Questions and answers (Phages)

  • How can I avoid failure when working with my phage and under what conditions is my complaint justified, when can I claim the viability of a phage?

    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.

  • 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 characterized?

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

  • 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 deposition of phages and/or their bacterial host strains cost a fee?

    Deposition of biological material with the DSMZ open collection is free. It is required that the depositor commits to the DSMZ 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, Dr. Christine Rohde or Dr. Johannes Wittmann.

  • 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, observe the different handling of both upon receipt.

  • How do I work with phages received from DSMZ, where can I find methods?

    Phage methods can be found under here.

  • 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.

  • Does an order on a phage include its host strain, 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.

  • 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.  

  • 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 and Conditions. Do not freeze phages without adding a cryoprotectant, e. g. 10% glycerol.

  • Does a phage plate only on 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.

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

    Bacterial cell suspensions are dried together with a protectant and a pellet forms that can be rehydrated for initial revitalisation, phages are dried as suspensions on filter paper strips and require their host strain for initial propagation, please see instructions given here.

  • 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.

  • 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 isolated phage DNA?

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

  • Does the DSMZ provide genome sequence data of phages?

    No, the DSMZ recommends 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.