Isolation, Identification and Characterization of Extremophilic Bacteria from Cosmetic Foundation

Abstract

Cosmetic products are prone to microbial contamination especially those that are resistant to preservatives which can survive under extreme pH environments. This paper sought to isolate and characterize alkali-tolerant bacteria in samples of cosmetic foundations and to computationally assess the potential antimicrobial targets. The isolates of bacteria were obtained through the culture of foundation samples using Luria-Bertani agar at pH 10. The isolate was determined to be Pseudomonas aeruginosa, a non-acid-fast, Gram-negative organism, and 99.85% similar to reference strains by 16S rRNA genome sequencing. Biochemical analysis showed a positive catalase, positive oxidase, and positive citrate metabolism characteristic of P. aeruginosa. The isolate survived at pH 10 and this confirms its alkali-tolerant nature. Computational studies were performed on the pyochelin biosynthesis protein F (pchF), with a Ramachandran score of 92.3, an ERRAT score of 94.77, and a VERIFY3D score of 90.48, and the quality of the model is acceptably good. Quercetin-3-glucuronide was found to have a high binding affinity ( ΔG = -8.6 kcal/mol) at binding pocket C2. The stability of the pchF-quercetin-3-glucuronide complex during 100 ns was verified by molecular dynamics simulations, and the RMSD (approximately 0.3 nm) was stable, as well as the radius of gyration (1.942.02 nm) and hydrogen bonding (6-10 bonds). These results demonstrate the necessity of greater microbial safety measures in cosmetics and indicate that pchF may be an effective therapeutic target. Quercetin-3-glucuronide is a promising natural antimicrobial agent and should be further proven by experimental studies. Keywords: Pseudomonas aeruginosa, cosmetic contamination, alkali-tolerant bacteria, pyochelin biosynthesis, molecular docking, quercetin-3-glucuronide