**5. Survival and growth parameters**

*Salmonella* sp. can multiply and survive in the estuarine environments and tropical freshwater environments for weeks although open marine waters are free from *Salmonella* (Huss,1994; Huss & Gram 2003). *Salmonella* prefers to grow at 37°C. Compared to other Gram-negative bacteria, *Salmonella* are relatively resistant to various environmental factors. They grow at temperatures between 5°C and 47°C. There are reports that they survive for longer than *E. coli* in sea and freshwater environments (Huss, 1994; Sugumar & Mariappan, 2003; Marriot & Gravani, 2006). *Salmonella* have been also reported to be able to grow within the temperature range of 2-54°C, although growth below 7°C has largely been observed only in microbiological culture media and growth above 48°C is confined to mutants or tempered strains (Bremer et al. 2003). A few *Salmonella* serotypes can grow over a pH range of 3.6–9.6, which is mildly basic to strongly acidic. Optimum growth occurs at a pH of 6.5–7.5, which is close to neutral. Other factors such as temperature, the type of acid present and the presence of antimicrobials can effect the minimum pH for growth (Brands, 2006; Marriot & Gravani, 2006; Lawley et al., 2008). It requires a minimum Aw of 0.94 (and possibly 0.93) with a maximum salt content of 4.0% to 5.0% (Huss, 1994; Lawley et al., 2008). A study by Basti et al., (2006), for example, showed complete elimination of *Salmonella* on heavy salted fish and heavy salted cold smoked fish due to the high concentration levels of NaCl (>7%). Limiting conditions were summarized for *Salmonella* in Table 3.


Table 3. Limiting Conditions for *Salmonella* Growth
