Inhibition of pathogenic bacterial biofilms on PDMS based implants by L. acidophilus derived biosurfactant

Abstract Background Lactobacillus spp. predominantly shows its presence as a normal mucosal flora of the mouth and intestine. Therefore, the objective of our research is to investigate the in-vitro conditions for the prospective of medically valuable biosurfactants (BSs) derived from Lactobacillus spp. Biosurfactant (BS) obtained from Lactobacillus spp. exhibit antibiofilm and antiadhesive activity against broad range of microbes. In the present study we investigated the production, purification and properties of key components of the cell-associated-biosurfactant (CABS) from Lactobacillus acidophilus NCIM 2903. Results Extracted, purified, freeze-dried CABS shows reduction in surface tension (SFT) of phosphate buffer saline (PBS @pH 7.0) from 71 to 26 mN/m and had a critical micelle concentration (CMC) of 23.6 mg/mL. The CABS showed reduction in interfacial tension (IFT) against various hydrocarbons and had effective spreading capability as reflected through the decrease in contact angle (CA) on different surfaces (polydimethylsiloxane - PDMS, Teflon tape, glass surface, polystyrene film and OHP sheet). The anionic nature of CABS displayed stability at different pH and temperatures and formed stable emulsions. Thin layer chromatography (TLC) and Fourier transform infrared spectroscopy (FTIR) revealed CABS as glycolipoprotein type. The Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis (SDS-PAGE) showed presence of multiple bands in a molecular range of 14.4 to 60 kDa, with prominent bands of 45 kDa. The CABS has significant antiadhesion and antibiofilm activity against tested bacterial strains. Conclusion The current challenging situation is to develop methods or search for the molecules that will prevent the formations of biofilm on medical bioimplants of PDMS based materials. These findings are supportive for the use of Lactobacilli derived BS as potential antiadhesive agent on various surfaces of biomedical devices

Lactobacillus acidophilus Derived Biosurfactant as a Biofilm Inhibitor: A Promising Investigation Using Microfluidic Approach

Background: Biomedical devices and implants are adversely affected by biofilm-associated infections that pose serious public health issues. Biosurfactants (BSs) can combat pathogenic biofilms through their antimicrobial, antibiofilm and antiadhesive capabilities. The objective of our research was to produce biosurfactant (BS) from Lactobacillus acidophilus NCIM 2903 and investigate its antibiofilm, antiadhesive potential using microfluidics strategies by mimicking the micro-environment of biofilm. Methods: Antibiofilm and antiadhesive potential was effectively evaluated using different methods like microfluidics assay, catheter assay, polydimethlysiloxane (PDMS) disc assay. Along with this chemical and physical characteristics of BS were also evaluated. Results: Cell free biosurfactant (CFBS) obtained was found to be effective against biofilm which was validated through the microfluidic (MF) or Lab on Chip (LOC) approach. The potency of CFBS was also evaluated on catheter tubing and PDMS surfaces (representative bioimplants). The efficacy of CFBS was also demonstrated through the reduction in surface tension, interfacial tension, contact angle and low critical micelle concentration. Conclusion: CFBS was found to be a potent antimicrobial and antibiofilm agent. We believe that perhaps this is the first report on demonstrating the inhibiting effect of Lactobacillus spp. derived CFBS against selected bacteria via LOC approach. These findings can be explored to design various BSs based formulations exhibiting antimicrobial, antibiofilm and antiadhesive potential for biomedical applications

Biosurfactants’ multifarious functional potential for sustainable agricultural practices

