Prevalence of coliphages in local foods

Nur Baizura Sa;dom, . and Asiah Abu Samah, . and Mohd Effendi Mohamed Noor, . and Nur Ilida Mohamad, . and Tan Geok Hun, . (2011) Prevalence of coliphages in local foods. [Proceedings Paper]

Bacteriophages are viruses that exclusively target and reproduce within bacteria. Bacteriophage that infected Escherichia coli is known as coliphage. The potential use of bacteriophages to control bacteria of importance to food quality and safety has been the subject of recent review. This study was conducted to evaluate the prevalence of coliphage in local foods for future use as biological control of E. coli in food industry. Two E. coli strains E. coli ATCC 25922 and E. coli UN were used in this study. A total number of 96 food samples were tested for this prevalence study. For each sample 10 g was homogenised with 90 ml Peptone water in a sterile stomacher bag. A 50 ml subsample of the suspension was mixed with 2 ml of log phase E. coli as host culture. This mixture was incubated in incubator shaker at 37C 100 rpm for 4 h. Then it was centrifuged at 10 000 rpm for 10 minutes. The supernatant was transferred to the new sterile conical flask and filtered to remove the unnecessary particles. The phage particles in the supernatant were precipitated by adding polyethylene glycol and natrium chloride. The suspension was kept at 4C for 1 hour and centrifuged at 15 000 rpm 4C for 2 hours. Finally phage pellet was resuspended in TBS. For phage titration a volume of 1 ml of phage and 1 ml of E. coli host culture were added to 3 ml of soft Luria Bertani agar. This mixture then poured onto Luria Bertani agar plate. The plates were allowed to cool and incubated overnight at 37C. Plaques formed were counted and the amount of phage was determined as plaque forming unit pfu. The results showed that a total of 20 isolates of coliphages were successfully isolated from the tested food samples. Out of the 20 isolates 18 were obtained from E. coli ATCC 25922 and two from E. coli UN. All isolates were obtained from raw chicken 60 raw meat 15 fresh milk 15 fresh coconut milk 5 and fresh ulam 5. Based on the morphology of the plaque the plaque diameters were ranging from 2.0 to 6.0 mm. Most of these phages formed a clear zone 18 isolates while the other two isolates formed turbid area with one small halo zone in the middle. The appearance of two of the isolates under transmission electron microscopy suggested that both isolates were belonged to the family Myoviridae. However more precise studies using TEM and DNA analyses need to be carried out on all isolates for further characterisation and identification of the all isolated phages.

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Abstract

Bacteriophages are viruses that exclusively target and reproduce within bacteria. Bacteriophage that infected Escherichia coli is known as coliphage. The potential use of bacteriophages to control bacteria of importance to food quality and safety has been the subject of recent review. This study was conducted to evaluate the prevalence of coliphage in local foods for future use as biological control of E. coli in food industry. Two E. coli strains E. coli ATCC 25922 and E. coli UN were used in this study. A total number of 96 food samples were tested for this prevalence study. For each sample 10 g was homogenised with 90 ml Peptone water in a sterile stomacher bag. A 50 ml subsample of the suspension was mixed with 2 ml of log phase E. coli as host culture. This mixture was incubated in incubator shaker at 37C 100 rpm for 4 h. Then it was centrifuged at 10 000 rpm for 10 minutes. The supernatant was transferred to the new sterile conical flask and filtered to remove the unnecessary particles. The phage particles in the supernatant were precipitated by adding polyethylene glycol and natrium chloride. The suspension was kept at 4C for 1 hour and centrifuged at 15 000 rpm 4C for 2 hours. Finally phage pellet was resuspended in TBS. For phage titration a volume of 1 ml of phage and 1 ml of E. coli host culture were added to 3 ml of soft Luria Bertani agar. This mixture then poured onto Luria Bertani agar plate. The plates were allowed to cool and incubated overnight at 37C. Plaques formed were counted and the amount of phage was determined as plaque forming unit pfu. The results showed that a total of 20 isolates of coliphages were successfully isolated from the tested food samples. Out of the 20 isolates 18 were obtained from E. coli ATCC 25922 and two from E. coli UN. All isolates were obtained from raw chicken 60 raw meat 15 fresh milk 15 fresh coconut milk 5 and fresh ulam 5. Based on the morphology of the plaque the plaque diameters were ranging from 2.0 to 6.0 mm. Most of these phages formed a clear zone 18 isolates while the other two isolates formed turbid area with one small halo zone in the middle. The appearance of two of the isolates under transmission electron microscopy suggested that both isolates were belonged to the family Myoviridae. However more precise studies using TEM and DNA analyses need to be carried out on all isolates for further characterisation and identification of the all isolated phages.

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Item Type:	Proceedings Paper
Additional Information:	Available at Perpustakaan Sultan Abdul Samad Universiti Putra Malaysia 43400 UPM Serdang Selangor Malaysia. QR22 M3I61 2011 vol. 1 Call Number.
AGROVOC Term:	Bacteriophages
AGROVOC Term:	Bacteria
AGROVOC Term:	Escherichia
AGROVOC Term:	Escherichia coli
AGROVOC Term:	Phages
AGROVOC Term:	Viruses
AGROVOC Term:	Isolation
AGROVOC Term:	Centrifuging
AGROVOC Term:	Chicken meat
AGROVOC Term:	Coconut milk
Geographical Term:	MALAYSIA
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 05:15
URI:	http://webagris.upm.edu.my/id/eprint/13034

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