Project description:For Streptococcus pneumoniae, biofilms have been suggested to promote long-term colonization of the nasopharynx and contribute to the pathology of recurrent middle ear infections. To date numerous studies have investigated the contribution of specific genetic determinants for the development of pneumococcal biofilms, however, studies examining the global changes that occur during biofilm development and how they contribute to disease are lacking. Using Scanning and Transmission electron microscopy we examined development of a mature pneumococcal biofilm in a continuous flow through reactor. We determined that a mature biofilm is formed in discrete stages, is marked by the formation of complex 3-dimensional structures, and is primarily composed of dead pneumococci. Using genomic microarrays we determined that pneumococci in mature biofilms down regulate genes involved in protein synthesis, energy production, metabolism, capsular polysaccharide production, and virulence. We confirmed these changes by testing bacterial resistance to antimicrobials, measuring capsule production by ELSIA, and immunoblotting for pneumolysin production. We determined that biofilm pneumococci are hyper-adhesive, binding to cell lines at levels 9 to 11-fold greater than planktonic counterparts. Using Western blot and ELISA, we determined that biofilm bacteria produce greater amounts of the adhesins PsrP, CbpA, and surface exposed phosphorylcholine. We subsequently determined that the hyper-adhesive phenotype was in part due to selection of the transparent phase variant during biofilm growth. Intranasal, intratracheal and intraperitoneal challenge of mice with biofilm and planktonic pneumococci determined that biofilm bacteria were highly attenuated for invasive disease but not nasopharyngeal colonization. Immunization of mice with ethanol-killed biofilm pneumococci of serotype 4 conferred protection against challenge with same isolate but not a serotype 3. ELISA for reactive IgG levels subsequently determined that biofilm pneumococci do not provide high levels of cross-reactive protein antigens. Together these studies suggest that biofilms do not directly contribute to disease but instead confer a protected mode of growth for the pneumococcus.

Project description:For Streptococcus pneumoniae, biofilms have been suggested to promote long-term colonization of the nasopharynx and contribute to the pathology of recurrent middle ear infections. To date numerous studies have investigated the contribution of specific genetic determinants for the development of pneumococcal biofilms, however, studies examining the global changes that occur during biofilm development and how they contribute to disease are lacking. Using Scanning and Transmission electron microscopy we examined development of a mature pneumococcal biofilm in a continuous flow through reactor. We determined that a mature biofilm is formed in discrete stages, is marked by the formation of complex 3-dimensional structures, and is primarily composed of dead pneumococci. Using genomic microarrays we determined that pneumococci in mature biofilms down regulate genes involved in protein synthesis, energy production, metabolism, capsular polysaccharide production, and virulence. We confirmed these changes by testing bacterial resistance to antimicrobials, measuring capsule production by ELSIA, and immunoblotting for pneumolysin production. We determined that biofilm pneumococci are hyper-adhesive, binding to cell lines at levels 9 to 11-fold greater than planktonic counterparts. Using Western blot and ELISA, we determined that biofilm bacteria produce greater amounts of the adhesins PsrP, CbpA, and surface exposed phosphorylcholine. We subsequently determined that the hyper-adhesive phenotype was in part due to selection of the transparent phase variant during biofilm growth. Intranasal, intratracheal and intraperitoneal challenge of mice with biofilm and planktonic pneumococci determined that biofilm bacteria were highly attenuated for invasive disease but not nasopharyngeal colonization. Immunization of mice with ethanol-killed biofilm pneumococci of serotype 4 conferred protection against challenge with same isolate but not a serotype 3. ELISA for reactive IgG levels subsequently determined that biofilm pneumococci do not provide high levels of cross-reactive protein antigens. Together these studies suggest that biofilms do not directly contribute to disease but instead confer a protected mode of growth for the pneumococcus. Pneumococcal biofilms compared to planktonic control at 4, 12, 24, 48 hours. 3 biological replicates each of 4 and 12 hour time points, and 2 biological replicates each of 24 and 48 hour time points. Flip dye (technical replicates) performed for 4, 12, and 24 hour time points; no technical replicate performed for 48 hour time point due to limiting material. Ratios were determined by averaging across technical and biological replicates. The following hybridizations made up each biological replicate: 14090167.tav.annot and 14090190.tav.annot (4hr biol rep 1); 14090169.tav.annot and 14090176.tav.annot (4hr biol rep 2); 14090192.tav.annot and 14090188.tav.annot (4hr biol rep 3); 14087688.tav.annot and 14090180.tav.annot (12hr biol rep 1); 14090185.tav.annot and 14090168.tav.annot (12hr biol rep 2); 14090191.tav.annot and 14090174.tav.annot (12hr biol rep 3); 14090170.tav.annot and 14090175.tav.annot (24hr biol rep 2); 14090193.tav.annot and 14087687.tav.annot (24hr biol rep 3); 14090181.tav.annot (48hr biol rep 1); 14090187.tav.annot (48hr biol rep 2)

Project description:Background: Air-pollutants containing toxic particulate matters (PM) deposit in the respiratory tract and increases microbial infections. However, the mechanism underline is not well understood. In this study, we evaluated the effect of urban particles (UP) on S. pneumoniae in-vitro biofilm formation, colonization on Human middle ear epithelium cells (HMEECs) and in mouse nasal cavity and transition to middle ear and lungs. Methods: S. pneumoniae in vitro biofilms and planktonic growth was evaluated in metal ion free medium in presence of UP, and biofilms were quantified by CV-microplate assay, cfu counts and resazurin staining. Biofilm structures were analyzed using scanning electron microscope (SEM) and confocal microscopy (CM). Gene expressions of biofilms were evaluated using real time RT-PCR. Effects of UP exposure on S. pneumoniae colonization to HMEECs was evaluated using fluorescent in-situ hybridization (FISH), cell viability was detected by EZcyto kit, apoptosis in HMEECs were evaluated using Annexin-V/PI based cytometry analysis and reactive oxygen species (ROS) production were evaluated using Oxiselect kit. Alteration of HMEECs gene expressions on UP exposure or pneumococci colonization were evaluated using microarray. In vivo colonization of pneumococci in presence of UP and transition to middle ear and lungs were evaluated using intranasal mice colonization model. Results: UP exposure significantly (*p< 0.05) increased pneumococcal in vitro biofilms and planktonic growth. In presence of UP pneumococci formed organized biofilms with matrix, while in absence of UP bacteria was unable to form biofilms. The luxS, ply, lytA, comA, comB and ciaR genes involved in bacterial pathogenesis, biofilms formation and quorum sensing were up-regulated in pneumococci biofilms grown in presence of UP. The HMEECs viability was significantly (p<0.05) decreased and bacteria colonization was significantly (p<0.05) elevated in co-treatment (UP+S. pneumoniae) in compare to single treatment. Similarly, increased apoptosis and ROS produce were detected in HMEECs treated with UP+ pneumococci. The microarray analysis of HMEECs revealed that the genes involve in apoptosis and cell death, inflammation, immune response were up-regulated in co-treatment, those genes were unchanged or expressed in less fold in single treatments of UP or S. pneumoniae. In vivo study showed increased pneumococcal colonization to nasal cavity in presence of UP and higher transition of bacteria to middle ear and lungs in presence of UP.

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.

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Pneumococci in the heart subvert the host response through biofilm-mediated macrophage killing

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