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Bajerski F, Nagel M, Overmann J. Microbial occurrence in liquid nitrogen storage tanks: a challenge for cryobanking? Appl Microbiol Biotechnol 2021; 105:7635-7650. [PMID: 34559283 PMCID: PMC8460408 DOI: 10.1007/s00253-021-11531-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 08/13/2021] [Accepted: 08/18/2021] [Indexed: 11/30/2022]
Abstract
Abstract Modern biobanks maintain valuable living materials for medical diagnostics, reproduction medicine, and conservation purposes. To guarantee high quality during long-term storage and to avoid metabolic activities, cryostorage is often conducted in the N2 vapour phase or in liquid nitrogen (LN) at temperatures below − 150 °C. One potential risk of cryostorage is microbial cross contamination in the LN storage tanks. The current review summarises data on the occurrence of microorganisms that may compromise the safety and quality of biological materials during long-term storage. We assess the potential for the microbial contamination of LN in storage tanks holding different biological materials based on the detection by culture-based and molecular approaches. The samples themselves, the LN, the human microbiome, and the surrounding environment are possible routes of contamination and can cause cross contaminations via the LN phase. In general, the results showed that LN is typically not the source of major contaminations and only a few studies provided evidence for a risk of microbial cross contamination. So far, culture-based and culture-independent techniques detected only low amounts of microbial cells, indicating that cross contamination may occur at a very low frequency. To further minimise the potential risk of microbial cross contaminations, we recommend reducing the formation of ice crystals in cryotanks that can entrap environmental microorganisms and using sealed or second sample packing. A short survey demonstrated the awareness for microbial contaminations of storage containers among different culture collections. Although most participants consider the risk of cross contaminations in LN storage tanks as low, they prevent potential contaminations by using sealed devices and − 150 °C freezers. It is concluded that the overall risk for cross contaminations in biobanks is relatively low when following standard operating procedures (SOPs). We evaluated the potential sources in detail and summarised our results in a risk assessment spreadsheet which can be used for the quality management of biobanks. Key points • Identification of potential contaminants and their sources in LN storage tanks. • Recommendations to reduce this risk of LN storage tank contamination. • Development of a risk assessment spreadsheet to support quality management. Supplementary Information The online version contains supplementary material available at 10.1007/s00253-021-11531-4.
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Affiliation(s)
- Felizitas Bajerski
- Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Inhoffenstraße 7B, 38124, Brunswick, Germany.
| | - Manuela Nagel
- Genebank Department, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466, Seeland OT Gatersleben, Germany
| | - Joerg Overmann
- Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Inhoffenstraße 7B, 38124, Brunswick, Germany.,Institute of Microbiology, Braunschweig University of Technology, 38106, Brunswick, Germany
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Voggenreiter T, Laport E, Kahn-Schapowal B, Lang J, Schenkel J. Simulation of Air Travel-Related Irradiation Exposure of Cryopreserved Mouse Germplasm Samples. Biopreserv Biobank 2021; 19:280-286. [PMID: 33646019 DOI: 10.1089/bio.2020.0046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cryopreservation of genetically modified mouse lines prevents the loss of specific mutants that are of enormous scientific value for both basic and applied research. Cryopreservation of spermatozoa or preimplantation embryos enables discontinuation of breeding as well as archiving of specific lines for future studies. Regarding active inter-laboratory exchange of mutants, cryopreserved material is more advantageous to transport than live animals. However, transportation stress should not be trivialized. Security scanning of transport boxes at airports and customs, in particular, as well as additional cosmic radiation, pose a threat to undefined dosages of irradiation exposure. To simulate this, cryopreserved samples of mouse spermatozoa and preimplantation embryos were exposed to an X-ray dosage of 1 mGy in an X-ray machine. For subsequent investigation of the cell integrity of irradiated spermatozoa and embryos, spermatozoa forward motility as well as embryo developmental capacity and apoptosis values were examined and compared with nonirradiated control samples. The percentage of forward-moving spermatozoa per sample appears to be significantly reduced after irradiation exposure. The in vitro developmental capacity of preimplantation embryos as well as their relative share of apoptotic cells do not seem to be influenced by irradiation exposure. This leads to the assumption that, at least in preimplantation embryos, X-ray dosages of 1 mGy do not induce sudden severe cellular harm. Nevertheless, stochastic effects of ionizing irradiation, such as mutations, do not have a dosage threshold and always represent the potential danger of alterations to cells and cellular components, especially the DNA. This could lead to undefined mutations inducing genetic drift, in the worst case to the loss of a mutant line. We therefore strongly recommend minimizing "transportation stress," in particular by irradiation exposure, to keep its potential consequences in mind, and to standardize shipping procedures.
