Effect of ε-polylysine combined with 1-MCP on the surface bacteria of Volvariella volvacea fruit bodies during storage

Abstract:

[Background] Volvariella volvacea has high nutritional and medicinal value. Post-harvest quality deterioration of V. volvacea fruit bodies (VVFB) is mainly caused by the surface spoilage bacteria. There is no report on the surface bacteria of VVFB under fresh-keeping treatment. [Objective] To investigate the effect of ε-polylysine (ε-PL) combined with 1-methylcyclopropene (1-MCP) on surface bacteria of VVFB during storage. [Methods] VVFB were treated with ε-PL and 1-MCP and then stored. Through the plate culture method and 16S rRNA gene high-throughput sequencing, the surface bacteria of VVFB during storage were isolated and identified, and the dominant spoilage bacteria were determined. [Results] The plate culture method showed that the total number of colonies on the surface of VVFB increased during the storage. To be specific, the colony number of the treatment group (PC, ε-PL+1-MCP) was up to 7.16 lg (CFU/g) on the 6th day, smaller (P<0.01) than that 7.42 lg (CFU/g) in the control group (CK). A total of 16 and 19 strains were isolated from the PC group and CK group, respectively, which were dominated by Pseudomonas, Chryseobacterium, Bacillus, and Stenotrophomonas. The 16S rRNA gene high-throughput sequencing suggested 370 bacterial generas in 27 phylas were identified in the PC group, and 366 generas in 25 phylas were identified in the CK group. Among the strains, Stenotrophomonas had the highest relative abundance. [Conclusion] Stenotrophomonas is one of dominant spoilage bacterial genus of VVFB, and ε-PL combined with 1-MCP can effectively inhibit the growth of bacteria on the surface of VVFB.

Key words:Volvariella volvacea;plate culture;high-throughput sequencing;bacterial flora structure