Journal of Animal Research: v.5 n.1, p. 85-93. April. 2015

DOI Number: 10.5958/2277-940X.2015.00014.5

Growth Dynamics of Salmonella, Isolated from Different Sources,

at different Temperature and pH

M.A. Malik 1 , S.K. Kotwal 1 , M. Rashid 1 , H.K. Sharma 1 , M. Singh 1 and Neelesh Sharma 2*

1 Division of Veterinary Public Health & Epidemiology, F.V.Sc. & A.H., SKUAST-J, R.S. Pura, Jammu, INDIA

2 Division of Veterinary Medicine, F.V.Sc. & A.H., SKUAST-J, R.S. Pura, Jammu, INDIA

*Corresponding author: N. Sharma; Email: drneelesh_sharma@yahoo.co.in

Received: 02 March, 2015

Accepted: 02 April, 2015

ABSTRACT

A total of 350 samples 50 each from raw poultry meat, poultry cloacal swabs and human diarrheic cases, besides 200 eggs were

processed for the isolation of Salmonella. Effect of varying temperature and pH on growth of Salmonella isolates was evaluated

by growing the organism in Brain Heart Infusion Broth at 4, 10, and 30 ° C with pH values of 4.5, 5.5 and 6.5. At 10°C, the mean

generation time of the isolates at pH values of 4.5, 5.5 and 6.5 was 44.23 ± 0.44, 15.51 ± 0.08 and 10.23 ± 0.10 hrs, respectively,

while at 30°C, the generation time of the isolates at pH values of 4.5, 5.5 and 6.5 was 126.10 ± 0.68, 59.96 ± 0.14 and 36.22 ±

0.07 min, respectively. No growth observed at 4 ° C, at any given pH value. As the temperature and pH were lowered, significant

increase in generation time of the organism was observed.

Keywords : Salmonella , growth, temperature, pH.

The genus Salmonella is a typical member of the family

are contaminated poultry, pork, beef, eggs and milk (Acha

Enterobacteriaceae and consists of Gram -ve, oxidase -ve,

and Szyfres, 2003).

straight sided rod shaped bacteria which are castalase +ve,

Salmonellae can grow over a wide range of temperature,

and have both a respiratory and a fermentative metabolism

pH, and a in good culture medium rather in a poor one.

of carbohydrates. Most Salmonellae are motile by

w

For example, minimal temperatures for growth in food

peritrichous flagella. More than 2,500 Salmonella serovars

range from 6.7 to 7.8°C in chicken to over 10°C in custard

have been identified, most belonging to the species

and ham salad. They grow well at room temperature, but

Salmonella bongori and Salmonella enterica . Based on

optimum temperature for their growth is about 37°C and

pathogenesis, S. enterica can be divided into two broad

maximal temperature at which they can grow is about

groups, Group 1 consists of a large number of serovars,

45.6°C. The pH range for their growth is 4.1 to 9.0,

including Salmonella enterica serovars Typhimurium

growing in low-acid foods, however, salad at pH 5.5 to

and Enteritidis, which can cause paratyphoid in infected

5.7 has been found unfavourable for growth. The lowest

animals. This group colonizes the alimentary tract of food

a for growth varies with the food but is about 0.93 to

animals, and leads to gastrointestinal disease in a broad

w

0.95. The species and strains of Salmonella differ too,

range of hosts, including humans. Group 2 comprises a

in heat resistance and effect of environmental factors on

small number of serovars that cause systemic typhoid-like

growth (Frazier and Westhoff, 2003) . Several years ago,

disease in a restricted range of host species. A wide variety

hurdle technology was developed as a new concept for the

of domestic and wild animals viz. cattle, swine, sheep,

realization of safe, stable, nutritious, tasty, and economical

goat, horses, and fowl could be the reservoirs of zoonotic

foods (McMeekin et al ., 2000). Several environmental

Salmonellae. Practically, any food of animal origin can be

factors such as temperature, pH, water activity (aw),

a source of infection for man. The most common vehicles

atmosphere, and presence or absence of preservatives