Characterization of a lytic bacteriophage for controlling Pseudomonas lactis in raw cow's milk
2018
The control of bacterial growth during milk processing is crucial for the quality maintenance of commercial milk and milk products. During a period of cold storage prior to heat treatments, some psychrotrophic bacteria grow and produce extracellular heat resistant lipases and proteases that cause product defects. The use of lytic bacteriophages (phage) that infect and kill bacteria could be a useful tool for suppressing bacterial growth during this cold storage phase. In this study, we isolated a Pseudomonas lactis and a phage from raw cow9s milk. Quantitative characterization of the phage was used to elucidate whether this phage was activity under low temperatures and neutral pHs, and whether it was inactivated during pasteurization. Phage titer determination was possible ranging from pHs 4 to 9, and from 3°C to 25°C; the phage was inactivated under pasteurization conditions, at 63°C for 30 min. Furthermore, we showed that this phage reduced viable bacterial cell counts in both skim and whole milk. The results of this study represent the potential uses of phages for controlling psychrotrophic bacterial growth in raw cow9s milk during cold storage. Importance Suppression of bacterial growth in raw milk under cold storage is crucial for the quality control of commercially supplied milk. The use of lytic phages as low-cost microbiocides is an attractive prospect. Due to strict host specificities, phages must be isolated from the raw milk where the host bacteria are growing. We first isolated the P. lactis bacterial strain, and then the phage infecting that strain. Partial phage genomic analysis showed that this is a newly isolated phage, different from any previously reported. This study reports a lytic phage for P. lactis , and we have presented evidence here that this phage reduced viable bacterial cell counts, not only in rich medium, but also in skim and whole milk. As a result, we have concluded that the phage reported in this study would be useful in milk processing.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
29
References
3
Citations
NaN
KQI