Abstract: To clarify the mechanism of action of natural composite preservative (NCP) and prolong the shelf life of aquatic products, Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) fingerprinting was used to study the effect of an NCP consisting of chitosan, lysozyme and tea polyphenols in 1.0% acetic acid solution at respective concentrations of 10.0 g/L, 6 × 106 U/L and 3.0 g/L on the evolution of diversity of microbial populations in cutlassfish (Trichiurus haumela) during cold storage. SDS pyrolysis method was used for total genomic DNA extraction from control and NCP-treatment samples of cutlassfish, and the V3 variable regions of 16 S rDNA were subjected to PCR amplification for DGGE fingerprinting of dynamic changes. The results of DGGE fingerprinting indicated that cutlassfish possessed abundant microbial communities during the early part of the storage period (16 d). However, with increasing storage time, only few bacterial species kept alive and became dominant at last. The main brands in the DGGE patterns of cutlassfish were sequenced to identify 12 bacterial species. The specific spoilage organisms (SOSs) of control and NCP-treatment samples of cutlassfish in the final stages of spoilage showed high similarity. Psychrobacter sp. was dominant in the early stages, whereas the proportions of Shewanella sp. and Pseudomonas sp. increased gradually with the extension of storage time, and became dominant. Moreover, both Pseudomonas fluorescens and Vibrio sp. were highly proportional. In addition, NCP treatment had no obvious inhibitory effect on Shewanella sp. or Pseudomonas sp.

Key words: Trichiurus haumela, natural composite preservative, polymerase chain reaction-denaturing gradient gel