Biosurfactant synergized with marine bacterial DNase disrupts polymicrobial biofilms.

Globally, the occurrence of biofilm associated infection has become an alarming menace to the medical fraternity because the thick exopolysaccharide layer encasing the biofilms makes the biofilm producing pathogens inherently resistant to antibiotics. Candida albicans, the most common pathogen among Candida spp. is the causative agent for superficial and invasive candidiasis. The morphological phase switching from yeast to hyphal form is one of the virulent traits of C. albicans critical for its pathogenicity. Owing to the emergence of antifungal resistance among this opportunistic fungus, there is a dire need for improvised alternative antifungal agents. In the present study, we have evaluated a biosurfactant from a marine bacterium for its biofilm disruption ability against C. albicans. This biosurfactant had the potential to disrupt biofilms as well as to inhibit the morphological transition from yeast to hyphae. In addition, this biosurfactant showed enhance disruption of mixed species biofilms of C. albicans and Staphylococcus epidermidis when combined with DNase isolated from marine bacteria. From the results obtained, it is evident that the biosurfactant could act as a potential antibiofilm agent against drug resistant C. albicans strains.

Extracted chitosan disrupts quorum sensing mediated virulence factors in Urinary tract infection causing pathogens.

Quorum sensing (QS) plays an important role during the aetiology of urinary tract infection (UTI), as several virulence factors are under the regulation of QS. Pseudomonas aeruginosa and Serratia marcescens, the primary causative agents of UTI, employ acyl homoserine lactone (AHL) as signal molecules to coordinate various virulence factors. In this present study, chitosan extracted from the marine crab Portunus sanguinolentus was screened for its ability to inhibit the QS-signaling molecules of P. aeruginosa (PA01) and few clinical isolates of P. aeruginosa and S. marcescens. The extracted chitosan on comparison with a commercial chitosan showed significant inhibition of several QS-dependent virulence factors in P. aeruginosa and S. marscenes. Furthermore, qPCR analysis was carried out to confirm the down-regulation of fimA, fimC and flhD genes involved in adhesion and pathogenesis of S. marcescens and lasI and rhlI genes that governs the P. aeruginosa quorum sensing system. Moreover, the chitosan when coated on a catheter was also able to disrupt the mature biofilms which was revealed by scanning electron microscopy. Collectively, the present study showcases the QS inhibitory property of extracted chitosan from crab shells which is being discarded as a recalcitrant biowaste.

Essential oils from unexplored aromatic plants quench biofilm formation and virulence of Methicillin resistant Staphylococcus aureus.

In the current study we have evaluated the antibiofilm and antivirulent properties of unexplored essential oils (EOs) obtained from Pogostemon heyneanus and Cinnamomum tamala against Methicillin Resistant Staphylococcus aureus (MRSA) strains. The EOs from both the aromatic plants was screened for their ability to prevent biofilm formation and to disrupt preformed biofilms. The efficacy of both the EOs to disrupt the preformed biofilms of various MRSA strains was determined by Confocal Laser Scanning Microscopy (CLSM) and Scanning Electron Microscopy (SEM).The EOs were further able to reduce the Extracellular polymeric substance (EPS) and slime synthesis the two factors of the biofilm assemblage. The EOs was also found to be effective in reducing virulence factors like staphyloxanthin and hemolysin. In silico docking studies were performed for the major components of essential oils and dehydroxysqualene synthase of MRSA which is responsible for the synthesis of staphyloxanthin. The results suggest that (E)-nerolidol showed better binding affinity towards the enzyme. Other compounds have similar binding strengths with the enzyme. Furthermore, the synergistic effect EOs along with the commercially available DNaseI and Marine Bacterial DNase (MBD) showed that the synergistic effect had enhanced biofilm disruption ability. The results show that EOs from P. heyneanus and C. tamala has potential antivirulent and biofilm inhibitory properties against clinical and drug resistant S. aureus strains. The present study highlights the importance of bioprospecting plant based natural products as an alternative for antibiotics owing to the emergence of multi-drug resistant strains.

Jacalin-copper sulfide nanoparticles complex enhance the antibacterial activity against drug resistant bacteria via cell surface glycan recognition.

In any therapeutic modality the usage of drug in high doses often leads to serious side-effects. Herein, we demonstrated a method to enhance the antibacterial efficacy of CuS NPs at lower concentration through interacting with jackfruit seed lectin, jacalin. Fluorescence quenching studies revealed that jacalin form complex with CuS NPs and the association constant was 1.91 × 104 M-1. Upon complex with jacalin, the bacterial minimum inhibitory concentration (MIC) of CuS NPs drastically decreases from 12.5 µM to 0.78 µM. The addition of jacalin specific sugar, galactose to jacalin-CuS NPs complex (JCuS NPs) reverses the MIC from 0.78 µM to 25 µM. Mechanistic study suggests that JCuS NPs kills bacteria in part by reactive oxygen species and membrane damage, but galactose prevents the action of JCuS NPs at 0.78 µM. JCuS NPs successfully reduce (14 fold) A. hydrophila colonization in an infected zerbra fish and rescue them completely from the infection, but galJCuS NPs and CuS NPs were ineffective at 0.78 µM. Collectively, our studies demonstrates that the enhance antibacterial activity of JCuS NPs is likely due to the interaction between the galactose binding site of jacalin and the bacterial strains, as a result NPs are targeted and delivered sufficiently.