NaCl对德氏乳杆菌AGDI基因转录及产腐胺的影响

Effects of NaCl on the Transcription of Genes Involved in AGDI and Putrescine Production of Lactobacillus delbrueckii

本实验研究不同浓度NaCl对德氏乳杆菌通过胍基丁胺脱亚胺酶(Agmatine deiminase,AGDI)途径产腐胺及其转录调控的影响。利用反转录实时荧光定量PCR(Reverse transcription quantitative polymerase chain reaction,RT-qPCR)技术分析德氏乳杆菌在不同NaCl浓度下通过AGDI途径产腐胺的相关基因表达情况,使用超高效液相色谱法(Ultra performance liquid chromatography,UPLC)连续48 h监测德氏乳杆菌产腐胺量。结果表明:在培养液中添加1%～6%的NaCl能显著(p<0.05)抑制德氏乳杆菌数量的增加,同时可减少培养液pH的下降。此外,1%～3%的NaCl可从基因水平上影响供试菌产腐胺,虽然对其AGDI基因束中调节基因aguR的转录影响不显著(p>0.05),但能极显著(p<0.01)抑制操纵子aguBDAC的转录,从而显著(p<0.05)减少腐胺的生成,且NaCl浓度越大,抑制作用越大。在熏马肠的制作过程中,可考虑用适当浓度的NaCl处理,抑制发酵过程中德氏乳杆菌等产腐胺杂菌的生长,从而降低产品中腐胺的含量。

The study explored the effects of different concentrations of NaC1 on Lactobacillus delbrueckii which could produce putrescine by AGDI pathway.Reverse transcription quantitative polymerase chain reaction（RT-qPCR） technique was used to analyze the related gene expression.Ultra performance liquid chromatography（UPLC） was used to monitor putreseine produced by Lactobacillus delbrueckii in 48 h. The research results were as follows： 1%- 6% NaCl in the medium could restrain an augment in the number of Lactobacillus delbrueckii significantly （p 〈 0.05 ）.At the same time, it could reduce the decline of pH. Furthermore,1%-3% NaCl could influence the putrescine produced by Lactobacillus delbrueckii at the level of genes.They had few effect on the regulating gene-aguR＇ s transcription（p 〉 0.05 ）but could inhibit the transcription of aguBDAC operon highly significantly（p 〈 0.01 ）.The production of putrescine was sinificantly （p 〈 0.05 ）decreased by 1% -3% NaCl. The larger concentration of NaCl caused greater inhibiting effects.Lactobacillus delbrueckii in this study was a kind of infectious microbe isolated from smoked horsemeat sausages. It could be dealed with proper concentration of NaCl in the smoked horsemeat sausages making process so that infectious microbe such as Lactobacillus delbrueckii which came into being in the fermentation process would be restrained.Therefore, putrescine accumulation in the product could be diminished.