RESUMO
In this study, five keratinolytic bacteria were isolated from poultry farm waste of Eastern Province, Saudi Arabia. The highest keratinase activity was obtained at 40-45 °C, pH 8-9, feather concentration 0.5-1%, and using white chicken feather as keratin substrate for 72 h. Enhancement of keratinase activity through physical mutagen UV radiation and/or chemical mutagen ethyl methanesulfonate (EMS) resulted in five mutants with 1.51-3.73-fold increased activity over the wild type. When compared with the wild type, scanning electron microscopy validated the mutants' effectiveness in feather degradation. Bacterial isolates are classified as members of the S8 family peptidase Bacillus cereus group based on sequence analysis of the 16S rRNA and keratinase genes. Interestingly, keratinase KerS gene shared 95.5-100% identity to keratinase, thermitase alkaline serine protease, and thermophilic serine protease of the B. cereus group. D137N substitution was observed in the keratinase KerS gene of the mutant strain S13 (KerS13uv+ems), and also seven substitution variations in KerS26 and KerS26uv of strain S26 and its mutant S26uv. Functional analysis revealed that the subtilisin-like serine protease domain containing the Asp/His/Ser catalytic triad of KerS gene was not affected by the predicted substitutions. Prediction of physicochemical properties of KerS gene showed instability index between 17.5-19.3 and aliphatic index between 74.7-75.7, which imply keratinase stability and significant thermostability. The docking studies revealed the impact of substitutions on the superimposed structure and an increase in binding of mutant D137N of KerS13uv+ems (affinity: -7.17; S score: -6.54 kcal/mol) and seven mutants of KerS26uv (affinity: -7.43; S score: -7.17 kcal/mol) compared to the wild predicted structure (affinity: -6.57; S score: -6.68 kcal/mol). Together, the keratinolytic activity, similarity to thermostable keratinases, and binding affinity suggest that keratinases KerS13uv+ems and KerS26uv could be used for feather processing in the industry.
RESUMO
Polymer nanoparticles are a promising approach for cancer treatment and detection, due to their biocompatibility, biodegradability, targeting capabilities, capacity for drug loading and long blood circulation time. This study aims to evaluate the impact of poly (styrene-acrylic acid) latex particles on colorectal and cervical cancer cells for anti-tumor efficiency. Latex particles were synthesized by a surfactant-free radical emulsion polymerization process and the obtained polymer particles were characterized in terms of size, size distribution, morphology using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and electrokinetic property (i.e., zeta potential). Human colorectal and cervical cancer, and normal cell lines, were then treated with different concentrations of poly (styrene-acrylic acid) latex particles. The cell morphology changes were pointed out using an optical microscope and the nanoparticles' (NPs) cell cytotoxicity was evaluated using MTT assay. The obtained results showed that poly (styrene-acrylic acid) latex particles are effective against colorectal and cervical cancer cells if treated with an appropriate particle concentration for 48 h. In addition, it showed that normal cells are the least affected by this treatment. This indicates that these NPs are safe as a drug delivery carrier when used at a low concentration.
