Rivarola V, Castro S, Mori G, Jofré E, Fabra A, Garnica R, Balegno H
Facultad de Ciencias Exactas, Físcio-Químicas y Naturales, Universidad Nacional de Río Cuarto, Argentina.
Antonie Van Leeuwenhoek. 1998 Apr;73(3):255-61. doi: 10.1023/a:1001053414777.
Growth of Azospirillum brasilense Cd in the presence of different NaCl concentrations showed that it tolerates up to 200 mM NaCl in the medium, without appreciable decline in growth rate. At 300 mM NaCl, a decrease of 66% in growth was observed at 24 h of culture. At 48 h of culture, bacteria in the presence of 300 mM NaCl reached the maximum optical density value that was attained at 12 h by control cultures. This investigation was designed to elucidate the effect of saline stress on Azospirillum brasilense Cd and the physiologic mechanism involved in its possible salinity tolerance. For this reason, studies of other osmolytes, as well as of putrescine metabolism and protein patterns were done with bacteria grown with this NaCl concentration in the medium, at 24 and at 48 hours. A. brasilense responded to saline stress elevating the intracellular concentration of glutamate at 24 h, and of K+ at 48 h. Glucan pattern, putrescine metabolism, and total and periplasmic protein patterns of the treated group showed several changes with respect to the control. In spite of the several cellular functions affected by saline stress, the results imply that A. brasilense Cd shows salinity tolerance in these experimental conditions.
在不同NaCl浓度条件下，巴西固氮螺菌Cd的生长情况表明，该菌能耐受培养基中高达200 mM的NaCl，且生长速率无明显下降。在300 mM NaCl条件下，培养24 h时观察到生长下降了66%。培养48 h时，处于300 mM NaCl条件下的细菌达到了对照培养物在12 h时所达到的最大光密度值。本研究旨在阐明盐胁迫对巴西固氮螺菌Cd的影响以及其可能的耐盐生理机制。因此，在培养基中该NaCl浓度条件下培养24 h和48 h的细菌，对其他渗透溶质以及腐胺代谢和蛋白质模式进行了研究。巴西固氮螺菌对盐胁迫的反应是，在24 h时提高细胞内谷氨酸浓度，在48 h时提高K+浓度。处理组的葡聚糖模式、腐胺代谢以及总蛋白和周质蛋白模式相对于对照组均表现出若干变化。尽管盐胁迫影响了多种细胞功能，但结果表明，在这些实验条件下巴西固氮螺菌Cd具有耐盐性。
