Diabetic foot ulcers often develop into non-healing chronic wounds due to their high risk of infection resulting from exposure to various microbes, combined with a lowered immune response due to the patient's diabetic status. Recently, an increased understanding of the polymicrobial nature of chronic wound infections has given rise to questions on the role of the microbiome on healing outcomes. In our study, we aimed to investigate the microbiome composition and its pathological influence in 128 patients using the Oxford NanoPore Sequencing platform and the 16S rRNA region for sample amplification. Overall, the most abundant genera and species present in the microbiomes of these patients resembled other published studies, namely Cutibacteria, Staphylococcus and Pseudomonas. A key factor in healing outcomes was the presence of fungi, which was strongly correlated with pathogenic anaerobes such as Prevotella bivia and associated with negative outcomes. While we could not determine a direct causal link between fungi and outcomes, the data strongly suggests that fungal presence plays a role in the composition of bacterial communities in the wound environment and is potentially enabling infection persistence. Furthermore, we observed that certain bacterial species were present in all outcomes, but part of different microbial networks, hinting that healing success could be determined by these associations established in the community rather than presence of a specific pathobiont. In conclusion, while an initial look at the composition can provide an insight into the most abundant genus/species present in certain outcomes, when investigating deeper we see that associations among different taxa may play a more significant role in determining healing. We postulate that interfering with these interactions could potentially be the key to tipping the balance towards positive healing outcomes.
Microbial biofilms are complex communities embedded in a self-produced extracellular polymeric substance (EPS) matrix that can influence both decomposition and mineral formation on organic substrates. While biofilms are often associated with tissue degradation, they may also contribute to preservation processes through microbially mediated biomineralization.In this study, we examined microbial community dynamics within leaf-associated biofilms and experimentally tested how selected metals and minerals influence the decay of biofilm-covered leaves under controlled laboratory conditions. Reconstructed microbial consortia derived from decaying leaves were exposed to varying ionic conditions to assess their effects on mineral precipitation and tissue degradation.Biofilm-forming communities combined with elevated Ca2+ concentrations promoted mineral formation on leaf surfaces and significantly reduced degradation, as confirmed by chlorophyll retention measurements. The biofilm-forming capacity of representative isolates was validated using a crystal violet assay. Heavy metals produced variable effects depending on the microbial community present, highlighting the importance of metal-microbe interactions in decay processes. In addition, the iron-reducing bacterium Shewanella promoted the precipitation of diverse iron minerals on leaf substrates. These findings demonstrate that microbial biofilms can create localized microenvironments favourable for biomineralization and may contribute to early stages of leaf preservation in natural depositional environments.
Persistent biofilms harboring pathogens can compromise drinking water quality in livestock housing, leading to animal health issues and reduced production. Microbial water quality can be maintained through various treatments and/or by cleaning and disinfecting drinking water systems to remove dirt and biofilms. However, despite routine monitoring of drinking water quality, biofilm persistence after treatment is often overlooked in practice. This study evaluated commonly used (cleaning and) disinfection protocols (peroxides, peracetic acid, chlorine dioxide, formic acid, chlorine, and enzymatic) for drinking water systems, both in vitro and in situ. Four selected three- or four-species communities were grown on polycarbonate and stainless-steel coupons in a stirred Centers for Disease Control (CDC) biofilm reactor. The in situ study was conducted on a pilot broiler farm during four consecutive six-week production cycles, with both water and biofilm samples collected during each cycle. Our in vitro study showed that the disinfectants reduced multispecies viable biofilm cells, but the effects varied with microbial composition. The in situ results showed little effect of the cleaning and disinfection protocols. Consequently, targeted intervention strategies, supported by regular monitoring of water quality and biofilm presence, are essential for making treatment decisions to minimize the risk of water contamination.
The transition of Vibrio cholerae from the host intestine to oligotrophic aquatic environments presents a severe nutrient downshift, yet the upstream sensory mechanism that triggers adaptive biofilm formation remains unclear. Here, we identify the periplasmic protease DegS as a critical nutrient-responsive regulator that suppresses biofilm development under low-nutrient conditions. We demonstrate that a ΔdegS mutant exhibits robust biofilm formation, enhanced antibiotic tolerance, and significantly increased colonization on environmentally relevant surfaces such as microplastics. Strikingly, this regulation is independent of the canonical σE stress pathway. Instead, we elucidate a novel signalling axis wherein DegS negatively regulates the diguanylate cyclase CdgH. Loss of DegS relieves this inhibition, leading to elevated cellular c-di-GMP levels, which in turn activates the master transcriptional regulator VpsR, upregulating biofilm matrix gene expression. This DegS-CdgH-c-di-GMP-VpsR pathway is functional not only in minimal medium but also in simulated natural aquatic environments. Our findings reveal DegS as a key upstream sensor that translates nutrient scarcity into a precise inhibitory signal via c-di-GMP-dependent transcription, providing new insights into the molecular basis of V. cholerae environmental adaptation and highlighting a potential target within its transmission chain.
