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首页> 外文期刊>Food microbiology >Evaluation of the response of Lactobacillus rhamnosus VTT E-97800 to sucrose-induced osmotic stress
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Evaluation of the response of Lactobacillus rhamnosus VTT E-97800 to sucrose-induced osmotic stress

机译：鼠李糖乳杆菌VTT E-97800对蔗糖诱导的渗透压响应的评估

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Environmental osmotic changes are one of the stresses live probiotics may encounter either in their natural habitats or as a result of usage in food formulations and processing. Response to osmotic stress, induced by sucrose, of the probiotic strain Lactobacillus rhamnosus VTT E-97800 (E800) was investigated. The fluorescence-based approach used, by combined staining with caboxyfluorescein (cFDA) and propidium iodide (PI) could give insights on the osmotic-induced changes of microbial esterase activity and membrane integrity; also the extrusion of intracellular accumulated carboxyfluorescein (cF) upon energizing with glucose. Comparison of the flowcytometric viability assessment with the conventional culture techniques revealed that sucrose-stressed cells had a slight loss of culturability (log N/N_0～-0.3) at 1.2 and 1.5 M sucrose concentration though they could perform an enzymatic conversion of cFDA into cF. The presence of such metabolically active bacteria in food might be critical as they may excrete toxic or food spoilage metabolites. Moreover, the perturbation of cF extrusion activities became a limiting factor for reproductive capacities. There was no change in the cell morphology. These results proved the ability of the strain of study to tolerate sucrose, even at extreme concentrations and these must be taken into consideration for its usage in the formulation/processing of sugar-based foods, e.g. jams, candies, etc.
机译：环境渗透性变化是益生菌在自然栖息地或在食品配方和加工中使用时可能遇到的压力之一。研究了益生菌鼠李糖乳杆菌VTT E-97800（E800）对蔗糖诱导的渗透胁迫的响应。使用基于荧光的方法，通过与卡巴氧荧光素（cFDA）和碘化丙啶（PI）结合染色，可以深入了解渗透诱导的微生物酯酶活性和膜完整性的变化。葡萄糖激发后，细胞内积聚的羧基荧光素（cF）也被挤出。流式细胞术可行性评估与常规培养技术的比较表明，蔗糖胁迫的细胞在蔗糖浓度为1.2和1.5 M时，虽然可以将cFDA酶促转化为cF，但其培养能力略有下降（log N / N_0〜-0.3）。 。食物中此类代谢活性细菌的存在可能至关重要，因为它们可能会排出有毒或食物变质的代谢产物。而且，cF挤出活动的扰动成为生殖能力的限制因素。细胞形态没有变化。这些结果证明了该菌株即使在极高浓度下也具有耐受蔗糖的能力，并且在将其用于糖基食品的配制/加工中时，必须考虑到这些因素。果酱，糖果等

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