Stefanovic E, Kilcawley K N, Rea M C, Fitzgerald G F, McAuliffe O
Department of Food Bioscience, Teagasc Food Research Centre, Moorepark, Fermoy, Ireland.
School of Microbiology, University College Cork, Cork, Ireland.
J Appl Microbiol. 2017 May;122(5):1245-1261. doi: 10.1111/jam.13420. Epub 2017 Apr 4.
The Lactobacillus casei group represents a widely explored group of lactic acid bacteria, characterized by a high level of biodiversity. In this study, the genetic and phenotypic diversity of a collection of more than 300 isolates of the Lact. casei group and their potential to produce volatile metabolites important for flavour development in dairy products, was examined.
Following confirmation of species by 16S rRNA PCR, the diversity of the isolates was determined by pulsed-field gel electrophoresis. The activities of enzymes involved in the proteolytic cascade were assessed and significant differences among the strains were observed. Ten strains were chosen based on the results of their enzymes activities and they were analysed for their ability to produce volatiles in media with increased concentrations of a representative aromatic, branched chain and sulphur amino acid. Volatiles were assessed using gas chromatography coupled with mass spectrometry. Strain-dependent differences in the range and type of volatiles produced were evident.
Strains of the Lact. casei group are characterized by genetic and metabolic diversity which supports variability in volatile production.
This study provides a screening approach for the knowledge-based selection of strains potentially enabling flavour diversification in fermented dairy products.
干酪乳杆菌组是一类经过广泛研究的乳酸菌，具有高度的生物多样性。在本研究中，对300多株干酪乳杆菌组菌株的遗传和表型多样性及其产生对乳制品风味形成重要的挥发性代谢物的潜力进行了研究。
通过16S rRNA PCR鉴定物种后，采用脉冲场凝胶电泳确定分离株的多样性。评估了参与蛋白水解级联反应的酶的活性，观察到菌株之间存在显著差异。根据酶活性结果选择了10株菌株，并分析了它们在含有代表性芳香族、支链和含硫氨基酸浓度增加的培养基中产生挥发物的能力。使用气相色谱-质谱联用仪评估挥发物。所产生挥发物的范围和类型存在明显的菌株依赖性差异。
干酪乳杆菌组菌株具有遗传和代谢多样性，这支持了挥发性物质产生的变异性。
本研究提供了一种筛选方法，用于基于知识选择可能使发酵乳制品风味多样化的菌株。