Increasing food demand by the ever-growing population imposes an extra burden on the agricultural and food industries. Chemical-based pesticides, fungicides, fertilizers, and high-breeding crop varieties are typically employed to enhance crop productivity. Overexploitation of chemicals and their persistence in the environment, however, has detrimental effects on soil, water, and air which consequently disturb the food chain and the ecosystem. The lower aqueous solubility and higher hydrophobicity of agrochemicals, pesticides, metals, and hydrocarbons allow them to adhere to soil particles and, therefore, continue in the environment. Chemical pesticides, viz., organophosphate, organochlorine, and carbamate, are used regularly to protect agriculture produce. Hydrophobic pollutants strongly adhered to soil particles can be solubilized or desorbed through the usage of biosurfactant/s (BSs) or BS-producing and pesticide-degrading microorganisms. Among different types of BSs, rhamnolipids (RL), surfactin, mannosylerythritol lipids (MELs), and sophorolipids (SL) have been explored extensively due to their broad-spectrum antimicrobial activities against several phytopathogens. Different isoforms of lipopeptide, viz., iturin, fengycin, and surfactin, have also been reported against phytopathogens. The key role of BSs in designing and developing biopesticide formulations is to protect crops and our environment. Various functional properties such as wetting, spreading, penetration ability, and retention period are improved in surfactant-based formulations. This review emphasizes the use of diverse types of BSs and their source microorganisms to challenge phytopathogens. Extensive efforts seem to be focused on discovering the innovative antimicrobial potential of BSs to combat phytopathogens. We discussed the effectiveness of BSs in solubilizing pesticides to reduce their toxicity and contamination effects in the soil environment. Thus, we have shed some light on the use of BSs as an alternative to chemical pesticides and other agrochemicals as sparse literature discusses their interactions with pesticides. Life cycle assessment (LCA) and life cycle sustainability analysis (LCSA) quantifying their impact on human activities/interventions are also included. Nanoencapsulation of pesticide formulations is an innovative approach in minimizing pesticide doses and ultimately reducing their direct exposures to humans and animals. Some of the established big players and new entrants in the global BS market are providing promising solutions for agricultural practices. In conclusion, a better understanding of the role of BSs in pesticide solubilization and/or degradation by microorganisms represents a valuable approach to reducing their negative impact and maintaining sustainable agricultural practices

Management and outcomes of unilateral group d tumors in retinoblastoma

Purpose: Retinoblastoma presents most commonly as advanced unilateral disease, particularly in developing countries for which primary enucleation has been the preferred method of treatment. However, with the evolution of newer treatment modalities including intravitreal chemotherapy, intra-arterial chemotherapy and newer chemotherapeutic combinations, a trend towards more conservative approaches is being observed. Our aim is to evaluate outcomes of group D eyes following conservative and non-conservative treatment options. Patients and Methods: The ocular oncology database was used to identify eyes with unilateral retinoblastoma that fulfilled the International Intraocular Retinoblastoma Classification (IIRC) group D criteria from August 2010 to August 2018 and these were retrospectively reviewed. Overall, 39 eyes were identified. Results: Nineteen (49%) eyes underwent primary enucleation and 20 (51%) received eyeconserving treatment. Eye salvage was possible in 15 (75%) eyes in the attempted salvage group. None of the patient revealed signs of metastasis. All eyes received conventional chemotherapy (carboplatin, vincristine, etoposide) and focal laser therapy. Additional treatment modalities offered included intravitreal chemotherapy, intra-arterial chemotherapy and topotecan. Three (11%) eyes in the primary enucleation group showed high-risk features on histopathology and none developed metastasis. Conclusion: The results of the study seem promising and conservative measures can be adopted in selected unilateral group D eyes

Natural quorum sensing inhibitors effectively downregulate gene expression of Pseudomonas aeruginosa virulence factors

At present, anti-virulence drugs are being considered as potential therapeutic alternatives and/or adjuvants to currently failing antibiotics. These drugs do not kill bacteria but inhibit virulence factors essential for establishing infection and pathogenesis through targeting non-essential metabolic pathways reducing the selective pressure to develop resistance. We investigated the effect of naturally isolated plant compounds on the repression of the quorum sensing (QS) system which is linked to virulence/pathogenicity in Pseudomonas aeruginosa. Our results show that trans-cinnamaldehyde (CA) and salicylic acid (SA) significantly inhibit expression of QS regulatory and virulence genes in P. aeruginosa PAO1 at sub-inhibitory levels without any bactericidal effect. CA effectively downregulated both the las and rhl QS systems with lasI and lasR levels inhibited by 13- and 7-fold respectively compared to 3- and 2-fold reductions with SA treatment, during the stationary growth phase. The QS inhibitors (QSI) also reduced the production of extracellular virulence factors with CA reducing protease, elastase and pyocyanin by 65%, 22% and 32%, respectively. The QSIs significantly reduced biofilm formation and concomitantly with repressed rhamnolipid gene expression, only trace amount of extracellular rhamnolipids were detected. The QSIs did not completely inhibit virulence factor expression and production but their administration significantly lowered the virulence phenotypes at both the transcriptional and extracellular levels. This study shows the significant inhibitory effect of natural plant-derived compounds on the repression of QS systems in P. aeruginosa