Identification and Spoilage Capacity Analysis of Main Spoilage Bacteria in Pickles

Abstract:

[Objective] This study aims to identify the main spoilage bacteria and evaluate their spoilage capacity in the spoilage process of pickles. [Method] High-throughput sequencing was employed to analyze the microbial community dynamics in the samples of pickles at the early, middle, and late stages of spoilage. The key spoilage bacteria were isolated, purified, and then identified through a combination of colony morphology observation, biochemical analysis, and 16S rDNA/ITS sequencing. Re-inoculation experiments were carried out for further validation of the primary spoilage bacteria in pickles. [Result]Acinetobacter and Bacillus were the dominant spoilage bacterial genera across the three spoilage stages. Notably, Bacillus exhibited rapid growth over time, with the relative abundance of 2.25%, 18.31%, and 44.19%, respectively, at the early, middle, and late stages of spoilage. This result indicated that the increase in the relative abundance of Bacillus might be the main cause of late spoilage in pickles. After isolation, purification, and identification, the five dominant spoilage bacterial strains were Bacillus velezensis, Acinetobacter baumannii, Virgibacillus salarius, Bacillus pumilus, and Pichia membranifaciens. The results of re-inoculation experiments showed that all the five strains affected the crispness of pickles, demonstrating considerable spoilage capacities. [Conclusion] These findings provide a theoretical foundation for targeted control against spoilage bacteria in pickles.