Salmonella typhimurium can encounter a wide variety of environments during its life cycle. S. typhimurium can experience and survive dramatic acid stress. However, in vitro the organism is very sensitive to acid. S. typhimurium was adapted to acid by exposure to HCl at pH ± for one growth cycle. Acid-adapted cells were much better protected from acid death than control cells. | Turk J Biol 27 (2003) 31-36 © TÜB‹TAK Acid Adaptation Protects Salmonella typhimurium From Environmental Stresses Halil TOSUN, fiahika AKTU⁄ GÖNÜL Department of Food Engineering, Faculty of Engineering, Ege University, ‹zmir - TURKEY Received: Abstract: Salmonella typhimurium can encounter a wide variety of environments during its life cycle. S. typhimurium can experience and survive dramatic acid stress. However, in vitro the organism is very sensitive to acid. S. typhimurium was adapted to acid by exposure to HCl at pH ± for one growth cycle. Acid-adapted cells were much better protected from acid death than control cells. The relationship between acid adaptation of S. typhimurium and tolerance to other environmental stresses was also examined. Acidadapted cells were found to have increased tolerance to various stresses including heat, salt and organic acids. No cross-protection was noted for cold (3 ± °C). Decimal reduction times of acid-adapted and control cells at 50 °C (D50) were also examined. The D50 value of acid-adapted cells was considerably higher than that of the control cells. These results show that acid adaptation alters cellular resistance to a variety of environmental stresses. Key Words: Salmonella typhimurium, acid adaptation, environmental stresses. Salmonella typhimurium’da Aside Adaptasyonun Çevresel Streslere Karfl› Koruma Sa¤lamas› Özet: Salmonella typhimurium yaflam sürecinde çok farkl› ortamlarla karfl› karfl›ya kal›r. Konakç› ortam› d›fl›nda aside oldukça duyarl› olan Salmonella typhimurium buna ra¤men etkili asit stresinde canl›l›¤›n› sürdürebilir. S. typhimurium pH ± ’e ayarlanm›fl HCl’ye bir generasyon süresi boyunca maruz b›rak›larak aside adapte edildi. Aside adapte edilen hücreler, kontrol hücreleriyle karfl›laflt›r›ld›¤›nda, asitten kaynaklanan ölümden korunduklar› görüldü. S. typhimurium’da aside adaptasyon ile di¤er çevresel streslere karfl› kazan›lan tolerans aras›ndaki iliflkide incelendi.
