Bacteriophage in the Dairy Industry

Heap, H. A.; Harnett, James

doi:10.1016/b0-12-227235-8/00042-0

Cited by 6 publications

(4 citation statements)

References 2 publications

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“…Thus, the strain rotation practice in dairy fermentation is very likely a factor that stimulates LAB phage evolution by horizontal gene transfer, plausibly contributing to the observed genetic mosaicism (2,6,10,11,33,37). With respect to managing the risks of phage-mediated fermentation failure in dairy industry, our work suggests that an undesirable long-term outcome of the strain rotation practice may actually be the appearance of highly promiscuous hybrid "super-phages" with an expanded host range, a phenomenon encountered in the industry (20,29,43 …”

Section: Discussionmentioning

confidence: 99%

Isolation of Lactococcal Prolate Phage-Phage Recombinants by an Enrichment Strategy Reveals Two Novel Host Range Determinants

2005

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Virulent lactococcal prolate (or c2-like) phages are the second most common phage group that causes fermentation failure in the dairy industry. We have mapped two host range determinants in two lactococcal prolate phages, c2 and 923, for the host strains MG1363 and 112. Each phage replicates on only one of the two host strains: c2 on MG1363 and 923 on 112. Phage-phage recombinants that replicated on both strains were isolated by a new method that does not require direct selection but rather employs an enrichment protocol. After initial mixed infection of strain 112, two rotations, the first of which was carried out on strain MG1363 and the second on 112, permitted continuous amplification of double-plating recombinants while rendering one of the parent phages unamplified in each of the two rotations. Mapping of the recombination endpoints showed that the presence of the N-terminal two-thirds of the tail protein L10 of phage c2 and a 1,562-bp cosR-terminal fragment of phage 923 genome overcame blocks of infection in strains MG1363 and 112, respectively. Both infection inhibition mechanisms act at the stage of DNA entry; in strain MG1363, the infection block acts early, before phage DNA enters the cytoplasm, and in strain 112, it acts late, after most of the DNA has entered the cell but before it undergoes cos-end ligation. These are the first reported host range determinants in bacteriophage of lactic acid bacteria required for overcoming inhibition of infection at the stage of DNA entry and cos-end ligation.Acquisition and exchange of functional modules by recombination has been proposed as the major mechanism of viral evolution, based on analyses of arrangements of conserved and nonconserved segments along the genomes of lambdoid phage and functional analysis of the recombinants (hybrids) between distant members of the family comprising phage P22 of Salmonella enterica serovar Typhimurium and phage of Escherichia coli K12 (3, 5, 22, 23, 55). The selective pressure for generating phage-phage recombinants in nature is most likely the ability to replicate on an increased number of hosts.Bacteriophages of Lactococcus lactis, a lactic acid bacterium (LAB) used in dairy fermentation, are numerous and diverse. The most frequently encountered are two groups of small isometric-headed phages named 936 and P335 and one group with prolate-headed phage named c2 (28, 38). Recent largescale sequence analyses of bacteriophages of LAB indicate that exchange of functional modules by recombination is widespread among these phages (2, 6, 10, 11, 33, 37).Prolate-headed (or prolate) phages are the secondmost common group isolated after fermentation failure in New Zealand dairy plants. This is a relatively conserved group with an exclusively lytic life style. The two prolate phages (c2 and bIL67) whose genome sequences have been determined to date have an overall identity of 80% (36,54). Both 20-to 22-kbp double-stranded DNA (dsDNA) genomes code for two blocks of divergently oriented open reading frames (ORFs), transcribed early and ...

