaccharide (LPS), the outermost component of Gram-negative bacterial cells, is critical to bacterial pathogenicity, functioning as an endotoxin that activates the human immune system and induces an inflammatory response during infection. LPS comprises three primary components: lipid A, the oligosaccharide core, and the O-antigen. The O-antigen, in particular, is highly variable and strain-specific, playing a pivotal role in how the host immune system recognizes bacterial cells. This study focuses on the Proteus mirabilis 1B-m strain, belonging to serogroup O78, the most prevalent serogroup in hospitals in Lodz, Poland. Given the increasing hospitalization rates, particularly among the elderly and catheterized patients, understanding the common strains and their virulence factors is crucial. This work presents bioinformatics analyses based on next-generation sequencing data (both short and long reads), aimed at elucidating the structure of the gene cluster responsible for O-antigen biosynthesis in the 1B-m strain. Our results suggest the presence of a unique wzx flippase in the strain, alongside the characterization of role of the licD gene, which was most often assigned a role in the phosphocholine decoration process of LPS. The function of licD in this strain appears to be linked to the ispD gene, potentially involved in the biosynthesis of CDP-ribitol. Additionally, we explored other genomic features, including the strain's genetic similarity to closely related microorganisms, the presence of antimicrobial resistance genes, and prophage elements. This study provides valuable insights into the genetic factors underlying the pathogenicity of the P. mirabilis 1B-m strain and its potential implications for hospital-acquired infections.

Biological Properties of S. warneri KYS-164 Isolated from Kefir Grains

Staphylococcus worderi KYS-164, isolated from homemade Tibetan kefir grains, produces bacteriocin-like inhibitory substances (BLIS), which are peptides with antimicrobial properties, but have not been fully characterized. The research on BLIS will lay the foundation for mining new bacteriocins. In this study, the optimal culture conditions for the production of highly active BLIS were found to be incubation at 30 °C and 120 rpm, and the most effective extraction method was ammonium sulfate precipitation (ASP) using ammonium sulfate at 80% saturation. The postantibiotic effect (PAE) of BLIS on Staphylococcus aureus CICC 10384 is significant, with a 4 × MIC BLIS concentration able to prolong the PAE to 2.39 h. BLIS has excellent biosafety, with no deleterious effects observed at 8 × MIC concentration. Gas chromatography-ion mobility spectrometry (GC-IMS) was used to analyze the volatile compounds synthesized by Staphylococcus warneri KYS-164 during its growth. Hydroxycitronellal, ethyl pyruvate, and α-pinene were found to be unique substances produced by this strain, which can provide fresh, refreshing floral and fruity aromas as well as strong pine and resinous aromas in the process of kefir grain fermentation of milk. Analysis of the S. warneri KYS-164 genome provided insights into the major metabolic pathways in which genes expressed in this strain are involved. This study represents the first isolation of S. warneri KYS-164 from kefir grains prepared by Tibetan families, and provides a comprehensive analysis of its physicochemical properties. This research provides a solid foundation for better understanding and utilization of S. warneri KYS-164.

Genomes comparison of two Proteus mirabilis clones showing varied swarming ability

BACKGROUND

Proteus mirabilis is a Gram-negative bacteria most noted for its involvement with catheter-associated urinary tract infections. It is also known for its multicellular migration over solid surfaces, referred to as 'swarming motility'. Here we analyzed the genomic sequences of two P. mirabilis isolates, designated K38 and K39, which exhibit varied swarming ability.

METHODS AND RESULTS

The isolates genomes were sequenced using Illumina NextSeq sequencer, resulting in about 3.94 Mbp, with a GC content of 38.6%, genomes. Genomes were subjected for in silico comparative investigation. We revealed that, despite a difference in swarming motility, the isolates showed high genomic relatedness (up to 100% ANI similarity), suggesting that one of the isolates probably originated from the other.

CONCLUSIONS

The genomic sequences will allow us to investigate the mechanism driving this intriguing phenotypic heterogeneity between closely related P. mirabilis isolates. Phenotypic heterogeneity is an adaptive strategy of bacterial cells to several environmental pressures. It is also an important factor related to their pathogenesis. Therefore, the availability of these genomic sequences will facilitate studies that focus on the host-pathogen interactions during catheter-associated urinary tract infections.

The biosynthesis and role of phosphorylcholine in pathogenic and nonpathogenic bacteria

Phosphorylcholine (ChoP) can be found in all life forms. Although this molecule was first thought to be uncommon in bacteria, it is now appreciated that many bacteria express ChoP on their surface. ChoP is usually attached to a glycan structure, but in some cases, it is added as a post-translational modification to proteins. Recent findings have demonstrated the role of ChoP modification and phase variation (ON/OFF switching) in bacterial pathogenesis. However, the mechanisms of ChoP synthesis are still unclear in some bacteria. Here, we review the literature and examine the recent developments in ChoP-modified proteins and glycolipids and of ChoP biosynthetic pathways. We discuss how the well-studied Lic1 pathway exclusively mediates ChoP attachment to glycans but not to proteins. Finally, we provide a review of the role of ChoP in bacterial pathobiology and the role of ChoP in modulating the immune response.