Formation mechanisms of ethyl acetate and organic acids in Kluyveromyces marxianus L1-1 in Chinese acid rice soup

This study aims to explore the formation mechanism of ethyl acetate and organic acids in acid rice soup(rice-acid soup)inoculated with Kluyveromyces marxianus L1-1 through the complementary analysis of transcriptome and proteome.The quantity of K.marxianus L1-1 varied significantly in the fermentation process of rice-acid soup and the first and third days were the two key turning points in the growth phase of K.marxianus L1-1.Importantly,the concentrations of ethyl acetate,ethanol,acetic acid,and L-lactic acid increased from day 1 to day 3.At least 4231 genes and 2937 proteins were identified and 610 differentially expressed proteins were annotated to 30 Kyoto Encyclopedia of Genes and Genomes(KEGG)pathways based on the analysis results of transcriptome and proteome.The key genes and proteins including up-regulated alcohol dehydrogenase family,alcohol O-acetyltransferase,acetyl-CoA C-acetyltransferase,acyl-coenzyme A thioester hydrolase,and down-regulated aldehyde dehydrogenase family were involved in glycolysis/gluconeogenesis pathways,starch and sucrose metabolism pathways,amino sugar and nucleotide sugar metabolism pathways,tricarboxylic acid(TCA)cycle,and pyruvate metabolism pathways,thus promoting the formation of ethyl acetate,organic acids,alcohols,and other esters.Our results revealed the formation mechanisms of ethyl acetate and organic acids in rice-acid soup inoculated with K.marxianus L1-1.

古里雅冰芯中生物有机酸的初步分析

甲酸、乙酸是全球对流层中普遍存在的化学成分，它们对偏远地区降水中的酸度有很大影响，降水中存在的甲酸、乙酸必然会在冰川和冰盖中保存下来．然而，目前很少有文章报道山地冰川中甲酸、乙酸的测定结果及环境意义．我们用离子色谱法测定了古里雅上部５ｍ冰芯中甲酸、乙酸的浓度，结果显示，甲酸、乙酸具有明显的季节变化，峰值一般对应于夏季层位，说明甲酸、乙酸的来源不同于阳离子，粉尘不是其主要来源．将甲酸、乙酸的记录与冰芯中δ１８Ｏ和阳离子的记录对比，得出甲酸具有较敏感的气候指示意义．

降水中甲酸和乙酸研究综述

对大气降水中甲酸和乙酸的相关研究进行了综述。介绍了过去曾采用的研究降水样品中两种有机酸的处理和分析方法,以及目前最常用的实验室分析方法。对降水中两种有机酸的浓度范围、全球时空分布以及受影响因素等相关研究工作进行了系统归纳,并且结合理论计算说明了有机酸对降水酸度的影响是不可忽视的。介绍了历史研究工作中得出的降水中两种有机酸的来源,包括天然源、人为源和有机物的二次化学转化等,以及有机酸源研究对于开展其它降水有机酸工作的研究意义。