Control of Escherichia coli O157:H7 Motility and Biofilm Formation by Salicylate and Decanoate: MarA/SoxS/Rob and pchE Interactions

Prophage-encoded Escherichia coli O157:H7 transcription factor (TF), PchE, inhibits biofilm formation and attachment to cultured epithelial cells by reducing curli fimbriae expression and increasing flagella expression. To identify pchE regulators that might be used in intervention strategies to reduce environmental persistence or host infections, we performed a computational search of O157:H7 strain PA20 pchE promoter sequences for binding sites used by known TFs. A common site shared by MarA/SoxS/Rob TFs was identified and the typical MarA/Rob inducers, salicylate and decanoate, were tested for biofilm and motility effects. Sodium salicylate, a proven biofilm inhibitor, but not sodium decanoate, strongly reduced O157:H7 biofilms by a pchE -independent mechanism. Both salicylate and decanoate enhanced O157:H7 motility dependent on pchE using media and incubation temperatures optimum for culturing human epithelial cells. However, induction of pchE by salicylate did not activate the SOS response. MarA/SoxS/Rob inducers provide new potential agents for controlling O157:H7 interactions with the host and its persistence in the environment. IMPORTANCE There is a need to develop E. coli serotype O157:H7 non-antibiotic interventions that do not precipitate the release and activation of virulence factor-encoded prophage and transferrable genetic elements. One method is to stimulate existing regulatory pathways that repress bacterial persistence and virulence genes. Here we show that certain inducers of MarA and Rob have that ability, working through both pchE -dependent and -independent pathways.

Effectiveness of Oxalis corniculata L. Ethanol Extract against Mono-Species of Biofilm Staphylococcus aureus

Inappropriate administration of antibiotics can cause resistance to bacteria. Staphylococcus aureus is one of the strong biofilm-forming bacteria that cause antibiotic resistance. Calincing (Oxalis corniculata L.) leaves have excellent antibacterial activity, but their antibiofilm activity against S. aureus has not been reported until now. Currently, the discovery of new antibiofilm against S. aureus biofilms is significant to prevent the impact of infections caused by biofilms. This study was intended to determine the effectiveness of the ethanol extract of O. corniculata leaves in inhibiting and eradicating S. aureus biofilm formation. Planktonic testing, inhibition, and biofilm eradication activity were carried out using the microtiter broth method. Antibiofilm activity of O. corniculata leaves against S. aureus biofilm was analyzed by calculating the minimum concentration of biofilm inhibitor (MBIC50) and minimum biofilm eradication concentration (MBEC50). Data were analyzed using the Statistical Package for the Social Sciences (SPSS) with a 95% confidence level. Oxalis corniculata leaves showed inhibitory activity on the formation of the tested S. aureus biofilm. The ethanol extract of 1% O. corniculata leaves gave 76.23±0.01% antibacterial activity of S. aureus and 71.32±0.01% of mid-phase antibiofilm activity, and 69.33±0.01% maturation phase. The results also prove that the ethanolic extract of O. corniculata leaves can eradicate S. aureus biofilm formation. Therefore, the ethanol extract of O. corniculata leaves can be developed as a new antibiofilm against S. aureus.

Dual Agents: Fungal Macrocidins and Synthetic Analogues with Herbicidal and Antibiofilm Activities

Eight analogues of the bioherbicides macrocidin A (1) and Z (2) with structural variance in the size of the macrocycle, its para- or meta-cyclophane character, and its functional groups were synthesized on two modular routes and tested for herbicidal, antibiotic, and antibiofilm activities. Apart from the lead compounds 1 and 2, the structurally simplified dihydromacrocidin Z (3) and normacrocidin Z (4) showed high herbicidal activity in either thistles, dandelions or in both. The derivatives 2, 3, and dibromide 9 also inhibited the growth of Staphylococcus aureus biofilms by ca 70% when applied at subtoxic concentrations as low as ca 20 µM, which are unlikely to induce bacterial resistance. They also led to the dispersion of preformed biofilms of S. aureus, exceeding a similar effect by microporenic acid A, a known biofilm inhibitor. Compounds 3 and 9 showed no noticeable cytotoxicity against human cancer and endothelial cells at concentrations below 50 µM, making them conceivable candidates for application as anti-biofilm agents in a medicinal context.

Staphylococcus aureus: biofilm formation and strategies against it

: The formation of Staphylococcus aureus biofilm causes significant infections in the human body. Biofilm forms through the aggregation of bacterial species and brings about many complications. It mediates drug resistance and persistence and facilitates the recurrence of infection at the end of antimicrobial therapy. Biofilm formation goes through a series of steps to complete, and any interference in these steps can disrupt its formation. Such interference may occur at any stage of biofilm production, including attachment, monolayer formation, and accumulation. Interfering agents can act as quorum sensing inhibitors and interfere in the functionality of quorum sensing receptors, attachment inhibitors and affect the cell hydrophobicity. Among these inhibiting strategies, attachment inhibitors could serve as the best agents against biofilm formation. If pathogens abort the attachment, the following stages of biofilm formation, e.g., accumulation and dispersion, will fail to materialize. Inhibition at this stage leads to suppression of virulence factors and invasion. One of the best-known inhibitors is a chelator that collects metal, Fe+, Zn+, and magnesium critical for biofilm formation. These influential factors in the binding and formation of biofilm are investigated, and the coping strategy is discussed. This review examines the stages of biofilm formation and determines what factors interfere in the continuity of these steps. Finally, the inhibition strategies are investigated, reviewed, and discussed. Keywords: Biofilm, Staphylococcus, Biofilm inhibitor, Dispersion, Antibiofilm agent, EPS, PIA.

