FAQ related to bacteriophages

This page provides information about the handling of phages.
For questions related to the ordering of microorganisms please see our FAQ here or download our short guideline on how to order from the DSMZ.

Please select the topic of interest:

  • What is the quality of the phages provided by the DSMZ?

    Phage suspensions provided by the DSMZ are bacteria-free lysates of the phage host culture and have been centrifuged and filtrated through 0.2 µm pore size filter after lysis, they are not further purified. We do not exclude the presence of temperate phages in the suspensions. Our phage production hosts may contain prophages.

  • Are phages of the DSMZ open collection natural phages or (genetically) manipulated?

    The phages offered by the DSMZ collection are natural phages, they are not genetically or otherwise manipulated.

  • Are all phages of the open DSMZ collection fully characterised?

    The level of characterisation of the phages of the DSMZ collection is varying by means of genome sequencing, ultrastructural description or estimation of efficiency and other parameters. 

  • What is the difference between dried bacterial strains and filter-dried phages?

    Bacterial cell suspensions are dried together with a protectant and a pellet that can be rehydrated for initial revitalization. Phages are dried as suspensions on filter paper strips and require their host strain for initial propagation.

  • Are phages allocated to risk groups?

    Phages are viruses that infect bacteria only, they do not infect humans, animals or plants and are for technical and administrational reasons officially allocated to the risk group 1.

  • Does the DSMZ provide genome sequence data of phages?

    No, the DSMZ recommends to check our PhageDive database or to search at NCBI or PHANTOME (PHage ANnotation TOols and MEthods).

  • Does the DSMZ offer a phage identification service?

    No, this service is not offered.

  • Does the DSMZ provide isolated phage DNA?

    No, currently the DSMZ exclusively offers phages in their complete natural form.

  • Why is there a general price for all phages, independent of the form of delivery?

    Propagation and preservation procedures for phages are different compared to bacteria. If a phage is available in both delivery forms, the DSMZ leaves it to the customer to choose between two delivery forms: phages in liquid or dried in ampoules. Please note the different handling of both upon receipt.

  • Does an order on a phage include its host strain, i.e. are phage and host delivered together?

    No, phage and host have to be mentioned separately on the order, they are different order positions. Please use only the host strain recommended by the DSMZ.

  • In what form will the phage be delivered, dried or liquid?

    The form of delivery is the customer´s choice: phages are available as suspensions delivered at ambient temperature (1 mL) or as vacuum-dried samples on filter paper in glass ampoules. The form of delivery is independent of the destination. Some phages are available in one form only. Please check the entry in our online catalogue for available delivery forms.

  • Does the DSMZ offer phages for therapy purposes in human or veterinary medicine?

    The DSMZ does not provide phages for any direct application in humans or animals and does not hold a special therapy phage bank.
    Phages of the DSMZ are filtrated bacteria-free lysates which are not further purified and only available for laboratory purposes, see our Terms & Conditions.

  • Does the DSMZ provide data or predictions with respect to application suitability of a phage?

    No, any such evaluations or assessments are not given by DSMZ. 

  • Does the DSMZ “Opening of Ampoules and Rehydration of Dried Cultures” scheme apply to the revitalisation of dried phages supplied in glass ampoules?

    The outer vial of the double-vial glass ampoule can be opened in the same way. In case of phages, the filter paper strip or the filter discs are removed from the inner vial under sterile conditions and used as described according to here.

  • Can phage suspensions be stored in the refrigerator?

    Most phages store well in the refrigerator unfrozen for some weeks or longer but DSMZ generally recommends immediate use, see Terms & Conditions. Do not freeze phages without adding a cryoprotectant, e. g. 10% glycerol.

  • What do phages always need for adsorption to the host bacterium?

    Addition of 1-5 mM MgSO4 and/or CaCl2 is maybe recommended for some phages. Avoid fast shaking or strong agitation of phages in liquids. Leaving phage and host for 5-10 minutes after infection without any agitation enhances adsorption.

  • How do I work with phages received from the DSMZ?

    Phage methods can be found here.

    We recommend only one particular strain as the host for each of our phages. Please use only this strain as mentioned in the phage entry and use the growth conditions that we recommend for this strain in the strain entry. Please visit our phage online information and methodology. Host culture and agar plates must always be fresh for working with a phage. Each phage suspension batch is routinely titer-controlled and each vacuum-drying production batch is viability-controlled.

    Complaints relating to viability of our phages in principle are not justified. A leaking receptacle containing a phage suspension or a broken glass ampoule is a justified reason for a complaint or if an ampoule does not contain filter discs. If a phage is not lysing at all in the recipient’s laboratory, it can be streaked like a microorganism with an inoculation loop on the top agar containing its host strain to get single phage plaques for further propagation.

  • How do I know the titre of a phage suspension supplied by DSMZ?

    Phage suspensions supplied by DSMZ have checked and documented sufficient phage activity to be used for further propagation. A certain titre calculation cannot be guaranteed in each case of a phage despatch as titres might drop over time or during transport.
    Comparable to our recommendations for revitalisation of bacterial cultures upon receipt, recipients should propagate phages and store aliquots prior to intended use in their laboratory.  

  • Does a phage lyse only the host strain recommended by DSMZ?

    Host spectra of phages are not routinely tested by DSMZ so that successful lysis is only guaranteed for the phage/host system as used and approved by DSMZ.

  • Does deposit of a phage in the DSMZ public collection cost anything?

    Deposit of biological material in the public collection of the DSMZ is free of charge.
    Charges for the deposit of strains for patent purposes or as a safe deposit are provided in our price list. Information about the different types of deposit can be found here.

    Please note that it is required that the depositor commits to the DSMZ e.g. data on the country of origin where a phage was sampled, on the date of sampling and on the habitat/source of isolation in order to fulfill the requirements of the Nagoya Protocol.

  • Is it necessary to deposit the phage host strain together with a phage?

    Yes, a suitable host strain is required together with a phage deposit.

  • What is the initial step before depositing a phage to the open DSMZ collection?

    Depositors are kindly asked to get in contact with the curators of the phage working group.