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Affiliation(s)
| | - Elke Laport
- German Cancer Research Center (DKFZ), Cryopreservation, Heidelberg, Germany
| | - Barbara Kahn-Schapowal
- German Cancer Research Center (DKFZ), Radiation Protection and Dosimetry, Heidelberg, Germany
| | - Jens Lang
- German Cancer Research Center (DKFZ), Radiation Protection and Dosimetry, Heidelberg, Germany
| | - Johannes Schenkel
- German Cancer Research Center (DKFZ), Cryopreservation, Heidelberg, Germany.,Department of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
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Bajerski F, Bürger A, Glasmacher B, Keller ERJ, Müller K, Mühldorfer K, Nagel M, Rüdel H, Müller T, Schenkel J, Overmann J. Factors determining microbial colonization of liquid nitrogen storage tanks used for archiving biological samples. Appl Microbiol Biotechnol 2019; 104:131-144. [PMID: 31781817 PMCID: PMC6942587 DOI: 10.1007/s00253-019-10242-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 10/25/2019] [Accepted: 11/04/2019] [Indexed: 01/19/2023]
Abstract
The availability of bioresources is a precondition for life science research, medical applications, and diagnostics, but requires a dedicated quality management to guarantee reliable and safe storage. Anecdotal reports of bacterial isolates and sample contamination indicate that organisms may persist in liquid nitrogen (LN) storage tanks. To evaluate the safety status of cryocollections, we systematically screened organisms in the LN phase and in ice layers covering inner surfaces of storage tanks maintained in different biobanking facilities. We applied a culture-independent approach combining cell detection by epifluorescence microscopy with the amplification of group-specific marker genes and high-throughput sequencing of bacterial ribosomal genes. In the LN phase, neither cells nor bacterial 16S rRNA gene copy numbers were detectable (detection limit, 102 cells per ml, 103 gene copies per ml). In several cases, small numbers of bacteria of up to 104 cells per ml and up to 106 gene copies per ml, as well as Mycoplasma, or fungi were detected in the ice phase formed underneath the lids or accumulated at the bottom. The bacteria most likely originated from the stored materials themselves (Elizabethingia, Janthibacterium), the technical environment (Pseudomonas, Acinetobacter, Methylobacterium), or the human microbiome (Bacteroides, Streptococcus, Staphylococcus). In single cases, bacteria, Mycoplasma, fungi, and human cells were detected in the debris at the bottom of the storage tanks. In conclusion, the limited microbial load of the ice phase and in the debris of storage tanks can be effectively avoided by minimizing ice formation and by employing hermetically sealed sample containers.
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Affiliation(s)
- F Bajerski
- Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Inhoffenstraße 7B, Braunschweig, Germany.
| | - A Bürger
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Developmental Genetics, München, Germany
| | - B Glasmacher
- Institute for Multiphase Processes, Leibniz University Hannover, Hannover, Germany
| | - E R J Keller
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Seeland, OT Gatersleben, Germany
| | - K Müller
- Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), Berlin, Germany
| | - K Mühldorfer
- Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW), Berlin, Germany
| | - M Nagel
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Seeland, OT Gatersleben, Germany
| | - H Rüdel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Schmallenberg, Germany
| | | | - J Schenkel
- German Cancer Research Centre, Heidelberg, Germany
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - J Overmann
- Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Inhoffenstraße 7B, Braunschweig, Germany
- Microbiology, Braunschweig University of Technology, Braunschweig, Germany
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Zhou G, Zeng Y, Guo J, Meng Q, Meng Q, Jia G, Cheng K, Zeng C, Zhang M, Liu G, Zhu S. Vitrification transiently alters Oct-4, Bcl2 and P53 expression in mouse morulae but does not affect embryo development in vitro. Cryobiology 2016; 73:120-5. [PMID: 27590081 DOI: 10.1016/j.cryobiol.2016.08.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 08/26/2016] [Accepted: 08/28/2016] [Indexed: 01/08/2023]
Abstract
This study was conducted to determine the impact of vitrification on the expression of genes regulating pluripotency and apoptosis in mouse morulae. The morulae were randomly allocated into three groups: (1) untreated (control), (2) exposed to vitrification solution without freezing (toxicity), or (3) vitrified by open-pulled straw method (vitrification). In vitro development was evaluated by morphology and assessed by the blastocyst rate and the blastocyst total cell number. Gene expression in morulae and blastocysts was assessed by quantitative Real Time-PCR (qRT-PCR) and western blot. The results showed that at morulae stage, the POU class 5 homeobox1 (Oct-4) and B-cell lymphoma2 (Bcl2) mRNA levels of vitrification group were significantly lower (P < 0.05) than those of control. Strikingly, the p53 mRNA level was significantly higher in vitrification group. However, the Oct-4, Bcl2 and p53 mRNA levels in mouse blastocysts were not statistically different. Furthermore, western blot results showed that there was no significant difference in Oct-4, Bcl2 and p53 expression at protein level in mouse morulae among three groups. Additionally, the blastocyst rate (96.67%-100.00%) and the average cell number of blastocysts (89.67-92.33) were similar between all groups. The data demonstrate that vitrification transiently changes the mRNA expression of several key genes in mouse morulae regulating early embryo development but does not affect embryo developmental potential in vitro.
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Affiliation(s)
- Guangbin Zhou
- Institute of Animal Genetics and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, PR China.
| | - Yan Zeng
- College of Animal Science and Technology, China Agricultural University, Beijing 100193, PR China; College of Animal Science and Technology, Southwest University, Chongqing 400715, PR China
| | - Jiang Guo
- Institute of Animal Genetics and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, PR China
| | - Qinggang Meng
- Department of Animal, Dairy and Veterinary Sciences, Utah State University, Logan, UT, USA
| | - Qingyong Meng
- State Key Laboratory of AgroBiotechnology, China Agricultural University, Beijing 100193, PR China
| | - Gongxue Jia
- Key Laboratory of Adaption and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, PR China
| | - Keren Cheng
- College of Animal Science and Technology, China Agricultural University, Beijing 100193, PR China
| | - Changjun Zeng
- Institute of Animal Genetics and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, PR China
| | - Ming Zhang
- Institute of Animal Genetics and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, PR China
| | - Guoshi Liu
- College of Animal Science and Technology, China Agricultural University, Beijing 100193, PR China
| | - Shi'en Zhu
- College of Animal Science and Technology, China Agricultural University, Beijing 100193, PR China
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