Aktivitas Ekstrak Etanol Daun Calincing terhadap Biofilm Candida Albicans

Daun calincing (Oxalis corniculata L.) merupakan salah satu tanaman yang tumbuh di indonesia yang memiliki aktivitas antijamur namun aktivitas antibiofilmnya terhadap C. albicans ATCC 10231 belum pernah dilaporkan. Pencarian antibiofilm baru terhadap biofilm C. albicans menjadi hal penting dalam mencegah infeksi yang berhubungan dengan biofilm. Penelitian ini bertujuan untuk mengetahui efektivitas ekstrak etanol daun calincing (Oxalis corniculata L.) dalam menghambat pembentukan biofilm C. albicans. Pengujian planktonik dan penghambatan biofilm dilakukan dengan menggunakan metode microtiter broth. Aktivitas antibiofilm ekstrak etanol daun calincing terhadap C. albicans. dianalisis dengan menghitung minimum biofilm inhibitor konsentrasi (MBIC50). Ekstrak etanol daun calincing 1 % memberikan aktivitas antijamur C. albicans sebesar 81,23 % ± 0,01 dan aktivitas antibiofilm fase pertengahan sebesar 76,00 % ± 0,01 dan fase pematangan 68,23 ± 0,01. Oleh karena itu, ekstrak etanol daun calincing berpotensi untuk dikembangkan sebagai kandidat obat-obat antibiofilm baru terhadap biofilm C. albicans.

Amylases: Biofilm Inducer or Biofilm Inhibitor?

Biofilm is a syntrophic association of sessile groups of microbial cells that adhere to biotic and abiotic surfaces with the help of pili and extracellular polymeric substances (EPS). EPSs also prevent penetration of antimicrobials/antibiotics into the sessile groups of cells. Hence, methods and agents to avoid or remove biofilms are urgently needed. Enzymes play important roles in the removal of biofilm in natural environments and may be promising agents for this purpose. As the major component of the EPS is polysaccharide, amylase has inhibited EPS by preventing the adherence of the microbial cells, thus making amylase a suitable antimicrobial agent. On the other hand, salivary amylase binds to amylase-binding protein of plaque-forming Streptococci and initiates the formation of biofilm. This review investigates the contradictory actions and microbe-associated genes of amylases, with emphasis on their structural and functional characteristics.

Biofunctionalization of Poly(lactide-co-glycolic acid) Using Potent NorA Efflux Pump Inhibitors Immobilized on Nanometric Alpha-Zirconium Phosphate to Reduce Biofilm Formation

Polymeric composites, where bioactive species are immobilized on inorganic nanostructured matrix, have received considerable attention as surfaces able to reduce bacterial adherence, colonization, and biofilm formation in implanted medical devices. In this work, potent in-house S. aureus NorA efflux pump inhibitors (EPIs), belonging to the 2-phenylquinoline class, were immobilized on nanometric alpha-zirconium phosphate (ZrP) taking into advantage of acid-base or intercalation reactions. The ZrP/EPI were used as filler of poly(lactide-co-glycolic acid) (PLGA) to obtain film composites with a homogeneous distribution of the ZrP/EPI fillers. As reference, PLGA films loaded with ZrP intercalated with thioridazine (TZ), that is recognized as both a NorA and biofilm inhibitor, and with the antibiotic ciprofloxacin (CPX) were prepared. Composite films were characterized by X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The ability of the composite films, containing ZrP/EPI, to inhibit biofilm formation was tested on Staphylococcus aureus ATCC 29213 and Staphylococcus epidermidis ATCC 12228, and it was compared with that of the composite loaded with ZrP/TZ. Finally, the antibacterial activity of CPX intercalated in ZrP was evaluated when used in combination with ZrP/EPI in the PLGA films.

The Large pBS32/pLS32 Plasmid of Ancestral Bacillus subtilis

ABSTRACT The ancestral strain of Bacillus subtilis NCIB3610 (3610) bears a large, low-copy-number plasmid, called pBS32, that was lost during the domestication of laboratory strain derivatives. Selection against pBS32 may have been because it encodes a potent inhibitor of natural genetic competence (ComI), as laboratory strains were selected for high-frequency transformation. Previous studies have shown that pBS32 and its sibling, pLS32 in Bacillus subtilis subsp. natto, encode a replication initiation protein (RepN), a plasmid partitioning system (AlfAB), a biofilm inhibitor (RapP), and an alternative sigma factor (SigN) that can induce plasmid-mediated cell death in response to DNA damage. Here, we review the literature on pBS32/pLS32, the genes found on it, and their associated phenotypes.