This Week In Biofilms And Microbiomes: Monday April 4, 2016

A round-up of what we read last week in the media's coverage of biofilms and microbiomes research.

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Antibiotics can continue to be effective if bacteria's cell-to-cell communication and ability to latch on to each other are disrupted, reports a new research, published in Nature Publishing Group’s open access journal, Nature Communications. In order to understand the mechanisms of how bacteria are able to tolerate antibiotics, scientists at Nanyang Technological University, Singapore (NTU Singapore), studied the biofilms of the common bacterium, Pseudomonas aeruginosa, which forms biofilm with extreme tolerance to antibiotics in nosocomial infections, such as pneumonia and surgical site infections. These biofilms were treated with colistin, a ‘last-resort’ antibiotic against multidrug-resistant Gram-negative pathogens. A large portion of the bacterial cells were killed by the antibiotic, leaving only a small fraction of antibiotic-tolerant cells, which migrated on top of the dead biofilm and were able to reproduce and dominate the community. The scientists then used the macrolide, erythromycin to inhibit the motility and cell to cell communication (quorum sensing) of P. aeruginosa. Together, colistin and erythromycin were able to kill all the bacterial cells. The same tests were then performed on mice with infected implants. It was found that only mice treated with a combination of anti-biofilm compound and antibiotics had their infections completely eradicated. The study highlights the importance of developing quorum sensing and motility inhibitors that can be given to chronically infected patients, with the aim of constituting functional anti-biofilm chemotherapies. The breakthrough discovery was made possible through an interdisciplinary approach, where experts from three different fields - microbiology ecology, systems biology and chemical biology - came together to tackle the problem. Proteomics approach, pulsed stable isotope labelling with amino acids (pulsed-SILAC), was the key method used to discover chemical signals that bacterial cells in the biofilm use to communicate with each other. The study was broadly covered by the media last week. Read the coverage by Science Daily.

Gut microbiota regulate nerve fibre insulation, according to a new study published in Translational Psychiatry. Researchers at University College Cork, have uncovered new links between gut microbiome and genes linked to myelination and myelin plasticity in the prefrontal cortex of the brain, a key region implicated in a range of neuropsychiatric disorders such as depression, schizophrenia and autism. Using RNA sequencing technology Professor John Cryan and Dr Gerard Clarke along with their PhD student Alan Hoban compared gene expression levels in the germ-free mice to that seen in normal animals. They identified approximately 90 genes that are differentially expressed in the germ-free animals and, to their surprise, they found that a handful of them are well known to be involved in myelination, and appear to be far more active in the prefrontal cortex of germ-free mice compared to that of normal animals. Some of the genes they identified encode proteins that form structural components of myelin, while others play a regulatory role in myelin formation. The dissection of the animals’ brains revealed that the differences in gene expression were associated with observable anatomical differences, with nerve fibres in the prefrontal cortex of the germ-free animals having thicker myelin sheaths than those in the normal animals. Additionally, the researchers found that colonizing these animals, so essentially introducing a normal microbiome had the ability to reverse some of the parameters used to measure the changes in myelination. The study indicates that appropriate cortical myelination relies on the presence of a functional microbiota during critical windows of neurodevelopment. It also highlights microbiota as a viable therapeutic target in psychiatric disorders and may allow to develop strategies to promote remyelination in myelination diseases, such as multiple sclerosis. The study was highlighted in a press release by The Irish Times.

We’d love to hear what you’ve been reading this week. Please comment below.

Richa Dandona

Partnerships and Operations Manager, Nature Partner Journals, Nature Research