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Section: Discussionmentioning

confidence: 99%

Isolation of Lactococcal Prolate Phage-Phage Recombinants by an Enrichment Strategy Reveals Two Novel Host Range Determinants

2005

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“…HPH of milk is helpful for bacteriophage [7], [18] and microbial inactivation [5], [19]. Bacteriophages are one of the main agents of failed fermentations in dairy industry [20] and raw milk is the most important source of phages [21]. HPH (>100 MPa) seems to be a useful technological alternatives to pasteurization, which is promising for dairy phages inactivation [5], [22].…”

Section: A Effect On Microorganismsmentioning

confidence: 99%

Effect of High Pressure Homogenization on Improving the Quality of Milk and Sensory Properties of Yogurt: A Review

Massoud¹,

Belgheisi²,

Massoud³

2016

IJCEA

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Abstract-High pressure processing is one of the advanced technologies to produce safe food, with better quality properties. In recent years, high pressure homogenization is a useful way which has attracted attention to improve the quality, increase shelf life, and maintain nutritional and sensory properties of milk and dairy products. Homogenization is considered a suitable alternative to thermal processes due to the lack of thermal damage. It is also one of the innovative technologies with a positive change in milk particles which leads to enhance the quality, shelf life and popularity of product. In this article, in addition to evaluation of the effect of homogenization on the fat particles, inactivating harmful bacteriophages and spoilage microorganisms, sensory and appearance properties of dairy products, the influence of high pressure homogenization on proteins and the viability of probiotic bacteria in dairy products especially yogurt will be reviewed. These changes result in the development of quality in dairy products and higher consumer's acceptance. IndexTerms-High pressure homogenization, microorganism, milk, yogurt, proteins.

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“…), during refrigerated storage of yoghurt. Bacteriophages are one of the principal causes of failed fermentations on dairy processes (Heap and Harnett ) and raw milk is one of the major sources of phages in dairy products (Neve ). At 100 MPa, probiotic bacteriophages were completely inactivated that improved the amount of probiotic bacteria (Suárez and Reinheimer ; Capra et al .…”

Section: Resultsmentioning

confidence: 99%

Improving the Viability of Probiotic Bacteria in Yoghurt by Homogenization

Massoud

Fadaei

Nikbakht

2015

Journal of Food Processing and Preservation

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In this study, the effect of homogenization pressures (100, 150 and 200 bar) at 50, 60 and 70C and stages (1 and 2) on viability of probiotic bacteria was investigated. The milk used for producing yoghurt samples was homogenized at 100, 150 and 200 bar at 50, 60 and 70C, then heated at 85C for 30 min. After cooling milk to fermentation temperature (42C), it was inoculated with mixture starter culture ABY-1 and incubated. During fermentation, pH dropped until it reached 4.5. After fermentation, yoghurt samples were held in refrigerator. Viability of Lactobacillus acidophilus and Bifidobacterium lactis was determined during a 21-day cold storage (4C). The results of this study showed that with increasing pressure, temperature and stages of homogenization, viability of probiotic bacteria increased during storage (P < 0.05). PRACTICAL APPLICATIONSThe viability of probiotic bacteria in probiotic products is so important; and nowadays, it is also considered by consumers. Probiotic yoghurt is one of the most widely used probiotic dairy products around the world, and therefore finding an efficient and practical way to produce it with the highest viability of the probiotic bacteria seems necessary. Homogenization is one of the most important steps in yoghurt production, and temperature, time and stages of homogenization are three main factors in this unit operation. In this study, by changing the homogenization conditions, positive results were found to produce yoghurt with the desirable viability of probiotic bacteria, so that by simultaneously increasing the homogenization temperature, time and stages, the probiotic viability improved during fridge storage.

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Bacteriophage in the Dairy Industry

Cited by 6 publications

References 2 publications

Isolation of Lactococcal Prolate Phage-Phage Recombinants by an Enrichment Strategy Reveals Two Novel Host Range Determinants

Isolation of Lactococcal Prolate Phage-Phage Recombinants by an Enrichment Strategy Reveals Two Novel Host Range Determinants

Effect of High Pressure Homogenization on Improving the Quality of Milk and Sensory Properties of Yogurt: A Review

Improving the Viability of Probiotic Bacteria in Yoghurt by Homogenization

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