Shortening of the Lactobacillus paracasei subsp. paracasei BGNJ1-64 AggLb Protein Switches Its Activity from Auto-aggregation to Biofilm Formation

AggLb is the largest (318.6 kDa) aggregation-promoting protein of Lactobacillus paracasei subsp. paracasei BGNJ1-64 responsible for forming large cell aggregates, which causes auto-aggregation, collagen binding and pathogen exclusion in vitro. It contains an N-terminus leader peptide, followed by six successive collagen binding domains, 20 successive repeats (CnaB-like domains) and an LPXTG sorting signal at the C-terminus for cell wall anchoring. Experimental information about the roles of the domains of AggLb is currently unknown. To define the domain that confers cell aggregation and the key domains for interactions of specific affinity between AggLb and components of the extracellular matrix (ECM), we constructed a series of variants of the aggLb gene and expressed them in Lactococcus lactis subsp. lactis BGKP1-20 using a lactococcal promoter. All of the variants contained a leader peptide, an inter collagen binding-CnaB domain region (used to raise an anti-AggLb antibody), an anchor domain and a different number of collagen binding and CnaB-like domains. The role of the collagen binding repeats of the N-terminus in auto-aggregation and binding to collagen and fibronectin was confirmed. Deletion of the collagen binding repeats II, III and IV resulted in a loss of the strong auto-aggregation, collagen and fibronectin binding abilities whereas the biofilm formation capability was increased. The strong auto-aggregation, collagen and fibronectin binding abilities of AggLb were negatively correlated to biofilm formation

Uncovering Differences in Virulence Markers Associated with Achromobacter Species of CF and Non-CF Origin

Achromobacter spp. are recognized as emerging pathogens in hospitalized as well as in cystic fibrosis (CF) patients. From 2012 to 2015, we collected 69 clinical isolates (41 patient) of Achromobacter spp. from 13 patients with CF (CF isolates, n = 32) and 28 patients receiving care for other health conditions (non-CF isolates, n = 37). Molecular epidemiology and virulence potential of isolates were examined. Antimicrobial susceptibility, motility, ability to form biofilms and binding affinity to mucin, collagen, and fibronectin were tested to assess their virulence traits. The nrdA gene sequencing showed that A. xylosoxidans was the most prevalent species in both CF and non-CF patients. CF patients were also colonized with A. dolens/A, ruhlandii, A. insuavis, and A. spiritinus strains while non-CF group was somewhat less heterogenous, although A. insuavis, A. insolitus, and A. piechaudii strains were detected beside A. xylosoxidans. Three strains displayed clonal distribution, one among patients from the CF group and two among non-CF patients. No significant differences in susceptibility to antimicrobials were observed between CF and non-CF patients. About one third of the isolates were classified as strong biofilm producers, and the proportion of CF and non-CF isolates with the ability to form biofilm was almost identical. CF isolates were less motile compared to the non-CF group and no correlation was found between swimming phenotype and biofilm formation. On the other hand, CF isolates exhibited higher affinity to bind mucin, collagen, and fibronectin. In generall, CF isolates from our study exhibited in vitro properties that could be of importance for the colonization of CF patients

Phylogenetic inferences of CarO protein among <i>Acinetobacter</i> spp.

<p>A phylogenetic tree of CarO proteins was constructed with the maximum likelihood (ML) method using a Jones-Taylor-Thornton (JTT) model distance matrix. The confidence levels were calculated from 1000 bootstrap resamples of alignment used for phylogenetic inferences by ML method. Bold gray and bold black lines represent the nodes with a support bootstrap value of ≥50% and ≥70%, respectively. The black triangles represent the clade consisting of only <i>A</i>. <i>baumannii</i> strains from the database. Gene bank accession numbers for all tree members are given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0122793#pone.0122793.s001" target="_blank">S1 Fig</a> Representatives and variants (I-VI) of each group (I-III) are the following: <i>A</i>. <i>baumannii</i> Ab21 (DQ309875), <i>A</i>. <i>baumannii</i> Ab244 (AY684798), <i>A</i>. <i>baumannii</i> Ab413 (FJ652395), <i>A</i>. <i>baumannii</i> Ab253 (EF537047), <i>A</i>. <i>baumannii</i> 146457 (EXB49165), <i>A</i>. <i>baumannii</i> 230853 (EXB72592), <i>A</i>. <i>baumannii</i> 1461402 (EXB34375), <i>A</i>. <i>baumannii</i> 348935 (EXA64785). The Serbian clinical isolates <i>A</i>. <i>baumannii</i> 6000 and <i>A</i>. <i>baumannii</i> 1955/12 are indicated.</p

IC50 values, genotyping results and CarO variants for <i>A</i>. <i>baumannii</i> isolates from Serbia.

<p>IC50 values, genotyping results and CarO variants for <i>A</i>. <i>baumannii</i> isolates from Serbia.</p

Primers used in this study.

<p>Primers used in this study.</p

Representation of β-lactamases detected in carbapenem-resistant <i>A</i>. <i>baumannii</i> clinical isolates from Serbia.

<p>Representation of β-lactamases detected in carbapenem-resistant <i>A</i>. <i>baumannii</i> clinical isolates from Serbia.</p

Dendrogram derived from <i>Apa</i>I PFGE patterns showing the relatedness of <i>A</i>. <i>baumannii</i> isolated in Serbia.

<p>The dendrogram was constructed using SPSS software. Letters A, B, C and D indicate different pulsotypes, while I and II designate two major clusters.</p