The use of β-glucosidase positive strains, as tailored-starter cultures for table olives fermentation, is a useful biotechnological tool applied to accelerate the debittering process. Nowadays, strains belonging to Lactiplantibacillus plantarum species are selected for their high versatility and tolerance to stress conditions. The present study investigated the effect of different stress factors (pH, temperature and NaCl) on growth and on oleuropein-degrading abilities of selected L. plantarum strains. In addition, the presence of the beta-glucosidase gene was investigated by applying a PCR based approach. Results revealed that, overall, the performances of the tested strains appeared to be robust toward the different stressors. However, the temperature of 16 °C significantly affected the growth performance of the strains both singularly and in combination with other stressing factors since it prolongs the latency phase and reduces the maximum growth rate of strains. Similarly, the oleuropein degradation was mainly affected by the low temperature, especially in presence of low salt content. Despite all strains displayed the ability to reduce the oleuropein content, the beta-glucosidase gene was detected in five out of the nine selected strains, demonstrating that the ability to hydrolyze the oleuropein is not closely related to the presence of beta-glucosidase. Data of the present study suggest that is extremely important to test the technological performances of strains at process conditions in order to achieve a good selection of tailored starter cultures for table olives.

中文翻译：

---

不同胁迫参数对天然食用橄榄量身定做的初学者培养的植物乳杆菌菌株的生长及其对油橄榄果苷降解能力的影响

使用β-葡萄糖苷酶阳性菌株作为食用橄榄发酵专用发酵剂，是一种有用的生物技术工具，可用于加速去苦味过程。如今，选择具有高通用性和对胁迫条件的耐受性的植物乳杆菌属菌株。本研究调查了不同胁迫因素（pH，温度和NaCl）对所选L. plantarum生长和橄榄苦苷降解能力的影响。株。另外，通过应用基于PCR的方法研究了β-葡糖苷酶基因的存在。结果表明，总的来说，测试菌株的性能似乎对不同的应激源均很稳定。但是，温度为16°C会单独或与其他胁迫因素一起显着影响菌株的生长性能，因为它延长了潜伏期并降低了菌株的最大生长速率。同样，橄榄苦苷的降解主要受低温影响，尤其是在盐含量低的情况下。尽管所有菌株都具有降低橄榄苦苷含量的能力，但在9个选定菌株中有5个检测到了β-葡萄糖苷酶基因，表明水解橄榄苦苷的能力与β-葡萄糖苷酶的存在没有密切关系。本研究的数据表明，对于在加工条件下测试菌株的技术性能，以实现对食用橄榄量身定制的发酵剂文化的良好选择，这一点极为重要。