Mauriello G, Casaburi A, Villani F
Department of Digestive Sciences, Division of Microbiology, Federico II University of Naples, 80055 Portici, Naples, Italy.
J Appl Microbiol. 2002;92(3):482-90. doi: 10.1046/j.1365-2672.2002.01551.x.
The aim of this study was to determine the proteolytic activities of Staphylococcus xylosus strains on sarcoplasmic and myofibrillar proteins in order to evaluate the suitability of selected strains as starter cultures in the processing of a dry fermented pork sausage.
The proteolytic activity of 27 strains of Staphylococcus xylosus on sarcoplasmic and myofibrillar proteins was determined by agar plate method, o-phtaldialdehyde (OPA) spectrophotometric assay and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Four strains were selected for the formulation of six starter cultures to use in the production of "Naples type" salami. The proteolytic contribution of starters was determined by SDS-PAGE, comparing the protein profile of inoculated sausages with that of uninoculated sausages after 0, 15 and 33 days of ripening. The results showed that the proteolytic activity of some strains, determined by the agar plate method, were not confirmed by electrophoretic and spectrophotometric assays. In fact, of 24 strains of Staphylococcus xylosus able to hydrolyse muscle protein extracts on agar plate, only 12 strains were shown to change SDS-PAGE profile of pork proteins. The SDS-PAGE profile of sarcoplasmic proteins extracted from all sausages showed that the major changes were produced with starters S3, S4 and S5 after 15 days of ripening. Also myofibrillar proteins undergo major changes after 15 days of ripening and the protein profiles showed the same pattern in all samples, except for the sausages produced with starter S4.
The results of this work showed that the muscle protein extracts hydrolysis test is suitable for preliminary screening of Staphylococcus xylosus strains on the basis of their proteolytic activity. However, evaluation of muscle protein hydrolysis in a food model system could then be more appropriate for selecting micro-organisms for use as starter cultures for fermented sausages.
The potential of the findings is discussed with reference to the formulation of starter cultures for the dry fermented sausages production.
本研究旨在测定木糖葡萄球菌菌株对肌浆蛋白和肌原纤维蛋白的蛋白水解活性，以评估所选菌株作为干发酵猪肉香肠加工中发酵剂的适用性。
采用琼脂平板法、邻苯二甲醛（OPA）分光光度法和十二烷基硫酸钠聚丙烯酰胺凝胶电泳（SDS-PAGE）测定了27株木糖葡萄球菌对肌浆蛋白和肌原纤维蛋白的蛋白水解活性。选择4株菌株用于配制6种发酵剂，用于生产“那不勒斯型”萨拉米香肠。通过SDS-PAGE测定发酵剂的蛋白水解作用，比较成熟0、15和33天后接种香肠与未接种香肠的蛋白质谱。结果表明，琼脂平板法测定的部分菌株的蛋白水解活性未得到电泳和分光光度法测定的证实。事实上，在琼脂平板上能够水解肌肉蛋白提取物的24株木糖葡萄球菌中，只有12株显示出能改变猪肉蛋白的SDS-PAGE图谱。从所有香肠中提取的肌浆蛋白的SDS-PAGE图谱表明，成熟15天后，发酵剂S3、S4和S5产生了主要变化。肌原纤维蛋白在成熟15天后也发生了主要变化，除了用发酵剂S4生产的香肠外，所有样品的蛋白质谱都显示出相同的模式。
本研究结果表明，肌肉蛋白提取物水解试验适用于基于木糖葡萄球菌菌株蛋白水解活性的初步筛选。然而，在食品模型系统中评估肌肉蛋白水解可能更适合选择用作发酵香肠发酵剂的微生物。
参考干发酵香肠生产发酵剂的配方，讨论了研究结果的潜力。
