Project description:Prolific heterotrophic biofilm growth is a common occurrence in airport receiving streams containing deicer and anti-icer runoff. This study investigated relations of heterotrophic biofilm prevalence and community composition to environmental conditions at stream sites upstream and downstream of Milwaukee Mitchell International Airport in Milwaukee, WI, during two deicing seasons (2009–2010 and 2010–2011). Modern genetic tools (such as microarray) have not previously been applied to biofilm communities in this type of setting. We used microarray results to characterize biofilm community composition as well as the response of the biofilm community to environmental factors (i.e., organic content (using chemical oxygen demand concentration) and temperature).
Project description:Multispecies biofilms are the predominant form of bacterial growth in natural and human-associated environments. Although the pathways involved in monospecies biofilm have been well characterized, less is known about the metabolic pathways and emergent traits of a multispecies biofilm community. Here, we performed a transcriptome survey of the developmental stages of a 3-species biofilm community and combined it with quantitative imaging and growth experiments. We report the remodelling of central metabolism of two of the three species in this community. Specifically, we observed an increase in the expression of genes associated with glycolysis and pentose phosphate pathways in K. pneumoniae. Similarly, a decrease in the expression of the same pathways in P. protegens was observed along with an increase in expression of glyoxalate cycle genes when grown as a mixed species biofilm, suggesting reorganisation of metabolic pathways and metabolite sharing for the community biofilms. To test the possibility of cross-feeding for the community, planktonic growth experiments revealed that both the Pseudomonads grew well in TCA cycle intermediates, while K. pneumoniae grew poorly when given those carbon sources. Despite this poor growth in mono-culture, K. pneumoniae was still the dominant species in mixed species biofilms cultivated in TCA intermediates as the sole source of carbon. The biofilm growth data, combined with the transcriptomics data, suggests there is reorganisation of metabolism for the community members and may allow for cross-feeding that allows K. pneumoniae to dominate the community. We also demonstrated that sdsA1 of P. aeruginosa was induced upon exposure to the surfactant SDS and that this gene was essential in protecting mono and mixed species biofilms from surfactant stress. This also suggests that the community members can share defence mechanisms. Overall, this study describes a comprehensive transcriptomics level investigation of shared resources, metabolites and stress defence that may underpin the emergent properties of mixed species biofilm communities.
Project description:We have completed the Arraystar Human m6A-mRNA&lncRNA Epitranscriptomic microarray analysis of the samples to validate the modulating role of Magnesium-based alloy on methylation of inflammatory genes.
Project description:Bacteria are known to adhere to surfaces via self-produced extracellular polymeric substances organized as biofilms. In subsurface areas with low oxygen, limited nutrients, and toxic contaminants, biofilms are crucial for microbial survival and persistence. However, the relationship between biofilm formation and survival in such environments is not well-documented. At the Oak Ridge Reservation Field Research Center (ORRFRC), we observed a high abundance of Rhodanobacter species in conditions with elevated nitrate, metals, organics, and nitric acid. This study investigated the role of biofilm formation in their survival and the underlying molecular mechanisms in diverse geochemical niches. We examined sixteen phylogenetically diverse Rhodanobacter strains for biofilm formation under varying nutrient, pH, and nitrate conditions. Our findings indicate that biofilm formation is a strain-specific phenotype, correlating with environmental stresses, especially in low pH and nitrate conditions. Comparative genomic analysis revealed unique traits in the high biofilm-forming FW021-MT20 strain, such as the absence of flagella and chemotaxis genes and the presence of unique secretion system VI genes, as supported by pangenomic results. Additional tests on biofilm formation in response to field-relevant metals highlighted increased biofilm formation under aluminum stress in strains typically exhibiting weaker biofilm capabilities. Further investigation using RB-Tnseq, proteomics, and TEM indicated flagellar loss under aluminum stress, linked to increased cyclic AMP and di-GMP levels. Our results shed light on the adaptive strategies of Rhodanobacter strains in subsurface environments, suggesting genetic factors linked to biofilm formation and metal stress tolerance, thereby enhancing our understanding of microbial survival under environmental stress.
Project description:ILS1 mutated Candida albicans was unable to grow as yeast-phase cells but was capable of producing a tridimensional biofilm structure in spite of reduced metabolic activity. This biofilm still relied on the classical biofilm genes, while it differentially induced groups of genes involved in adhesion, protein synthesis, cell wall organization, and protein folding. Although the conditional mutant repressed genes annotated for morphology and homeostasis processes affecting morphology and metabolism, the dynamic cell growth enabled the construction of a complex biofilm community independent of ILS1.