Steroidal fraction ofCarissa carandasL. inhibits microbial hyaluronidase activity by mixed inhibition mechanism

Genus Carissa L.: a newly explored sustainable source of virulence inhibitors: a mini review

Misuse of antibiotics led to the world wide spread of antimicrobial resistance threatening human lives. The notable resistance of bacterial cells to antibiotics and immune system is the difficulty associated with biofilm-linked illnesses. Natural products from plant origin with antibiofilm activity could provide more therapeutic activity with fewer adverse effects. Carissa L. is a potential drug candidate that can be considered as an agro-food waste sustainable virulence inhibitor source. This mini-review sheds light on recent studies dealing with the anti-virulence potential of Carissa species and its different mechanisms of action. The traced articles revealed that Carissa species exhibited potent antibiofilm, anti-quorum sensing, hyaluronidase inhibitory and anti-adhesion potentials, in addition to violacein, and swimming motility inhibition activities. Ursolic acid, oleanolic acid, and methyl oleanate are the main phytoconstituents of Carissa with claimed virulence inhibitory potentials. Carissa species are safe, valuable, and effective anti-virulence drugs suppressing pathogenicity when compared to conventional antibiotics.

Metal nanoparticles as inhibitors of enzymes and toxins of multidrug-resistant Staphylococcus aureus

Staphylococcus aureus is an aerobic Gram-positive spherical bacterium known to cause a broad range of infections worldwide. It is a major cause of infective skin and soft infections and severe and life-threatening conditions, such as pneumonia, bloodstream infections, and endocarditis. The emergence of drug-resistant strains of S aureus, particularly methicillin-resistant S aureus (MRSA), has become a significant concern in the healthcare community. Antibiotic-resistant S aureus is commonly acquired in hospitals and long-term care facilities. It often affects patients with weakened immune systems, those undergoing invasive medical procedures, or those who have been hospitalized for extended periods. In the US, S aureus is known to cause potentially fatal illnesses, such as toxic shock syndrome (TSS) and acute-onset toxic shock syndrome (TSS), which are characterized by fever and hypotension. It develops resistance to antibiotics through several mechanisms, such as the production of enzymes that inactivate antibiotics, target site modification, efflux pumps, and plasmid-mediated resistance. Therefore, preventing the spread of drug-resistant S aureus is needed, and there is an urgent need to explore novel approaches in the development of anti-staphylococcal agents. This article reviews the principal infections caused by S aureus, major virulence factors, mechanisms of resistance development, and nanotechnology-based solutions for the control of drug-resistant S aureus.

Evaluation of Safety and Probiotic Potential of Enterococcus faecalis MG5206 and Enterococcus faecium MG5232 Isolated from Kimchi, a Korean Fermented Cabbage

The purpose of this study was to evaluate the genotypic and phenotypic toxicity of Enterococcus faecalis MG5206 and Enterococcus faecium MG5232 isolated from kimchi (fermented vegetable cabbage). In this study, the genotypic toxicity of the strains MG5206 and MG5232 was identified through whole-genome sequencing analysis, and phenotypic virulence, such as susceptibility to antibiotics, hemolytic activity, and gelatinase and hyaluronidase activities, was also evaluated. In addition, the in vivo toxicity of both strains was evaluated using an acute oral administration test in Sprague–Dawley rats. In all the tests, both the strains were determined to be safety by confirming that they did not show antibiotic resistance or virulence factors. In addition, these strains exhibited a low level of autoaggregation ability (37.2–66.3%) and hydrophobicity, as well as a high survival rate in gastrointestinal condition in vitro. Therefore, the safety and high gastrointestinal viability of E. faecalis MG5206 and E. faecium MG5232 suggests that both the strains could be utilized in food as potential probiotics in the future.

A halotolerant hyaluronidase from newly isolated Brevibacterium halotolerans DC1: Purification and characterization

An enzyme hyaluronidase (hyase) producing halotolerant bacterium was isolated from dental caries and identified as Brevibacterium halotolerans DC1. Higher growth and hyase production were observed in nutrient broth fortified with hyaluronic acid at pH 7.0, temperature 37 °C, 120 rpm upon 48 h of incubation. Hyase was purified using salt precipitation, DEAE cellulose ion exchange, and Sephadex G-100 gel filtration chromatography. The enzyme was purified to 13-fold with 67.19% recovery of activity and 26.37 U/mg of specific activity. SDS-PAGE and zymography revealed it to be near to homogeneity showing a relative molecular weight of about 43 kDa that was confirmed by MALDI-TOF MS. This hyase was very active and stable at pH 7.0 and temperature 40 °C. The presence of metal ions Ca²⁺ and Mg²⁺ increased its activity while Zn²⁺ and Cu²⁺ severely inhibited it. Being stable at 2 M NaCl, hyase exhibited its halotolerant nature. This enzyme showed wide substrate specificity where hyaluronic acid (HA) was the best substrate. The kinetic studies revealed that K_m and V_max were 91.3 μg/mL and 306.2 μg/mL/min respectively. This is the first report of hyaluronidase from a halotolerant Brevibacterium spp. which can find applications under high salinity.