The CpAL Quorum Sensing System Regulates Production of Hemolysins CPA and PFO To Build Clostridium perfringens Biofilms

Abstract

Mexico bClostridium perfringens strains produce severe diseases, including myonecrosis and enteritis necroticans, in humans and animals. Diseases are mediated by the production of potent toxins that often damage the site of infection, e.g., skin epithelium during myonecrosis. In planktonic cultures, the regulation of important toxins, such as CPA, CPB, and PFO, is controlled by the C. perfringens Agr-like (CpAL) quorum sensing (QS) system. Strains also encode a functional LuxS/AI-2 system. Although C. perfringens strains form biofilm-like structures, the regulation of biofilm formation is poorly understood. Therefore, our studies investigated the role of CpAL and LuxS/AI-2 QS systems and of QS-regulated factors in controlling the formation of biofilms. We first demonstrate that biofilm production by reference strains differs depending on the culture medium. Increased biomass correlated with the presence of extracellular DNA in the supernatant, which was released by lysis of a fraction of the biofilm population and planktonic cells. Whereas ⌬agrB mutant strains were not able to produce biofilms, a ⌬luxS mutant produced wild-type levels. The transcript levels of CpAL-regulated cpa and pfoA genes, but not cpb, were upregulated in biofilms compared to planktonic cultures. Accordingly, ⌬cpa and ⌬pfoA mutants, in type A (S13) or type C (CN3685) backgrounds, were unable to produce biofilms, whereas CN3685⌬cpb made wild-type levels. Biofilm formation was restored in complemented ⌬cpa/cpa and ⌬pfoA/ pfoA strains. Confocal microscopy studies further detected CPA partially colocalizing with eDNA on the biofilm structure. Thus, CpAL regulates biofilm formation in C. perfringens by increasing levels of certain toxins required to build biofilms.

Detection and Identification of Clostridium Perfringens in Some Locally Oral Pharmaceutical Samples

“…Alpha-toxin (cpa) was present in the six C. perfringens isolates in our study. Hence, the importance of its existence is consistent with many previous studies as well as Vidal et al (2015) mentioned that alpha-toxin (cpa) may help in the building of C. perfringens biofilms and incorporated into the matrix, where it was seen partially colocalizing with extracted DNA. Moreover, Smedley et al (2004) had stated that C. perfringens is a major cause of enteric diseases due to the production of several toxins.…”

Biofilm Formation Drives Transfer of the Conjugative Element ICE Bs1 in Bacillus subtilis

“…Here, we have shown that both components of the extracellular matrix are required for the positive effect of biofilm on conjugation, suggesting that these polymers could help stabilize the donor-recipient pair and compensate for the lack of adhesion factors of ICE Bs1 . Other conjugative elements that are not known to encode adhesion factors, such as pCW3 and Tn 916 , are found in the biofilm-forming bacteria Clostridium perfringens and E. faecalis , respectively ( 57 – 59 ). Lack of adhesion factors in those elements could be compensated for by the ability of their host cells to form biofilms.…”

The pathogenesis of necrotic enteritis in chickens: what we know and what we need to know: a review

“…Whether the prominent C. perfringens observed layered on the surface of the necrotic but unsloughed mucosa in NE represents a true biofilm rather than bacteria that are tightly adherent to different ligands exposed through the disease process remains to be determined (Charlebois et al, 2015). The Agr-like quorum-sensing system is involved in regulating production of the alpha toxin (CPA) and perfringolysin (PFO) in building biofilms (Vidal et al, 2015).…”