Within the genus Streptococcus, S. thermophilus and S. macedonicus are the 2 known species related to foods. Streptococci are widely used as starter cultures to rapidly lower milk pH. As S. macedonicus has been introduced quite recently, much less information is available on its technological potential. Because temperature is an important factor in fermented food production, we compared the growth kinetics over 24 h of 8 S. thermophilus and 7 S. macedonicus strains isolated from various dairy environments in Italy, at 4 temperatures, 30°C, 34°C, 37°C and 42°C. We used the Gompertz model to estimate the 3 main growth parameters; namely, lag phase duration (λ), maximum growth rate (µ_max), and maximum cell number at the stationary phase (N_max). Our results showed significant differences in average growth kinetics between the 2 species. Among the strains tested, 37°C appeared to be the optimal temperature for the growth of both species, particularly for S. macedonicus strains, which showed mean shorter lag phases and higher cell numbers compared with S. thermophilus. Overall, the growth curves of S. macedonicus strains were more similar to each other whereas S. thermophilus strains grew very differently. These results help to better define and compare technological characteristics of the 2 species, in view of the potential use of S. macedonicus in place of S. thermophilus in selected technological applications.

在链球菌属中，嗜热链球菌和马其顿链球菌是与食物有关的两个已知物种。链球菌被广泛用作发酵剂以迅速降低牛奶的pH值。由于马其顿链球菌是最近才引进的，因此关于其技术潜力的信息很少。由于温度是发酵食品生产中的重要因素，因此我们比较了从意大利各种乳制品环境中分离到的8个嗜热链球菌和7个马其顿氏菌在4个温度，30°C，34°C， 37°C和42°C。我们使用Gompertz模型估算了3个主要的增长参数。即，滞后阶段持续时间（λ），最大增长率（µ_max），以及固定阶段的最大细胞数（N _max）。我们的结果表明，这两个物种之间的平均生长动力学存在显着差异。在测试的菌株中，似乎37°C是两个物种生长的最佳温度，特别是马其顿酵母菌株，与嗜热链球菌相比，平均滞后期短，细胞数高。总体而言，马其顿酵母菌株的生长曲线彼此更相似，而嗜热链球菌菌株的生长曲线差异很大。考虑到马氏链球菌的潜在用途，这些结果有助于更好地定义和比较这两个物种的技术特征。在选定的技术应用中代替嗜热链球菌。