一株戊糖片球菌(Pediococcus pentosaceus)在模拟鱼露中的代谢行为及转录组学分析

Metabolic Behavior and Transcriptomic Analysis of A Pediococcus pentosaceus Strain in Simulated Fish Sauce

本文采用模拟鱼露体系,通过化学成分分析及转录组测序的手段研究了接种Pediococcus pentosaceus对鱼露发酵效果的影响。结果发现Pediococcus pentosaceus可显著提高鱼露中Glu、Gly、Ala、Ser、Asp等良好风味氨基酸的含量,降低Phe等不良风味氨基酸含量;并且鱼露的挥发性成分中烃类、酯类的成分的种类和含量均大幅减少,芳香族化合物的种类大大减少但总量大幅增加;而醛类、酮类、酸类和胺类成分的种类和含量均显著增加;感官评定结果表明接种Pediococcus pentosaceus可显著改善鱼露的鲜味和香气。转录组测序结果表明,在模拟鱼露中Pediococcus pentosaceus的碳水化合物和氨基酸的代谢最为活跃,且处于最活跃的代谢通路中的氨基酸也是鱼露中含量变化最大的氨基酸;还发现Pediococcus pentosaceus有较强的蛋白酶和肽酶活性;柠檬烯和松萜的降解也是Pediococcus pentosaceus的主要代谢通路之一,该通路与挥发性成分的产生有关;本研究未发现Pediococcus pentosaceus在模拟鱼露发酵过程中有氨基酸脱羧酶表达。

The influence of Pediococcus pentosaceus inoculation on the fermentation in a simulated fish sauce system was investigated by chemical analysis and transcriptomic sequencing technique in this paper.The results showed that P.pentosaceus remarkably increased the content of amino acids with an agreeable taste,including glutamic acid（Glu）,glycine（Gly）,alanine（Ala）,serine（Ser）,aspartic acid（Asp）,and others,and reduced the content of amino acids with an unpleasant taste,including phenylalanine（Phe） and others.Additionally,after inoculation with P.pentosaceus,the volatile compound content changed significantly.The types and content of hydrocarbon and ester compounds were reduced dramatically;the types of aromatic compounds decreased but the total content was increased greatly;and the types and content of aldehydes,ketones,acids,and amines increased significantly.Sensory evaluation showed that P.pentosaceus remarkably improved the flavor and aroma of fish sauce.The results of transcriptomic sequencing indicated that carbohydrate and amino acid metabolism of P.pentosaceus in the simulated fish sauce were the most active.The content of the amino acids,which were involved in the most active pathways,showed the most significant changes in fish sauce.Additionally,P.pentosaceus had relatively strong protease and peptidase activities.The degradation of limonene and pinene was found to be a major pathway in P.pentosaceus and was associated with the formation of volatile compounds.In this study,the expression of various amino acid decarboxylases was not detected in P.pentosaceus during fermentation of the simulated fish sauce.