超高压处理抑制低温烟熏火腿中的优势腐败菌

研究尝试应用微生物菌体总RNA提取代替DNA提取,进而通过反转录-PCR( RT-PCR),结合变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)技术,以期揭示超高压处理后低温烟熏火腿中腐败微生物的存活情况,探索RNA-DGGE手段判定超高压处理后微生物存活状态的可行性.分别以400 MPa和600 MPa的压力在室温(22℃)条件下,对包装后的烟熏火腿进行10 min超高压处理,未经高压处理样品作对照,于4℃冷藏条件下,贮藏1、15、30、60、90 d,直接提取样品中微生物的总RNA,对其进行RT-PCR和DGGE指纹图谱分析.DGGE指纹图谱显示,超高压处理对烟熏火腿中的优势腐败菌具有较强的抑制作用,且随压力的升高抑菌效应增强；超高压处理后烟熏火腿微生物种群结构变得单一,Weissella viridescens和Leuconostoc mesenteroides是超高压处理后烟熏火腿中的优势腐败菌.基于菌体总RNA提取的DGGE手段能够有效检测超高压处理后微生物的存活状况,揭示超高压对低温烟熏火腿中优势腐败微生物的抑菌效果.

Inactivation of the Predominant Spoilage Bacteria in Sliced Cooked Ham by High Pressure

In this study,total RNA,instead of genome DNA,was extracted from pressurized cooked ham and then performed with RT-PCR-denaturing gradient gel electrophoresis(DGGE) analysis to explore whether this molecular method was feasible to reveal the active species in the samples.Sliced vacuum-packed cooked ham were high pressure treated at 400 MPa and 600 MPa for 10 min at room temperature(22 ℃) and then stored at 4 ℃.Directly RNA extraction from meat samples and RT-PCR-DGGE analysis was performed at storage time 1,30,60,90 days(after HPP).Results showed that the major spoilage bacteria in the samples were largely inactivated by HPP and that higher level of pressure leaded to better effect.The microbial diversity of HPP samples during the whole refrigerated storage was extremely simple.Only Weissella viridescens survived the HPP of 600 MPa for 10 min at 22 ℃ and Weissella viridescens coupled with Leuconostoc mesenteroides survived the HPP of 400 MPa for 10 min at 22 ℃.The RNA-based DGGE method adopted is shown to be an efficient tool for the detection of active bacteria in pressurized cooked ham.