Biofilm inhibition mechanism of BiVO inserted zinc matrix in marine isolated bacteria

Biofilm plays an important role on microbial corrosion and biofouling in marine environments.Inhibiting biofilm formation on construction surfaces is of great importance.Photocatalytic material with visiblelight response,especially BiVO_(4),is regarded as a promising material for biofilm inhibition due to its green biocidal effect and high antibacterial efficiency.Approaches which can immobilize the photocatalytic particles onto metal surfaces with high mechanical strength are requisite.In this study,zinc matrixes were served as carriers for BiVO_(4)particles.The BiVO_(4)-inserted zinc matrixes were successfully obtained by ultrasound assisted electrodeposition.The insertion content of BiVO_(4)showed positive correlation with ultrasound power.Highly enhanced biofilm inhibition properties were obtained by BiVO_(4)inserted zinc·matrixes with an over 95%decreased bacterial coverage.It was proved that O2-(chief)andOH(subordinate)radicals were responsible for the high biocidal performance.Possible antibacterial mechanism was proposed,indicating that the photoinduced holes would both attack zinc crystals to generate active electrons to form O2-radicals,and react with H2 O to generate·OH,finally.Furthermore,corrosion resistance of the matrixes was proved to be stable due to the insertion of BiVO_(4).This study provides a potential application for photocatalyst in marine antifouling and anti-biocorrosion aspects.

Antibiofilm activity of 3,3'-diindolylmethane on Staphylococcus aureus and its disinfection on common food-contact surfaces

This study explored the antibiofilm efficacy of 3,3’-diindolylmethane(DIM)on Staphylococcus aureus and its disinfection on common food-contact surfaces.The minimum biofilm inhibitory concentration(MBIC)of DIM on S.aureus was 62.5μmol/L,while it did not impede the bacterial growth evaluated by growth curve and XTT reduction assay.DIM in the concentration range of 31.2-62.5μmol/L demonstrated a dose-dependent antibiofilm activity to S.aureus,as confirmed by light microscopic(LM),confocal laser scanning microscopic(CLSM),and scanning electron microscopic(SEM)analyses.At DIM of62.5μmol/L,the biomass of S.aureus biofilm was significantly reduced by 97%and its average thickness by 58%(P<0.05).DIM of 62.5μmol/L inhibited the bacterial initial adhesion and proliferation,as well as cell motility;the release of extracellular DNA(eDNA)and extracellular polysaccharide(EPS)were reduced by 75%and 69%,respectively.DIM exhibited a strong inhibition to S.aureus biofilm formation on common food-contact surfaces,including 304 stainless steel,glass,and polyvinyl chloride(PVC)but not disperse the mature biofilm.Overall,our investigation identified DIM as a promising antibiofilm agent and its suitability to prevent the biofilm formation of S.aureus on common food-contact surfaces utilized during food processing.

<i>In Vitro</i>Efficacy of Clove Oil and Eugenol against <i>Staphylococcus</i>spp and <i>Streptococcus mutans</i>on Hydrophobicity, Hemolysin Production and Biofilms and their Synergy with Antibiotics

The present study aimed to evaluate Syzygium aromaticum (clove) plant extract, clove oil and eugenol for their antibacterial activity and their potential to eradicate bacterial biofilms alone and in combination with antibiotics. Anti-bacterial efficacy of S. aromaticum extract, clove oil and eugenol was evaluated as minimum inhibitory concentration (MIC) and subsequently sub-MICs was selected for inhibition of virulence factors against test bacterial strains. Biofilm cultivation and eradication was assayed using XTT reduction in 96-well microtiter plate. Checkerboard method was used to study the interaction between essential oils and antibiotics. Staphylococcus aureus MTCC3160, Staphylococcus epidermidis MTCC435, Staphylococcus sciuri (SC-01), Staphylococcus auricularis (SU-01) and Streptococcus mutans MTCC497 were found strong biofilm former among all the test bacterial strains. The potency of test agents was found in the order of eugenol > clove oil > S. aromaticum methanolic extract. Sub-MIC (0.5 × MIC) of clove oil and eugenol showed a significant reduction in cell surface hydrophobicity (p < 0.05) and hemolysin production in the test bacterial strains. Eugenol showed no increase in sessile MIC (SMIC) against S. auricularis (SU-01), S. epidermidis MTCC435 and S. mutans MTCC497 compared to planktonic MIC (PMIC). Antibiotics (vancomycin and azithromycin) exhibited upto 1000-folds increased in SMIC compared to PMIC against all the test bacterial strains. Synergy was observed between eugenol and antibiotics (vancomycin/azithromycin) against all the test bacterial strains in both planktonic and sessile mode. Highest synergy was exhibited between eugenol and azithromycin in planktonic mode (FICI value 0.141). Further, microscopy also confirmed the spectacular effect of combination treatment on pre-formed S. aureus MTCC3160 and S. mutans MTCC497 biofilms. These findings highlighted the promising role of clove oil and eugenol alone and in combination on pathogenic bacterial biofilms.

Medical titanium surface-modified coatings with antibacterial and anti-adhesive properties for the prevention of implant-associated infections

Implant-associated infections(IAIs)caused by drug-resistant bacteria remain a critical factor in the fail-ure of implant procedures.Therefore,it is urgent to develop an effective anti-infection coating for im-plant surface modification to prevent IAIs.Herein,an antibacterial and anti-adhesive coating(CMP-Ti)constructed on the surface of titanium implants is reported,formed by the nanomaterial CeO_(2)@Mn_(3)O_(4) NRs(CM NRs)with antibacterial activity and the superhydrophilic polymer polyethylene glycol(PEG).The nanocatalyst CM NRs on the surface of CMP-Ti induce ferroptosis-like death of bacteria by catalyzing the production of hydroxyl radical(·OH)and singlet oxygen(^(1)O_(2))and the consumption of glutathione(GSH).The superhydrophilic coating of CMP-Ti can effectively prevent adherence of drug-resistant bac-teria and avoid biofilm formation.By combining the"active offense"antibacterial mechanism with the"passive defense"anti-adhesion mechanism,CMP-Ti can kill bacteria and inhibit biofilm formation.The results of in vivo studies showed that CMP-Ti effectively prevented implant-associated infections caused by Methicillin-resistant Staphylococcus aureus(MRSA),thus promoting tissue repair and osseointegra-tion.Therefore,this multifunctional coating combining"active offense"and"passive defense"provides a promising way to prevent IAIs caused by drug-resistant bacteria and to promote tissue repair in the future.