Bacterial biofilm growth and perturbation by serine protease from Bacillus sp

In nature, bacteria are ubiquitous and can be categorized as beneficial or harmless to humans, but most bacteria have one thing in common which is their ability to produce biofilm. Biofilm is encased within an extracellular polymeric substance (EPS) which provides resistance against antimicrobial agents. Protease enzymes have the potential to degrade or promote the growth of bacterial biofilms. In this study, the effects of a recombinant intracellular serine protease from Bacillus sp. (SPB) on biofilms from Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa were analyzed. SPB was purified using HisTrap HP column and concentrated using Amicon 30 ultra-centrifugal filter. SPB was added with varying enzyme activity and assay incubation period after biofilms were formed in 96-well plates. SPB was observed to have contrasting effects on different bacterial biofilms, where biofilm degradations were observed for both 7-day-old A. baumannii (37.26%) and S. aureus (71.51%) biofilms. Meanwhile, SPB promoted growth of P. aeruginosa biofilm up to 176.32%. Compatibility between protein components in S. aureus biofilm with SPB as well as a simpler membrane structure morphology led to higher biofilm degradation for S. aureus compared to A. baumannii. However, SPB promoted growth of P. aeruginosa biofilm due likely to its degrading protein factors that are responsible for biofilm detachment and dispersion, thus resulting in more multi-layered biofilm formation. Commercial protease Savinase which was used as a comparison showed degradation for all three bacterial biofilms. The results obtained are unique and will expand our understanding on the effects that bacterial proteases have toward biofilms.

Recombinant Prevotella melaninogenica α-1,3 glucanase and Capnocytophaga ochracea α-1,6 glucanase as enzymatic tools for in vitro degradation of S. mutans biofilms

Dental biofilms represent a serious oral health problem playing a key role in the development of caries and other oral diseases. In the present work, we cloned and expressed in E. coli two glucanases, Prevotella melaninogenica mutanase (PmGH87) and Capnocytophaga ochracea dextranase (CoGH66), and characterized them biochemically and biophysically. Their three-dimensional structures were elucidated and discussed. Furthermore, we tested the capacity of the enzymes to hydrolyze mutan and dextran to prevent formation of Streptococcus mutans biofilms, as well as to degrade pre- formed biofilms in low and abundant sugar conditions. The percentage of residual biofilm was calculated for each treatment group in relation to the control, as well as the degree of synergism. Our results suggest that both PmGH87 and CoGH66 are capable of inhibiting biofilm formation grown under limited or abundant sucrose conditions. Degradation of pre-formed biofilms experiments reveal a time-dependent effect for the treatment with each enzyme alone. In addition, a synergistic and dose-dependent effects of the combined enzymatic treatment with the enzymes were observed. For instance, the highest biomass degradation was 95.5% after 30 min treatment for the biofilm grown in low sucrose concentration, and 93.8% after 2 h treatment for the biofilm grown in sugar abundant condition. Strong synergistic effects were observed, with calculated degree of synergism of 5.54 and 3.18, respectively and their structural basis was discussed. Jointly, these data can pave the ground for the development of biomedical applications of the enzymes for controlling growth and promoting degradation of established oral biofilms.

Chitosan enhanced the stability and antibiofilm activity of self-propelled Prussian blue micromotor

The emergence, spread and difficult removal of bacteria biofilm, represent an ever-increasing persistent infections and medical complications challenge worldwide. Herein, a self-propelled system Prussian blue micromotor (PB MMs) were constructed by gas-shearing technology for efficient degradation of biofilms by combining chemodynamic therapy (CDT) and photothermal therapy (PTT). With the interpenetrating network crosslinked by alginate, chitosan (CS) and metal ions as the substrate, PB was generated and embedded in the micromotor at the same time of crosslinking. The micromotors are more stable and could capture bacteria with the addition of CS. The micromotors show excellent performance, containing photothermal conversion, reactive oxygen species (ROS) generation and bubble produced by catalyzing Fenton reaction for motion, which served as therapeutic agent could chemically kill bacteria and physically destroy biofilm. This research work opens a new path of an innovative strategy to efficiently remove biofilm.

Proteomic analysis revealed the biofilm-degradation abilities of the bacteriophage UPMK_1 and UPMK_2 against Methicillin-resistant Staphylococcus aureus

OBJECTIVE

The degradation activity of two bacteriophages UPMK_1 and UPMK_2 against methicillin-resistant Staphylococcus aureus phages were examined using gel zymography.

METHODS

The analysis was done using BLASTP to detect peptides catalytic domains. Many peptides that are related to several phage proteins were revealed.

RESULTS

UPMK_1 and UPMK_2 custom sequence database were used for peptide identification. The biofilm-degrading proteins in the bacteriophage UPMK_2 revealed the same lytic activity towards polysaccharide intercellular adhesin-dependent and independent of Methicillin-resistant Staphylococcus aureus (MRSA) biofilm producers in comparison to UPMK_1, which had lytic activity restricted solely to its host.

CONCLUSION

Both bacteriophage enzymes were involved in MRSA biofilm degradation during phage infection and they have promising enzybiotics properties against MRSA biofilm formation.

The in vitro effect of antimicrobial photodynamic therapy with indocyanine green on Enterococcus faecalis: Influence of a washing vs non-washing procedure

INTRODUCTION

The purpose of this study was to evaluate the in vitro effect of washing and non-washing of indocyanine green (ICG) as photosensitizer (PS) on bacterial count, biofilm formation, development and degradation of Enterococcus faecalis.

METHODS

The anti-bacterial, anti-biofilm formation, anti-biofilm development and biofilm degradation of anti-microbial photodynamic therapy (aPDT) against E. faecalis was determined at concentrations of 3 to 2000μg/mL of ICG, subject to 18J/cm² dose of diode laser (808nm) in washing and non-washing producers. Bacterial viability measurements and biofilm assays were evaluated by broth microdilution method and crystal violet assays, respectively.

RESULTS

ICG-mediated aPDT, using 25 to 2000μg/mL and 50 to 2000μg/mL showed significant reduction in E. faecalis growth when compared to the control in non-washing and washing producers, respectively (P<0.05). Also, ICG-mediated aPDT showed a significantly inhibitory effect on biofilm formation of E. faecalis in concentration of 6 to 2000μg/mL and 100 to 2000μg/mL in non-washing and washing groups (P<0.05). The biofilm development was inhibited by concentrations of 12 to 2000μg/mL and 100 to 2000μg/mL in non-washing and washing groups. The biofilm degradation increased from concentrations of 12 to 2000μg/mL and 250 to 2000μg/mL in non-washing and washing groups, respectively.

CONCLUSION

This study shows that the application of ICG should be accompanied by laser irradiation without being washed out to achieve better result for bacterial count reduction and anti-biofilm effects.