title: Isolation and characterisation of a novel Podoviridae-phage infecting Weissella cibaria N 22 from Nham, a Thai fermented pork sausage.
abstract: A novel Podoviridae lactic acid bacteria (LAB) phage from Nham, a Thai fermented pork sausage, is reported. From a total of 36 samples, 41 isolates of LAB were obtained and employed as hosts for the isolation of phages. From these LAB, only one phage, designated Φ 22, was isolated. The lactic acid bacterial isolate named N 22, sensitive to phage Φ 22 infection was identified by an API 50 CHL kit and N 22's complete sequence of the 16S rDNA sequence. BLASTN analysis of the 16S rDNA sequence revealed a 99% similarity to the 16S rDNA sequence of Weissella cibaria in the GenBank database. Electron micrographs indicated that the phage head was icosahedral with head size and tail length of 92 × 50 nm and 27 nm, respectively. On the basis of the morphology, this phage belongs to the family Podoviridae. Host-range determination revealed that the phage Φ 22 was not capable of infecting the other 40 isolates of LAB and referenced Weissella strains used. A one-step growth experiment showed that the latent period and burst size were estimated at 110 min and 55 phage particles/infected cell, respectively. Furthermore, the phage was infective over a wide range of pH (pH 5.0-8.0) and the D time of Φ 22 was calculated as 88 s at 70 °C and 15s at 80 °C. Phage titers decreased below the detection limit (20 PFU/ml) after heating for more than 60s at 80 °C, or 20s at 90 °C or less than 10s at 100 °C. The results from the study of Nham revealed that Φ 22 was active against the potential starter culture (W. cibaria N 22) for Nham fermentation. Phage infection could adversely affect the fermentation process of Nham by delaying acidification when using W. cibaria N 22 as a starter. However, the results from a sensory test revealed that the panelists did not detect any defects in the final products. This is the first report on the isolation of W. cibaria phage.
authors.affiliation: Department of Biology, Faculty of Science, Srinakharinwirot University, Wattana, Bangkok 10110, Thailand. onanong@swu.ac.th
authors.forename: Onanong
authors.initials: O
authors.lastname: Pringsulaka
authors.forename: Nuttaporn
authors.initials: N
authors.lastname: Patarasinpaiboon
authors.forename: Nuttika
authors.initials: N
authors.lastname: Suwannasai
authors.forename: Wisrutta
authors.initials: W
authors.lastname: Atthakor
authors.forename: Achariya
authors.initials: A
authors.lastname: Rangsiruji
mesh_terms: D000818:Animals; D003257:Consumer Product Safety; D005285:Fermentation; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006801:Humans; D008461:Meat Products / Q000382:microbiology* / Q000821:virology; D017902:Podoviridae / Q000302:isolation & purification*; D013552:Swine; D013785:Thailand; D058836:Weissella / Q000821:virology*