Susceptibility pattern of methicillin resistance Staphylococcus aureus (MRSA) by flow cytometry analysis and characterization of novel lead drug molecule from Streptomyces species

Impact of eugenol on biofilm development in Shigella flexneri 1457: a plant terpenoid based-approach to inhibit food-borne pathogen

Shigella flexneri is a gram-negative bacterium responsible for shigellosis and bacterial dysentery. Despite using various synthetic antimicrobial agents and antibiotics, their efficacy is limited, prompting concerns over antibiotic resistance and associated health risks. This study investigated eugenol, a polyphenol with inherent antioxidant and antibacterial properties, as a potential alternative treatment. We aimed to evaluate eugenol's antibacterial effects and mechanisms of action against S. flexneri and its impact on biofilm formation. We observed significant growth suppression of S. flexneri with eugenol concentrations of 8-10 mM (98.29%). Quantitative analysis using the Crystal Violet assay demonstrated a marked reduction in biofilm formation at 10 mM (97.01 %). Assessment of Cell Viability and morphology via Fluorescence-Activated Cell Sorting and Scanning Electron Microscopy confirmed these findings. Additionally, qPCR analysis revealed the downregulation of key genes responsible for adhesion (yebL), quorum sensing (rcsC, sdiA), and EPS production (s0482) associated with bacterial growth and biofilm formation. The present study suggests eugenol could offer a promising alternative to conventional antibiotics for treating shigellosis caused by S. flexneri.

Novel fungal alternative proteins from Penicillium limosum for enhancing structural and functional properties of plant-based meat analogues

Fungal proteins are excellent novel protein resources due to their high nutritional value and biological activity. In this study, a non-toxic strain of Penicillium limosum with a high biomass yield, protein, and essential amino acid contents, was isolated from wheat Qu (solid-state fermentation starter culture). Pea protein isolate (PPI) and P. limosum mycelial protein powder were extruded to prepare high-moisture meat analogues (HMMA), and their structural and functional properties were evaluated. Compared with 100% PPI, the addition of 5% mycoprotein enhanced the viscosity, gelling properties, chewiness, fibrous degree and in vitro protein digestibility (68.65%) of HMMA. Protein aggregates formed during high temperature extrusion, which increased the oil absorption capacity of HMMA (5% MY substitution). Conversely, their water absorption capacity indices were reduced by 5%. These findings provide a theoretical basis for the functional application of novel fungal alternative proteins.

Assessment of the growth inhibition and anti-biofilm activity of aptamer (PmA2G02) against Proteus mirabilis 1429T

Proteus mirabilis is known to cause Catheter-associated urinary tract infections (CAUTIs), which exhibit virulence factors linked to forming biofilms. Aptamers have recently been explored as potential anti-biofilm agents. This study demonstrates the anti-biofilm activity of aptamer (PmA2G02) targeting P. mirabilis 1429T, a pathogenic bacteria known to cause Catheter-associated urinary tract infections (CAUTIs). The studied aptamer inhibited biofilm formation, swarming motility, and cell viability at a concentration of 3 μM. The study also showed that the PmA2G02 had a binding affinity towards fimbrial outer membrane usher protein (PMI1466), flagellin protein (PMI1619), and regulator of swarming behavior (rsbA), which are responsible for adhesion, motility, and quorum sensing, respectively. Crystal violet assay, SEM, and confocal imaging confirmed the effectiveness of the PmA2G02 as an anti-biofilm agent. Moreover, as verified by qPCR, the expression levels of fimD, fliC2, and rsbA were significantly reduced compared to the untreated group. This study suggests that aptamer may be a potential alternative to traditional antibiotics for the treatment of CAUTIs caused by P. mirabilis. These findings shed light on the mechanisms by which the aptamer inhibits biofilm formation.

Evaluation of Mangrove Soil Streptomyces spp. Exhibiting Culture and Biochemical Variation for Determination of Antibacterial Activity

Among actinobacteria, the genus Streptomyces are found in abundance in specific soil environments. Streptomyces are cultivable using Streptomyces-specific media, including starch casein, yeast extract, or ISP 2 media. Streptomyces isolates can be identified based on their macroscopic culture morphology and microscopic observations, and can be taxonomically placed within the Streptomyces genus. In the present study, mangrove soil samples collected from the coast of Mangalore harboring a multitude of microorganisms were enriched with calcium carbonate and pre-heated to isolate Streptomyces organisms. Cultures were quantified in colony forming units and their diversity was evaluated based on phenotypic features, enzyme hydrolysis, biochemical testing, and antibiotic sensitivity tests. The cross streaking method was used to select Streptomyces isolates, which were then further subjected to intracellular buffer extraction and evaluated against test organisms to determine their antibacterial efficacy. This study highlights the occurrence of prominent Streptomyces species with effective antibacterial activity in a unique environmental habitat of mangrove soil on the Mangalore coast.