Genetic Characteristics and Preservative Tolerance of Spoilage Microorganisms in Daily Chemical Products

Daily chemical products (DCPs), including cosmetics and cleaning products, are widely used in everyday life but are vulnerable to microbial contamination during production, storage, and use. Such contamination can cause product spoilage, reduce product quality, and pose potential health risks to consumers. In this study, we performed a comprehensive surveillance of spoilage microorganisms isolated from 185 abnormal DCPs batches collected from 2019 to 2021, followed by phenotypic identification, multilocus sequence typing (MLST), phylogenetic analysis, and preservative susceptibility testing. A total of 1655 microbial isolates were recovered from raw materials, the production environment, and finished products. The most prevalent contaminants in finished products were Burkholderia spp. and Pseudomonas spp., and correlation analysis suggested that raw materials were a major reservoir of contamination. Species-level identification showed that the Burkholderia cepacia complex (Bcc) and Pseudomonas aeruginosa were the dominant spoilage bacteria. MLST analysis of 41 Bcc isolates identified 15 sequence types (STs), including six novel STs, while 23 P. aeruginosa isolates were assigned to nine STs. Among these, Bcc ST621 and P. aeruginosa ST2230 were the most frequently detected lineages. Preservative challenge assays showed that several Bcc and P. aeruginosa isolates exhibited tolerance to Kathon at or above the maximum permitted concentration. These findings indicate that raw materials are an important source of microbial contamination in DCPs and that Bcc and P. aeruginosa lineages with elevated preservative tolerance may contribute to product spoilage. Our results support the inclusion of Bcc in routine microbial monitoring of DCPs and highlight the need for improved raw material control and preservative efficacy evaluation.