Esterification of the Primary Benzylic C–H Bonds with Carboxylic Acids Catalyzed by Ionic Iron(III) Complexes Containing an Imidazolinium Cation

The first iron-catalyzed esterification of the primary benzylic C–H bonds with carboxylic acids using di-<i>tert</i>-butyl peroxide as an oxidant is achieved by novel ionic iron­(III) complexes containing an imidazolinium cation. The use of well-defined, air-stable, and available iron­(III) complex in a 5 mol % loading and readily available starting materials with a broad generality and outstanding sterically hindered tolerance renders this methodology a useful alternative to other protocols that are typically employed for the synthesis of benzyl esters

A commensal streptococcus hijacks a <i>Pseudomonas aeruginosa</i> exopolysaccharide to promote biofilm formation

<div><p><i>Pseudomonas aeruginosa</i> causes devastating chronic pulmonary infections in cystic fibrosis (CF) patients. Although the CF airway is inhabited by diverse species of microorganisms interlaced within a biofilm, many studies focus on the sole contribution of <i>P</i>. <i>aeruginosa</i> pathogenesis in CF morbidity. More recently, oral commensal streptococci have been identified as cohabitants of the CF lung, but few studies have explored the role these bacteria play within the CF biofilm. We examined the interaction between <i>P</i>. <i>aeruginosa</i> and oral commensal streptococci within a dual species biofilm. Here we report that the CF <i>P</i>. <i>aeruginosa</i> isolate, FRD1, enhances biofilm formation and colonization of <i>Drosophila melanogaster</i> by the oral commensal <i>Streptococcus parasanguinis</i>. Moreover, production of the <i>P</i>. <i>aeruginosa</i> exopolysaccharide, alginate, is required for the promotion of <i>S</i>. <i>parasanguinis</i> biofilm formation and colonization. However, <i>P</i>. <i>aeruginosa</i> is not promoted in the dual species biofilm. Furthermore, we show that the streptococcal adhesin, BapA1, mediates alginate-dependent enhancement of the <i>S</i>. <i>parasanguinis</i> biofilm <i>in vitro</i>, and BapA1 along with another adhesin, Fap1, are required for the <i>in vivo</i> colonization of <i>S</i>. <i>parasanguinis</i> in the presence of FRD1. Taken together, our study highlights a new association between streptococcal adhesins and <i>P</i>. <i>aeruginosa</i> alginate, and reveals a mechanism by which <i>S</i>. <i>parasanguinis</i> potentially colonizes the CF lung and interferes with the pathogenesis of <i>P</i>. <i>aeruginosa</i>.</p></div

The <i>P</i>. <i>aeruginosa</i> chronic CF isolate, FRD1, promotes biofilm formation and planktonic cell growth by <i>S</i>. <i>parasanguinis</i> FW213.

<p>A. Quantification of FW213 and FRD1 cells in a six hour single and dual-species biofilm. B. Quantification of FW213 and FRD1 planktonic cells in single and dual species cultures. Data are representative of three experiments performed in triplicate. *<i>P<</i>0.05 (Student’s <i>t</i>-test).</p

FRD1 promotes colonization of <i>S</i>. <i>parasanguinis</i> in <i>Drosophila melanogaster</i>.

<p>24-hour colonization of <i>Drosophila</i> with single or co-infection with <i>S</i>. <i>parasanguinis</i> and <i>P</i>. <i>aeruginosa</i> using the following strains: FW213, <i>bapA1</i>, <i>fap1</i>, <i>bapA1-fap1</i>, FRD1, and FRD1 <i>mucA</i>⁺. ns = not significant. nd = not detected. Data are representative of three experiments performed in triplicate. **<i>P<</i>0.005 (<i>t</i>-test).</p

Survey of oral streptococci and <i>P</i>. <i>aeruginosa</i> dual species biofilms.

<p>A. 16 hour dual-species biofilm formation by <i>P</i>. <i>aeruginosa</i> strains FRD1 and PAO1 with oral streptococci, <i>S</i>. <i>parasanguinis</i> FW213, <i>S</i>. <i>sanguinis</i> SK36, and <i>S</i>. <i>gordonii</i> DL1. *<i>P<</i>0.05 (Student’s <i>t</i>-test).</p

Bacterial strains used in this study.

<p>Bacterial strains used in this study.</p

Quantification of FW213/alginate colocalization in dual biofilms.

<p>Quantification of FW213/alginate colocalization in dual biofilms.</p

Purified <i>P</i>. <i>aeruginosa</i> alginate promotes FW213 biofilm formation.

<p>A. Biofilm formation by FW213 is increased by purified alginate and inhibited by alginate lyase dose-dependently. B. CLSM of FW213 control and FW213 with alginate (140 μg/milliliter) at 40x magnification. FW213 was probed with an α-Fap1 monoclonal antibody and stained with a goat anti-mouse Alexa Fluor 594 secondary antibody. Alginate was probed with an α-alginate polyclonal antibody and stained with a goat anti-rabbit Alexa Fluor 488 secondary antibody. C. Bio-volume analysis of biofilm depicted in ‘B’ using NIS Elements imaging software. Scale bar: 50 μM. Data are representative of three experiments performed in triplicate. *<i>P<</i>0.05 (Student’s <i>t</i>-test).</p

Co-localization of alginate and FW213 in the dual species biofilm.

<p>Confocal laser scanning microscopy (CLSM) images of FW213 and alginate in a dual species biofilm with FRD1, FRD1 <i>mucA</i>⁺, PAO1 and PAO1 <i>mucA</i> at 40X magnification. FW213 was probed with an α-Fap1 monoclonal antibody and stained with a goat anti-mouse Alexa Fluor 594 secondary antibody. Alginate was probed with an α-alginate polyclonal antibody and stained with a goat anti-rabbit Alexa Fluor 488 secondary antibody. Scale bar: 20 μM.</p

Sortase A anchored-BapA1 is required for the promotion of FW213 biofilm by alginate.

<p>A. Dual species biofilms by either FRD1 or PAO1 with the FW213 sortase A or B mutant. B. Dual species biofilms by either FRD1 or PAO1 with wild-type FW213 or FW213 <i>bapA1</i>, <i>fap1</i>, and <i>bapA1-fap1</i> mutants. C. Single species biofilms of FW213, <i>bapA1</i>, <i>fap1</i>, and <i>bapA1-fap1</i> mutants with purified alginate. Data are representative of three experiments performed in triplicate. *<i>P<</i>0.05 and **<i>P</i><0.005 (<i>t</i>-test).</p